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Sample records for cu fe mg

  1. Preparation of 24Mg-Fe-Cu Target

    Institute of Scientific and Technical Information of China (English)

    FAN; Qi-wen; DU; Ying-hui; ZHANG; Rong

    2012-01-01

    <正>The three-layer-sandwich targets of 24Mg-Fe-Cu needed to be prepared in the physics experiment. The middle layers are thin ferromagnetic Fe layers of about 3.2 mg/cm2. The recoil stopper layers are thick crystallized and defect-free Cu layers of about 15 mg/cm2. The thickness of the 24Mg target layers is about 300 μg/cm2, and the uniformity should be better than 90%.

  2. Structure and magnetic properties of Ni/Cu/Fe/MgO(001) films.

    Science.gov (United States)

    Lauhoff, G; Vaz, C A F; Bland, J A C

    2009-04-15

    The structural and magnetic properties of thin Ni films grown on Cu/Fe/MgO(001) and Cu/MgO(001) buffer layers are investigated and compared to those grown on Cu/Si(001). The use of an Fe seed layer a few monolayers thick leads to the epitaxial growth of high surface quality Cu(001) buffer layers on MgO(001), while Cu growth on the bare MgO(001) substrate results in polycrystalline films. Magneto-optic Kerr effect magnetometry shows that Ni films grown on Cu/Fe/MgO(001) exhibit dominant perpendicular magnetic anisotropy up to ∼90 Å, which is similar to that of Ni films grown on Cu/Si(001). The polycrystalline Ni films also exhibit perpendicular magnetic remanence, but with a dominant in-plane magnetization component.

  3. Structure and magnetic properties of Ni/Cu/Fe/MgO(001) films

    Energy Technology Data Exchange (ETDEWEB)

    Lauhoff, G; Vaz, C A F; Bland, J A C [Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE (United Kingdom)], E-mail: georglauhoff@georglauhoff.com, E-mail: carlos.vaz@cantab.net

    2009-04-15

    The structural and magnetic properties of thin Ni films grown on Cu/Fe/MgO(001) and Cu/MgO(001) buffer layers are investigated and compared to those grown on Cu/Si(001). The use of an Fe seed layer a few monolayers thick leads to the epitaxial growth of high surface quality Cu(001) buffer layers on MgO(001), while Cu growth on the bare MgO(001) substrate results in polycrystalline films. Magneto-optic Kerr effect magnetometry shows that Ni films grown on Cu/Fe/MgO(001) exhibit dominant perpendicular magnetic anisotropy up to {approx}90 A, which is similar to that of Ni films grown on Cu/Si(001). The polycrystalline Ni films also exhibit perpendicular magnetic remanence, but with a dominant in-plane magnetization component.

  4. Ca, Mg, Zn, Fe, Cu and Mn content of ass’s milk

    Directory of Open Access Journals (Sweden)

    Elisabetta Salimei

    2010-01-01

    Full Text Available The aim of this study was to determine Ca, Mg, Zn, Fe, Cu and Mn content of ass’s milk. Twenty four individual milk samples were collected from 4 lactating asses. During the experi- mental period milk samples were collected every 3 weeks interval, using a milking machine; asses were housed with the foals that were separated from the jennets 3 hours before milking. Milk was analysed for Ca, Mg, Zn, Fe, Cu and Mn content by atomic absorption spectrometry. The concentration mean (±SD of Ca Mg, Zn, Fe, and Cu were respectively 334.61±39.80, 58.46±8.43, 1.99±0.51, 1.15±0.52, 0.16±0.06 mg/kg. Mn was found only at trace level. Iron content of ass’s milk was the most variable ranging from 0.43 to 1.88 mg/kg. Correlation coefficients were positive and significant between Ca and Mg (r=0.63, Zn and Mg (r=0.45, Zn and Fe (r=0.49 and Zn and Cu (r=0.50. In this study, except for Fe, mean concentration of Ca, Mg, Zn, and Cu in ass’s milk was similar to those reported in literature for human milk.

  5. Mechanical alloying in Fe2O3-MO (M: Zn, Ni, Cu, Mg) systems

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Gerward, Leif; Mørup, Steen

    1999-01-01

    of MFe2O4 ferrites are critically discussed. No significant with respect to ferrite formation rates was observed in open and closed containers used here. In the Fe2O3/ZnO system, a single ferrite phase can be synthesized but in other systems no significant amounts of ferrites are formed by high......Mechanical alloying processes in four Fe2O3MO (M: Zn, Ni, Cu, Mg) systems by high-energy ball milling from simple oxide powder mixtures in both open and closed tungsten carbide containers have been investigated by x-ray powder diffraction and Mossbauer spectroscopy. Mechanisms for the formation......-energy ball milling under the conditions used here. The dominant alloying mechanism depends on the interdiffusion at relatively low temperatures. The experimental results may also be explained by the crystal structures of the reactants and the ferrites....

  6. The content of Ca, Cu, Fe, Mg and Mn and antioxidant activity of green coffee brews.

    Science.gov (United States)

    Stelmach, Ewelina; Pohl, Pawel; Szymczycha-Madeja, Anna

    2015-09-01

    A simple and fast method of the analysis of green coffee infusions was developed to measure total concentrations of Ca, Cu, Fe, Mg and Mn by high resolution-continuum source flame atomic absorption spectrometry. The precision of the method was within 1-8%, while the accuracy was within -1% to 2%. The method was used to the analysis of infusions of twelve green coffees of different geographical origin. It was found that Ca and Mg were leached the easiest, i.e., on average 75% and 70%, respectively. As compared to the mug coffee preparation, the rate of the extraction of elements was increased when infusions were prepared using dripper or Turkish coffee preparation methods. Additionally, it was established that the antioxidant activity of green coffee infusions prepared using the mug coffee preparation was high, 75% on average, and positively correlated with the total content of phenolic compounds and the concentration of Ca in the brew.

  7. Synthesis of mesoporous Cu/Mg/Fe layered double hydroxide and its adsorption performance for arsenate in aqueous solutions

    Institute of Scientific and Technical Information of China (English)

    Yanwei Guo; Zhiliang Zhu; Yanling Qiu; Jianfu Zhao

    2013-01-01

    The mesoporous Cu/Mg/Fe layered double hydroxide (Cu/Mg/Fe-LDH) with carbonate intercalation was synthesized and used for the removal of arsenate from aqueous solutions.The Cu/Mg/Fe-LDH was characterized by Fourier transform infrared spectrometry,X-ray diffraction crystallography,scanning electron microscopy,X-ray photoelectron spectroscopy and Brunauer-Emmett-Teller.Effects of various physico-chemical parameters such as pH,adsorbent dosage,contact time and initial arsenate concentration on the adsorption of arsenate onto Cu/Mg/Fe-LDH were investigated.Results showed that it was efficient for the removal of arsenate,and the removal efficiency of arsenate increased with the increment of the adsorbent dosage,while the arsenate adsorption capacity decreased with increase of initial pH from 3 to 11.The adsorption isotherms can be well described by the Langmuir model with R2 > 0.99.Its adsorption kinetics followed the pseudo second-order kinetic model.Coexisting ions such as HPO42-,CO32-,SO42-and NO3-could compete with arsenate for adsorption sites on the Cu/Mg/Fe-LDH.The adsorption of arsenate on the adsorbent can be mainly attributed to the ion exchange process.It was found that the synthesized Cu/Mg/Fe-LDH can reduce the arsenate concentration down to a final level of < 10 μg/L under the experimental conditions,and makes it a potential material for the decontamination of arsenate polluted water.

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

    Directory of Open Access Journals (Sweden)

    Guskos Niko

    2016-09-01

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

  9. Microstructure and mechanical properties of spray-deposited Al-Si-Fe-Cu-Mg alloy containing Mn

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Al-20Si-5Fe-3Cu-lMg alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the spray deposited hypereutectic Al-Si alloy were studied using optical microscopy, scanning electron microscopy, X-ray diffraction, TEM (Transmission Electron Microscope) and HREM (High-resolution Electron Microscope), DSC (Differential Scanning Calorimetry), microhardness measurement, and tensile tests. The effects of Mn on the microstructural evolution of the highsilicon aluminum alloy after extrusion and heat treatment have been examined. The results show that two kinds of phases, i.e. S (Al2CuMg) and σ(Al5Cu6Mg2), precipitated from matrix and improved the tensile strength of the alloy efficiently at both the ambient and elevated temperatures (300℃). The tensile test results indicate that the spray-deposited Al-20Si-SFe-3Cu-1Mg alloy has better strength than the powder metallurgy processed Al-20Si-3Cu-1Mg alloy at elevated temperature.

  10. Structure-dependent magnetoresistance and spin-transfer torque in antiferromagnetic Fe |MgO |FeMn |Cu tunnel junctions

    Science.gov (United States)

    Jia, Xingtao; Tang, Huimin; Wang, Shizhuo; Qin, Minghui

    2017-02-01

    We predict large magnetoresistance (MR) and spin transfer torque (STT) in antiferromagnetic Fe |MgO |FeMn |Cu tunnel junctions based on first-principles scattering theory. MR as large as ˜100 % is found in one junction. Magnetic dynamic simulations show that STT acting on the antiferromagnetic order parameter dominates the spin dynamics, and an electronic bias of order 10-1mV and current density of order 105Acm-2 can switches a junction of three-layer MgO, they are about one order smaller than that in Fe |MgO |Fe junction with the same barrier thickness, respectively. The multiple scattering in the antiferromagnetic region is considered to be responsible for the enhanced spin torque and smaller switching current density.

  11. Structure, grain connectivity and pinning of as-deformed commercial MgB2 powder in Cu and Fe/Cu sheaths

    Science.gov (United States)

    Kovác, P.; Husek, I.; Pachla, W.; Melisek, T.; Diduszko, R.; Fröhlich, K.; Morawski, A.; Presz, A.; Machajdik, D.

    2002-07-01

    Single-core MgB2 wires and tapes have been made by the powder-in-tube (PIT) method using commercial MgB2 powder (Alfa Aesar). Composites have been made using the two-axial rolling process in Cu and/or Fe/Cu sheaths. Alternative deformations by wire drawing, rotary swaging and cold isostatic pressing have been applied to PIT wires and tapes. Current-voltage characteristics and transport current densities in the self-field and in the external field were measured. It was found that the grain connectivity of ex situ MgB2 is affected by the applied sheath and the mode of deformation. Two-axial rolling has generated the highest powder density resulting in the best grain connectivity. The highest transport current densities of 8700 A cm-2 and 55 830 A cm-2 were measured for Cu and Fe/Cu sheathed square wires, respectively. Cold isostatic pressing at 1.5 GPa has increased current density and n-exponent, which suggests an improvement in grain connectivity. It was found that the external pressure improves the inter-grain connectivity but decreases the pinning in MgB2 cores.

  12. Microstructure and magnetic properties of FePt film with combined MoC/(Mg-X)O (X=Cu, Ni, Co) intermediate layers

    Science.gov (United States)

    Tsai, Jai-Lin; Tzeng, Jie-Lin; Hu, Keng-Chun; Li, Hsu-Kang; Pan, Zu-Yu; Chang, Yuan-Shuo; Liao, Chang-Chun

    2017-01-01

    The magnetic properties and microstructure of FePt films grown on MoC layer and MoC/(Mg-X)O (X=Cu, Ni, Co) combined intermediate layers were studied. The (Mg-X)O (X=Cu, Ni, Co) layer with thickness of 5 nm was deposited on CrRu seed layer at 395 °C. The CrRu (200) texture was enhanced which may due to well grains growth in specific orientation and small lattice mismatch with (Mg-X)O (X=Cu, Ni, Co). Finally, the FePt/MoC layers were deposited on (Mg-X)O layer at 425 °C. Using MoC/MgCuO combined intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were changed from 7.1° to 6.1°, and 5.7° to 3.8°, respectively. For MoC/MgCoO dual intermediate layers, the rocking width of FePt (001) and CrRu (200) diffraction peak were 6.7° and 4.1°. The FePt/MoC/MgCoO film illustrates perpendicular magnetic anisotropy with out-of plane coercivity of 9.3 kOe which is higher than FePt film deposited on MoC layer (8.5 kOe) and the in-plane loops is linear. From microstructure, the FePt grains were more separated on MoC/(Mg-X)O (X=Cu, Ni, Co) combined intermediate layers.

  13. Effects of Cu or Ag additions on the kinetics of MgB2 phase formation in Fe-sheated wires

    DEFF Research Database (Denmark)

    Grivel, Jean-Claude; Abrahamsen, Asger Bech; Bednarcik, J.

    2008-01-01

    MgB2/Fe wires have been produced by the powder-in-tube technique following the in situ route. The influence of low amounts of Cu or Ag additions into the precursor powder mixture on the kinetics of MgB2 formation was studied in situ by means of synchrotron x-ray diffraction during heat-treatments......MgB2/Fe wires have been produced by the powder-in-tube technique following the in situ route. The influence of low amounts of Cu or Ag additions into the precursor powder mixture on the kinetics of MgB2 formation was studied in situ by means of synchrotron x-ray diffraction during heat......-treatments at 504 and 547 degrees C. Both Cu and Ag additions result in a significant increase of the MgB2 formation rate. A thin, discontinuous Fe2B layer was formed at the interface between the MgB2 core and the Fe sheath. At the end of the heat-treatment, Cu and Ag were found in submicrometer-sized particles...

  14. Designed synthesis of MOx (M = Zn, Fe, Sn, Ni, Mn, Co, Ce, Mg, Ag), Pt, and Au nanoparticles supported on hierarchical CuO hollow structures.

    Science.gov (United States)

    Zhang, Zailei; Jung, Ji Chul; Yan, Ning

    2016-12-01

    Despite intensive research into support substrates for the dispersal of nanoparticles and their applications, there has been a lack of general methods to produce metal oxide hollow substrates supporting a wide range of metal and metal oxides. Herein, a synthetic protocol for the preparation of CuO hollow structure-supported MOx (M = Zn, Fe, Ni, Sn, Mn, Co, Ce, Mg, and Ag) and noble metals (Pt and Au) with the desired properties and shell structure, such as CuO/Fe2O3, CuO/ZnO, CuO/SnO2, CuO/MgO, CuO/NiO, CuO/Mn2O3, CuO/CoO, CuO/CeO2, CuO/Ag2O, CuO/Pt, CuO/Au hollow cubes, CuO/ZnO double-shell hollow cubes, CuO/SnO2 double-shell hollow octahedra, CuO/SnO2/Fe2O3 and CuO/Mn2O3/NiO double-shell hollow cubes, was developed based on controlled calcination and etching. These hybrid hollow structures were employed not only as support substrates but also as active constituents for catalytic reactions. As an example, we demonstrated that CuO/ZnO hollow cubes are remarkably efficient in converting solid chitin biomass to liquid chemicals in methanol. In addition, CuO/ZnO double-shell hollow cubes were highly effective in the oxidation of benzyl alcohol in the presence of H2O2, whereas CuO/Pt and CuO/Au hollow cubes promoted the oxidation of benzyl alcohol in pure O2. The strategy developed in this work extends the controllable fabrication of high-quality CuO hollow structure-supported nanoparticles using various compositions and shell structures, paving the way to the exploration and systematic comparison of these materials in a wider range of applications.

  15. Seasonal variation of major elements (Ca, Mg) and trace metals (Fe, Cu, Zn, Mn) and cultured mussel Perna viridis L. and seawater in the Dona Paula Bay, Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Rivonker, C.U.; Parulekar, A.H.

    The major elements and trace metals were analysed from nussel tissue and the seawater taken from three depths (0, 5 and 9 meters) from the culture site. Range of variation in Ca, Mg, Fe, Cu, Zn and Mn were 226-399; 708-1329; 0.005-0.084; BDL-0...

  16. Microstructural evolution of Fe-rich particles in an Al-Zn-Mg-Cu alloy during equal-channel angular pressing

    Energy Technology Data Exchange (ETDEWEB)

    Sha, G., E-mail: gang.sha@sydney.edu.au [ARC Centre of Excellence for Design in Light Metals, University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, University of Sydney, NSW 2006 (Australia); Wang, Y.B.; Liao, X.Z. [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); Duan, Z.C. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States); Ringer, S.P. [ARC Centre of Excellence for Design in Light Metals, University of Sydney, NSW 2006 (Australia); Australian Centre for Microscopy and Microanalysis, University of Sydney, NSW 2006 (Australia); Langdon, T.G. [Department of Aerospace and Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1453 (United States); Materials Research Group, School of Engineering Sciences, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2010-07-15

    The microstructures of a severely deformed Al-Zn-Mg-Cu (AA7136) alloy have been characterized carefully using transmission electron microscopy and three-dimensional atom probe analysis. The Fe-rich intermetallic particles are predominantly Al{sub 13}Fe{sub 4} type in the as-extruded alloy. Significantly, equal-channel angular pressing (ECAP) at 200 deg. C refines Fe-rich particles from {approx}1 to 2 {mu}m to as small as {approx}50 nm after 4 passes processing, and effectively narrow down their size distribution with the increase of number of ECAP passes. In addition, small Fe-rich particles evolve into spherical morphology and are in a more uniform distribution. The formations of Fe-rich phases in AA7136, the kinetic and thermodynamic effects in relation to the refinement of Fe-rich particles and their morphology evolution during ECAP processing are discussed.

  17. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  18. Nd21Pr7Gd4Fe66.02Cu0.2Al0.7B1.08磁体添加纳米粉MgO研究%Research on Nd21Pr7Gd4Fe66.02Cu0.2Al0.7B1.08 Magnet Adding Nano Powder MgO

    Institute of Scientific and Technical Information of China (English)

    管立斌; 杨俊杰; 张宏超

    2015-01-01

    This paper studies the effects of adding nano MgO powder on Nd21 Pr7Gd4Fe66.02Cu0.2Al0.7B1.08 magnet. Research by SEM and EDS analysis show. nano powder MgO is mainly in the grain boundary of magnets. By XRD analysis and adding 0.2% MgO magnets main crystal grain(006)orientation are well developed with bet-ter crystal orientation. The Nd21 Pr7Gd4Fe66.02Cu0.2Al0.7B1.08 magnet of adding 0.2% MgO has the highest residual magnetic flux density of 1.204 T, adding 0.4% MgO magnet has the highest coercivity of 11.71 KA m-1;mag-net adding MgO corrosion resistance is better than that without the addition of MgO magnet.%研究了添加纳米粉MgO对Nd21Pr7Gd4Fe66.02Cu0.2Al0.7B1.08磁体的影响。通过扫描电镜能谱研究分析可知,纳米粉MgO主要分布于磁体的晶界相当中。通过XRD分析可知:添加w(MgO)=0.2%的纳米粉MgO,磁体主晶粒(006)晶向晶粒发育良好,晶粒取向度较好;添加w(MgO)=0.2%的纳米粉MgO,磁体Nd21Pr7Gd4Fe66.02Cu0.2Al0.7B1.08有最高的剩磁(1.204 T);添加w(MgO)=0.4%纳米粉MgO,磁体Nd21Pr7Gd4Fe66.02Cu0.2Al0.7B1.08有最高的矫顽力(11.70 kA/m);添加MgO的磁体比未添加MgO的磁体耐腐蚀性要好。

  19. MgCl{sub 2} doped Cu{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} ferrite humidity sensors

    Energy Technology Data Exchange (ETDEWEB)

    Bagum, Nishat; Bhuiyan, A.H. [Department of Physics, Bangladesh University of Engineering and Technology (BUET), Dhaka 1000 (Bangladesh); Gafur, M.A. [PPDC, BCSIR, Dhaka 1205 (Bangladesh); Saha, D.K. [Materials Science Division, Atomic Energy Centre, Dhaka, BAEC (Bangladesh)

    2010-04-15

    The microstructure and humidity sensitivity of Cu{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} ferrites (where x varies from 0 to 1 mol% in steps of 0.2) doped with 0.05 and 0.1 wt% of magnesium chloride (MgCl{sub 2}) prepared by standard ceramic route have been studied. X-ray diffraction (XRD) analysis indicates the formation of ferrite. Infrared (IR) transmission spectra show the presence of chlorine band, octahedral and tetrahedral group complexes. Scanning electron micrographs reveal the presence of granulation and pores, which play an important role in determining the humidity sensitivity. Microhardness, bulk density, porosity and water absorption properties were studied. It was found that the humidity sensitivity depends on composition and porosity. Dependence of electrical resistivity on composition, temperature and humidity was also investigated. Electrical resistivity decreases with the increase of temperature, humidity and molar weight of copper oxide (CuO) content. The resistivity of the 0.05 wt% MgCl{sub 2} doped Cu{sub x}Zn{sub 1-x}Fe{sub 2}O{sub 4} ferrite is more dependent on humidity. The resistance-humidity characteristics was examined. The good results concerning humidity sensitivity were obtained for 0.05 wt% MgCl{sub 2} doped ferrites except CuFe{sub 2}O{sub 4} ferrite doped with 0.05 and 0.1 wt% MgCl{sub 2}. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Use of multivariate statistical tool for data processing in the analysis of Cu, Cr, Fe, Pb, Mo and Mg in lubricating oil by LIBS

    Energy Technology Data Exchange (ETDEWEB)

    Alves, Luana F.N.; Sarkis, Jorge E.S.; Bordon, Isabela C.A.C., E-mail: ludemar1@hotmail.com, E-mail: jesarkis@ipen.br, E-mail: isabella.bordon@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    Analysis of industrial lubricants is widely used for monitoring and predicting maintenance requirements in a broad range of mechanical systems. Laser induced breakdown spectroscopy has been used to evaluate the potentiality of the technique for the determination of metals in lubricating oils. Prior to quantitative analysis, the LIBS system was calibrated using standard samples containing the elements investigated (Cu, Cr, Fe, Pb, Mo and Mg). This study presents the usefulness of multivariate statistical techniques for evaluation and interpretation of large complex data sets in order to get more information about concentration of metals in oils lubricants is related to engine wear. (author)

  1. Detection and comparison of reactive oxygen species (ROS) generated by chlorophyllin metal (Fe, Mg and Cu) complexes under ultrasonic and visible-light irradiation.

    Science.gov (United States)

    Wang, Jun; Guo, Yuwei; Gao, Jingqun; Jin, Xudong; Wang, Zhiqiu; Wang, Baoxin; Li, Kai; Li, Ying

    2011-09-01

    In this paper, in order to examine the mechanisms of sonodynamic and photodynamic reactions, the chlorophyllin metal (Chl-M (M=Fe, Mg and Cu)) complexes were irradiated by ultrasound (US) and visible-light (VL), respectively, and the generation of reactive oxygen species (ROS) were detected by the method of Oxidation-Extraction Spectrometry (OES). That is, the 1,5-diphenyl carbazide (DPCI) is oxidized by the generated ROS into 1,5-diphenyl carbazone (DPCO), which can display a various visible absorption around 563 nm wavelength. Besides, some influence parameters on the generation of ROS were also reviewed. The results demonstrated an apparent synergistic effect of Chl-M and ultrasonic or visible-light irradiation for the generation of ROS. Moreover, the quantities of generated ROS increase with the increase of (ultrasonic or visible-light) irradiation time and Chl-M (M=Fe, Mg and Cu) concentration. Finally, several quenchers were used to determine the kind of the generated ROS. It is wished that this paper might offer some valuable references for the study on the sonodynamic therapy (SDT) and photodynamic therapy (PDT) mechanisms and the application of Chl-M in tumor treatment.

  2. Structural and complex impedance spectroscopic studies of Ni0.5Mg0.3Cu0.2Fe2O4 ferrite nanoparticle

    Science.gov (United States)

    Dhaou, Mohamed Houcine; Hcini, Sobhi; Mallah, Abdulrahman; Bouazizi, Mohamed Lamjed; Jemni, Abdelmajid

    2017-01-01

    Spinel ferrite having composition Ni0.5Mg0.3Cu0.2Fe2O4 was prepared by the sol-gel technique at 1473 K. The X-ray diffraction results indicate that the ferrite sample has a cubic spinel-type structure with Fdbar{3}m space group. The electrical properties of the studied sample using complex impedance spectroscopy technique have been investigated in the frequency range 102-107 Hz and in the temperature range 300-500 K. The total conductivity curves for sample are found to obey Jonscher power law ( σ( ω) = σ dc + Aω n ) with an increase in the frequency exponent ( n) as temperature increases. The activation energy deduced from the analysis of the conductivity curves matches very well with the value estimated from the relaxation time, indicating that relaxation process and electrical conductivity are attributed to the same defect. Nyquist plots of impedance show semicircle arcs for sample, and an electrical equivalent circuit has been proposed to explain the impedance results. The effect of frequency and temperature on dielectric constant ( ɛ″) and dielectric loss (tan δ) has also been discussed in terms of hopping of charge carriers between Fe2+ and Fe3+ ions.

  3. Influência dos Íons Mg, Ca, Fe, Cu e Zn sobre a tensão superficial estática de soluções contendo surfatante Influence of Mg, Ca, Fe, Cu and Zn Ions on static surface tension of surfactant solutions

    Directory of Open Access Journals (Sweden)

    F.M.L. Silva

    2006-09-01

    Full Text Available O objetivo do estudo foi avaliar a influência da presença de cinco íons em uma calda de pulverização contendo o surfatante Aterbane. A tensão superficial foi analisada por meio da medição da massa de um conjunto de 25 gotas, com quatro repetições constituindo um tratamento. O trabalho foi dividido em duas etapas. Na primeira, os tratamentos foram combinados em esquema fatorial 9x5x2, sendo nove concentrações do surfatante Aterbane (0,01; 0,025; 0,05; 0,1; 0,2; 0,5; 1; 2; e 3%, cinco íons (Mg++, Ca++, Fe+++, Cu+++ e Zn+++ e duas concentrações desses elementos (10 e 100 ppm. Na segunda etapa, os tratamentos foram combinados em esquema fatorial 5x5x1, utilizandose os mesmos cinco elementos (Mg++, Ca++, Fe+++, Cu+++ e Zn+++, em cinco concentrações (1, 5, 20, 50 e 200 ppm, com apenas uma concentração do surfatante Aterbane (0,025%. Outros nove tratamentos permitiram avaliar as tensões superficiais das concentrações do surfatante (0,01; 0,025; 0,05; 0,1; 0,2; 0,5; 1; 2; e 3% sem a adição dos íons. Os resultados mostraram que houve interferência dos íons sobre as soluções, já que, com exceção do Fe+++ (na concentração de 10 e 100 ppm e do Cu+++ (na concentração de 100 ppm, todos os íons reduziram a tensão mínima alcançada e aumentaram a eficiência do surfatante, implicando benefícios à ação do surfatante e sobre as características de possíveis soluções de aplicação. Todos os íons avaliados promoveram reduções nas tensões superficiais de soluções do surfatante na concentração de 0,025%.The objective of this study was to evaluate the influence of 5 ions on a spray solution containing the surfactant aterbane. Surface tension was analyzed by measuring the mass of a set of 25 drops, with four repetitions constituting a treatment. The work was divided in two stages. In the first, the treatments were arranged in a 9x5x2 factorial design, nine Aterbane concentrations (0.01; 0.025; 0.05; 0.1; 0.2; 0

  4. Sodium, K, Ca, Mg, Fe, Cu, and Zn concentrations in molluscs from the Magellan Strait (Chile): their contribution to dietary intake.

    Science.gov (United States)

    España, M S Astorga; Rodríguez, E M Rodríguez; Romero, C Díaz

    2005-08-01

    The concentrations of the essential metals Na, K, Ca, Mg, Fe, Cu, and Zn were determined in 126 specimens of molluscs belonging to five different species: Mytilus chilensis, n=47; Nacella deaurata, n=65; Aulacomya ater, n=4; Fissurella picta, n=4; Acanthina monodon, n=6, collected from the coastline of the Magellan Strait. Significant differences were obtained among the mean metal concentrations in the mollusc species considered. The contribution to the dietary daily intake of these metals for the consumption of one serving of these molluscs was high, especially the contribution to the Fe intake for the consumption of N. deaurata. Some significant differences were observed among the mean concentrations for the studied metals according to the zone of sampling. The influence of the zone of sampling on the mean concentration of metals in N. deaurata was higher than in M. chilensis. The application of lineal discriminant analysis (LDA) made it possible to differentiate statistically between specimens according to the mollusc species. Within the each mollusc species, the LDA helped to identify specimens according to the zone of sampling and weight/length ratio.

  5. Efeitos da suplementação de fitase sobre a disponibilidade aparente de Mg, Ca, Zn, Cu, Mn e Fe em alimentos vegetais para a tilápia-do-nilo Effects of phytase supplementation on apparent availability of Mg, Ca, Zn, Cu, Mn, and Fe of plant feedstuffs for nile tilapia

    Directory of Open Access Journals (Sweden)

    Giovani Sampaio Gonçalves

    2005-12-01

    Full Text Available Cem juvenis de tilápia-do-nilo (Oreochromis niloticus; PV = 100.0 ± 5.0 g foram distribuídos em 10 tanques-rede com o objetivo de avaliar o efeito da suplementação da enzima fitase (0, 1.000 e 2.000 UFA/kg sobre a disponibilidade de minerais em alguns alimentos energéticos (milho, milho extrusado, farelo de trigo, farelo de arroz e farelo de sorgo e protéicos (farelo de soja extrusado, farelo de soja, farelo de girassol, farelo de algodão e glúten de milho utilizados na alimentação de tilápia-do-nilo (Oreochromis niloticus. Para determinação dos coeficientes de disponibilidade aparente (CDA do cálcio (Ca, magnésio (Mg, zinco (Zn, cobre (Cu, ferro (Fe e manganês (Mn, foram confeccionadas 31 rações, marcadas com 0,10% de óxido de crômio III uma referência (ração purificada e 30 contendo os dez alimentos e os diferentes níveis de suplementação da enzima fitase. O CDA dos nutrientes foi calculado com base no teor de crômio da ração e das fezes. A fitase aumenta, nos vegetais, a disponibilidade do Mg, Cu, Zn e Mn, os quais apresentam tendência diferenciada, em razão do seu valor biológico e do nível de suplementação de enzima.One hundred Nile tilapia juveniles (Oreochromis niloticus; BW= 100.0 ± 5.0 g were assigned to 10 experimental cages to evaluate the effects of phytase supplementation (0, 1,000, and 2,000 FTU/kg on calcium (Ca, magnesium (Mg, zinc (Zn, copper (Cu, iron (Fe and manganese (Mn availability of ten feedstuffs: five energetic (corn, extruded corn, wheat meal, rice meal and low-tannin sorghum and five protein (extruded soybean, soybean meal, sunflower meal, cottonseed meal and corn gluten meal. As reference, an albumin and gelatin-based diet [with 0.10 % chromic oxide (III as external marker] was fed to the juveniles. Thirty-one diets (one reference and 30 based on all feedstuffs and increasing levels of phytase were formulated to determine the coefficients of apparent availability of minerals (Mg

  6. Preparation of high-strength Al-Mg-Si-Cu-Fe alloy via heat treatment and rolling

    Institute of Scientific and Technical Information of China (English)

    Chong-yu Liu; Peng-fei Yu; Xiao-ying Wang; Ming-zhen Ma; Ri-ping Liu

    2014-01-01

    An Al–Mg–Si–Cu–Fe alloy was solid-solution treated at 560°C for 3 h and then cooled by water quenching or furnace cooling. The alloy samples which underwent cooling by these two methods were rolled at different temperatures. The microstructure and mechanical properties of the rolled alloys were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and tensile testing. For the water-quenched alloys, the peak tensile strength and elongation occurred at a rolling temperature of 180°C. For the furnace-cooled alloys, the tensile strength decreased initially, until the rolling temperature of 420°C, and then increased;the elongation increased consistently with increasing rolling temperature. The effects of grain boundary hardening and dislocation hardening on the mechanical properties of these rolled alloys decreased with increases in rolling temperature. The mechanical properties of the 180°C rolling water-quenched alloy were also improved by the presence ofβ″phase. Above 420°C, the effect of solid-solution hardening on the mechanical properties of the rolled alloys increased with increases in rolling temperature.

  7. The phase relations in the system In 2O 3 A2BO 4 BO at elevated temperatures ( A: Fe, Ga, or Cr; B: Mg, Co, Ni, or Cu): Part II

    Science.gov (United States)

    Kimizuka, Noboru; Mohri, Takahiko; Nakamura, Masaki

    1990-08-01

    The phase relations in the systems In 2O 3Ga 2MgO 4MgO at 1300°C, In 2O 3Fe 2NiO 4NiO at 1200°C, In 2O 3Ga 2NiO 4NiO at 1200°C, In 2O 3Cr 2NiO 4NiO at 1200°C, In 2O 3Cr 2CoO 4CoO at 1200°C, and In 2O 3Cr 2CuO 4CuO at 1000°C were determined by classical quenching methods. In the system In 2O 3Ga 2MgO 4MgO there exist two ternary phases, namely, InGaO 3(MgO) with the YbFe 2O 4-type crystal structure and InGaO 3(MgO) 2 with the InFeO 3(ZnO) 2-type crystal structure. In the system In 2O 3 A2NiO 4NiO ( A = Fe, Ga, or Cr), there is a spinel solid-solution between In ANiO 4 and A2NiO 4. There is no ternary compound in the systems In 2O 3Cr 2CoO 4CoO and In 2O 3Cr 2CuO 4CuO, respectively. The classification of the phase relations in the system In 2O 3 A2BO 4 BO ( A: Fe, Ga, or Cr; B: Mg, Co, Ni, Cu, or Zn) is made in terms of the crystal structure of the ternary In ABO 4 compound.

  8. Analysis of six elements (Ca, Mg, Fe, Zn, Cu, and Mn) in several wild vegetables and evaluation of their intakes based on Korea National Health and Nutrition Examination Survey 2010-2011.

    Science.gov (United States)

    Bae, Yun-Jung; Kim, Mi-Hyun; Lee, Je-Hyuk; Choi, Mi-Kyeong

    2015-03-01

    Wild vegetables, those edible among naturally grown vegetables, have been reported to contain many bioactive substances, dietary fibers, vitamins, and minerals. The purpose of this study is to examine the six elements of the wild vegetables frequently consumed by Koreans and assess the element intakes through them. Contents of six kinds of elements (Ca, Mg, Fe, Zn, Cu, and Mn) in 11 wild vegetables were analyzed by inductively coupled plasma optical emission spectroscopy. Using these analysis data, the 6-element intakes from the wild vegetables were evaluated in healthy Korean adults aged 19-64 years from the Korea National Health and Nutrition Examination Survey (2010-2011). Sedum and shepherd's purse contained over 100 mg of Ca in 100 g of their edible portion. The Mg content per 100 g of the 11 wild vegetables ranged from 12.1 mg to 43.4 mg. The wild vegetable with the highest mineral content per 100 g was sedum for Ca, spinach for Mg, shepherd's purse for Fe, spinach for Zn, bracken for Cu, and fragrant edible wild aster for Mn. The element intakes from the 11 wild vegetables compared with dietary reference intakes in the healthy Koreans were 1.0 % for Ca, 2.1 % for Mg, 5.3 % for Fe, 1.4 % for Zn, 0.3 % for Cu, and 1.8 % for Mn. Considering the low intake ratio (1.2 %) of the wild vegetable to total food intake, wild vegetables may contribute to some element intakes. Our results show the nutritional value of the wild vegetables in the aspect of mineral nutrition; however, further research is needed to evaluate the bioavailability of various elements in wild vegetables.

  9. Phase equilibrium in Mg-Cu-Y

    Science.gov (United States)

    Mezbahul-Islam, Mohammad; Medraj, Mamoun

    2013-10-01

    Magnesium-based bulk metallic glasses (BMG) have potential in applications ranging from biomedical to sports equipment and the Mg-Cu-Y system offers some of the most promising alloys. Phase relations and ternary solubility of the binary and ternary compounds of this system have been experimentally investigated. The Isothermal section of Mg-Cu-Y system at 673 K for the entire composition range has been constructed. Phase relations in the Cu-rich (>66 at.% Cu) region of the Mg-Cu-Y system has been determined for the first time. The homogeneity range of three ternary compounds has been determined. Solidifications behavior of several key alloys have been discussed based on the differential scanning calorimetry (DSC) experiments and thermodynamic calculations. Extensive analysis of the DSC curves has been carried out to relate them to the corresponding phase transformation reactions and temperatures. Some of the most promising metallic glass forming regions have been analyzed using thermodynamic calculations.

  10. Correlation between Antioxidant Enzymes Activity and Intraerythrocyte Concentration of Fe, Mg, Zn, Cu in Pulmonary Arterial Hypertension and Cor Pulmonale in Children with Congenital Lung Disease and Cystic Fibrosis

    Directory of Open Access Journals (Sweden)

    Elena M. Vasilyeva, PhD,ScD¹

    2013-03-01

    Full Text Available Significant changes in the levels of the potential prooxidant Cu (increase and the antioxidant Zn (decrease in plasma were revealed in children having bronchopulmonary dysplasia (BPD complicated by pulmonary arterial hypertension (PAH and chronic cor pulmonale (CCP when compared with the control. The Zn / Cu ratio in the blood plasma of patients with BPD, especially in CCP, was found to be lower than in the control group (p<0.001. This could indicate the activation of the prooxidant processes; simultaneously, the total antioxidant status (AOS decreased. No significant increase in the intracellular free (“ionized” (i form of magnesium (iMg was found; in fact, the concentration of iFe in all the patient groups was higher than in the control. An increase in the iCu and iZn levels (nonprotein-bound was observed in the blood cells of the affected children. A significant increase in the glutathione peroxidase activity in the CCP patients may indicate an accumulation of organic peroxides, and partially compensate for the lesser activity of superoxide dismutase (SOD and other antioxidants. The Zn / Cu and iZn/ iCu ratios were reduced in patients with CCP when compared with patients with PD without CCP.

  11. Evolution of intermetallic phases of Al-Zn-Mg-Cu alloy during heat treatment

    Institute of Scientific and Technical Information of China (English)

    FAN Xi-gang; JIANG Da-ming; MENG Qing-chang; LI Nian-kui; SUN Zhao-xia

    2006-01-01

    Al-Zn-Mg-Cu alloy is a favorable choice for aerospace applications requiring good combination of strength and toughness,which is greatly influenced by the coarse intermetallic particles. The evolution of intermetallic particles in an Al-Zn-Mg-Cu alloy during heat treatment was studied by field emission gun scanning electron microscopy (FEG-SEM) and X-ray diffractometry(XRD).The results show that there are lamellar eutectic structure (α(Al)+Mg(Zn,Al,Cu)2) and Al7Cu2Fe particles in the solidified structure.The Al7Cu2Fe particles are embedded in the eutectic structure. The content of eutectic structure decreases with the increase of holding time and disappears after 24 h. The size and morphology of Al7Cu2Fe particles exhibit no change during the heat treatment. It is found that the Al2CuMg phase is formed during the treatment at 460 ℃. A transformation process from the primary eutectic phase Mg(Zn,Al,Cu)2 to Al2CuMg is observed, and the transformation mechanism and kinetics are analyzed. The Al2CuMg constituents form in the primary Mg(Zn,Al,Cu)2 phase, and grow along the eutectic microstructure.

  12. Interstitial Fe in MgO

    CERN Document Server

    Mølholt, T E; Gunnlaugsson, H P; Svane, A; Masenda, H; Naidoo, D; Bharuth-Ram, K; Fanciulli, M; Gislason, H P; Johnston, K; Langouche, G; Ólafsson, S; Sielemann, R; Weyer, G

    2014-01-01

    Isolated Fe-57 atoms were studied in MgO single-crystals by emission Mossbauer spectroscopy following implantation of Mn-57 decaying to Fe-57. Four Mossbauer spectral components were found corresponding to different Fe lattice positions and/or charge states. Two components represent Fe atoms substituting Mg as Fe2+ and Fe3+, respectively; a third component is due to Fe in a strongly implantation-induced disturbed region. The fourth component, which is the focus of this paper, can be assigned to Fe at an interstitial site. Comparison of its measured isomer shift with ab initio calculations suggests that the interstitial Fe is located on, or close to, the face of the rock-salt MgO structure. To harmonize such an assignment with the measured near-zero quadrupole interaction a local motion process (cage motion) of the Fe has to be stipulated. The relation of such a local motion as a starting point for long range diffusion is discussed.

  13. Structural, dielectric and magnetic studies of (x) Mg0.2Cu0.3Zn0.5Fe2O4 + (1-x) Ba0.8Zr0.2TiO3 magnetoelectric composites

    Science.gov (United States)

    Khader, S. Abdul; Giridharan, N. V.; Chaudhuri, Arka; Sankarappa, T.

    2016-05-01

    The Magneto-electric composites (x) Mg0.2Cu0.3Zn0.5Fe2O4 + (1-x) Ba0.8Zr0.2TiO3 (x=15%,30%,45%) were synthesized by sintering mixtures of highly ferroelectric Ba0.8Zr0.2TiO3 (BZT) and highly magneto-strictive component Mg0.2Cu0.3Zn0.5Fe2O4 (MCZF). The presences of two phases in magneto-electric composites were probed by X-ray diffraction (XRD) studies. The peaks observed in the XRD spectrum indicated spinel cubic structure for MCZF ferrite and tetragonal perovskite structure for BZT and, both spinel and pervoskite structures for synthesized composites. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). Frequency dependent dielectric properties of synthesized composites were measured from 100 Hz to 1 MHz at RT using HIOKI LCR HI-TESTER. The dielectric dispersion is observed at lower frequencies for the synthesized ME composites. The magnetic properties of synthesized composites were analyzed using a Vibrating Sample Magnetometer (VSM). It is observed that the values of saturation magnetization increases along with the ferrite content.

  14. Quaternary M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4} (M = Ni, Zn, Co, Mn) ferrite oxides: Synthesis, characterization and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Ciocarlan, Radu George [Faculty of Chemistry, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd., no. 11, 700506, Iasi (Romania); Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerpen (CDE), Universiteitsplein 1, 2610, Wilrijk, Antwerpen (Belgium); Pui, Aurel, E-mail: aurel@uaic.ro [Faculty of Chemistry, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd., no. 11, 700506, Iasi (Romania); Gherca, Daniel; Virlan, Constantin [Faculty of Chemistry, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd., no. 11, 700506, Iasi (Romania); Dobromir, Marius; Nica, Valentin [Faculty of Physics, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd., no. 11, 700506, Iasi (Romania); Craus, Mihail Liviu [Laboratory of Neutron Physics – JINR, Joliot Curie 6, 141980, Dubna, Moscow region, Russia, (Russian Federation); National Institute of Research & Development for Technical Physics, Bd. Mangeron 47, 700050 Iasi (Romania); Gostin, Irina Neta [Faculty of Biology, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd. nr. 20 A, 700505, Iasi (Romania); Caltun, Ovidiu [Faculty of Physics, “Alexandru Ioan Cuza” University of Iasi, Carol I Bd., no. 11, 700506, Iasi (Romania); Hempelman, Rolf [Saarland University, Physical Chemistry, 66123 Saarbrüken (Germany); Cool, Pegie [Laboratory of Adsorption and Catalysis, Department of Chemistry, University of Antwerpen (CDE), Universiteitsplein 1, 2610, Wilrijk, Antwerpen (Belgium)

    2016-09-15

    Highlights: • Superparamagnetic quaternary nanoferrite (M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4,} where M = Mn, Zn, Co, Ni) were obtained. • C, O, H and metals were observed by XPS analysis. • Phases purity were confirmed by XRD diffraction and crystallite size (3–10 nm) were determind. - Abstract: We report the synthesis of M{sub 0.25}Cu{sub 0.25}Mg{sub 0.5}Fe{sub 2}O{sub 4} (where M = Mn, Zn, Co, Ni) nanoparticles using the coprecipitation method in the presence of carboxymethyl cellulose (CMC) as the in-situ surfactant. The crystalline structure and surface morphology were examined by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) and it was established that the average diameter of the magnetic nanoparticles (MNPs) is in the range of 3–10 nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) show that the MNPs are activated by the hydrophilic groups of the surfactant, which coat them and enhance their stability. The vibrating sample magnetometry measurements show the superparamagnetic behavior of the nanoparticles. Due to their small crystallite size, which implies large surface area, and their functionalization with organic groups, the obtained nanoparticles could have medical and catalytic applications.

  15. Structural, dielectric and ferroelectric studies of (x) Mg0.25Cu0.25Zn0.5Fe2O4 + (1-x) BaTiO3 magnetoelectric nano-composites

    Science.gov (United States)

    Khader, S. Abdul; Muneeswaran, M.; Giridharan, N. V.; Sankarappa, T.

    2016-05-01

    The Particulate nano-composites of ferrite and ferroelectric phases having the general formula (x) Mg0.25Cu0.25Zn0.5Fe2O4 + (1-x) BaTiO3 (x=15%, 30% and 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO3 (BT) and highly magneto-strictive magnetic component Mg0.25Cu0.25Zn0.5Fe2O4(MCZF). The presence of constituent phases of ferrite, ferroelectric and their composites were probed and confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). The variation of dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz at room temperature were carried out using a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric data has been thoroughly analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model. The ferroelectric properties of synthesized magneto-electric nano-composites were measured using P-E loop tracer.

  16. Coupled perpendicular magnetization in Fe/Cu/Fe trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Repetto, D. [Max Planck Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany)]. E-mail: D.Repetto@fkf.mpg.de; Enders, A. [Max Planck Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany); Kern, K. [Max Planck Institut fuer Festkoerperforschung, Heisenbergstr. 1, D-70569 Stuttgart (Germany)

    2006-05-15

    Ultrathin epitaxial Fe films on Cu(1 0 0) with perpendicular magnetization have been used as templates for the preparation of FCC Fe/Cu/Fe trilayers. The magnetic anisotropy and the coupling of these films have been studied by in-situ magneto optical Kerr effect measurements and Kerr microscopy. The magnetic coupling of both Fe layers is found to be dominated by magnetostatic interaction. Adsorbate-induced spin reorientation in the top layer also causes spin reorientation in the bottom layer. The governing role of the Fe-vacuum interface for the magnetism of the whole trilayer is demonstrated.

  17. FeII/MgII, [Fe/Mg] Ratios and High-z Quasars

    CERN Document Server

    Korista, K; Corbin, M R; Freudling, W; Korista, Kirk; Kodituwakku, Nalaka; Corbin, Michael; Freudling, Wolfram

    2003-01-01

    It has been suggested in the literature that the (Fe/alpha) abundance ratio may be used as a chronometer, due to a delay in this ratio reaching its solar value as predicted by galactic chemical evolution models. Using grids of photoionization models along a sequence of the (Fe/Mg) abundance ratio vs.\\ metallicity with time in a giant elliptical starburst scenario, we investigate the relationship between the (Fe/Mg) abundance ratio and the FeII/MgII emission line flux ratio under the assumption that these lines originate in photoionized clouds within the broad emission line regions of quasars.

  18. GMI in FeCuNbSiB/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Correa, M.A. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil)]. E-mail: mmacorrea@gmail.com; Viegas, A.D.C. [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Silva, R.B. da [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Andrade, A.M.H. de [Departamento de Fisica, CCNE, UFSM, 97105-900, Santa Maria, RS (Brazil); Sommer, R.L. [Centro Brasileiro de Pesquisas Fisicas, 22290-180, Rio de Janeiro, RJ (Brazil)

    2006-10-01

    Very high magnetoimpedance (MI) measured at frequencies up to 1.8 GHz in single and multilayered thin films with composition Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} and (Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9}+Cu) are reported. The magnetic properties of both systems are also compared. MI ratio as high as 300% for the multilayered samples were obtained.

  19. Ageing processes in Al-Cu-Mg alloys with different Cu/Mg ratios

    Energy Technology Data Exchange (ETDEWEB)

    Macchi, C. [IFIMAT, UNCentro and CONICET, Pinto, Tandil (Argentina); Somoza, A. [IFIMAT, UNCentro and CICPBA, Pinto, Tandil (Argentina); Ferragut, R.; Dupasquier, A. [LNESS and CNISM, Politecnico di Milano, Como (Italy); Polmear, I.J. [Emeritus Professor, Department of Materials Engineering, Monash University, Melbourne, Vic. (Australia)

    2009-11-15

    Three age-hardenable Al-Cu-Mg alloys with different Cu/Mg ratios were studied by means of positron annihilation lifetime spectroscopy and Vickers hardness as a function of the artificial ageing time at 175 C. Complementary information on the decomposition sequence was obtained by means of differential scanning calorimetry. The results are discussed in terms of the different structures that are formed during the precipitation sequence of the supersaturated solid solution. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  20. Phase Equilibria of ``Cu2O''-``FeO''-CaO-MgO-Al2O3 Slags at PO2 of 10-8.5 atm in Equilibrium with Metallic Copper for a Copper Slag Cleaning Production

    Science.gov (United States)

    Henao, Hector M.; Pizarro, Claudio; Font, Jonkion; Moyano, Alex; Hayes, Peter C.; Jak, Evgueni

    2010-12-01

    Limited data are available on phase equilibria of the multicomponent slag system at the oxygen partial pressures used in the copper smelting, converting, and slag-cleaning processes. Recently, experimental procedures have been developed and have been applied successfully to characterize several complex industrial slags. The experimental procedures involve high-temperature equilibration on a substrate and quenching followed by electron probe X-ray microanalysis. This technique has been used to construct the liquidus for the “Cu2O”-“FeO”-SiO2-based slags with 2 wt pct of CaO, 0.5 wt pct of MgO, and 4.0 wt pct of Al2O3 at controlled oxygen partial pressures in equilibrium with metallic copper. The selected ranges of compositions and temperatures are directly relevant to the copper slag-cleaning processes. The new experimental equilibrium results are presented in the form of ternary sections and as a liquidus temperature vs Fe/SiO2 weight ratio diagram. The experimental results are compared with the FactSage thermodynamic model calculations.

  1. Effect of pre-aging on precipitation behavior of Al- 1.29Mg- 1.22Si-0.68Cu-0.69Mn-0.3Fe-0.2Zn-0.1 Ti alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; CHEN Yang; ZHAO Gang; LIU Chun-ming; ZUO Liang

    2006-01-01

    By means of Vickers-hardness and electrical conductivity measurements, DSC tests and TEM analyses, the effect of different pre-aging treatments on precipitation characteristic of the Al- 1.29Mg- 1.22Si-0.68Cu-0.69Mn-0.3Fe-0.2Fe-0.1 Ti (mass fraction, %) alloy during subsequent artificial aging was investigated. The results indicate that with increasing pre-aging time from 2.5 min to 10 min at 170 ℃, the number of formedβ" nuclei increases, resulting in promoting artificial aging kinetics and enhancing peak hardness. The hardness of pre-aged alloy reduces within lower temperature range of non-isothermal aging and increases in early stage of isothermal aging at 170 ℃. The size and density of clusters in pre-aged samples determine the hardenability in early stage of artificial aging. Pre-aging has dual mechanisms: namely, clusters (β" nuclei) formed by pre-aging can inhibit the precipitation of GP zones during natural aging, and can quicken the precipitation of β" phase in the early stage of subsequent artificial aging.

  2. Secondary ageing in an Al-Cu-Mg alloy with high Cu/Mg ratio

    Energy Technology Data Exchange (ETDEWEB)

    Dupasquier, A.; Folegati, P. [Politecnico di Milano (Italy). Ist. di Fisica della Materia; Ferragut, R. [Politecnico di Milano (Italy). Ist. di Fisica della Materia; IFIMAT, Univ. Nacional del Centro de la Provincia de Buenos Aires and CICPBA, Tandil (Argentina); Massazza, M.; Riontino, G. [Ist. Nazionale di Fisica della Materia, Dipt. di Chimica I.F.M., Univ. di Torino (Italy); Somoza, A. [IFIMAT, Univ. Nacional del Centro de la Provincia de Buenos Aires and CICPBA, Tandil (Argentina)

    2002-07-01

    The mechanisms governing secondary ageing (structural transformations occurring at low temperature after a heat treatment at higher temperature) were investigated by combined measurements of positron lifetimes, Vickers microhardness measurements and differential scanning calorimetry (DSC) on a laboratory alloy (Al-4.5 wt.% Cu-0.56 wt.% Mg). The results show that hardening occurs at a much slower rate than in case of primary ageing at RT. The positron lifetime data suggest that the hardening rate is controlled by slow release of vacancies from Cu-rich clusters formed during the initial high temperature treatment. The hardening stage is concomitant with an increase of the positron lifetime, and has probably the same origin, which is the formation of solute clusters containing vacancies and Mg as essential components. The formation at low temperature of new structures is also demonstrated by DSC. (orig.)

  3. Thermodynamic re-optimization of the Cu-Mg-Sn system at the Cu-Mg side

    Directory of Open Access Journals (Sweden)

    Miettinen J.

    2012-01-01

    Full Text Available Thermodynamic description of the ternary Cu-Mg-Sn system at its Cu-Mg side is presented. The thermodynamic parameters of the binary sub-systems, Cu-Mg, Cu-Sn and Mg-Sn, are taken from the earlier SGTE-based assessments (modifying the Mg-Sn description slightly and those of the Cu-Mg-Si system are optimized in this study using the experimental thermodynamic and phase equilibrium data. The solution phases of the systems are described with the substitutional solution model and the intermetallic Cu2Mg compound (Laves C15, treated as simple semi-stoichiometric phases of the (A,BpCq type, is described with the twosublattice model. The present ternary description is valid for tin contents up to 45 wt% (xSn≈0.30.

  4. Structural and magnetic properties of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite prepared by NaOH-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Wei-xiao; Wang, Zhi, E-mail: zhiwang@tju.edu.cn

    2015-09-15

    Highlights: • NiMgCuZn ferrites were successfully prepared by low-temperature sintering. • NiMgCuZn ferrites have the advantages of both NiCuZn and MgCuZn ferrites. • NiMgCuZn ferrites exhibit high Curie temperature & high stability of permeability. - Abstract: The Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite powders have been prepared by NaOH co-precipitation method and characterized by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The XRD patterns confirm the single phase spinel structure of synthesized nanoparticles. The average crystallite size of the particles increases from 12 to 36 nm with calcining temperature (T{sub a}) from 500 to 800 °C. The saturation magnetization (M{sub s}) of the superparamagnetic particles was deduced by Langevin theory. Subsequently, the densification characteristics and magnetic properties of the low-temperature 950 °C-sintered ferrite bulk samples were also investigated. The magnetic measurement showed that the sintered bulk sample of T{sub a} = 600 °C has the highest initial permeability (μ{sub i}), lowest coercivity (H{sub c}), largest saturation magnetization (M{sub s}) and satisfactory thermal stability of μ{sub i}. The microstructures of sintered samples were examined using field emission scanning electric microscope (FESEM). The T{sub a} has significant influence on the bulk density, initial permeability, saturation magnetization and coercivity of Ni{sub 0.15}Mg{sub 0.1}Cu{sub 0.3}Zn{sub 0.45}Fe{sub 2}O{sub 4} ferrite.

  5. Reduction of nitrobenzene by the catalyzed Fe/Cu process

    Institute of Scientific and Technical Information of China (English)

    XU Wenying; LI Ping; FAN Jinhong

    2008-01-01

    The polarization behavior of the couple Fe/Cu in 100 mg/L nitrobenzene aqueous solution was studied using Evans coupling diagrams. The results indicated that the iron corrosion was limited by both anodic and cathodic half-cell reactions under the neutral conditions and cathodically controlled under the alkaline conditions. Batch experiments were performed to study the effect of solution pH, reaction duration, concentration, type of electrolyte and dissolved oxygen (DO) on the reduction of nitrobenzene by the catalyzed Fe/Cu process. This process proved effective in the pH range of 3 to 11. The conversion efficiency of nitrobenzene at pH ≈ 10.1 was almost the same as that under highly acid conditions (pH ≈ 3). The degradation of nitrobenzene fell into two phases: adsorption and surface reduction, and the influence of adsorption and mass transfer became more extensive with solution concentration. The reduction rate decreased in the presence of DO in the solution, indicating that a need for aeration was eliminated in the catalyzed Fe/Cu process. Accordingly, spending on energy consumption would be reduced. Economic analysis indicated that merely 0.05 kg was required for the treatment of a ton of nitrobenzene-containing water with pH from 3 to 11. The catalyzed Fe/Cu process is cost-effective and of practical value.

  6. Removal of remazol yellow from aqueous solution using Fe-Cu and Fe-Ni nanoscale oxides and their carbonaceous composites.

    Science.gov (United States)

    Trujillo-Reyes, Jésica; Sánchez-Mendieta, Víctor; Solache-Ríos, Marcos José; Colín-Cruz, Arturo

    2012-01-01

    Fe-Cu and Fe-Ni nanoscale oxides and their carbonaceous composites (C/Fe-Cu and C/Fe-Ni, 75/25 wt.%; C/Fe-Cu and C/Fe-Ni 95/5 wt.%), made from pyrolysis of sewage sludge, have been evaluated to remove remazol yellow textile dye from aqueous solution. The kinetic and sorption isotherms experimental results were best fitted to the pseudo-second-order kinetic and Langmuir-Freundlich isotherm models, which indicates that the sorption mechanism may be chemisorption onto heterogeneous surfaces. Fe-Ni and Fe-Cu nanoscale oxides adsorption capacities were 157.8 mg/g and 117.6 mg/g, resulting in nearly 83% and 70% of dye removal, respectively, using 100 mg/L of initial dyestuff concentration and 10 mg of each material. The adsorption capacities of Fe-Cu, Fe-Ni oxides and C/FCu 75/25%, C/Fe-Ni 75/25% composites provide better results at pH between 3 and 5. In addition, three sorption-desorption cycles using 30% H2O2 solution and distilled water were performed: sorption efficiencies for all materials decreased after each cycle; nevertheless, Fe-Cu and Fe-Ni nanoscale oxides were the best materials for the removal of remazol yellow dye.

  7. Bias voltage effects on tunneling magnetoresistance in Fe/MgAl2O4/Fe (001 ) junctions: Comparative study with Fe/MgO/Fe(001) junctions

    Science.gov (United States)

    Masuda, Keisuke; Miura, Yoshio

    2017-08-01

    We investigate bias voltage effects on the spin-dependent transport properties of Fe/MgAl 2O 4 /Fe(001) magnetic tunneling junctions (MTJs) by comparing them with those of Fe/MgO/Fe(001) MTJs. By means of the nonequilibrium Green's function method and the density functional theory, we calculate bias voltage dependencies of magnetoresistance (MR) ratios in both the MTJs. We find that in both the MTJs, the MR ratio decreases as the bias voltage increases and finally vanishes at a critical bias voltage Vc. We also find that the critical bias voltage Vc of the MgAl 2O 4 -based MTJ is clearly larger than that of the MgO-based MTJ. Since the in-plane lattice constant of the Fe/MgAl 2O 4 /Fe(001) supercell is twice that of the Fe/MgO/Fe(001) one, the Fe electrodes in the MgAl 2O 4 -based MTJs have an identical band structure to that obtained by folding the Fe band structure of the MgO-based MTJs in the Brillouin zone of the in-plane wave vector. We show that such a difference in the Fe band structure is the origin of the difference in the critical bias voltage Vc between the MgAl 2O 4 - and MgO-based MTJs.

  8. Ethylbenzene dehydrogenation over binary FeOx–MeOy/Mg(Al)O catalysts derived from hydrotalcites

    KAUST Repository

    Balasamy, Rabindran J.

    2010-12-20

    A series of FeOx-MeOy/Mg(Al)O catalysts were prepared from hydrotalcite-like compounds as precursors and were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The hydrotalcite-like precursors of the metal compositions of Mg3Fe 0.25Me0.25Al0.5 (Me = Cu, Zn, Cr, Mn, Fe, Co and Ni) were coprecipitated from the nitrates of metal components and calcined to mixed oxides at 550 °C. After the calcination, the mixed oxides showed high surface area of 150-200 m2 gcat -1, and were mainly composed of (MgMe)(Fe3+Al)O periclase in the bulk, whereas the surface was enriched by (MgMe)(Fe3+Al)2O 4 pinel. Among the Me species tested, Co2+ was the most effective, followed by Ni2+. Co2+ addition increased the activity of original FeOx/Mg(Al)O catalyst, whereas Ni2+ increased the activity at the beginning of reaction, but deactivated the catalyst during the reaction. The other metals formed isolated MeOx species in the catalyst, resulting in a decrease in the activity compared to the original FeOx/Mg(Al)O catalyst. The active Fe species exists as metastable Fe3+ on the FeOx/Mg(Al)O catalyst. By the addition of Co2+, the reduction-oxidation between Fe3+ and Fe2+ was facilitated and, moreover, the active Fe3+ species was stabilized. It is likely that the dehydrogenation proceeds on the active Fe3+ species via its reduction-oxidation assisted by Co 2+. © 2010 Elsevier B.V.

  9. Hyperfine and magnetic properties of Fe-Cu clusters and Fe precipitates embedded in a Cu matrix

    Energy Technology Data Exchange (ETDEWEB)

    Klautau, A B [Faculdade de Fisica, Universidade Federal do Para, 66075-110, Belem, PA (Brazil); Socolovsky, L M [Laboratorio de Solidos Amorfos, INTECIN, Facultad de Ingenieria, Universidad de Buenos Aires, C1063ACV, Buenos Aires (Argentina); Nogueira, R N [Faculdade Taboao da Serra, 06768-000, Taboao da Serra, SP (Brazil); Petrilli, H M, E-mail: aklautau@ufpa.b [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05315-970 Sao Paulo, SP (Brazil)

    2009-12-16

    Using the first-principles real-space linear muffin-tin orbital method within the atomic sphere approximation (RS-LMTO-ASA) we study hyperfine and local magnetic properties of substituted pure Fe and Fe-Cu clusters in an fcc Cu matrix. Spin and orbital contributions to magnetic moments, hyperfine fields and the Moessbauer isomer shifts at the Fe sites in Fe precipitates and Fe-Cu alloy clusters of sizes up to 60 Fe atoms embedded in the Cu matrix are calculated and the influence of the local environment on these properties is discussed.

  10. Comparison of Microstructural and Morphological Properties of Electrodeposited Fe-Cu Thin Films with Low and High Fe : Cu Ratio

    Directory of Open Access Journals (Sweden)

    Umut Sarac

    2013-01-01

    Full Text Available Fe-Cu films with low and high Fe : Cu ratio have been produced from the electrolytes with different Fe ion concentrations at a constant deposition potential of −1400 mV versus saturated calomel electrode (SCE by electrodeposition technique onto indium tin oxide (ITO coated conducting glass substrates. It was observed that the variation of Fe ion concentration in the electrolyte had a very strong influence on the compositional, surface morphological, and microstructural properties of the Fe-Cu films. An increase in the Fe ion concentration within the plating bath increased the Fe content, consequently Fe : Cu ratio within the films. The crystallographic structure analysis showed that the Fe-Cu films had a mixture of face-centered cubic (fcc Cu and body centered cubic (bcc α-Fe phases. The average crystallite size decreased with the Fe ion concentration. The film electrodeposited from the electrolyte with low Fe ion concentration exhibited a morphology consisting of dendritic structures. However, the film morphology changed from dendritic structure to cauliflower-like structure at high Fe ion concentration. The surface roughness and grain size were found to decrease significantly with increasing Fe ion concentration in the electrolyte. The significant differences observed in the microstructural and morphological properties caused by the change of Fe ion concentration in the electrolyte were ascribed to the change of Fe : Cu ratio within the films.

  11. Investigations on structural, vibrational and dielectric properties of nanosized Cu doped Mg-Zn ferrites

    Science.gov (United States)

    Yadav, Anand; Rajpoot, Rambabu; Dar, M. A.; Varshney, Dinesh

    2016-05-01

    Transition metal Cu2+ doped Mg-Zn ferrite [Mg0.5Zn0.5-xCuxFe2O4 (0.0 ≤ x ≤ 0.5)] were prepared by sol gel auto combustion (SGAC) method to probe the structural, vibrational and electrical properties. X-ray diffraction (XRD) pattern reveals a single-phase cubic spinel structure without the presence of any secondary phase corresponding to other structure. The average particle size of the parent Mg0.5Zn0.5Fe2O4 is found to be ~29.8 nm and is found to increase with Cu2+ doping. Progressive reduction in lattice parameter of Mg0.5Zn0.5Fe2O4 has been observed due to difference in ionic radii of cations with improved Cu doping. Spinel cubic structure is further confirmed by Raman spectroscopy. Small shift in Raman modes towards higher wave number has been observed in doped Mg-Zn ferrites. The permittivity and dielectric loss decreases at lower doping and increases at higher order doping of Cu2+.

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

    Science.gov (United States)

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

    2017-02-01

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

  13. Structural and magnetic properties of epitaxial Fe/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Harada, Y. E-mail: t5101008@iwate-u.ac.jp; Nakanishi, Y.; Yoshimoto, N.; Yamaguchi, A.; Nakamura, M.; Yoshizawa, M

    2004-05-01

    We have grown FCC-Fe/Cu multilayers by molecular beam epitaxy method. The structural and magnetic properties were studied by RHEED, XRD and magnetoresistance measurement (MR). The RHEED images confirmed that Fe/Cu multilayers were epitaxially grown on Cu(1 0 0). Furthermore, a clear negative MR was observed. The buffer layer condition for MR effect will be discussed.

  14. Preparation of magnetic recoverable nanosize Cu-Fe2O3/Fe photocatalysts.

    Science.gov (United States)

    Kang, Hsu-Ya; Wang, H Paul

    2013-07-02

    Iron based catalysts generally have the advantage of the easily operated magnetically recovery from application sites. In the present work, paramagnetic iron and copper core-shell nanoparticles having the iron fractions (X(Fe) = Fe/(Cu+Fe)) of 0.33-1.0 were prepared and characterized by in situ synchrotron X-ray absorption and scattering spectroscopy. During the temperature-programmed carbonization (TPC) of Cu(2+)- and Fe(3+)-β-cyclodextrin (CD) complexes, a rapid reduction of Cu(II) occurs at about 453 K together with a growth of the metallic copper (Cu). Iron proceeds in the distinct growth path. At 453-513 K, the Fe(III) → Fe(II) → Fe consecutive reduction is observed. The unreduced Fe(III) (7-13%) is coated on the surfaces of the Fe nanoparticles (as Fe2O3/Fe). Growth of the Fe nanoparticle is inhibited by the surface Fe2O3, while the steady growth in Cu is observed. The Cu has a size range of 14-18 nm in diameter, compared to the small Fe2O3/Fe ones (3-6 nm). Under the UV-visible light irradiation for four hours, methylene blue can be photocatalytically degraded (>90%) by the (Cu-Fe2O3/Fe)@C. The (Cu-Fe2O3/Fe)@C photocatalysts can effectively oxidize dye molecules, providing a promising alternative for dye degradation using solar energy. Recovery of the (Cu-Fe2O3/Fe)@C photocatalysts can be attained by applying external magnetic field to trap the ferromagnetic Cu-Fe2O3/Fe nanoparticles, which suggests an economically attractive process, especially applied in photocatalytic degradation of dye-contaminated wastewater.

  15. Effect of Mg on microstructures and properties of Al-Mg-Si-Cu aluminium alloys for automotive body sheets

    Institute of Scientific and Technical Information of China (English)

    LIU Hong; SONG Wen-ju; ZHAO Gang; LIU Chun-ming; ZUO Liang

    2005-01-01

    The effects of variation of Mg content on microstructures,the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy,optical metallographic analysis,tensile and Ericsson tests.The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si,with an increment of Mg content,the strength enhances,the specific elongation and Erisson values of alloys decrease,and the number of Mg2 Si constituent increases and that of Al(MnFe)Si type constituents reduces.Al-MgSi-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint bake cycle (I.e.artificial aging at 170 ℃ for 30 min immediately after the solution treatment and quenching).Suitable Mg content should be controlled in the range of 0.8% and 1.2 % (mass fraction).

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

    Science.gov (United States)

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

    2016-08-01

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

  17. Magnetism and site exchange in CuFeAs and CuFeSb: A microscopic and theoretical investigation

    Science.gov (United States)

    Kamusella, Sirko; Klauss, Hans-Henning; Thakur, Gohil S.; Haque, Zeba; Gupta, Laxmi C.; Ganguli, Ashok K.; Kraft, Inga; Burkhardt, Ulrich; Rosner, Helge; Luetkens, Hubertus; Lynn, Jeffrey W.; Zhao, Yang

    2017-03-01

    We have investigated the magnetic ground state of CuFeAs and CuFeSb by means of 57Fe-Mössbauer spectroscopy, muon spin rotation/relaxation (μ SR ), neutron diffraction, and electronic structure calculations. Both materials share the 111-LiFeAs crystal structure and are closely related to the class of iron-based superconductors. In both materials there is a considerable occupancy of the Cu site by Fe, which leads to ferromagnetic moments, which are magnetically strongly coupled to the regular Fe site magnetism. Our study shows that CuFeAs is close to an antiferromagnetic instability, whereas a ferromagnetic ground state is observed in CuFeSb, supporting theoretical models of anion height driven magnetism.

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

    Science.gov (United States)

    Liu, Hongyuan; Guo, Min; Zhang, Yan

    2014-01-01

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

  19. Change of Electronic Structure and Magnetic Properties with MgO and Fe Thicknesses in Fe/MgO/Fe Magnetic Tunnel Junction

    Institute of Scientific and Technical Information of China (English)

    YANG Fan; BI Xiao-fang

    2006-01-01

    The effects of the thickness of MgO and Fe on the electronic structure and magnetic properties of Fe/MgO/Fe magnetic tunnel junction was studied using the first principle method. Two series of models with MgO of different thicknesses: Fe(3)MgO(t)Fe(3) (t=1,3,5,7) and with Fe of varied thicknesses: Fe(t)MgO(3)Fe(t) (t=3,4,5,6,7) were established. Calculated results show that in all the models the magnetic moment of Fe increases at the Fe/MgO interface and surface as compared with that of the inner layers. The magnetic moment of each Fe layer was found to be independent of MgO thicknesses, while the spin-polarization of Fe layer at the interface shows a slight change in function of the MgO thicknesses. The tunneling magnetoresistance (TMR) ratio estimated by the Julliere model has the same change tendency as the spin-polarization has, and the largest value is obtained at the MgO thickness of 5 atomic layers. When the Fe thickness increases, the spin-polarization of interface Fe layer follows up an increase with a decrease. The highest TMR value is achieved when the Fe thickness is of 4 atomic layers.

  20. Formation and Oxidation Behavior of Al-Cu-Fe Quasicrystal

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Al62.5Cu25Fe12.5 alloy was prepared by arc melting. It was found that the formation of quasicrystalline phase is related to the condition of annealing, such as temperature and duration. Weight gain of Al-Cu-Fe quasicrystal during the oxidation at 700 and 800 C in dry air was measured by means of thermal balance. The oxidation kinetics showed that the quasicrystal has good oxidation resistance. Only α-Al2O3 was formed on Al62.5Cu25Fe12.5 quasicrystal. The surface morphologies of Al-Cu-Fe quasicrystal after isothermal oxidation for different times were observed.

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

    Science.gov (United States)

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

    2014-02-28

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

  2. Fe3O4/MgO/Fe Heteroepitaxial Structures for Magnetic Tunnel Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Orna, J. [University of Zaragoza, Spain; Morellon, Luis [University of Zaragoza, Spain; Algarabel, Pedro A. [University of Zaragoza, Spain; Pardo, J. A. [University of Zaragoza, Spain; Sangiao, S [Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, 50009 Spain; Magen, C [Oak Ridge National Laboratory (ORNL); Snoeck, E. [CEMES-CNRS, Toulouse, France; De Teresa, J M [Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, Zaragoza, 50009 Spain; Ibarra, M. Ricardo [University of Zaragoza, Spain

    2008-01-01

    In this work we report the growth and structural and magnetic characterization of heteroepitaxial Fe O/MgO/Fe junctions. All three layers have been deposited by pulsed laser deposition. Combining High Resolution Transmission Electron Microscopy and X-ray results, we have obtained for the heterostructure the epitaxy relation MgO(001) [100]//Fe O(001)[100]/MgO(001) [100]/Fe(001)[110]. All interfaces appear very sharp with relatively small root-mean square (rms) roughness, 0.2 nm. The magnetic coupling between Fe O and Fe electrodes is also very small, 0.03 mJ/

  3. Dechlorination of carbon tetrachloride by the catalyzed Fe-Cu process

    Institute of Scientific and Technical Information of China (English)

    XU Wen-ying; GAO Ting-yao

    2007-01-01

    The electrochemical reduction characteristics of carbon tetrachloride (CT) were investigated using cyclic voltammetry in this study. In addition, the difference in reduction mechanisms of CT between Master Builders' iron and the catalyzed Fe-Cu process was discussed. The results showed that CT was reduced directly on the surface of copper rather than by atomic hydrogen produced at the cathode in the catalyzed Fe-Cu process. The reduction was realized largely by atomic hydrogen in Master Builders' iron. The entire CT in 350 ml aqueous solution with 320 mg/L was reduced to trichloromethane and dichloromethane in 2.25 h when 100 g of scrap iron with Fe/Cu ratio of 10:1 (w/w) were used. Moreover, the reduction rate slowed with time. CT could be reduced at acidic, neutral and alkaline pH from solution by Fe-Cu bimetallic media, but the mechanisms were different. The degradation rate was not significantly influenced by pH in the catalyzed Fe-Cu process; in Master Builders' iron it clearly increased with decreasing pH. The kinetics of the reductions followed pseudo-first order in both cases. Furthermore, the reductions under acidic conditions proceeded faster than that under the neutral and alkaline conditions. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating CT-containing water and this advantage was particularly noticeable under alkaline conditions. The reduction was investigated in the cathode (Cu) and anode (Fe) compartments respectively, the results showed that the direct reduction pathway played an important role in the reduction by the catalyzed Fe-Cu process. The catalyzed Fe-Cu process is of practical value.

  4. Magnetic ordering in Fe/Co sandwiches on Cu(100).

    Science.gov (United States)

    Razee, S S A; Staunton, J B; Szunyogh, L

    2009-07-01

    We investigate magnetic correlations and local magnetic moments at finite temperatures of some Fe and Co multilayers on Cu(100) substrates, such as Co(m)Fe(n)Co(m)/Cu(100) and Fe(m)Co(n)Fe(m)/Cu(100). We use an ab initio mean-field theory of magnetic fluctuations for layered materials based on the first-principles local spin-density functional theory implemented through the screened Korringa-Kohn-Rostoker method. We find that the presence of Fe layers in the neighbourhood of a Co layer always leads to a reduction in the magnetic moment of the Co atoms, whereas that of the Fe atoms is enhanced. Of particular interest is the lack of local moment formation on the single fcc-Co layer sandwiched between two fcc-Fe layers. However, a Co layer completely immersed in a Cu environment remains ferromagnetic. The Curie temperature of the Co(m)Fe(n)Co(m)/Cu(100) system oscillates as the Fe layer thickness is increased whereas that of the Fe(m)Co(n)Fe(m)/Cu(100) system increases almost monotonically with Co layer thickness.

  5. Magnetic properties of nanostructured CuFe2O4

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  6. Computer simulations of nanoindentation in Mg-Cu and Cu-Zr metallic glasses

    DEFF Research Database (Denmark)

    Paduraru, Anca; Andersen, Ulrik Grønbjerg; Thyssen, Anders

    2010-01-01

    The formation of shear bands during plastic deformation of Cu0.50Zr0.50 and Mg0.85Cu0.15 metallic glasses is studied using atomic-scale computer simulations. The atomic interactions are described using realistic many-body potentials within the effective medium theory, and are compared with similar...... simulations using a Lennard-Jones description of the material. The metallic glasses are deformed both in simple shear and in a simulated nanoindentation experiment. Plastic shear localizes into shear bands with a width of approximately 5 nm in CuZr and 8 nm in MgCu. In simple shear, the shear band formation...

  7. First-principle Calculations of Mechanical Properties of Al2Cu, Al2CuMg and MgZn2 Intermetallics in High Strength Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    LIAO Fei

    2016-12-01

    Full Text Available Structural stabilities, mechanical properties and electronic structures of Al2Cu, Al2CuMg and MgZn2 intermetallics in Al-Zn-Mg-Cu aluminum alloys were determined from the first-principle calculations by VASP based on the density functional theory. The results show that the cohesive energy (Ecoh decreases in the order MgZn2 > Al2CuMg > Al2Cu, whereas the formation enthalpy (ΔH decreases in the order MgZn2 > Al2Cu > Al2CuMg. Al2Cu can act as a strengthening phase for its ductile and high Young's modulus. The Al2CuMg phase exhibits elastic anisotropy and may act as a crack initiation point. MgZn2 has good plasticity and low melting point, which is the main strengthening phase in the Al-Zn-Mg-Cu aluminum alloys. Metallic bonding mode coexists with a fractional ionic interaction in Al2Cu, Al2CuMg and MgZn2, and that improves the structural stability. In order to improve the alloys' performance further, the generation of MgZn2 phase should be promoted by increasing Zn content while Mg and Cu contents are decreased properly.

  8. Dehydrogenation kinetics of air-exposed MgH2/Mg2Cu and MgH2/MgCu2 studied with in situ X-ray powder diffraction

    DEFF Research Database (Denmark)

    Andreasen, A.; Sørensen, M.B.; Burkarl, R.

    2006-01-01

    The dehydrogenation kinetics of air exposed samples of MgH2/Mg2Cu and MgH2/MgCu2 have been studied with in situ time resolved X-ray powder diffraction. The X-ray setup enabled the recording of full diffraction patterns within 150 s, thereby allowing the study of structural changes combined...... sample was found to be 108 kJ/mol and 160 kJ/mol, respectively. Furthermore, substantially improved dehydrogenation kinetics of MgH2 and resistance towards oxidation of Mg due to the presence of Mg2Cu/MgCu2 are discussed in relation to previous work....

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

    Science.gov (United States)

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

    2011-12-01

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

  10. Evolution of eutectic structures in Al-Zn-Mg-Cu alloys during heat treatment

    Institute of Scientific and Technical Information of China (English)

    FAN Xi-gang; JIANG Da-ming; MENG Qing-chang; ZHANG Bao-you; WANG Tao

    2006-01-01

    The evolution of the eutectic structures in the alloys with different copper contents during heat treatment was studied by scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and differential scanning calorimetry(DSC). The as cast microstructures involve α(Al), eutectic(α(Al) + Mg(Al, Cu, Zn)2) and Al7Cu2Fe. The Al2CuMg particles form during heat treatment. The volume of coarse phases decreases quickly in the initial 12 h during heat treatment. The volume of coarse phases change a little at 400 and 420 ℃. Copper content has a great influence on the evolution of the eutectic. The coarse phases dissolve slowly in alloy with higher copper content.

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

    DEFF Research Database (Denmark)

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

    1999-01-01

    The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary crystalliza......The Cu clustering stage before the crystallization of Fe-Si-B-Nb-Cu amorphous alloys have been studied by three dimensional atom probe (3DAP) small-angle neutron scattering (SANS) and high sensitive differential calorimetry (DSC). Cu clustering occurs prior to the onset of the primary...

  12. Superconducting spin-valve effect and triplet superconductivity in Co Ox/Fe1/Cu /Fe2/Cu /Pb multilayer

    Science.gov (United States)

    Leksin, P. V.; Garif'yanov, N. N.; Kamashev, A. A.; Fominov, Ya. V.; Schumann, J.; Hess, C.; Kataev, V.; Büchner, B.; Garifullin, I. A.

    2015-06-01

    We report magnetic and superconducting properties of the modified spin-valve system CoOx/Fe1/Cu /Fe2/Cu /Pb . Introduction of a Cu interlayer between Fe2 and Pb layers prevents material interdiffusion process, increases the Fe2/Pb interface transparency, stabilizes and enhances properties of the system. This allowed us to perform a comprehensive study of such heterostructures and to present theoretical description of the superconducting spin-valve effect and of the manifestation of the long-range triplet component of the superconducting condensate.

  13. Microwave-absorbing properties of Ni{sub 0.50-x}Zn{sub 0.50-x}Me{sub 2x}Fe{sub 2}O{sub 4} (Me=Cu, Mn, Mg) ferrite-wax composite in X-band frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, Alexandre R. [DCMM, Pontificia Universidade Catolica do Rio de Janeiro-R. Marques de Sao Vicente, 225, 22453-900, Rio de Janeiro, RJ (Brazil)], E-mail: arbueno@rdc.puc-rio.br; Gregori, Maria L. [IPqM-Instituto de Pesquisas da Marinha-Rua Ipiru, Praia da Bica, Ilha do Governador, 21931-090, Rio de Janeiro, RJ (Brazil); Nobrega, Maria C.S. [COPPE/UFRJ PEMM-Universidade Federal do Rio de Janeiro-Ilha do Fundao, C.P. 68505, 21945-970, Rio de Janeiro, RJ (Brazil)

    2008-03-15

    Ni{sub 0.5-x}Zn{sub 0.5-x}Me{sub 2x}Fe{sub 2}O{sub 4} (Me=Cu, Mg, Mn; x=0.00 and 0.10) ferrite powders were prepared by the nitrate-citrate precursor method and investigated as a radar absorbing material (RAM) in a frequency range of 8-12 GHz (X-band). The effects of Cu{sup 2+}, Mn{sup 2+} and Mg{sup 2+} substitution on the microwave-absorbing feature, the complex permeability ({mu}{sub r}*) and the complex permittivity ({epsilon}{sub r}*) were investigated. The microwave-absorbing properties were studied as a function of frequency, Me{sup 2+} content, and thickness of absorber. The adoption of Cu{sup 2+} and Mn{sup 2+} substitution was found to improve the microwave absorption and bandwidth, while the substitution of Mg{sup 2+} was found to reduce the microwave absorption in relation to non-substituted NiZn ferrite.

  14. Simulation of Cu-Mg metallic glass: Thermodynamics and structure

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2004-01-01

    We have obtained effective medium theory interatomic potential parameters suitable for studying Cu-Mg metallic glasses. We present thermodynamic and structural results from simulations of such glasses over a range of compositions. We have produced low-temperature configurations by cooling from...

  15. Position of Fe ions in MgO crystalline structure

    Directory of Open Access Journals (Sweden)

    Szczerba Jacek

    2015-03-01

    Full Text Available Magnesium oxide (MgO is one of the most important raw materials in many branches of industry. Magnesium oxide is a popular refractory raw material because of its high refractoriness and high resistance to basic slags and environment. In many cases, use of MgO is limited by its properties, especially the presence of secondary phases like iron oxides. The amount and distribution of iron oxides can strongly influence the technological properties of MgO and depend on the manufacturing method, particularly the heat-treatment process. The aim of the study was to evaluate the influence of the heat-treatment process on amount and distribution of iron ions in a magnesium oxide lattice. The 57Fe Mössbauer effect measurements of fused and sintered magnesium oxide samples doped by the iron oxide were conducted. Investigation reveals in both cases the presence of Fe2+ as well as Fe3+ ions. Fe2+ ions occupy Mg2+ octahedral sites in the MgO lattice, whereas the Fe3+ ions are located in highly distorted octahedral coordination. The amount of Fe2+ varies from around 66% for fused samples to 30% for sintered samples.

  16. Effect of Fe Particle on the Surface Peeling in Cu-Fe-P Lead Frame

    Institute of Scientific and Technical Information of China (English)

    SU Juanhua; LIU Ping; DONG Qiming; LI Hejun; TIAN Baohong

    2006-01-01

    Under the surface peeling of Cu-Fe-P lead frame alloy larger Fe particles were observed by energy dispersive spectroscopy. By using the large strain two-dimension plane strain model and elastic-plastic finite element method, the cause for peeling damage of Cu-Fe-P lead frame alloy was investigated. The results show that when the content of Fe particles is more than 30% at local Fe-rich area the intense stress concentration in the Fe particle would make the Fe particle broken up. The high equivalent stress mutation and the mismatch of equivalent strain 10% at the two sides of interface make it easy to develop the crack and peeling damage on finish rolling. The larger Fe particles in the Cu-Fe-P alloy should be avoided.

  17. Structural, dielectric and ferroelectric studies of (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} magnetoelectric nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Khader, S. Abdul, E-mail: khadersku@gmail.com; Sankarappa, T., E-mail: sankarappa@rediffmail.com [Department of Physics, Gulbarga University, Gulbarga-585106, Karnataka (India); Muneeswaran, M.; Giridharan, N. V. [Department of Physics, National Institute of Technology, Tiruchirapalli-620015 (India)

    2016-05-06

    The Particulate nano-composites of ferrite and ferroelectric phases having the general formula (x) Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4} + (1-x) BaTiO{sub 3} (x=15%, 30% and 45%) were synthesized by sintering mixtures of highly ferroelectric BaTiO{sub 3} (BT) and highly magneto-strictive magnetic component Mg{sub 0.25}Cu{sub 0.25}Zn{sub 0.5}Fe{sub 2}O{sub 4}(MCZF). The presence of constituent phases of ferrite, ferroelectric and their composites were probed and confirmed by X-ray diffraction (XRD) studies. Surface morphology of the samples has been investigated using Field Emission Scanning Electron Microscope (FESEM). The variation of dielectric constant and dissipation factor as a function of frequency from 100 Hz to 1 MHz at room temperature were carried out using a Hioki LCR Hi-Tester. The dielectric constant and dielectric loss were found to decrease rapidly in the low frequency region and became almost constant in the high frequency region. The electrical conductivity deduced from the measured dielectric data has been thoroughly analyzed and found that the conduction mechanism in these composites is in conformity with small polaron hopping model. The ferroelectric properties of synthesized magneto-electric nano-composites were measured using P-E loop tracer.

  18. The suitability of the simplified method of the analysis of coffee infusions on the content of Ca, Cu, Fe, Mg, Mn and Zn and the study of the effect of preparation conditions on the leachability of elements into the coffee brew.

    Science.gov (United States)

    Stelmach, Ewelina; Pohl, Pawel; Szymczycha-Madeja, Anna

    2013-12-01

    A fast and straightforward method of the analysis of coffee infusions was developed for measurements of total concentrations of Ca, Cu, Fe, Mg, Mn and Zn by flame atomic absorption spectrometry. Its validity was proved by the analysis of spiked samples; recoveries of added metals were found to be within 98-104% while the precision was better than 4%. The method devised was used for the analysis of re-distilled water infusions of six popular ground coffees available in the Polish market. Using the mud coffee preparation it was established that percentages of metals leached in these conditions varied a lot among analysed coffees, especially for Ca (14-42%), Mg (6-25%) and Zn (1-24%). For remaining metals, the highest extractabilities were assessed for Mn (30-52%) while the lowest for Fe (4-16%) and Cu (2-12%). In addition, it was found that the water type and the coffee brewing preparation method influence the concentration of studied metals in coffee infusions the most.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-08

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

  20. Characterization, structural and magnetic properties of the as-prepared Mg-substituted Cu-nanoferrites

    Energy Technology Data Exchange (ETDEWEB)

    Amer, M.A., E-mail: moazamer@hotmail.com [Physics Department, Faculty of Science, Tanta University, 31527 Tanta (Egypt); Meaz, T. [Physics Department, Faculty of Science, Tanta University, 31527 Tanta (Egypt); Yehia, M.; Attalah, S.S. [Reactor Physics Department, NRC, Atomic Energy Authority, 13759 Cairo (Egypt); Fakhry, F. [Physics Department, Faculty of Science, Tanta University, 31527 Tanta (Egypt)

    2015-06-05

    Graphical abstract: RT Mössbauer spectra of the as-prepared Cu{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} nanoparticles. - Highlights: • Cu{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} nanoparticles were prepared by the co-precipitation method. • They behaved superparamagnetically and their crystallite size was decreased with x. • Sample patterns and spectra, results and parameters showed x dependence. • Saturation magnetization was dependent on x and R. • Strain, Debye temperature and stiffness constant were changed nonlinearly with x. - Abstract: The as-prepared Cu{sub 1−x}Mg{sub x}Fe{sub 2}O{sub 4} nanoferrites, 0 ⩽ x ⩽ 1, were synthesized using the co-precipitation method. The samples were characterized using the X-ray diffraction, transmission electron microscopy, infrared (IR) and Mössbauer spectroscopy and vibrating sample magnetometer. This study proved that the samples have single-phase cubic spinel structure, nanometric size and superparamagnetic behavior. The nanoparticle and crystallite size (R) showed a dependence on the Mg ion content x. The Mössbauer spectra were analyzed and assigned to two magnetic subpatterns and/or two quadrupole doublets due to Fe ions among the tetrahedral A-sites and octahedral B-sites. Six IR absorption bands were observed and assigned to the corresponding vibration modes. The saturation magnetization showed decrease against x and proved dependence on R. The lattice constant, hopping lengths, strain, site characteristic bands and B-site force constant showed x dependence, whereas oxygen parameter and A-site force constant did not. The site ionic radii and edges, density, porosity, Debye temperature, stiffness constant, hyperfine interaction and magnetic parameters were deduced and discussed as functions of x and the cation distributions were estimated.

  1. Thermal Spin Transfer in Fe-MgO-Fe Tunnel Junctions

    NARCIS (Netherlands)

    Jia, X.; Xia, K.; Bauer, G.E.W.

    2011-01-01

    We compute thermal spin transfer (TST) torques in Fe-MgO-Fe tunnel junctions using a first principles wave-function-matching method. At room temperature, the TST in a junction with 3 MgO monolayers amounts to 10-7  J/m2/K, which is estimated to cause magnetization reversal for temperature difference

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-01-01

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

  3. EXAFS investigations of Cu-Mg-O compound

    CERN Document Server

    Sidorenko, A F; Babanov, Y A; Naumov, S V; Samokhvalov, A A

    2001-01-01

    The interest to systems containing copper oxide is connected with the problem of high-temperature superconductivity because of the closeness of its basic physical properties and properties of superconductor mother Cu-compounds. In this work, EXAFS study of the Cu sub 0 sub . sub 2 Mg sub 0 sub . sub 8 O compound is presented. A new iterative algorithm of the solution of ill-posed problem on determining three partial pair correlation functions from one EXAFS-data set near the Cu K-edge is described. The results of X-ray scattering study of a given sample show a presence of a single phase with the MgO structure and a lattice parameter of 4.219 A instead of 4.208 A for pure MgO. From the EXAFS investigations, we find the local distortion of the lattice. We revealed that the short range order differs both from a hypothetical alloy with the MgO structure and from copper oxide.

  4. Geochemistry of magnetite from Proterozoic Fe-Cu deposits in the Kangdian metallogenic province, SW China

    Science.gov (United States)

    Chen, Wei Terry; Zhou, Mei-Fu; Gao, Jian-Feng; Hu, Ruizhong

    2015-10-01

    Fe-Cu deposits in the Kangdian Fe-Cu metallogenic province, SW China, are hosted in Paleoproterozoic meta-volcanic-sedimentary sequences and are spatially associated with coeval mafic intrusions. Several well-known examples are the giant Lala, Dahongshan, and Yinachang deposits. They have a common paragenetic sequence of an early Fe-oxide stage associated with sodic alteration and a late Cu-sulfide stage associated with potassic-carbonate alteration. Magnetite dominates the Fe-oxide stage of these deposits but is also present in the Cu-sulfide stage of the Lala deposit. This study uses trace element compositions of magnetite to examine the nature and origin of the ore-forming fluids. The magnetite has variable concentrations of Ti, Al, Mg, Mn, Si, V, Cr, Ca, Co, Ni, Sc, Zn, Cu, Mo, Sn, and Ga, which are thought to have been controlled mainly by fluid compositions and/or intensive parameters (e.g., temperature and oxygen fugacity ( fO2)). Fluid-rock interaction and coprecipitating mineral phases appear to be less important in controlling the magnetite compositions. Magnetite grains in the Fe-oxide stage of the Lala and Dahongshan deposits have comparable trace element compositions and were likely precipitated from chemically similar fluids. High Ni contents of magnetite in both deposits, coupled with previous isotopic data and the fact that the two deposits are spatially associated with coeval mafic intrusions, strongly suggest that the ore-forming fluids were genetically related to the mafic magmas that formed the intrusions. Magnetite grains in the Fe-oxide stage of the Yinachang deposit have much lower V and Ni but higher Sn and Mo contents than those of the Lala and Dahongshan deposits and are thus thought to have precipitated from more oxidized and Mo-Sn-rich fluids that may have evolved from relatively felsic magmas. Magnetite grains from the Cu-sulfide and Fe-oxide stages of the Lala deposit are broadly similar in composition, but those in the Cu

  5. Effects of an intensive hog farming operation on groundwater in east Mediterranean (II): a study on K⁺, Na⁺, Cl ⁻, PO₄³⁻-P, Ca²⁺, Mg²⁺, Fe³⁺/Fe²⁺, Mn²⁺, Cu²⁺, Zn²⁺ and Ni²⁺.

    Science.gov (United States)

    Michalopoulos, Charalampos; Tzamtzis, Nikolaos; Liodakis, Stylianos

    2014-12-01

    The application of treated animal wastewater generated in concentrated animal feeding operations on surface soil (within farm borders) leads to degradation of groundwater. Effects of an intensive hog farming operation, located at a Mediterranean limestone soil coastal area, on groundwater were investigated. Treated animal wastewater was discharged on a small plot (~10.8 ha) with a geologic fault. Samples were taken from seven groundwater monitoring wells close to the farm. A significant increase of K(+), Na(+), Cl(-), PO4 (3-)-P, Ca(2+) and Mg(2+) concentrations was found in monitoring wells which are affected by the subsurface flow of groundwater. Concentrations of Fe(3+)/Fe(2+), Mn(2+), Cu(2+), Zn(2+) and Ni(2+) in all groundwater monitoring wells were extremely low. During the winter, significant increases in concentrations of K(+) and PO4 (3-)-P were noted and attributed to high precipitation, which assisted in the leaching of K and P to groundwater.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

  7. Hydrogen absorption in Mg-Ni-Fe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lupu, D. (Inst. of Isotopic and Molecular Tech., Cluj-Napoca, Romania); Biris, A.; Indrea, E.; Aldea, N.; Bucur, R.V.; Morariu, M.

    1983-01-01

    The hydrogenation properties of the alloys of overall formula Mg/sub 2/Ni/sub 1-x/Fe/sub x/ (x less than or equal to 0.37) have been studied. In this range of composition multi-phase alloys were obtained containing Mg/sub 2/Ni, Mg and more or less finely dispersed Fe in different coordination as provided by the EXAFS technique and Moessbauer spectroscopy. There is no significant substitution of Ni by Fe atoms in the Mg/sub 2/Ni lattice. Two or three plateau-pressures are observed on the pressure-composition isotherms of the hydrides with the heats of formation in the range -18.4 to 20.4 kcal/mol H/sub 2/ (-77 to -85.4 kJ/mol H/sub 2/). The hydrides of the Fe-containing alloys show higher desorption rates of hydrogen compared to the pure Mg/sub 2/Ni hydride. 17 references, 5 figures, 1 table.

  8. Thermodynamic Assessments of the Fe-Si-Cr and Fe-Si-Mg Systems

    Science.gov (United States)

    Cui, Senlin; Jung, In-Ho

    2017-09-01

    Thermodynamic assessments for the Fe-Si-Cr and Fe-Si-Mg ternary systems were conducted based on the critically evaluated and optimized thermodynamic and phase diagram data in the literature. The Gibbs energy of the liquid phase was described using the modified quasi-chemical model in pair approximation. The obtained thermodynamic descriptions of the Fe-Si-Cr and Fe-Si-Mg systems can be used to calculate any sections of the phase diagrams and thermodynamic properties of these two systems with high accuracy from room temperature to above the melting temperature.

  9. Removal of Cd2+ and Cu2+ ions from aqueous solution by using Fe-Fe3O4/graphene oxide as a novel and efficient adsorbent

    Science.gov (United States)

    Le, Giang H.; Ha, Anh Q.; Nguyen, Quang K.; Nguyen, Kien T.; Dang, Phuong T.; Tran, Hoa T. K.; Vu, Loi D.; Nguyen, Tuyen V.; Lee, Gun D.; Vu, Tuan A.

    2016-10-01

    The nano Fe-Fe3O4/graphene oxide (GO) was successfully synthesized by the precipitation method and followed by chemical reduction using FeCl3 as iron sources and NaBH4 as reducing agent. The products were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy, transmission electron microscopy (TEM), BET, x-ray photoelectron spectroscopy (XPS) and VMS. From the obtained XRD and XPS results, it revealed the formation of both Fe and Fe3O4 nano particles on GO surface. TEM images showed that both Fe3O4/GO and Fe-Fe3O4/GO had small particle size of 10-20 nm and uniform size distribution. Fe3O4/GO and Fe-Fe3O4/GO were used as adsorbents for removal of Cd2+ and Cu2+ ions from aqueous solution. Maximum adsorption capacity (Q max) of Fe-Fe3O4/GO for Cu2+ and Cd2+ are 90.0 mg g-1 and 108.6 mg g-1, respectively. These values are much higher as compared to those of Fe3O4/GO as well as those reported in the literature. Additionally, this novel adsorbent can be reused by washing with diluted Hcl solution and easily recovered by applying the magnetic field. The Cd2+ adsorption isotherm fits better for the Langmuir model that of the Freundlich model and it obeys the pseudo-second order kinetic equation.

  10. La0.8Sr0.2Fe0.8Cu0.2O3-δ as “cobalt-free” cathode for La0.8Sr0.2Ga0.8Mg0.2O3-δ electrolyte

    Science.gov (United States)

    Zurlo, Francesca; Di Bartolomeo, Elisabetta; D'Epifanio, Alessandra; Felice, Valeria; Natali Sora, Isabella; Tortora, Luca; Licoccia, Silvia

    2014-12-01

    A "cobalt-free" cathode material with stoichiometric composition La0.8Sr0.2Fe0.8Cu0.2O3-δ (LSFCu) was specifically developed for use with La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte in intermediate temperature solid oxide fuel cell (IT-SOFC) systems. The chemical stability of LSFCu in contact with LSGM electrolyte was investigated by structural and morphological analysis. The electrochemical properties of LSFCu dense pellets were investigated in the temperature range 600-750 °C by electrochemical impedance spectroscopy (EIS). LSFCu|LSGM|LSFCu symmetrical cells were prepared and area specific resistance (ASR) values, directly depending on the rate limiting step of the oxygen reduction reaction, were evaluated. Fuel cells were prepared using LSFCu as cathode material on a LSGM pellet and electrochemical tests were performed in the 700-800 °C temperature range and compared to similar fuel cells prepared by using commercial La0.6Sr0.4Fe0.8Co0.2O3-δ (LSFCo) as a cathode. The maximum current density and power density recorded for LSFCu and LSFCo were similar. This fact demonstrates that Cu can be used as Co substitute in perovskite cathode materials.

  11. Atomic Structure of Ca40+xMg25Cu35-x Metallic Glasses (Preprint)

    Science.gov (United States)

    2011-12-01

    13 Approved for public release; distribution unlimited fivefold bonds, with local atom arrangements very similar to the competing Mg2Cu ( Laves phase ...Ca50Mg25Cu25 alloys forms three equally probable crystal phases , CaMg2 Cu2Mg and CaCu [5,6]. CaMg2 is a hexagonal Laves phase (space group P63/mmc...containing 12 Mg and 4 Ca atoms in the first shell. Cu2Mg is a cubic Laves phase (space group is Fd-3m, space group number 227) with the lattice

  12. Itinerant magnetism in metallic CuFe2Ge2.

    Science.gov (United States)

    Shanavas, K V; Singh, David J

    2015-01-01

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

  13. Effect of Mg, Si and Cu content on the microstructure of dilute 6000 series aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jaafar, Aiza, E-mail: cnaizza@gmail.com [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Rahmat, Azmi [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibah, 02600 Jejawi, Arau Perlis (Malaysia); Hussain, Zuhailawati [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Zainol, Ismail [Chemistry Department, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, 35900 Tanjung Malim, Perak (Malaysia)

    2011-09-01

    Highlights: > The main precipitates formed in the artificially aged dilute alloys are needle-shaped. > The ageing temperature of 100 deg. C is found to be too low to form precipitates. > The number density of precipitates increases with increasing solute contents. > There is a correlation between Mg{sub 2}Si, Si and Cu content and alloys microstructure. > The precipitates kinetics is faster in the less dilute alloys. - Abstract: The effect of Mg, Si and Cu content on the microstructural development during ageing treatment of dilute 6000 series alloys have been investigated using transmission electron microscopy (TEM). Four dilute alloys were used in this study. These alloys were subjected to quenching and artificial ageing at 100 deg. C, 185 deg. C and 300 deg. C. The microstructural developments of the precipitates formed were monitored by TEM. The ageing temperature of 100 deg. C was found to be too low to form precipitates. It was found that needle or rod-shaped precipitates were formed in the alloys after ageing at 185 and 300 deg. C. Prolong ageing up to 1000 h at 300 deg. C resulted in the formation of Mg{sub 2}Si precipitate that coexists with the type of AlFeSi and Si precipitates. The results show a correlation between the Mg{sub 2}Si, Si and Cu content on the microstructure of the four dilute alloys after ageing treatment.

  14. Magnetic properties of nanocrystalline Fe-Cu-Si-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, Y; Ohta, M, E-mail: yoshihito_yoshizawa@hitachi-metals.co.j [Advanced Electronics Research Laboratory, Hitachi Metals, Ltd., 5200 Mikajiri, Kumagaya, Saitama 360-0843 (Japan)

    2009-01-01

    Recently, nanocrystalline Fe-Cu-B and Fe-Cu-Si-B soft magnetic alloys with high saturation magnetic flux density more than 1.8 T and low coercivity of about 6 A m{sup -1} were developed by annealing melt-quenched alloys containing 1.3 -1.5 at % Cu and 0 - 7 at % Si. In this work, the magnetic properties of annealed Fe{sub 77.5-x}Cu{sub x}Si{sub 15.5}B{sub 7} alloys with high Si content prepared by melt spinning are reported. The appropriate Cu content in this alloy system shifted to Cu content higher than that of the reported Fe-Cu-Si-B alloys with high B{sub s}. The annealed alloy with x = 2.0 showed the H{sub c} of about 10 A m{sup -1}, the B{sub 8000} of 1.47 T, and low magnetostriction of +4.8 x 10{sup -6}.

  15. Magneto Seebeck effect in Co-Fe-B/MgO/Co-Fe-B tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Muenzenberg, Markus [I. Physikalisches Institut, Universitaet Goettingen (Germany); Drewello, Volker; Ebke, Daniel; Reiss, Guenter; Thomas, Andy [Department of Physics, Bielefeld University (Germany); Peretzki, Patrick; Seibt, Michael [IV. Physikalisches Institut, Universitaet Goettingen (Germany); Czerner, Michael; Bachmann, Michael; Heiliger, Christian [I. Physikalisches Institut, Universitaet Giessen (Germany)

    2011-07-01

    Co-Fe-B/MgO/Co-Fe-B devices showing a giant TMR effect are possible candidates for the generation of spin-currents by thermal heating. We present the observation of a magneto Seebeck effect in Co-Fe-B/MgO/Co-Fe-B magnetic tunnel junctions (MTJs). The effects could be used for thermal spin-injection and thermally driven spin-transfer torque. The samples presented in this work consist of a minimal pseudo-spin-valve stack with sputtered Ta and Co-Fe-B layers and an e-beam evaporated MgO barrier. The MTJs are heated by a diode laser which achieves powers of up to 100 mW and is focused onto the sample in a standard confocal microscope setup. The heating is simulated by finite element methods and the experimental results are compared with ab initio calculations of the magneto-thermoelectric power and of the spin-Seebeck coefficient.

  16. Fe nanoparticles embedded in MgO crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shalimov, Artem; Potzger, Kay; Talut, Georg; Reuther, Helfried; Zhou, Shengqiang; Baehtz, Carsten; Fassbender, Juergen [Forschungszentrum Dresden-Rossendorf, Bautzner Landstrasse 128, 01328 Dresden (Germany); Geiger, Dorin; Lichte, Hannes [Technical University, Dresden (Germany); Misiuk, Andrzej [Institute of Electron Technology, Warsaw (Poland); Stromberg, Frank [Universitaet Duisburg-Essen (Germany)

    2009-07-01

    Iron nanoparticles embedded in MgO crystals were synthesized by Fe{sup +} ion implantation at an energy of 100 keV and varying fluences from 3.10{sup 16} to 3.10{sup 17} cm{sup -2}. Investigations of structural and magnetic properties of Fe nanoparticles have been performed using magnetometry, X-ray diffraction, transmission electron microscopy and Moessbauer spectroscopy, as well as by theoretical Preisach modeling of bistable magnetic systems. It has been found that {alpha}- and {gamma}-Fe nanoparticles are formed for all fluences. The content of the {alpha}-Fe phase increases at higher fluences and after annealing. The influence of post-implantation annealing at 800 C in vacuum and under enhanced up to 10 kbar hydrostatic pressure in argon atmosphere on the formation of nanoparticles has been analyzed.

  17. Thermoelectricity and disorder of FeCo/MgO/FeCo magnetic tunnel junctions

    NARCIS (Netherlands)

    Wang, S.Z.; Xia, K.; Bauer, G.E.W.

    2014-01-01

    We compute the thermoelectric transport parameterized by the Seebeck coefficient and thermal/electric conductance of random-alloy FeCo/MgO/FeCo(001) magnetic tunnel junctions (MTJs) from first principles using a generalized Landauer-Büttiker formalism. The thermopower is found to be typically smalle

  18. CASTABILITY OF Al-Li-Mg AND Al-Li-Cu-Mg ALLOYS

    OpenAIRE

    1987-01-01

    The objective of the present work is to study the casting characteristics of various Al-Li alloys, which include fluidity and strengths of the alloys and their interaction with cast molds. Materials investigated are Al-Li-Mg and Al-Li-Cu-Mg alloys with Li content of 2.5 wt%. The results show that sand molds with resin binders are good for Al-Li casting. Ceramic coatings can further reduce the metal-mold interactions. However, the permeability is also reduced by coating. The fluidity of Li-bea...

  19. Magnetic behaviour investigation on symmetric spin valves of Co/Cu/NiFe and NiFe/Cu/Co

    Institute of Scientific and Technical Information of China (English)

    李铁; 沈鸿烈

    2002-01-01

    In this paper, we have obtained and investigated the magnetic behaviours of the ferromagnetic layer in thesymmetric spin valves of Co/Cu/NiFe and NiFe/Cu/Co by measuring with a vibrating sample magnetometer andanalysing in terms of the multi-domain Ising models. It has been found that some magnetic layer can have quitedifferent magnetic behaviours in different structures of spin valves, depending on the properties of the under-layer. Inour investigation, we have found that the magnetic behaviour of a Co layer depends mainly on the magnetization of theunder-layer, whereas this is not the case for the NiFe layer.

  20. Effect of Cu surface segregation on the exchange coupling field of NiFe/FeMn bilayers

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The NiFe/FeMn bilayers with different buffer layers (Ta or Ta/Cu) were prepared by magnetron sputtering.Results show that the exchange coupling field of NiFe/FeMn films with Ta buffer is higher than that of the films with Ta/ Cu buffer. We analysed the reasons by investigating the crystallographic texture, surface roughness and surface segregation of both films, respectively. We found that the decrease of the exchange coupling fields of NiFe/FeMn films with Ta/Cu buffer layers was mainly caused by the Cu surface segregation on NiFe surface.

  1. The role of Mg interface layer in MgO magnetic tunnel junctions with CoFe and CoFeB electrodes

    Directory of Open Access Journals (Sweden)

    Hyunsoo Yang

    2012-03-01

    Full Text Available The tunneling spin polarization (TSP is directly measured from reactively sputter deposited crystalline MgO tunnel barriers with various CoFe(B compositions using superconducting tunneling spectroscopy. We find that the Mg interface layer thickness dependence of TSP values for CoFeB/Mg/MgO junctions is substantially different from those for CoFe/Mg/MgO especially in the pre-annealed samples due to the formation of boron oxide at the CoFeB/MgO interface. Annealing depletes boron at the interface thus requiring a finite Mg interface layer to prevent CoFeOx formation at the CoFeB/MgO interface so that the TSP values can be optimized by controlling Mg thickness.

  2. Atomistic simulations of Mg-Cu metallic glasses: Mechanical properties

    DEFF Research Database (Denmark)

    Bailey, Nicholas; Schiøtz, Jakob; Jacobsen, Karsten Wedel

    2004-01-01

    The atomistic mechanisms of plastic deformation in amorphous metals are far from being understood. We have derived potential parameters for molecular dynamics simulations of Mg-Cu amorphous alloys using the Effective Medium Theory. We have simulated the formation of alloys by cooling from the melt......, and have used these glassy configurations to carry out simulations of plastic deformation. These involved different compositions, temperatures (including zero), and types of deformation (uniaxial strain/pure shear), and yielded stress-strain curves and values of flow stress. Separate simulations were...

  3. Site occupation, phase stability, crystal and electronic structures of the doped S phase (Al2CuMg)

    Science.gov (United States)

    Gu, Jianglong; Gu, Huimin; Zhai, Yuchun; Ma, Peihua

    2016-07-01

    The S phase (Al2CuMg) is an important strengthening phase for the Al-Cu-Mg alloys, which are widely used in the aerospace and transportation industries. The commonly added alloying elements (Mn, Ti, Zr) and the impurity elements (Fe and Si) in the Al-Cu-Mg alloys are always found in the S phase. First-principles calculations based on the density functional theory (DFT) were used to investigate the influence of doping Mn, Ti, Zr, Fe and Si elements on the S phase. Key findings demonstrated that these elements prefer to occupy different atomic sites in the S phase. Ti and Zr improved the structural stability of the S phase. The bulk modulus of the Fe, Si, Ti and Zr doped S phases becomes larger than that of the pure S phase. Both the crystal and electronic structures of the S phase are affected by the dopants. The results of this study provide a better theoretical understanding of the S phase, providing guidance for improved composition design and performance optimization of Al-Cu-Mg alloys.

  4. Piezoelectric, dielectric and magnetic properties of (1-x)Pb[Zr, Ti, (Mg{sub 1/2}W{sub 1/2}), (Ni{sub 1/3}Nb{sub 2/3})]O{sub 3}+x(Ni, Co, Cu)FeO{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Chao Xiaolian [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China); Yang Zupei, E-mail: yangzp@snnu.edu.c [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China); Dong Mingyuan; Zhang Yi [Key Laboratory for Macromolecular Science of Shaanxi Province, School of Chemistry and Materials Science, Shaanxi Normal University, Xi' an, 710062 Shaanxi (China)

    2011-08-15

    The phase structure, microstructure, piezoelectric properties, dielectric characteristic and the ME effect of magnetoelectric Pb[Zr{sub 0.23}Ti{sub 0.36}+0.02(Mg{sub 1/2}W{sub 1/2})+0.39(Ni{sub 1/3}Nb{sub 2/3})]O{sub 3} (PZT)+xNi{sub 0.8}Co{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} (NCCF) composite ceramics were prepared by the conventional solid state reaction method. The structural analysis of both the constituent phases and their composites was carried out by X-ray diffraction, energy dispersive spectrometry and scanning electron microscopy. The results showed cubic spinel structure for ferrite phase and tetragonal perovskite structure for ferroelectric phase. The piezoelectric constant, dielectric constant, Curie temperature, remanent polarization and coercive electric field decreased with increase of ferrite content. The coercive field strength, saturation magnetization and remanent magnetization increased with increasing ferrite content. - Highlights: (1-x)Pb[Zr{sub 0.23}Ti{sub 0.36}+0.02(Mg{sub 1/2}W{sub 1/2})+0.39(Ni{sub 1/3}Nb{sub 2/3})] O{sub 3}+xNi{sub 0.8}Co{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} composites have been prepared by the conventional ceramics technique. However, there is little work that can give piezoelectric characteristics of ME. In this work, the magnetoelectric and piezoelectric properties of magnetoelectric composites are investigated.

  5. Phase diagram determination and thermodynamic modeling of the Cu-Mg-Si system

    Directory of Open Access Journals (Sweden)

    Zhao J.

    2016-01-01

    Full Text Available 13 ternary Cu-Mg-Si alloys were prepared by means of the powder metallurgy method. Phase equilibria at 500 and 700 oC of the Cu-Mg-Si system were determined using X-ray diffraction analysis (XRD. The existence of 3 ternary compounds in this system was verified: CuMgSi_Sigma (Cu16Mg6Si7, Tau (Cu3Mg2Si, and Laves ((Cu0.8Si0.22(Mg0.88Cu0.12. A thermodynamic modeling for the Cu-Mg-Si system was then conducted on the basis of the experimental data obtained in this work and those critically reviewed from the literature. The complex phase relationship between Laves phase and other phases has been successfully modeled in this work. Comparisons between the calculated and the measured phase diagrams show that most of the experimental data can be reproduced by the presently obtained thermodynamic parameters.

  6. Room-temperature perpendicular magnetic anisotropy of MgO/Fe/MgO ultrathin films

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, A.; Ślęzak, T.; Przewoźnik, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Skowroński, W.; Stobiecki, T. [Department of Electronics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Wilgocka-Ślęzak, D. [Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland); Qin, Q. H.; Dijken, S. van [NanoSpin, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto (Finland); Korecki, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

    2013-12-14

    We used the anomalous Hall effect to study the magnetic properties of MgO/Fe(t)/MgO(001) structures in which the Fe thickness t ranged from 4 Å to 14 Å. For the iron deposited at 140 K, we obtained perpendicular magnetization at room temperature below the critical thickness of t{sub c} = (9 ± 1) Å. In the vicinity of t{sub c}, the easy magnetization axis switched from an out-of-plane orientation to an in-plane orientation, and the observed spin-reorientation transition was considered in terms of the competition among different anisotropies. The perpendicular magnetization direction was attributed to magnetoelastic anisotropy. Finally, the temperature-dependent spin-reorientation transition was analyzed for Fe thicknesses close to t{sub c}.

  7. Preparation and Properties of Amorphous NiFe/Cu/NiFe Thin Films

    Institute of Scientific and Technical Information of China (English)

    YE Yun; JIANG Ya-dong; HU Wen-cheng; ZENG Hong-juan

    2004-01-01

    The amorphous of Permalloy on the copper subtract was studied using composite electroplating method. A portion of hydrogen brings the counteraction on the surface of cathode leading nickel-iron alloys to be anomalous in the process of co-depositing. The results of X-ray diffraction (XRD) show that the Ni-Fe alloys layer is amorphous. The Giant Magneto -Impedance (GMI) effect of Ni-Fe alloys was obtained under the optimal conditions, dependence on the soft magnetic property of Ni-Fe amorphous thin film. As a result, the ratios△ Z/Z of NiFe/Cu/NiFe amorphous thin film are 30% at 40 kHz which is in low frequency. Furthermore, the GMI value of NiFe/Cu/NiFe amorphous thin film with a sandwich structure is higher than that of single-layer ferromagnetic films of the same thickness.

  8. Tunneling conductance studies in the ion-beam sputtered CoFe/Mg/MgO/NiFe magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Braj Bhusan; Chaudhary, Sujeet [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2013-06-03

    Magnetic tunnel junctions consisting of CoFe(10 nm)/Mg(1 nm)/MgO(3.5 nm)/NiFe(10 nm) are grown at room temperature using dual ion beam sputtering via in-situ shadow masking. The effective barrier thickness and average barrier height are estimated to be 3.5 nm (2.9 nm) and 0.69 eV (1.09 eV) at 290 K (70 K), respectively. The tunnel magnetoresistance value of 0.2 % and 2.3 % was observed at 290 K and 60 K, respectively. The temperature dependence of tunneling conductance revealed the presence of localized states present within the forbidden gap of the MgO barrier leading to finite inelastic spin independent tunneling contributions, which degrade the TMR value.

  9. In Situ Characterization of CuFe2O4 and Cu/Fe3O4 Water-Gas Shift Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Estrella, M.; Barrio, L; Zhou, G; Wang, X; Wang, Q; Wen, W; Hanson, J; Frenkel, A; Rodriguez, J

    2009-01-01

    Mixtures of copper and iron oxides are used as industrial catalysts for the water-gas shift (WGS, CO + H2O f H2 + CO2). In-situ time-resolved X-ray diffraction, X-ray absorption fine structure, and atomic pair distribution function analysis were used to study the reduction of CuFe2O4 with CO and the behavior of CuFe2O4 and Cu/Fe2O3 catalysts under WGS reaction conditions. MetalToxygenTmetal interactions enhance the stability of Cu 2+ and Fe 3+ in the CuFe2O4 lattice, and the mixed-metal oxide is much more difficult to reduce than CuO or Fe2O3. Furthermore, after heating mixtures of CuFe2O4/CuO in the presence of CO or CO/H2O, the cations of CuO migrate into octahedral sites of the CuFe2O4 lattice at temperatures (200-250 C) in which CuO is not stable. Above 250 C, copper leaves the oxide, the occupancy of the octahedral sites in CuFe2O4 decreases, and diffraction lines for metallic Cu appear. From 350 to 450 C, there is a massive reduction of CuFe2O4 with the formation of metallic Cu and Fe3O4. At this point, the sample becomes catalytically active for the production of H2 from the reaction of H2O with CO. Neutral Cu 0 (i.e., no Cu 1+ or Cu 2+ cations) is the active species in the catalysts, but interactions with the oxide support cannot be neglected. These studies illustrate the importance of in situ characterization when dealing with mixed-metal oxide WGS catalysts.

  10. In-situ Characterization of CuFe2O4 and Cu/Fe3O4 Water-Gas Shift Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez,J.A.; Estrella, M.; Barrio, L.; Zhou, G.; Wang, X.; Wang, Q.; Wen, W.; Hanson, J.C.; Frenkel, A.

    2009-08-13

    Mixtures of copper and iron oxides are used as industrial catalysts for the water-gas shift (WGS, CO + H2O → H2 + CO2). In-situ time-resolved X-ray diffraction, X-ray absorption fine structure, and atomic pair distribution function analysis were used to study the reduction of CuFe2O4 with CO and the behavior of CuFe2O4 and Cu/Fe2O3 catalysts under WGS reaction conditions. Metal↔oxygen↔metal interactions enhance the stability of Cu2+ and Fe3+ in the CuFe2O4 lattice, and the mixed-metal oxide is much more difficult to reduce than CuO or Fe2O3. Furthermore, after heating mixtures of CuFe2O4/CuO in the presence of CO or CO/H2O, the cations of CuO migrate into octahedral sites of the CuFe2O4 lattice at temperatures (200-250 oC) in which CuO is not stable. Above 250 oC, copper leaves the oxide, the occupancy of the octahedral sites in CuFe2O4 decreases, and diffraction lines for metallic Cu appear. From 350 to 450 oC, there is a massive reduction of CuFe2O4 with the formation of metallic Cu and Fe3O4. At this point, the sample becomes catalytically active for the production of H2 from the reaction of H2O with CO. Neutral Cu0 (i.e. no Cu+1 or Cu+2 cations) is the active species in the catalysts, but interactions with the oxide support are necessary in order to obtain high catalytic activity. These studies illustrate the importance of in-situ characterization when dealing with mixed-metal oxide WGS catalysts.

  11. Foaming behaviour of Al-Si-Cu-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A. [Kongju National University (Korea). Dept. of Mechanical Engineering; Cho, S.S. [Chungnam National University, Daejeon (Korea). School of Materials Engineering; Lee, H.J. [Hanbat National University, Daejeon (Korea). Dept. of Building Service Engineering

    2004-12-15

    The powder metallurgical route was utilised to obtain the Al-5Si-4Cu-4Mg (alloy 544) and Al-3Si-2Cu-2Mg (alloy 322) foams. Various steps such as centrifugal atomisation, mixing alloy powder and foaming agent (1 wt-%TiH{sub 2}), cold compaction of mixture, hot extrusion and foaming in a preheated furnace were performed. Foaming behaviour of the alloys was investigated by digital microscopy, image analysis, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) mapping in this study. It was found that alloy 544 takes a shorter period of time to initiate pore nucleation than alloy 322. Alloy 544 had a higher pore growth rate than alloy 322 at the same pre-set furnace temperature. In both alloys, crack-like pore nucleation occurred between aluminium alloy powders elongated in a direction parallel to the extrusion direction. Both alloys showed the same foaming sequence of crack-like pore nucleation, spherical pore growth, coalescence of neighbouring pores and collapse of pores adjacent to the free surface of specimen. The time required to start pore nucleation decreased with the increase of foaming temperature. The cell walls of both alloys consisted of {alpha}-Al phase and eutectic phase. (author)

  12. Thermodynamic Property Study of Nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H Systems by High Pressure DSC Method

    Directory of Open Access Journals (Sweden)

    Huaiyu Shao

    2013-01-01

    Full Text Available Mg, Ni, and Cu nanoparticles were synthesized by hydrogen plasma metal reaction method. Preparation of Mg2Ni and Mg2Cu alloys from these Mg, Ni, and Cu nanoparticles has been successfully achieved in convenient conditions. High pressure differential scanning calorimetry (DSC technique in hydrogen atmosphere was applied to study the synthesis and thermodynamic properties of the hydrogen absorption/desorption processes of nanostructured Mg-H, Mg-Ni-H, and Mg-Cu-H systems. Van’t Hoff equation of Mg-Ni-H system as well as formation enthalpy and entropy of Mg2NiH4 was obtained by high pressure DSC method. The results agree with the ones by pressure-composition isotherm (PCT methods in our previous work and the ones in literature.

  13. Transport properties of microwave sintered pure and glass added MgCuZn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Madhuri, W., E-mail: madhuriw12@gmail.com [School of Advanced Sciences, VIT University, Vellore 632 014 (India); Penchal Reddy, M.; Kim, Il Gon [Department of Physics, Changwon National University, Changwon 641 773 (Korea, Republic of); Rama Manohar Reddy, N. [Department of Materials Science and Nanotechnology, Yogi Vemana University, Kadapa 516 227 (India); Siva Kumar, K.V. [Ceramic Composites Materials Laboratory, Sri Krishnadevaraya University, Anantapur 515 055 (India); Murthy, V.R.K. [Microwave Laboratory, IIT Madras, Chennai 600 036 (India)

    2013-07-01

    Highlights: • MgCuZn ferrite was successfully prepared by novel microwave sintering (MS) method. • The sintering temperature was notably reduced from 1150 °C to 950 °C for MS. • Temperature dependence of DC conductivity and AC conductivity are studied. • 1 wt% PBS glass added MS MgCuZn ferrite samples are suitable for core materials in multilayer chip inductors (MLCI). -- Abstract: A series of pure stoichiometric and 1 wt% lead borosilicate (PBS) glass added MgCuZn ferrite with the general formula Mg{sub 0.5}Cu{sub x}Zn{sub 0.5−x}Fe{sub 2}O{sub 4} with x = 0.05, 0.1, 0.15, 0.2, 0.25 and 0.3 were synthesized by microwave sintering technique. Single phase spinel structure is exhibited by the XRD patterns of these ferrites. DC and AC conductivity were investigated as a function of composition, temperature and frequency. DC conductivities were also estimated using the impedance spectroscopy analysis of Cole–Cole plots. The DC conductivities thus obtained are in good agreement with the experimental results. All the investigated samples exhibited two regions of conductivity one in the low temperature and the second in the high temperature region. It is observed that PBS glass added samples have lower conductivities than pure samples. Due to their lower conductivities and sintering temperatures the 1 wt% PBS glass added samples are suitable for multilayer chip inductor (MLCI) and high definition TV deflection yoke material application.

  14. Interfacial electronic transport phenomena in single crystalline Fe-MgO-Fe thin barrier junctions

    Energy Technology Data Exchange (ETDEWEB)

    Gangineni, R. B., E-mail: rameshg.phy@pondiuni.edu.in [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R. V. Nagar, Kalapet, Pondicherry 605 014 (India); SPINTEC, UMR 8191 CEA/CNRS/UJF-Grenoble 1/Grenoble INP, INAC, 17 rue des Martyrs, F-38054 Grenoble Cedex (France); Bellouard, C., E-mail: christine.bellouard@ijl.nancy-universite.fr; Duluard, A. [Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, BP 239, 54506 Vandoeuvre (France); Negulescu, B. [Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, BP 239, 54506 Vandoeuvre (France); UFR de Sciences et Techniques, Matériaux, microélectronique, acoustique, nanotechnologies (GREMAN), University François Rabelais, Parc de Grandmont, 37200 Tours (France); Baraduc, C.; Gaudin, G. [SPINTEC, UMR 8191 CEA/CNRS/UJF-Grenoble 1/Grenoble INP, INAC, 17 rue des Martyrs, F-38054 Grenoble Cedex (France); Tiusan, C., E-mail: coriolan.tiusan@phys.utcluj.ro [Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, BP 239, 54506 Vandoeuvre (France); Department of Physics and Chemistry, Center of Superconductivity, Spintronics and Surface Science, Technical University of Cluj Napoca, Str. Memorandumului No. 28, RO-400114 Cluj-Napoca (Romania)

    2014-05-05

    Spin filtering effects in nano-pillars of Fe-MgO-Fe single crystalline magnetic tunnel junctions are explored with two different sample architectures and thin MgO barriers (thickness: 3–8 monolayers). The two architectures, with different growth and annealing conditions of the bottom electrode, allow tuning the quality of the bottom Fe/MgO interface. As a result, an interfacial resonance states (IRS) is observed or not depending on this interface quality. The IRS contribution, observed by spin polarized tunnel spectroscopy, is analyzed as a function of the MgO barrier thickness. Our experimental findings agree with theoretical predictions concerning the symmetry of the low energy (0.2 eV) interfacial resonance states: a mixture of Δ{sub 1}-like and Δ{sub 5}-like symmetries.

  15. Metastable Demixing of Supercooled Cu-Co and Cu-Fe Alloys in an Oxide Flux

    Science.gov (United States)

    Li, D.; Robinson, M. B.; Rathz, T. J.; Williams, G.

    1998-01-01

    A systematic study on the liquid separation in supercooled Cu-Co and Cu-Fe alloys was performed using a melt fluxing which permits high supercooling to be achieved. Moreover, this method renders it possible to directly measure binodal temperatures and establish metastable liquid miscibility gap (LMG). All phase-separated samples at compositions ranging from 10 to 80 wt pct Co or to 83 wt pct Fe were found to exhibit droplet-shaped morphologies, in spite of various droplet distributions. Uniformly dispersed microstructures were obtained as the minority component was less than 20 vol.%; while beyond this percentage, serious coarsening was brought about. Calculations of the miscibility gap in the Cu-Co system and Stokes movement velocity of Co and Fe droplets in Cu matrix were made to analyze the experimental results.

  16. Unusually large spin polarization and magnetoresistance in a FeMg8-FeMg8 superatomic dimer

    Science.gov (United States)

    Zhu, Lin; Qian, Meichun; Khanna, Shiv N.

    2013-08-01

    Electronic transport across a FeMg8 magnetic superatom and its dimer has been investigated using a density functional theory combined with Keldysh nonequilibrium Green's-function formalism. For a single cluster, our studies for the cluster supported in various orientations on a Au(100) surface show that the transport is sensitive to the contact geometry. Investigations covering the cases where the axes of Mg square antiprism are 45°, perpendicular, and parallel to the transport direction, show that the equilibrium conductance, transferred charge, and current polarizations can all change significantly with orientation. Our studies on the transport across a magnetic superatom dimer FeMg8-FeMg8 focus on the effect of electrode contact distance and the support. The calculated I-V curves show negative differential resistance behavior at larger electrode-cluster contact distances. Further, the equilibrium conductance in ferromagnetic state shows an unusually high spin polarization that is about 81.48% for specific contact distance, and a large magnetoresistance ratio exceeding 500% is also found. The results show that the superatom assemblies can provide unusual transport characteristics, and that the spin polarization and magnetoresistance can be controlled via the contact geometry.

  17. Kinetic process of mechanical alloying in Fe50Cu50

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  18. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  19. A variety of microstructures in Mg/Cu super-laminate composites caused by competitive reactions during hydrogenation

    Science.gov (United States)

    Tanaka, K.; Shibata, K.; Nishida, Y.; Kurumatani, K.; Kondo, R.; Kikuchi, S.; Takeshita, H. T.

    2015-04-01

    A variety of microstructures in Mg/Cu super-laminate composites (SLCs) caused by competitive reactions during hydrogenation has been shown experimentally. Two types of MgCu2 structures, three-dimensional (3-D) network and layer, were observed after initial hydrogenation of Mg/Cu SLCs under the conditions of 573K, 86.4ks in H2 of 3-3MPa. It was proposed that Mg/Cu SLCs could be hydrogenated by two kinds of processes. The one is alloying Mg with Cu to form Mg2Cu followed by hydrogenation of Mg2Cu, leading to the formation of 3-D network of MgCu2. The other is hydrogenation of Mg followed by the reaction of MgH2 to Cu, leading to the formation of layer MgCu2. SEM observations revealed that there existed Mg2Cu nano-crystals at the interface between Mg and Cu in as-rolled Mg/Cu SLCs, and layer MgCu2 at the interface between MgH2 and Cu in pellets of MgH2 powder and Cu powder heated under the conditions of 673K, 86.4ks in H2 of 8.0 MPa. The existence of Mg2Cu nano-crystals enables alloying Mg with Cu at low temperatures (<473K).

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

    DEFF Research Database (Denmark)

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

    1996-01-01

    We have used a first-principles Green's function technique to investigate the formation of magnetic moments in Fe/Cu-N/Fe bcc (001) trilayers. We show that the magnetic moment in the paramagnetic spacer material to a first approximation may be described as a linear superposition of the magnetic...

  1. Influence of roughness at interfaces on tunneling magnetoresistance in Fe/MgO/Fe

    Energy Technology Data Exchange (ETDEWEB)

    Edalati Boostan, Saeideh [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany); Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Moradi, Hosein [Department of Physics, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Heiliger, Christian [I. Physikalisches Institut, Justus Liebig University Giessen, D-35392 (Germany)

    2010-07-01

    We propose a theoretical model for magnetic tunnel junction devices with rough interfaces based on a single-band tight-binding approximation. The high tunneling magnetoresistance (TMR) for crystalline MgO barrier was observed at room temperature which is desirable for magnetic random access memory (MRAM) applications. In real junctions the Fe and MgO atoms are interdiffused at interfaces and the numbers of diffused Fe and MgO atoms are not the same. The interface disorder is modeled by considering replacement of MgO sites by Fe atoms with a probability of n>0.5. The non-equilibrium Green's function formalism is used to calculate transport in Fe/MgO/Fe junctions. We investigate the voltage dependencies of TMR and current densities for parallel and anti-parallel configurations for majority and minority spins. The results show that the roughness decreases the TMR. The current density for the parallel (antiparallel) orientations of magnetizations decreases (increases) by including roughness at the interface.

  2. Electronic structure of ferromagnet-insulator interfaces: Fe/MgO and Co/MgO

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, M.

    2007-07-11

    In this thesis the electronic structure of Fe/MgO{sub x} and Co/MgO{sub x} ferromagnet-insulator interfaces, representing material systems which are widely used in magnetic tunnel junctions, is studied by means of spin- and angle-resolved photoemission spectroscopy. The photoemission studies focus particularly on the response of the ferromagnetic electronic system in contact with MgO of varying stoichiometries, as this reflects the mechanisms of metal-oxide bonding at real ferromagnet-insulator interfaces. The correlation between chemical bonding and electronic structure formation is analyzed by combining information from core- and valence-band photoemission spectroscopy. The spectral features are compared to band structure calculations, which are performed using the SPR-KKR method. The Fe/MgO and Co/MgO systems are prepared by molecular beam epitaxy under ultrahigh vacuum conditions on well-defined (4 x 6) GaAs(001) substrates. A structural analysis by means of low-energy electron diffraction (LEED) reveals their body-centered cubic crystalline structure, whereas the chemical characterization by Auger electron spectroscopy is used to quantify the chemical environment at the sample surfaces. The magnetic analysis, using the magneto-optical Kerr effect, reveals the uniaxial anisotropy of the ferromagnetic layers. A crucial parameter is given by the MgO degree of oxidation, which is addressed by means of core-level spectroscopy and quantified by suitable fitting procedures of the Mg 2p core level. The results of the photoemission experiments show, that the electronic structure of the Fe/MgO and Co/MgO ferromagnet/insulator interfaces and, consequently, the interfacial spin polarization are sensitively controlled by the interface chemistry. In particular, three distinct scenarios are identified: the nearly stoichiometric, the oxygen-deficient and the over-oxidized ferromagnet/MgO interface. Each case is defined by innate characteristics of the electronic structure at

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-01-01

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

  4. Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2016-03-01

    Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

  5. Microstructure development in Al-Cu-Ag-Mg quaternary alloy

    Science.gov (United States)

    Zhou, Bin; Froyen, L.

    2012-01-01

    The solidification behaviour of multi-component and multi-phase systems has been largely investigated in binary and ternary alloys. In the present study, a quaternary model system is proposed based on the well known Al-Cu-Ag and Al-Cu-Mg ternary eutectic alloys. The quaternary eutectic composition and temperature were determined by EDS (Energy Dispersive Spectrometry) and DSC (Differential Scanning Calorimetry) analysis, respectively. The microstructure was then characterised by SEM (Scanning Electron Microscope). In the DSC experiments, two types of quaternary eutectics were determined according to their phase composition. For each type of eutectic, various microstructures were observed, which result in different eutectic compositions. Only one of the determined eutectic compositions was further studied by the controlled growth technique in a vertical Bridgeman type furnace. In the initial part of the directionally solidified sample, competing growth between two-phase dendrites and three-phase eutectics was obtained, which was later transformed to competing growth between three-phase and four-phase eutectics. Moreover, silver enrichment was measured at the solidification front, which is possibly caused by Ag sedimentation due to gravity and Ag rejection from dendritic and three-phase eutectic growth, and its accumulation at the solidification front.

  6. Multistage growth of Fe-Mg-carpholite and Fe-Mg-chloritoid, from field evidence to thermodynamic modelling

    Science.gov (United States)

    Pourteau, Amaury; Bousquet, Romain; Vidal, Olivier; Plunder, Alexis; Duesterhoeft, Erik; Candan, Osman; Oberhänsli, Roland

    2015-04-01

    We provide new insights into the prograde evolution of HP/LT meta-sedimentary rocks on the basis of detailed petrologic examination, element-partitioning analysis, and thermodynamic modelling of well-preserved Fe-Mg-carpholite- and chloritoid-bearing rocks from the Afyon zone (Anatolia). Study samples, stemming from three different areas of the metamorphic belt, include typical quartz-carpholite veins as well as quartz-free and quartz-bearing phyllites. All samples exhibit multiple stages of carpholite, whereas zoning was until now rarely documented in this type of rocks. We document continuous, and discontinuous compositional (ferro-magnesian substitution) zoning of carpholite (overall XMg = 0.27-0.73) and chloritoid (overall XMg = 0.07-0.30), as well as clear equilibrium, and disequilibrium (i.e. reaction-related) textures involving carpholite and chloritoid, which consistently account for the consistent enrichment in Mg of both minerals through time, and the progressive replacement of carpholite by chloritoid. Mg/Fe distribution coefficients calculated between carpholite and chloritoid vary widely within samples (2.2-20.0). Among this range, only values of 7-11 correlate with equilibrium textures, in agreement with data from the literature. Equilibrium phase diagrams for (NaK)FMASH rock compositions are calculated using a newly modified thermodynamic dataset, including most recent data for carpholite, chloritoid, chlorite, and white mica, as well as further refinements for Fe-carpholite, and both chloritoid end-members, as required to reproduce accurately petrologic observations (phase relations, experimental constraints, Mg/Fe partitioning). Modelling reveals that Mg/Fe partitioning between carpholite and chloritoid is greatly sensitive to temperature, and calls for a future evaluation of possible use as a thermometer, valid for blueschist-facies conditions, which has so far been missing. In addition, calculations show significant effective bulk composition

  7. Interface characterization of epitaxial Fe/MgO/Fe magnetic tunnel junctions.

    Science.gov (United States)

    Wang, S G; Ward, R C C; Hesjedal, T; Zhang, X G; Wang, C; Kohn, A; Ma, Q L; Zhang, Jia; Liu, H F; Han, X F

    2012-02-01

    Following predictions by first-principles theory of a huge tunnel magnetoresistance (TMR) effect in epitaxial Fe/MgO/Fe magnetic tunnel junctions (MTJs), measured magnetoresistance (MR) ratios of about 200% at room temperature (RT) have been reported in MgO-based epitaxial MTJs. Recently, a MR ratio of about 600% has been reported at RT in MgO-based MTJs prepared by magnetron sputtering, using amorphous CoFeB as the ferromagnetic electrode. These MTJs show great potential for application in spintronic devices. Fully epitaxial MTJs are excellent model systems that enhance our understanding of the spin-dependent tunneling process as the interface is well defined and can be fully characterized. Both theoretical calculations and experimental results clearly indicate that the interfacial structure plays a crucial role in the coherent tunneling across a single crystal MgO barrier, especially in epitaxial MgO-based MTJs grown by molecular beam epitaxy (MBE). Surface X-ray diffraction, Auger electron spectroscopy, X-ray absorption spectra, and X-ray magnetic circular dichroism techniques have been reported previously for interface characterization. However, no consistent viewpoint has been reached on the interfacial structures (such as FeO layer formation at the bottom Fe/MgO interface), and it is still an open issue. In this article, our recent studies on the interface characterization of MgO-based epitaxial MTJs by X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, and spin-dependent tunneling spectroscopy, will be presented.

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

    KAUST Repository

    Wille, Catharina Gabriele

    2011-05-01

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

  9. Itinerant magnetism in metallic CuFe2Ge2.

    Directory of Open Access Journals (Sweden)

    K V Shanavas

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

  10. Rapid solidification of Cu-Fe-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Baricco, M.; Bosco, E.; Acconciaioco, G.; Rizzi, P.; Coisson, M

    2004-07-15

    Cu{sub 80-x}Ni{sub x}Fe{sub 20} (x=0, 5 and 20) alloys have been rapidly solidified by planar flow casting. X-ray diffraction (XRD) analysis of as-quenched ribbons shows bcc-Fe precipitates embedded in an fcc phase (x=0), two co-existing fcc solid solutions (x=5) and a complete solid solution of the parent elements (x=20). Thermal treatments in the temperature range between 400 and 600 deg. C give precipitation and spinodal decomposition reactions. These phase transformations have been evidenced from a variation of lattice constants, from a broadening of diffraction peaks and from TEM observations. The role of Ni content on competition between precipitation and decomposition reactions during rapid solidification and annealing is discussed in terms of thermodynamic arguments. Recent CALPHAD assessment of thermodynamic properties for Cu-Fe-Ni system has been used for an estimation of composition and volume fraction of equilibrium phases.

  11. Low temperature sintering of MgCuZn ferrite and its electrical and magnetic properties

    Indian Academy of Sciences (India)

    S R Murthy

    2001-08-01

    The low temperature sintering of MgCuZn ferrite was investigated using the usual ceramic method. The effect of Cu substitution on the properties of MgZn ferrites was also investigated and it was found that the densification of MgCuZn ferrite is dependent upon Cu concentration. The sintered ferrite with a density of 4.93 g/cm3 and electrical resistivity > 1011-cm was obtained for the ferrite with 12 mol% Cu at relatively low sintering temperature (910°C). The magnetic properties of the ferrites also improved by the Cu substitution. The chip inductors made of the ferrite fired at 910 C with 12 mol% Cu exhibited higher d.c. resistance. From these studies it is concluded that the good quality chip inductor can be obtained using the MgCuZn ferrites.

  12. Comparison of initial permeability of MgCuZn ferrites sintered by both conventional and microwave methods

    Energy Technology Data Exchange (ETDEWEB)

    Madhuri, W; Penchal Reddy, M; Rammanohar Reddy, N; Siva Kumar, K V [Ceramic Composite Materials Laboratory, Department of Physics, Sri Krishnadevaraya University, Anantapur-515 003 (India); Murthy, V R K, E-mail: sivakumar.sivani@gmail.co [Microwave Laboratory, Department of Physics, Indian Institute of Technology, Chennai-600 036 (India)

    2009-08-21

    NiCuZn ferrites are widely employed for many electronic applications, but can be replaced by MgCuZn ferrites owing to their superior properties like low magnetostriction, environmental stability, low stress sensitivity and low cost. In view of this, a series of non-stoichiometric MgCuZn ferrites (Mg{sub 0.5-x}Cu{sub x}Zn{sub 0.5}Fe{sub 1.9}O{sub 4-{delta}} with x = 0.0, 0.05, 0.10, 0.15, 0.20, 0.25) have been successfully synthesized by both conventional and microwave sintering techniques. The non-stoichiometry was intentionally introduced into the ferrites to ensure high resistivity of the samples. X-ray diffraction patterns confirm the single phase spinel structure in both cases. The elemental composition of these ferrites was analysed by energy-dispersive x-ray spectrometry. The samples sintered by the microwave technique were found to be denser than the conventionally sintered samples. The initial permeability of MgCuZn ferrites was studied with an increase in copper concentration from x = 0.0 to 0.25. The temperature variation of the initial permeability of these samples was carried out from 30 {sup 0}C to 150 {sup 0}C. The results are discussed in the light of microstructure variations of the conventionally and microwave sintered samples. The phenomena involved in microwave sintering are also discussed.

  13. A new combined process for efficient removal of Cu(II) organic complexes from wastewater: Fe(III) displacement/UV degradation/alkaline precipitation.

    Science.gov (United States)

    Xu, Zhe; Gao, Guandao; Pan, Bingcai; Zhang, Weiming; Lv, Lu

    2015-12-15

    Efficient removal of heavy metals complexed with organic ligands from water is still an important but challenging task now. Herein, a novel combined process, i.e., Fe(III)-displacement/UV degradation/alkaline precipitation (abbreviated as Fe(III)/UV/OH) was developed to remove copper-organic complexes from synthetic solution and real electroplating effluent, and other processes including alkaline precipitation, Fe(III)/OH, UV/OH were employed for comparison. By using the Fe(III)/UV/OH process, some typical Cu(II) complexes, such as Cu(II)-ethylenediaminetetraacetic acid (EDTA), Cu(II)-nitrilotriacetic acid (NTA), Cu(II)-citrate, Cu(II)-tartrate, and Cu(II)-sorbate, each at 19.2 mg Cu/L initially, were efficiently removed from synthetic solution with the residual Cu below 1 mg/L. Simultaneously, 30-48% of total organic carbon was eliminated with exception of Cu(II)-sorbate. Comparatively, the efficiency of other processes was much lower than the Fe(III)/UV/OH process. With Cu(II)-citrate as the model complex, the optimal conditions for the combined process were obtained as: initial pH for Fe(III) displacement, 1.8-5.4; molar ratio of [Fe]/[Cu], 4:1; UV irradiation, 10 min; precipitation pH, 6.6-13. The mechanism responsible for the process involved the liberation of Cu(II) ions from organic complexes as a result of Fe(III) displacement, decarboxylation of Fe(III)-ligand complexes subjected to UV irradiation, and final coprecipitation of Cu(II) and Fe(II)/Fe(III) ions. Up to 338.1 mg/L of Cu(II) in the electroplating effluent could be efficiently removed by the process with the residual Cu(II) below 1 mg/L and the removal efficiency of ∼99.8%, whereas direct precipitation by using NaOH could only result in total Cu(II) removal of ∼8.6%. In addition, sunlight could take the place of UV to achieve similar removal efficiency with longer irradiation time (90 min).

  14. First-principles study on mechanical properties of LaMg3 and LaCuMg2

    Institute of Scientific and Technical Information of China (English)

    王明辉; 潘荣凯; 李鹏博; 卞楠; 唐壁玉; 彭立明; 丁文江

    2014-01-01

    With the substitution of part Mg in LaMg3by Cu, the elastic constantsC11 andC12 increase whileC44 decreases, implying an enhanced Poisson effect and smaller resistance to (100) shear. Furthermore, the bulk modulusB increases, while the shear modulusG, elastic modulusE and anisotropic ratioA are reduced. The calculated Debye temperature of LaCuMg2 is lower, implying the weaker interaction between atoms in LaCuMg2. Then, the stress-strain curves in entire range and the ideal strength at critical strain are studied. The present results show that the lowest ideal tensile strength for LaMg3 and LaCuMg2is in the direction. The ideal shear strength on the (110) slip system of LaMg3 is greater than LaCuMg2. The density of states and charge density distribution are further studied to understand the inherent mechanism of the mechanical properties.

  15. The ferromagnetic shape memory system Fe-Pd-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Hamann, S. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany); Gruner, M.E. [Faculty of Physics and Center for Nanointegration, CeNIDE, University of Duisburg-Essen, 47048 Duisburg (Germany); Irsen, S. [Forschungszentrum caesar, Electron Microscopy, 53175 Bonn (Germany); Buschbeck, J. [IFW Dresden, P.O. Box: 270116, 01171 Dresden (Germany); Bechtold, C. [Inorganic Functional Materials, Christian-Albrechts-University, 24143 Kiel (Germany); Kock, I. [I. Physikalisches Institut, Georg-August-University Goettingen, 37077 Goettingen (Germany); Mayr, S.G. [I. Physikalisches Institut, Georg-August-University Goettingen, 37077 Goettingen (Germany)] [Leibniz-Institut fuer Oberflaechenmodifizierung eV, Translationszentrum fuer regenerative Medizin und Fakultaet fuer Physik und Geowissenschaften, University Leipzig, 04318 Leipzig (Germany); Savan, A.; Thienhaus, S. [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany); Quandt, E. [Inorganic Functional Materials, Christian-Albrechts-University, 24143 Kiel (Germany); Faehler, S. [IFW Dresden, P.O. Box: 270116, 01171 Dresden (Germany); Entel, P. [Faculty of Physics and Center for Nanointegration, CeNIDE, University of Duisburg-Essen, 47048 Duisburg (Germany); Ludwig, A., E-mail: alfred.ludwig@rub.de [Institute of Materials, Faculty of Mechanical Engineering, Ruhr-University Bochum, 44801 Bochum (Germany)

    2010-10-15

    A new ferromagnetic shape memory thin film system, Fe-Pd-Cu, was developed using ab initio calculations, combinatorial fabrication and high-throughput experimentation methods. Reversible martensitic transformations are found in extended compositional regions, which have increased fcc-fct transformation temperatures in comparison to previously published results. High resolution transmission electron microscopy verified the existence of a homogeneous ternary phase without precipitates. Curie temperature, saturation polarization and orbital magnetism are only moderately decreased by alloying with nonmagnetic Cu. Compared to the binary system; enhanced Invar-type thermal expansion anomalies in terms of an increased volume magnetostriction are predicted. Complementary experiments on splat-fabricated bulk Fe-Pd-Cu samples showed an enhanced stability of the disordered transforming Fe{sub 70}Pd{sub 30} phase against decomposition. From the comparison of bulk and thin film results, it can be inferred that, for ternary systems, the Fe content, rather than the valence electron concentration, should be regarded as the decisive factor determining the fcc-fct transformation temperature.

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

    Energy Technology Data Exchange (ETDEWEB)

    Brombacher, Christoph

    2011-01-10

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

  17. Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects

    Science.gov (United States)

    Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K.

    2016-01-01

    A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications. PMID:27271057

  18. Biodegradable Mg-Cu alloys with enhanced osteogenesis, angiogenesis, and long-lasting antibacterial effects.

    Science.gov (United States)

    Liu, Chen; Fu, Xuekun; Pan, Haobo; Wan, Peng; Wang, Lei; Tan, Lili; Wang, Kehong; Zhao, Ying; Yang, Ke; Chu, Paul K

    2016-06-07

    A series of biodegradable Mg-Cu alloys is designed to induce osteogenesis, stimulate angiogenesis, and provide long-lasting antibacterial performance at the same time. The Mg-Cu alloys with precipitated Mg2Cu intermetallic phases exhibit accelerated degradation in the physiological environment due to galvanic corrosion and the alkaline environment combined with Cu release endows the Mg-Cu alloys with prolonged antibacterial effects. In addition to no cytotoxicity towards HUVECs and MC3T3-E1 cells, the Mg-Cu alloys, particularly Mg-0.03Cu, enhance the cell viability, alkaline phosphatase activity, matrix mineralization, collagen secretion, osteogenesis-related gene and protein expressions of MC3T3-E1 cells, cell proliferation, migration, endothelial tubule forming, angiogenesis-related gene, and protein expressions of HUVECs compared to pure Mg. The favorable osteogenesis and angiogenesis are believed to arise from the release of bioactive Mg and Cu ions into the biological environment and the biodegradable Mg-Cu alloys with osteogenesis, angiogenesis, and long-term antibacterial ability are very promising in orthopedic applications.

  19. Microstructure Properties of Rapidly Solidified Al-Zn-Mg-Cu Alloys

    Directory of Open Access Journals (Sweden)

    Emad M. Ahmed

    2014-01-01

    Full Text Available The Rietveld X-ray diffraction analysis was applied to analyze the weight fraction of precipitation phases and microstructure characterizations of rapidly solidified Al-8Zn-4Mg-xCu, x = 1, 4, 8, and 10 alloys (in wt.%, prepared by melt spun technique. A good agreement between observed and calculated diffraction pattern was obtained and the conventional Rietveld factors (Rp, Rwp, and GOF converged to satisfactory values. Solid solubilities of Zn, Mg, and Cu in α-Al were extended to high values. Besides, metastable Al0.71Zn0.29, intermetallic Al2CuMg, Al2Cu, and CuMgZn phases have been observed for x = 4, 8, and 10 Cu alloys. The crystal structure and microstructure characterizations exhibit strong Cu content dependence.

  20. Exponentially decaying magnetic coupling in sputtered thin film FeNi/Cu/FeCo trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yajun, E-mail: yajun.wei@angstrom.uu.se; Akansel, Serkan; Thersleff, Thomas; Brucas, Rimantas; Lansaker, Pia; Leifer, Klaus; Svedlindh, Peter [Department of Engineering Sciences, Uppsala University, 75121 Uppsala (Sweden); Harward, Ian; Celinski, Zbigniew [Department of Physics, University of Colorado, Colorado Springs, Colorado 80918 (United States); Ranjbar, Mojtaba; Dumas, Randy K. [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Jana, Somnath; Pogoryelov, Yevgen; Karis, Olof [Department of Physics and Astronomy, Uppsala University, 75120 Uppsala (Sweden); Åkerman, Johan [Department of Physics, University of Gothenburg, 41296 Gothenburg (Sweden); Department of Applied Physics and Microelectronics, Royal Institute of Technology, 10044 Kista (Sweden)

    2015-01-26

    Magnetic coupling in trilayer films of FeNi/Cu/FeCo deposited on Si/SiO{sub 2} substrates have been studied. While the thicknesses of the FeNi and FeCo layers were kept constant at 100 Å, the thickness of the Cu spacer was varied from 5 to 50 Å. Both hysteresis loop and ferromagnetic resonance results indicate that all films are ferromagnetically coupled. Micromagnetic simulations well reproduce the ferromagnetic resonance mode positions measured by experiments, enabling the extraction of the coupling constants. Films with a thin Cu spacer are found to be strongly coupled, with an effective coupling constant of 3 erg/cm{sup 2} for the sample with a 5 Å Cu spacer. The strong coupling strength is qualitatively understood within the framework of a combined effect of Ruderman-Kittel-Kasuya-Yosida and pinhole coupling, which is evidenced by transmission electron microscopy analysis. The magnetic coupling constant surprisingly decreases exponentially with increasing Cu spacer thickness, without showing an oscillatory thickness dependence. This is partially connected to the substantial interfacial roughness that washes away the oscillation. The results have implications on the design of multilayers for spintronic applications.

  1. Phase Transformations in Low-Fe Alloys of the Al-Cu-Fe System

    Institute of Scientific and Technical Information of China (English)

    Liming Zhang

    2004-01-01

    Microstructure and phase transformation in the Al-Cu-Fe alloys of the approximate compositional range of 20 -50 at.% Cu and 2 - 10 Fe at.% have been investigated from samples quenched from their respective temperatures by means of different thermal analysis, magnetothermal analysis, scanning electron microscopy, electron probe analysis and powder X-ray diffraction. Representative phase transformations categorized as polymorphic, discontinuous precipitation,quasi-binary eutectoid, and ternary transitional U-type phase transformation are presented. These phase transformations were found to have a common feature which consumes the β phase and appears the φ phase. A schematic diagram was proposed to demonstrate the transition processes with decreasing temperature.

  2. Antiferromagnetic coupling between spinel ferrite and {alpha}-Fe layers in Fe{sub 3-{delta}O4}/MgO/Fe(0 0 1) epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Yanagihara, Hideto; Toyoda, Yuta; Kita, Eiji [Institute of Applied Physics, University of Tsukuba, Ibaraki 305-8573 (Japan)

    2011-02-16

    We have investigated interlayer exchange coupling (IEC) in epitaxial films of both Fe{sub 3}O{sub 4}/MgO/Fe(0 0 1) and {gamma}-Fe{sub 2}O{sub 3}/MgO/Fe(0 0 1). Depending on the thickness of the MgO spacer, both systems exhibit strong antiferromagnetic IEC of -1 to -2 erg cm{sup -2}. The {gamma}-Fe{sub 2}O{sub 3}/MgO/Fe(0 0 1) trilayer exhibits the strongest IEC when the thickness of the MgO spacer is approximately 7 A, whereas the Fe{sub 3}O{sub 4}/MgO/Fe(0 0 1) trilayer exhibits the strongest IEC when the thickness of the MgO spacer is zero. The results suggest that two different types of exchange coupling exist in the magnetic trilayers which consist of metallic iron and spinel ferrite layers.

  3. As-cast microstructure of Al-Zn-Mg and Al-Zn-Mg-Cu alloys added erbium

    Institute of Scientific and Technical Information of China (English)

    MAO Jian-wei; JIN Tou-nan; XU Guo-fu; NIE Zuo-ren

    2005-01-01

    The effects of different contents of rare earth element, and erbium, on the as-cast microstructures of Al-6Zn-2Mg and Al-6Zn-2Mg-1.8Cu alloys were studied by optical microscopy, scanning electron microscopy, X-ray diffractometry, transmission electron microscopy and EDS analysis. The results show that the netlike structure of as-cast alloys can be remarkably refined, and the distance of dendritic structure decreases, with Er addition. However, the improvement results on Al-Zn-Mg-Cu are not better than that of Al-Zn-Mg. Er and Al can interact to form Al3Er phase, which is coherent with α(Al) matrix, with trace Er addition to the Al-Zn-Mg alloy. The refinement effect of Al-Zn-Mg alloys is familiar with the formation and precipitation of coherent Al3Er phases. The ternary compound AlCuEr, similar with AlCuSc phase, will form when Er is added to Al-Zn-Mg-Cu alloy, which suppresses the formation of Al3Er phase and doesn't solve in the following heat treatment.

  4. The catalytic reactions in the Cu-Li-Mg-H high capacity hydrogen storage system.

    Science.gov (United States)

    Braga, M H; El-Azab, A

    2014-11-14

    A family of hydrides, including the high capacity MgH2 and LiH, is reported. The disadvantages these hydrides normally display (high absorption/desorption temperatures and poor kinetics) are mitigated by Cu-hydride catalysis. This paper reports on the synthesis of novel CuLi0.08Mg1.42H4 and CuLi0.08Mg1.92H5 hydrides, which are structurally and thermodynamically characterized for the first time. The CuLi0.08Mg1.42H4 hydride structure in nanotubes is able to hold molecular H2, increasing the gravimetric and volumetric capacity of this compound. The catalytic effect these compounds show on hydride formation and decomposition of CuMg2 and Cu2Mg/MgH2, Li and LiH, Mg and MgH2 is analyzed. The Gibbs energy, decomposition temperature, and gravimetric capacity of the reactions occurring within the Cu-Li-Mg-H system are presented for the first time. First principles and phonon calculations are compared with experiments, including neutron spectroscopy. It is demonstrated that the most advantageous sample contains CuLi0.08Mg1.92 and (Li) ∼ Li2Mg3; it desorbs/absorbs hydrogen according to the reaction, 2CuLi0.08Mg1.42H4 + 2Li + 4MgH2 ↔ 2CuLi0.08Mg1.92 + Li2Mg3 + 8H2 at 114 °C (5.0 wt%) - 1 atm, falling within the proton exchange membrane fuel cell applications window. Finally the reaction 2CuLi0.08Mg1.42H4 + MgH2 ↔ 2CuLi0.08Mg1.92 + 5H2 at 15 °C (4.4 wt%) - 1 atm is found to be the main reaction of the samples containing CuLi0.08Mg1.92 that were analyzed in this study.

  5. Comparing the Electrochemical Performance of LiFePO4/C Modified by Mg Doping and MgO Coating

    Directory of Open Access Journals (Sweden)

    Jianjun Song

    2013-01-01

    Full Text Available Supervalent cation doping and metal oxide coating are the most efficacious and popular methods to optimize the property of LiFePO4 lithium battery material. Mg-doped and MgO-coated LiFePO4/C were synthesized to analyze their individual influence on the electrochemical performance of active material. The specific capacity and rate capability of LiFePO4/C are improved by both MgO coating and Mg doping, especially the Mg-doped sample—Li0.985Mg0.015FePO4/C, whose discharge capacity is up to 163 mAh g−1, 145.5 mAh g−1, 128.3 mAh g−1, and 103.7 mAh g−1 at 1 C, 2 C, 5 C, and 10 C, respectively. The cyclic life of electrode is obviously increased by MgO surface modification, and the discharge capacity retention rate of sample LiFePO4/C-MgO2.5 is up to 104.2% after 100 cycles. Comparing samples modified by these two methods, Mg doping is more prominent on prompting the capacity and rate capability of LiFePO4, while MgO coating is superior in terms of improving cyclic performance.

  6. New procedure of quantitative mapping of Ti and Al released from dental implant and Mg, Ca, Fe, Zn, Cu, Mn as physiological elements in oral mucosa by LA-ICP-MS.

    Science.gov (United States)

    Sajnóg, Adam; Hanć, Anetta; Koczorowski, Ryszard; Barałkiewicz, Danuta

    2017-12-01

    A new procedure for determination of elements derived from titanium implants and physiological elements in soft tissues by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is presented. The analytical procedure was developed which involved preparation of in-house matrix matched solid standards with analyte addition based on certified reference material (CRM) MODAS-4 Cormorant Tissue. Addition of gelatin, serving as a binding agent, essentially improved physical properties of standards. Performance of the analytical method was assayed and validated by calculating parameters like precision, detection limits, trueness and recovery of analyte addition using additional CRM - ERM-BB184 Bovine Muscle. Analyte addition was additionally confirmed by microwave digestion of solid standards and analysis by solution nebulization ICP-MS. The detection limits are in range 1.8μgg(-1) to 450μgg(-1) for Mn and Ca respectively. The precision values range from 7.3% to 42% for Al and Zn respectively. The estimated recoveries of analyte addition line within scope of 83%-153% for Mn and Cu respectively. Oral mucosa samples taken from patients treated with titanium dental implants were examined using developed analytical method. Standards and tissue samples were cryocut into 30µm thin sections. LA-ICP-MS allowed to obtain two-dimensional maps of distribution of elements in tested samples which revealed high content of Ti and Al derived from implants. Photographs from optical microscope displayed numerous particles with µm size in oral mucosa samples which suggests that they are residues from implantation procedure. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Electrical switching in Fe/V/MgO/Fe tunnel junctions

    Science.gov (United States)

    Najjari, N.; Halley, D.; Bowen, M.; Majjad, H.; Henry, Y.; Doudin, B.

    2010-05-01

    Bipolar hysteretic resistance switching in epitaxial Fe/V/MgO/Fe magnetic tunnel junctions is observed in highly reproducible I(V) curves and found to be modified by the frequency of the bias voltage sweep. Observation of slow relaxation of the resistance state values is reported. A model is proposed that takes into account the incidence of time-dependent electric-field-induced migration of atomic species on the effective barrier thickness. This model provides a good qualitative agreement with experimental data.

  8. Electrical switching in Fe /Cr/MgO/Fe magnetic tunnel junctions

    Science.gov (United States)

    Halley, D.; Majjad, H.; Bowen, M.; Najjari, N.; Henry, Y.; Ulhaq-Bouillet, C.; Weber, W.; Bertoni, G.; Verbeeck, J.; Van Tendeloo, G.

    2008-05-01

    Hysteretic resistance switching is observed in epitaxial Fe /Cr/MgO/Fe magnetic tunnel junctions under bias voltage cycling between negative and positive values of about 1V. The junctions switch back and forth between high- and low-resistance states, both of which depend on the device bias history. A linear dependence is found between the magnitude of the tunnel magnetoresistance and the crafted resistance of the junctions. To explain these results, a model is proposed that considers electron transport both by elastic tunneling and by defect-assisted transmission.

  9. Mechanical alloying in the Fe-Cu system

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  10. Fatigue fracture of high-strength Al-Zn-Mg-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    JIAN Hai-gen; JIANG Feng; WEN Kang; JIANG Long; HUANG Hong-feng; WEI Li-li

    2009-01-01

    X-ray diffractometry(XRD), optical microscopy(OM), scanning electron microscopy(SEM) were used to study the fatigue fracture of the T7451 Al-Zn-Mg-Cu alloy (470 ℃, 60 min+115 ℃, 8 h+165 ℃, 16 h). The study reveals mainly the microscopic structure of the alloy in the process of crack formation and crack growth. The fatigue fracture is characterized by three zones: fatigue crack source zone, fatigue crack propagation zone and fatigue fracture zone. The fatigue damage preferably incubates at the fractured inclusion particles at or near (about 25 μm) the specimen free surfaces, and these brittle Fe-rich intermetallic inclusion particles are (7-10) μm×(11-14) μm in size. Some features such as "feather-like", "river and range" and boundary extrusions can be observed in the fatigue propagation zone, and in the fatigue fracture zone the surface is rough and uneven.

  11. Giant Magnetoresistance Effect of [bcc-Fe(M)/Cu](M=Co,Ni)Multilayers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    GMR effect of multilayers of bcc-Fe(M)(M=Co, Ni) alloy and Cu layers has been investigated. The maximum MR ratio is found at 1.1 nm Fe(Co) and 1.3~1.4 nm Cu layer thickness in [Fe(Co)/Cu], and at 1.6 nm Fe(Ni) and 1.4 nm Cu layer thickness in [Fe(Ni)/Cu]. Under the optimum annealing condition, the MR ratio increases up to 50% and 38% for Fe(Co) and Fe(Ni) systems, respectively. The origin of the increase of GMR is discussed, taking the progress of preferred orientation of Fe(Co)[100] or Fe(Ni)[100] by annealing into account.

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

    DEFF Research Database (Denmark)

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

    2003-01-01

    In order to investigate any influence of steps and possible positive effects of making surface alloys the ammonia synthesis has been investigated over Au modified Fe(111) and Ag and Cu modified Fe(100) single crystals in the temperature range 603-773 K, using a system combining ultra-high vacuum...... and a high-pressure cell. Ammonia was synthesized from a stoichiometric (N-2:3H(2)) gas mixture at a pressure of 2 bar. By deposition of small amounts of An, the ammonia production activity of the Fe(1 1 1) surface can be enhanced. More important, for the gold modified surface, the reaction order in ammonia...

  13. Structures and energies of Cu clusters on Fe and Fe3C surfaces from density functional theory computation.

    Science.gov (United States)

    Tian, Xinxin; Wang, Tao; Yang, Yong; Li, Yong-Wang; Wang, Jianguo; Jiao, Haijun

    2014-12-28

    Spin-polarized density functional theory computations have been carried out to study the stable adsorption configurations of Cun (n = 1-7, 13) on Fe and Fe3C surfaces for understanding the initial stages of copper promotion in catalysis. At low coverage, two-dimensional aggregation is more preferred over dispersion and three-dimensional aggregation on the Fe(110) and Fe(100) surfaces as well as the metallic Fe3C(010) surfaces, while dispersion is more favorable over aggregation on the Fe(111) surface. On the Fe3C(001) and Fe3C(100) surfaces with exposed iron and carbon atoms, the adsorbed Cu atoms prefer dispersion at low coverage, while aggregation along the iron regions at high coverage. On the iron surfaces, the adsorption energies of Cun (n = 2-7) are highest on Fe(111), medium on Fe(100) and lowest on Fe(110). On the Fe3C surfaces, the adsorption energies of Cun (n = 1-3) are highest on Fe3C(100), medium on Fe3C(010) and lowest on Fe3C(001), while, for n = 4-7 and 13, Fe3C(010) has stronger adsorption than Fe3C(100). On the basis of their differences in electronegativity, the adsorbed Cu atoms can oxidize the metallic Fe(110), Fe(100) and Fe3C(010) surfaces and become negatively charged. On the Fe3C(001) and Fe3C(100) surfaces with exposed iron and carbon atoms, the adsorbed Cu atoms interacting with surface carbon atoms are oxidized and positively charged. Unlike the most stable Fe(110) and Fe3C(001) surfaces, where the Fe(110) surface has stronger Cu affinity than the Fe3C(001) surface, which is in agreement with the experimental finding, the less and least stable Fe3C(010) and Fe3C(100) surfaces have stronger Cu affinities than the Fe(110) and Fe(100) surfaces. Since less stable facets are not preferably formed thermodynamically, it is crucial to prepare such surfaces to explore Cu adsorption and promotion, and this provides challenges to surface sciences.

  14. Asymmetric angular dependence of spin-transfer torques in CoFe/Mg-B-O/CoFe magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ling, E-mail: lingtang@zjut.edu.cn; Xu, Zhi-Jun, E-mail: xzj@zjut.edu.cn; Zuo, Xian-Jun; Yang, Ze-Jin, E-mail: zejinyang@zjut.edu.cn [Department of Applied Physics, College of Science, Zhejiang University of Technology, Hangzhou 310023 (China); Gao, Qing-He [College of Science, Northeastern University, Shenyang 110004, China, Information Engineering College, Liaoning University of Traditional Chinese Medicine, Shenyang 110847 (China); Linghu, Rong-Feng, E-mail: linghu@gznu.edu.cn [School of Physics and Electronics Sciences, Guizhou Education University, Guiyang 550018 (China); Guo, Yun-Dong, E-mail: g308yd@126.com [College of Engineering and Technology, Neijiang Normal University, Neijiang 641112 (China)

    2016-04-28

    Using a first-principles noncollinear wave-function-matching method, we studied the spin-transfer torques (STTs) in CoFe/Mg-B-O/CoFe(001) magnetic tunnel junctions (MTJs), where three different types of B-doped MgO in the spacer are considered, including B atoms replacing Mg atoms (Mg{sub 3}BO{sub 4}), B atoms replacing O atoms (Mg{sub 4}BO{sub 3}), and B atoms occupying interstitial positions (Mg{sub 4}BO{sub 4}) in MgO. A strong asymmetric angular dependence of STT can be obtained both in ballistic CoFe/Mg{sub 3}BO{sub 4} and CoFe/Mg{sub 4}BO{sub 4} based MTJs, whereas a nearly symmetric STT curve is observed in the junctions based on CoFe/Mg{sub 4}BO{sub 3}. Furthermore, the asymmetry of the angular dependence of STT can be suppressed significantly by the disorder of B distribution. Such skewness of STTs in the CoFe/Mg-B-O/CoFe MTJs could be attributed to the interfacial resonance states induced by the B diffusion into MgO spacer.

  15. Microstructural and Optical Absorption Properties of Cu-MgF2 Nanoparticle Cermet Film

    Institute of Scientific and Technical Information of China (English)

    孙兆奇; 孙大明; 阮图南

    2002-01-01

    We examine the microstructural and optical absorption spectra of 10-30 vol% Cu-MgF2 nanoparticle cermet films prepared by co-evaporation in vacuum. The results show that the Cu-MgF2 cermet films are mainly composed of the amorphous MgF2 matrix with embedded fcc Cu nanoparticles of average size 12-24 nm. The results also show that the optical absorption of the films decreases as the wavelength increases in the range of 200-800nm. The surface plasmon resonance absorption peaks of Cu nanoparticles in 10, 20 and 30 vo1% Cu-MgF2 films appear at 578, 588 and 606nm, respectively. The interband transition absorption of Cu starts from 590nm downwards.Based on the Maxwell-Garnett theory, the experimental optical absorption properties of the films have been quantitatively evaluated.

  16. FeGa/MgO/Fe/GaAs(001) magnetic tunnel junction: Growth and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Gobaut, B., E-mail: benoit.gobaut@elettra.eu [Sincrotrone Trieste S.C.p.A., S.S. 14-km 163.5, Area Science Park, 34012 Trieste (Italy); Ciprian, R.; Salles, B.R.; Krizmancic, D. [Laboratorio TASC, IOM-CNR, S.S. 14-km 163.5, Basovizza, 34149 Trieste (Italy); Rossi, G. [Laboratorio TASC, IOM-CNR, S.S. 14-km 163.5, Basovizza, 34149 Trieste (Italy); Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); Panaccione, G. [Laboratorio TASC, IOM-CNR, S.S. 14-km 163.5, Basovizza, 34149 Trieste (Italy); Eddrief, M.; Marangolo, M. [Sorbonne Universites, UPMC Univ Paris 06, UMR 7588, INSP, 4 place Jussieu, 75005 Paris (France); CNRS, UMR 7588, Institut des NanoSciences de Paris, 4 place Jussieu, 75005 Paris (France); Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14-km 163.5, Basovizza, 34149 Trieste (Italy)

    2015-06-01

    Research on spintronics and on multiferroics leads now to the possibility of combining the properties of these materials in order to develop new functional devices. Here we report the integration of a layer of magnetostrictive material into a magnetic tunnel junction. A FeGa/MgO/Fe heterostructure has been grown on a GaAs(001) substrate by molecular beam epitaxy (MBE) and studied by X-ray magnetic circular dichroism (XMCD). The comparison between magneto optical Kerr effect (MOKE) measurements and hysteresis performed in total electron yield allowed distinguishing the ferromagnetic hysteresis loop of the FeGa top layer from that of the Fe buried layer, evidencing a different switching field of the two layers. This observation indicates an absence of magnetic coupling between the two ferromagnetic layers despite the thickness of the MgO barrier of only 2.5 nm. The in-plane magnetic anisotropy has also been investigated. Overall results show the good quality of the heterostructure and the general feasibility of such a device using magnetostrictive materials in magnetic tunnel junction.

  17. Synchrotron X-Ray Study on Structures of Ni80Fe20/Cu Superlattices

    Institute of Scientific and Technical Information of China (English)

    XU Ming; LUO Guang-Ming; CHAI Chun-Lin; YANG Tao; MAI Zhen-Hong; LAI Wu-Yan; WU Zhong-Hua; WANG De-Wu

    2001-01-01

    We have shown that, in contrast to the results in the literature, the Bragg peak intensity of Ni80Fe20/Cu superlattices is enhanced at the incident x-ray energy slightly higher than the absorption edge of the heavier element (Cu). The atomic density at Ni80Fe20/Cu interface was analysed by the diffraction anomalous fine structure technology with the incident angle of x-ray fixed at the first Bragg peak. Our results demonstrate the epitaxy growth of Ni80Fe20/Cu superlattices. Upon annealing, the epitaxity of Ni80Fe20/Cu multilayers becomes poor but the local crystallinity in each layer is improved.

  18. Magneto-volume effects in Fe-Cu solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorria, P. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain)]. E-mail: pgorria@uniovi.es; Martinez-Blanco, D. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Iglesias, R. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Palacios, S.L. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Perez, M.J. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, Calvo Sotelo, s/n, 33007 Oviedo (Spain); Fernandez Barquin, L. [Departamento CITIMAC, F. Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Hernando, A. [Instituto de Magnetismo Aplicado, UCM-RENFE, 28230 Las Rozas, Madrid (Spain); Gonzalez, M.A. [Instituto de Ciencia de Materiales de Aragon, CSIC, 50009 Zaragoza (Spain); Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9 (France)

    2006-05-15

    The magnetic properties of Fe-Cu metastable solid solutions have been investigated by means of neutron diffraction and magnetisation measurements. These compounds exhibit ferromagnetic order with Curie temperatures above room temperature for concentrations beyond 40 at% in Fe. The magnetic moment at 5 K can reach values over 2 {mu} {sub B}, while the high field susceptibility is similar to that found in FCC-FeNi Invar alloys. These features together with the low values for the linear coefficient for thermal expansion in the ferromagnetic region suggest that magneto-volume anomalies, including Invar behaviour, play a major role in the magnetic properties of this system when the crystal structure is face centred cubic. Such behaviour could be explained using theoretical total-band energy calculations.

  19. Preparation and hydrogen sorption properties of Mg-Cu-Y-H systems

    Institute of Scientific and Technical Information of China (English)

    LI Zhinian; LIU Xiaopeng; HUANG Zuo; JIANG Lijun; WANG Shumao

    2006-01-01

    Mg-xwt.%CuY (x=15, 20, 25) composites were successfully prepared by reactive mechanical alloying (RMA).X-ray diffraction (XRD) measurement shows that main phases of the as milled composites are MgH2 and Mg2Cu, and they converted into Mg and MgCu2 after dehydrogenation, respectively.Pressure-Composition-Isotherm (PCI) test shows that the composites exhibit double pressure plateau at each isothermal desorption process.The hydrogen absorption and desorption kinetics of the composites become worse with increasing x content, indicating that Mg-Cu phase has a negative effect on the hydrogen sorption properties of the composites.It is supposed that the good hydrogen sorption properties of the composites attribute to the catalyst effect of yttrium hydride distributed in Mg substrate and the particles size reduction and crystal defects formed by RMA.

  20. Enhancement of spin-Seebeck effect by inserting ultra-thin Fe70Cu30 interlayer

    Science.gov (United States)

    Kikuchi, D.; Ishida, M.; Uchida, K.; Qiu, Z.; Murakami, T.; Saitoh, E.

    2015-02-01

    We report the longitudinal spin-Seebeck effects (LSSEs) for Pt/Fe70Cu30/BiY2Fe5O12 (BiYIG) and Pt/BiYIG devices. The LSSE voltage was found to be enhanced by inserting an ultra-thin Fe70Cu30 interlayer. This enhancement decays sharply with increasing the Fe70Cu30 thickness, suggesting that it is not due to bulk phenomena, such as a superposition of conventional thermoelectric effects, but due to interface effects related to the Fe70Cu30 interlayer. Combined with control experiments using Pt/Fe70Cu30 devices, we conclude that the enhancement of the LSSE voltage in the Pt/Fe70Cu30/BiYIG devices is attributed to the improvement of the spin-mixing conductance at the Pt/BiYIG interfaces.

  1. Pyrosequencing investigation into the influence of Cu2+, Zn2+, Fe2+ and I− mixtures on fungal diversity and toxigenic fungal growth in a fermented liquid feed

    Directory of Open Access Journals (Sweden)

    Yuyong He

    2016-03-01

    Full Text Available A L9(34 orthogonal experiment was conducted to evaluate the influence of 9 mixtures which consisted of Cu2+, Zn2+, Fe2+ and I− ions at different ion concentrations on fungal diversity and toxigenic fungal growth in a Bacillus subtilis-fermented liquid feed (FLF using pyrosequencing. The maximal Chao estimator and Shannon index were achieved in the FLF with a mixture of Cu2+ (200 mg/kg, Zn2+ (160 mg/kg, Fe2+ (150 mg/kg and I− (2.4 mg/kg. The minimal relative abundance of Aspergillus was achieved when a mixture of Cu2+ (200 mg/kg, Zn2+, Fe2+ and I− was added to the FLF. Compared with Zn2+, Fe2+ and I−, Cu2+ was the most important ion in inhibiting Aspergillus growth. Adding Zn2+ (160 mg/kg, Cu2+, Fe2+ and I− to the FLF minimized the relative abundance of Fusarium. It was Zn2+ instead of Cu2+ played a critical role in suppressing the growth of Fusarium. The proper use of the mixture of Cu2+, Zn2+, Fe2+ and I− in FLF contributes to inhibit the growth of mycotoxin-producing fungi during storage. The new findings of this study help farmers properly use the mixture of Cu2+, Zn2+, Fe2+ and I− to inhibit the growth of mycotoxin-producing fungi in the production of high quality FLF and alleviate mycotoxins damages to animals and humans.

  2. Geometrical and Compositional Structure at Metal-Oxide Interfaces: MgO on Fe(001)

    Energy Technology Data Exchange (ETDEWEB)

    Meyerheim, H. L.; Popescu, R.; Kirschner, J.; Jedrecy, N.; Sauvage-Simkin, M.; Heinrich, B.; Pinchaux, R.

    2001-08-13

    The geometric structure of MgO deposited on Fe(001) in ultrahigh vacuum by electron evaporation was determined in detail by using surface x-ray diffraction. In contrast to the common belief that MgO grows in direct contact on the Fe(001) substrate, we find an FeO interface layer between the substrate and the growing MgO structure which has not been considered thus far. This result opens new perspectives for the understanding of the Fe/MgO/Fe(001) interface and the tunneling magnetoresistance effect in general.

  3. Characterization of the metastable Cu-Fe nanoparticles prepared by the mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Mahsa Barzegar Vishlaghi

    2014-12-01

    Full Text Available Although Cu and Fe are immiscible under equilibrium conditions, they can form supersaturated solid solutions by mechanical alloying. In this paper, nano-structured of the metastable Cu-Fe phase containing 10, 15, 20 and 25% wt Fe were synthesized by intensive ball milling for 15h, in order to achieve a solid solution of Fe in Cu. The phase composition, dissolution of the Fe atoms into the Cu matrix, and the morphology of the milling products were studied by X-ray Diffraction (XRD, Energy Dispersive Spectrometer (EDS, and Field Emission Scanning Electron Microscope (FESEM techniques, respectively. The mean crystallite size of the milled samples was determined by XRD peak broadening using the Williamson-Hall approximation. The XRD analysis results showed that the solid solubility of the Fe in the Cu was extended to 20%wt after milling for 15 h, and a homogeneous solid solution of Cu80Fe20 with a mean crystallite size of 19nm was obtained. The mean crystallite size decreased with increasing milling time and it was more evident in the initial stage of the milling. The Cu lattice parameter increased by dissolving the Fe into the Cu matrix probably due to the magneto-volume effect in the Cu-Fe alloys. The FESEM observations showed that the milling products were agglomerates consisting of uniform particles. The Vibrating Sample Magnetometer (VSM results showed that the Cu80Fe20 powder has soft magnetic properties.

  4. Extraordinary Hall effect on Fe-rich amorphous thin films and Fe-rich/Cu multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Michea, S. [Universidad de Santiago de Chile, Avda. Ecuador, 3493, Estacion Central, Santiago (Chile); Denardin, J.C., E-mail: juliano.denardin@usach.cl [Universidad de Santiago de Chile, Avda. Ecuador, 3493, Estacion Central, Santiago (Chile); Gamino, M.; Dorneles, L.S. [Departamento de Fisica, Universidade Federal de Santa Maria, Santa Maria 97105-900, RS (Brazil); Correa, M.A. [Departamento de Fisica Teorica e Experimental, Universidade Federal do Rio Grande do Norte, Campus Universitario Lagoa Seca, 59072-970 - Natal, RN - Brazil (Brazil)

    2012-08-15

    In this study we investigated the magnetic and transport properties of thin Fe-rich amorphous films and Fe-rich/Cu multilayers. We compared the extraordinary Hall effect in these two types of samples and discussed it in terms of thickness and sample structure. The thicker films exhibited a strong in-plane magnetic anisotropy, and by decreasing film thickness both saturated Hall resistivity and Hall sensitivity increase. A Hall resistivity value of 20 {mu} Ohm-Sign cm is observed in 100 nm thick Fe-rich films at 12 K and a sensitivity of 1.3 Ohm-Sign /T is obtained at room temperature. Electrical conductance increases and Hall resistivity decreases when the films are sandwiched with Cu.

  5. High spin polarization and the origin of unique ferromagnetic ground state in CuFeSb

    Science.gov (United States)

    Sirohi, Anshu; Singh, Chandan K.; Thakur, Gohil S.; Saha, Preetha; Gayen, Sirshendu; Gaurav, Abhishek; Jyotsna, Shubhra; Haque, Zeba; Gupta, L. C.; Kabir, Mukul; Ganguli, Ashok K.; Sheet, Goutam

    2016-06-01

    CuFeSb is isostructural to the ferro-pnictide and chalcogenide superconductors and it is one of the few materials in the family that are known to stabilize in a ferromagnetic ground state. Majority of the members of this family are either superconductors or antiferromagnets. Therefore, CuFeSb may be used as an ideal source of spin polarized current in spin-transport devices involving pnictide and the chalcogenide superconductors. However, for that the Fermi surface of CuFeSb needs to be sufficiently spin polarized. In this paper we report direct measurement of transport spin polarization in CuFeSb by spin-resolved Andreev reflection spectroscopy. From a number of measurements using multiple superconducting tips we found that the intrinsic transport spin polarization in CuFeSb is high (˜47%). In order to understand the unique ground state of CuFeSb and the origin of large spin polarization at the Fermi level, we have evaluated the spin-polarized band structure of CuFeSb through first principles calculations. Apart from supporting the observed 47% transport spin polarization, such calculations also indicate that the Sb-Fe-Sb angles and the height of Sb from the Fe plane are strikingly different for CuFeSb than the equivalent parameters in other members of the same family thereby explaining the origin of the unique ground state of CuFeSb.

  6. CuFe2 O4 -CuO Nanocomposites as Promising Materials for Solar Hydrogen Generation

    Science.gov (United States)

    Razavi, Mehdi; Amrollahi, Pouya; Yazdimamaghani, Mostafa; Tayebi, Lobat; Vashaee, Daryoosh

    2014-03-01

    Currently, hydrogen is produced, almost exclusively, by waterelectrolysis. This method can take advantage of economies of scale and most established techniques of producing hydrogen. We developed a nanocomposite material system composed of CuFe2O4 and CuO semiconductor particles to produce hydrogen by electrolysis of water. The nanocomposite powder was prepared using the sol-gel method. Techniques of X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, transmission electron microscopy and UV diffuse reflectance analysis were employed to characterize the synthesized products.The results confirmed the formation of CuFe2O4-CuO nanocomposite powder. The hydrogen evolution was successfully observed over the new hetero-system of CuFe2O4-CuO. The electrolysis activity depended on the concentration of CuO in the system. In order to enhance the hydrogen production, we further optimized the composite material versus the concentration of the compounds.

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

    Science.gov (United States)

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

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

  8. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001) magnetic tunnel junctions

    Science.gov (United States)

    Belmoubarik, Mohamed; Sukegawa, Hiroaki; Ohkubo, Tadakatsu; Mitani, Seiji; Hono, Kazuhiro

    2017-05-01

    We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001) magnetic tunnel junctions (MTJs) on their spin-dependent transport properties. The tunnel magnetoresistance (TMR) ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm) induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  9. Effect of Mg-Al insertion on magnetotransport properties in epitaxial Fe/sputter-deposited MgAl2O4/Fe(001 magnetic tunnel junctions

    Directory of Open Access Journals (Sweden)

    Mohamed Belmoubarik

    2017-05-01

    Full Text Available We investigated the effect of an Mg-Al layer insertion at the bottom interface of epitaxial Fe/MgAl2O4/Fe(001 magnetic tunnel junctions (MTJs on their spin-dependent transport properties. The tunnel magnetoresistance (TMR ratio and differential conductance spectra for the parallel magnetic configuration exhibited clear dependence on the inserted Mg-Al thickness. A slight Mg-Al insertion (thickness 0.2 nm induced a reduction of TMR ratios and featureless conductance spectra, indicating a degradation of the bottom-Fe/MgAl2O4 interface. Therefore, a minimal Mg-Al insertion was found to be effective to maximize the TMR ratio for a sputtered MgAl2O4-based MTJ.

  10. Physical properties of the superconducting spin-valve Fe/Cu/Fe/In heterostructure

    Science.gov (United States)

    Leksin, P. V.; Garif'yanov, N. N.; Garifullin, I. A.; Schumann, J.; Kataev, V.; Schmidt, O. G.; Büchner, B.

    2012-01-01

    We report on structural, magnetic, and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. For most of the thicknesses of the second iron layer dFe2 up to 2 nm, we have observed a full spin-valve effect for the superconducting current, i.e., a complete transition from the normal to the superconducting state by changing the mutual orientation of the magnetizations of the Fe1 and Fe2 layers. For dFe2<1 nm, the superconducting transition temperature TcP for the parallel orientation of magnetizations of the Fe1 and Fe2 layers is smaller than that for the antiparallel orientation TcAP, which corresponds to the direct spin-valve effect. For dFe2⩾1 nm, we have found the inverse spin-valve effect with ΔTc=TcAP-TcP<0. Further, in samples with a fixed thickness of the In layer, we have observed an oscillating dependence of its superconducting transition temperature Tc on dFe2. The analysis of the Tc(dFe2) dependence using the theory of the superconducting-ferromagnetic proximity effect has enabled determination of all microscopic parameters of the studied system. With these parameters, a satisfactory description of the sign-changing oscillating behavior of the spin-valve effect ΔTc(dFe2) has been obtained using a recent theory by Fominov [Ya. V. Fominov , Pis'ma Zh. Eksp. Teor. Fiz. 91, 329 (2010) [JETP Lett.JTPLA20021-364010.1134/S002136401006010X 91, 308 (2010)

  11. A route for recycling Nd from Nd-Fe-B magnets using Cu melts

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Martina; Gebert, Annett, E-mail: a.gebert@ifw-dresden.de; Stoica, Mihai; Uhlemann, Margitta; Löser, Wolfgang

    2015-10-25

    Phase evolutions in Nd-Fe-B magnet/Cu systems have been explored with regard to Nd recycling. It was demonstrated that large scale phase separation into a ferromagnetic Fe(B)-rich ingot core with α-Fe main phase and a non-magnetic (Cu,Nd)-rich ingot rim takes place upon arc melting with Cu fractions ≥ 21.5 wt.-%. The re-solidification of the Nd{sub 2}Fe{sub 14}B magnet main phase is suppressed. The rim consists of the Cu{sub 2}Nd main phase and CuNd/Cu{sub 4}Nd minority phases in which Al traces from the magnetic material are gathered. Induction melting of such Nd-Fe-B/Cu mixtures can support the separation of these phase regions with very sharp boundaries. Main features of liquid phase separation and microstructure evolution have been interpreted on the basis of Nd-Fe-Cu phase diagram data. The key advantage with respect to Nd recycling from Nd-Fe-B permanent magnet scrap is the substantial accumulation of Nd in the (Cu,Nd)-rich region of the phase separated solidified specimen, which can be easily detached from the Fe-rich part by mechanical-magnetic treatments. Such portions contained up to ∼44 wt.-% Nd (25 at.-%) in first lab-scale experiments. Nd recovery from the (Cu,Nd)-rich fractions is possible by exploiting the large chemical property differences between the reactive rare earths elements and Cu. - Highlights: • phase evolution analysis in Nd-Fe-B magnet/Cu systems with regard to Nd recycling. • Cu ≥ 21 wt.-%, large scale phase separation- Fe(B)-rich ingot core, (Cu,Nd)-rich rim. • high Nd content (∼44 wt.-%) of (Cu,Nd)-rich region, mechanical-magnetic treatments.

  12. Dielectric loss, conductivity relaxation process and magnetic properties of Mg substituted Ni-Cu ferrites

    Science.gov (United States)

    Singh, Navneet; Agarwal, Ashish; Sanghi, Sujata; Khasa, Satish

    2012-08-01

    The dielectric properties, dc and ac electrical resistivities of Mg substituted Ni-Cu ferrites with general formula Ni0.5Cu0.5-xMgxFe2O4 (0.0≤x≤0.5) have been investigated as a function of frequency, temperature and composition. ac resistivity of all the samples decreases with increase in the frequency exhibiting normal ferrimagnetic behavior. The frequency dependence of dielectric loss tangent showed a maximum in between 10 Hz and 1 kHz in all the ferrites. The conductivity relaxation of the charge carriers was examined using the electrical modulus formulism, and the results indicate the presence of the non-Debye type of relaxation in the prepared ferrites. Similar values of activation energies for dc conduction and for conductivity relaxation reveal that the mechanism of electrical conduction and dielectric polarization is the same in these ferrites. A single 'master curve' for normalized plots of all the modulus isotherms observed for a given composition indicates that the distribution of relaxation time is temperature independent. The saturation magnetization and coercivity as calculated from the hysteresis loop measurement show striking dependence on composition.

  13. Yb9+xCuMg4-x (x = 0.034): A κ-Phase Formed by Lanthanoids.

    Science.gov (United States)

    De Negri, Serena; Romaka, Vitaliy; Solokha, Pavlo; Saccone, Adriana; Giester, Gerald; Michor, Herwig; Rogl, Peter F

    2016-08-15

    Atom order in the crystal structures of Yb2Cu2-xMg (x = 0.17; Mo2FeB2-type; P4/mbm; a = 0.75592(2) nm; c = 0.40282(1) nm) and Yb9+xCuMg4-x (x = 0.034; Hf9Mo4B-type; P63/mmc; a = 1.0169(5) nm; c = 1.0290(5) nm) was determined from powder and X-ray single-crystal counter data analyses supported by electron probe microanalyses. Among the group of the so-called κ-phases, Yb9+xCuMg4-x is the first representative formed by a lanthanoid element. The structure of this κ-phase can be viewed as a typical network of corner-connected empty Yb6-octahedra, which encompass Yb6Mg6-icosahedra (filled by a mix of Mg/Yb atoms) and Yb6-trigonal prisms centered by Cu atoms to complete the three-dimensional metal framework. From another point of view, the same structure is considered as built from infinite polyicosahedral columns of Yb9Mg4 composition with Cu atoms located in trigonal prismatic interstices, highlighting similarities with other Yb-rich Yb-Cu-Mg phases. Density functional theory (DFT) calculations classify Yb9CuMg4 as a polar intermetallic. Metallic-like behavior is inferred from the Sommerfeld constant, γ = 49.2 mJ/mol·K(2), derived from the electronic density of states, calculated at the Fermi level. DFT integration of the f-density of states indicates almost completely filled f-states, revealing 13.6 and 13.7 electrons in the valence band for Yb1 and Yb2 atoms, respectively, close to the Yb(2+) ground state ((1)S0) for both Yb atoms. Magnetic susceptibility data recorded on the same compound are consistent with a nonmagnetic divalent Yb(2+) state. Temperature-dependent heat capacity data display a metallic behavior characterized by a small Sommerfeld constant γ = 64.8 mJ/mol·K(2) and a rather low Debye temperature ΘD = 140 K as typical for soft materials.

  14. Theory of perpendicular magnetocrystalline anisotropy in Fe/MgO (001)

    Science.gov (United States)

    Odkhuu, Dorj; Yun, Won Seok; Rhim, S. H.; Hong, Soon Cheol

    2016-09-01

    The origin of large perpendicular magnetocrystalline anisotropy (PMCA) in Fe/MgO (001) is revealed by comparing Fe layers with and without the MgO. Although Fe-O p-d hybridization is weakly present, it cannot be the main origin of the large PMCA as claimed in previous study. Instead, perfect epitaxy of Fe on the MgO is more important to achieve such large PMCA. As an evidence, we show that the surface layer in a clean free-standing Fe (001) dominantly contributes to EMCA, while in the Fe/MgO, those by the surface and the interface Fe layers contribute almost equally. The presence of MgO does not change positive contribution from , wherease it reduces negative contribution from z2 |ℓX | yz > and .

  15. Efficiency of Chitosan for the Removal of Pb (II, Fe (II and Cu (II Ions from Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Soheil Sobhanardakani

    2014-09-01

    Full Text Available Background: Heavy metals have been recognized as harmful environmental pollutant known to produce highly toxic effects on different organs and systems of both humans and animals. The aim of this paper is to evaluate the adsorption potential of chitosan for the removal of Pb(II, Fe(II and Cu(II ions from aqueous solutions. Methods: This study was conducted in laboratory scale. In this paper chitosan has been used as an adsorbent for the removal of Pb(II, Fe(II and Cu(II from aqueous solution. In batch tests, the effects of parameters like pH solution (1.0-8.0, initial metal concentrations (100-1000 mgL-1, contact time (5.0-150 min and adsorbent dose (1.0-7.0 g on the adsorption process were studied. Results: The results showed that the adsorption of Pb(II, Fe(II and Cu(II ions on chitosan strongly depends on pH. The experimental isothermal data were analyzed using the Langmuir and Freundlich equations and it was found that the removal process followed the Langmuir isotherm and maximum adsorption capacity for the adsorption of Pb(II, Fe(II and Cu(II ions by the chitosan were 55.5mg g−1, 71.4 mg g−1 and 59 mg g−1, respectively, under equilibrium conditions at 25±1 ºC. The adsorption process was found to be well described by the pseudo-second-order rate model. Conclusion: The obtained results showed that chitosan is a readily, available, economic adsorbent and was found suitable for removing Pb(II, Fe(II and Cu(II ions from aqueous solution.

  16. Thermal Stability of CoFe/Cu/CoFe/IrMn Top Spin Valve

    Institute of Scientific and Technical Information of China (English)

    ZHOU Guang-Hong; WANG Yin-Gang; QI Xian-Jin

    2009-01-01

    We present a study of thermal stability of the top spin valve with a structure of seed Ta (5nm)/Co75Fe25 (5nm)/Cu (2.5nm)/Co75Fe25n (5nm)/Ir20 Mn80 (12nm)/cap Ta (8nm) deposited at room temperature by magnetron sputtering. A vibrating sample magnetometer fixed with a heater was used to record the magnetic hysteresis loops at variational temperatures and x-ray diffraction was performed to characterize the structure of the multilayer.The exchange field Hex and the coercivity of the pinned CoFe layer Hcp decrease monotonically with increasing temperature.The coercivity of the free CoFe layer Hcf in the spin valve shows a maximum at 498K.The temperature dependences of Hex,Hcp and Hcf have also been discussed.

  17. Interlayer exchange coupling, dipolar coupling and magnetoresistance in Fe/MgO/Fe trilayers with a subnanometer MgO barrier

    Science.gov (United States)

    Kozioł-Rachwał, A.; Skowroński, W.; Frankowski, M.; Chęciński, J.; Ziętek, S.; Rzeszut, P.; Ślęzak, M.; Matlak, K.; Ślęzak, T.; Stobiecki, T.; Korecki, J.

    2017-02-01

    Fe/MgO/Fe trilayers with a subnanometer MgO tunnel barrier were grown by molecular beam epitaxy. Longitudinal magnetooptic Kerr effect measurements confirmed the existence of the antiferromagnetic interlayer exchange coupling (IEC) between the Fe layers for 2 Ådetermined dependence of the dipolar coupling on the pillar diameter. Finally, magnetoresistance (MR) was measured as a function of MgO thickness (dMgO), and a non-zero MR was found for the MgO as thin as 3.4 Å. Extrapolation of the MR (dMgO) dependence to MR=0 allowed us to determine the length of the pinholes in our sample, which was estimated to be (3.2±0.5) Å.

  18. Synthesis and magnetic properties of multilayer Ni/Cu and NiFe/Cu nanowires

    Indian Academy of Sciences (India)

    R S Liu; S C Chang; I Baginskiy; S F Hu; C Y Huang

    2006-07-01

    Highly ordered composite nanowires with multilayer Ni/Cu and NiFe/Cu have been fabricated by pulsed electrodeposition into nanoporous alumina membrane. The diameter of wires can be easily varied by pore size of alumina, ranging from 30 to 100 nm. The applied potential and the duration of each potential square pulse determine the thickness of the metal layers. The nanowires have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer (VSM) measurements. The MFM images indicate that every ferromagnetic layer separated by Cu layer was present as single isolated domain-like magnet. This technique has potential use in the measurement and application of magnetic nanodevices.

  19. In Vitro Degradation Behavior of Ternary Mg-Zn-Se and Mg-Zn-Cu Alloys as Biomaterials

    Science.gov (United States)

    Persaud-Sharma, Dharam; Budiansky, Noah

    2013-01-01

    In this study, the corrosion behavior of Mg-Zn-Se and Mg-Zn-Cu alloys was investigated to evaluate their corrosion behavior related to use as implantable biomaterials. The corrosion behavior of these alloys and a commercially available Mg-Zn alloy were examined using static solution electrochemical testing, dynamic solution gravimetric testing, ion leaching testing, and microscopic evaluation. Fluctuations in the pH of the Dulbecco’s Modified Eagles Medium (DMEM) used for the gravimetric and ion leaching immersion testing were also recorded over the 30-day duration to assess whether the media conditions induced by the alloy degradation would permit for cellular survival. Weight loss experimentation and electrochemical tests revealed the Mg-Zn-Cu alloy to have the greatest corrosion rate. PMID:24465245

  20. Induced effects of Cu underlayer on (111) orientation of Fe50 Mn50 thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; WANG Feng-ping; LIU Huan-ping; WU Ping; QIU Hong; PAN Li-qing

    2005-01-01

    Effects of Cu underlayer on the structure of Fe50 Mn50 films were studied. Samples with a structure of Fe50 Mn50 (200 nm)/Cu(tCu) were prepared by magnetron sputtering on thermally oxidized silicon substrates at room temperature. The thickness of Cu underlayer varied from 0 to 60 nm in the intervals of 10 nm. High-vacuum annealing treatments, at different temperatures of 200, 300 and 400 ℃ for 1 h, respectively, on the Fe50 Mn50 (200 nm)/Cu(20 nm) thin films were performed. The surface morphologies and textures of the samples were measured by field emission scan electronic microscope (FE-SEM) and X-ray diffraction(XRD). Energy dispersive X-ray spectroscopy (EDX) and Auger electron spectroscopy(AES) were used to analyze the compositional distribution. It is found that Cu underlayer has an obvious induce effect on (111) orientation of Fe50 Mn50 thin films. The induce effects of Cu on (111) orientation of Fe50 Mn50 changed with the increase of Cu layer thickness and the best effect was obtained at the Cu layer thickness of 20 nm. High-vacuum annealing treatments cause the migration of Mn atoms towards surface of the film and interface between Cu layer and substrate. With the increasing annealing temperature, migration of Mn atoms is more obvious, which leads to a Fe-riched Fe-Mn alloy film.

  1. Synthesis and soft magnetic properties of Zn{sub 0.8−x}Ni{sub x}Mg{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} (x = 0.0−0.8) ferrites prepared by sol–gel auto-combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Satalkar, M., E-mail: satalkar.manvi@gmail.com [School of Physics, D. A. University, Khandwa Road Campus, Indore 452001 (India); Kane, S.N., E-mail: kane_sn@yahoo.com [School of Physics, D. A. University, Khandwa Road Campus, Indore 452001 (India); Ghosh, A. [School of Physics, D. A. University, Khandwa Road Campus, Indore 452001 (India); Ghodke, Nandkishor [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Barrera, G. [INRIM, Electromagnetism Division, Strada Delle Cacce 91, I-10135 Torino (Italy); Università degli Studi di Torino, via P. Giuria 7, 10125 Torino (Italy); Celegato, F.; Coisson, M.; Tiberto, P.; Vinai, F. [INRIM, Electromagnetism Division, Strada Delle Cacce 91, I-10135 Torino (Italy)

    2014-12-05

    Highlights: • Ni2+ occupies A and B site, when Zn2+ is fully replaced by Ni2+, it goes to A site. • Change in distribution of cations has significant effect on magnetic properties. • Highest Ms value of 25.04 emu/g, was obtained for x = 0.60. - Abstract: Single phase nanocrystalline Zn{sub 0.8−x}Ni{sub x}Mg{sub 0.1}Cu{sub 0.1}Fe{sub 2}O{sub 4} (x = 0.0−0.8), were synthesized by sol–gel auto-combustion method without post-preparation treatment and, effect of Ni content on structural and magnetic properties is studied by X-ray diffraction (XRD), magnetic measurements and cation distribution. Scherrer’s grain diameter range between 23.5 and 35.1 nm. Experimental and theoretical lattice parameter values suggest that the estimated cation distribution is close to the real distribution. Change in Ni-content leads to variation in cation distribution at site A and B. Ni{sup 2+} ions occupy both A and B site, but when Zn{sup 2+} is fully replaced by Ni{sup 2+}, it totally goes to A site. Both coercivity measured at 50 Hz and quasi static coercivity value is found to increase with nickel content. Same trend is observed for anisotropy constant values. Best magnetization value of 25.04 emu/g was obtained for the specimen with x = 0.60. Variation of magnetic properties and other parameters (obtained via cation distribution) can be understood in terms of observed changes in distribution of cation(s) on A and B site.

  2. Magnetization reversal of Fe ultrathin film on Cu (100)

    Institute of Scientific and Technical Information of China (English)

    He Wei; Zhan Qing-Feng; Wang De-Yong; Chen Li-Jun; Cheng Zhao-Hua

    2008-01-01

    The magnetization reversal of Fe/Cu(100) ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimcter with a magnet that can rotate in a plane of incidence.There occur spin reorientation transitions from out-of-plane to in-plane magnetizations in 8 and 12 monolayers (ML) thick iron films.The coercive fields axe observed to be proportional to the reciprocal of the cosine with respect to the easy axis,suggesting that the domain-wall displacement plays a main role in the magnetization reversal process.

  3. The Fe-Cu system: A thermodynamic evaluation

    Science.gov (United States)

    Chen, Qing; Jin, Zhanpeng

    1995-02-01

    Thermochemical and phase diagram data in the Fe-Cu system have been critically evaluated by using phenomenological models for the Gibbs energy of various phases. A set of thermodynamic parameters more consistent with most of the selected experimental data than previous assess-ments has been obtained by a computerized least-squares method. Stable and metastable phase equilibria, T 0 curves, and thermodynamic properties are calculated with the optimized param-eters. The calculated liquid/face-centered cubic (fcc) T 0 curve and metastable liquid spinodal seem to permit an accurate prediction of maximum solid solubility obtained upon melt quenching in this system.

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

    DEFF Research Database (Denmark)

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

    1999-01-01

    The compressibility of nanostructured Fe-Cu materials prepared by mechanical milling has been investigated by in-situ high-pressure x-ray diffraction using synchrotron radiation. It is found that the bulk modulus of both fcc-Cu and bcc-Fe phases decreases with decreasing grain sizes. The unstable...... ferromagnetic fcc-FeCu solid solution prepared by mechanical alloying has a bulk modulus of about 85 GPa, which is much smaller than the corresponding values for bulk fcc-Cu and bcc-Fe....

  5. Measurements of low photon doses using LiF:Mg,Cu,P and CaF{sub 2}:Cu dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Prokert, K. [Dresden Univ. of Technology (Germany). Inst. of Radiation Protection Physics; Mann, G. [Dresden Univ. of Technology (Germany). Inst. of Radiation Protection Physics

    1997-03-01

    The new thermoluminophors LiF:Mg, Cu, P and CaF{sub 2}:Cu in form of pellets exhibit a significantly higher TL-response than the well-known dosimeters of the types TLD-100 (LiF:Mg, Ti), TLD-400 (CaF{sub 2}:Mn), TLD-900 (CaSO{sub 4}:Dy), etc. Furthermore, the thermoluminophor LiF:Mg, Cu, P shows besides its high sensitivity a good tissue equivalence and therefore, only a small variation of the dose response with the photon energy. The lower limits of detection of these new materials are about 5 {mu}Gy and 0.2 {mu}Gy resp. Therefore, short term measurements of absorbed dose can be realised in radiation fields at very low dose rates (environmental radiation, scattering radiation at medical equipment`s etc.) with an accuracy of {+-}10%. In the field of environmental monitoring the period of exposure can be limited to about 10 days. Using CaF{sub 2}:Cu detectors an exposure of 24 hours is sufficient for dose measurements with lower accuracy. The reusability of CaF{sub 2}:Cu pellets is guaranteed without loss of sensitivity independently of the application of different reading and annealing procedures. In the case of LiF:Mg, Cu, P detectors special procedures are needed in order to keep constant TL-properties. The results of dose measurements at low dose levels in different radiation fields demonstrate the advantages of these detector types. (orig.)

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

    Science.gov (United States)

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

    2015-12-09

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

  7. Growth and magnetic properties of ultrathin epitaxial FeO films and Fe/FeO bilayers on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Kozioł-Rachwał, A., E-mail: akoziol@agh.edu.pl [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Ślęzak, T. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, T.; Yuasa, S. [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Korecki, J. [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Kraków (Poland); Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, ul. Niezapominajek 8, 30-239 Kraków (Poland)

    2016-01-25

    Ultrathin FeO(001) films were grown via molecular beam epitaxy on MgO(001) using reactive deposition of Fe. The growth conditions were adjusted toward stabilization of the wüstite phase, the existence of which was confirmed by means of conversion electron Mössbauer spectroscopy. It was shown how the metallic Fe overlayer modified the chemical state and the magnetic properties of the FeO oxide. Finally, we observed the exchange bias for an epitaxial Fe/FeO bilayer grown on MgO(001)

  8. DC conductivity and Seebeck coefficient of nonstoichiometric MgCuZn ferrites

    Directory of Open Access Journals (Sweden)

    Madhuri W.

    2017-03-01

    Full Text Available Nonstoichiometric series of Mg0.5−xCuxZn0.5Fe1.9O4−δ where x = 0.0, 0.1, 0.15, 0.2 and 0.25 has been synthesized by conventional solid state reaction route. The single phase spinel structure of the double sintered ferrites was confirmed by X-ray diffraction patterns (XRD. The ferrite series was studied in terms of DC electrical conductivity and thermoelectric power in the temperature ranging from room temperature to 300 °C and 400 °C, respectively. It was observed that DC electrical conductivity and Seebeck coefficient α decreased with the increase in x. DC electrical conductivity was found to decrease by about 4 orders. All the compositions showed a negative Seebeck coefficient exhibiting n-type semiconducting nature. From the above experimental results, activation energy and mobility of all the samples were estimated. Small polaron hopping conduction mechanism was suggested for the series of ferrites. Owing to their low conductivity the nonstoichiometric MgCuZn ferrites are the best materials for transformer core and high definition television deflection yokes.

  9. FINITE ELEMENT ANALYSIS ABOUT STRESS AND STRAIN OF SURFACE PEELING IN Cu-Fe-P SHEET

    Institute of Scientific and Technical Information of China (English)

    Su Juanhua; Li Hejun; Dong Qiming; Liu Ping; Kang Buxi

    2005-01-01

    The microstructure of surface peeling in finish rolled Cu-0.1Fe-0.03P sheet is analyzed by scanning electron microscope and energy dispersive spectroscope. Fe-rich areas of different contents are observed in the matrix. The stress distributions and strain characteristics at the interface between Cu matrix and Fe particle are studied by elastic-plastic finite element plane strain model. Larger Fe particles and higher deforming extent of finish rolling are attributed to the intense stress gradient and significant non-homogeneity equivalent strain at the interface and accelerate surface peeling of Cu-0.1Fe-0.03P lead frame sheet.

  10. Layered Double Hydroxides with Hydrotalcite-type Structure Containing Fe3+, Al3+ and Mg2+

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Layered double hydroxides(LDHs) with hydrotalcite-type structure containing Fe3+, Al3+ and Mg2+ were prepared by means of a coprecipitation method. The products were characterized by element analysis, X-ray powder diffraction and transmission electron microscopy. It was found that even if the molar ratio of n(Fe+Al)/n(Fe+Al+Mg)>0.33, yet a pure hydrotalcite-like compound(HTlc) phase was gained when n(Fe)/n(Al+Mg+Fe)≤0.30 and n(Al)/n(Al+Mg+Fe)≤0.30; the Al(OH)3 phase appeared in the products when n(Al)/n(Al+Mg+Fe)>0.30; and an amorphous phase emerged when n(Fe)/n(Al+Mg+Fe)>0.33. These results show that there is no concentration superposition effect between Fe3+ and Al3+ on the crystalline state of the produced samples. In our previous work, the concentration superposition effect between Zn2+ and Mg2+ in the synthesis of Zn-Mg-Al-LDHs was found. For the prepared Fe-Al-Mg-LDHs samples, the value of lattice parameter a is between 0.30-0.32 nm; and the value of lattice parameter c is between 2.30-2.47 nm, the basal spacing is in the range of 0.76-0.83 nm. When the ratio of n(Fe)/n(Al) is a constant, the values of a and c increase with the increase of the Mg2+ content of the produced samples. The mean particle size and the mean crystal grain were determined by virtue of a particle-size instrument, XRD-Scherrer formula and TEM method, respectively.

  11. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    Directory of Open Access Journals (Sweden)

    Chao Peng

    2015-05-01

    Full Text Available In this work, methyl orange (MO was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH. The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g−1. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  12. Calcined Mg-Fe layered double hydroxide as an absorber for the removal of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Chao [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China); State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Dai, Jing [Key Laboratory of Advanced Technology for Special Functional Materials of Ministry of Education, Wuhan 430070 (China); Yu, Jianying, E-mail: Yujianyingwhut@163.com [State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Technology, Wuhan 430070 (China); Yin, Jian [School of Civil Engineering and Mechanics, Central South University of Forestry and Technology, Changsha 410004, Hunan (China)

    2015-05-15

    In this work, methyl orange (MO) was effectively removed from aqueous solution with the calcined product of hydrothermal synthesized Mg/Fe layered double hydroxide (Mg/Fe-LDH). The structure, composition, morphology and textural properties of the Mg/Fe-LDH before and after adsorption were characterized by X-ray diffraction, Fourier transformation infrared spectroscopy, transmission electron microscopy, nitrogen adsorption apparatus and X-ray photoelectron spectroscopy. It was confirmed that MO had been absorbed by calcined Mg/Fe-LDH which had strong interactions with MO. The adsorption of MO onto the Mg/Fe-LDH was systematically investigated by batch tests. The adsorption capacity of the Mg/Fe-LDH toward MO was found to be 194.9 mg • g{sup −1}. Adsorption kinetics and isotherm studies revealed that the adsorption of MO onto Mg/Fe-LDH was a spontaneous and endothermic process. These results indicate that Mg/Fe-LDH is a promising material for the removal of MO.

  13. Effect of precipitation on elastic modulus of Al-Zn-Mg-Cu-Li alloys

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhong-kui; ZHOU Tie-tao; LIU Pei-ying; LI Huan-xi; CHEN Chang-qi

    2006-01-01

    Al-5.6Zn-3.0Mg-1.6Cu-1.1Li-0.24Cr alloys and Al-8.0Zn-2.4Mg-2.4Cu-1.1Li-0.18Zr alloys (mass fraction, %) were aged by different processes. The microstructure and mechanical properties were determined by transmission electron microscopy(TEM),tensile test and Vicker's hardness test. The experimental results show that the most signified hardening is obtained by double-ageing or multi-ageing for the Al-Zn-Mg-Cu-Li alloys. The yield strength and the elastic modulus of the Li-containing alloys have relationships with ageing processes. The elastic modulus of Li-containing alloys decreases with the increment of precipitates though it is higher than that of Al-Zn-Mg-Cu alloy.

  14. Magnetic Properties and Nanostructures of FePtCu:C Thin Films with FePt Underlayers

    Institute of Scientific and Technical Information of China (English)

    JIN Ling-Fang; YAN Ming-Lang

    2007-01-01

    Magnetic properties and nanostructures of FePtCu:C thin films with FePt underlayers (ULs) are studied. The effect of FePt ULs on the orientation and magnetic properties of the thin films are investigated by adjusting FePt UL thicknesses from 2nm to 14nm. X-ray diffraction (XRD) scans reveal that the orientation of the films is dependent on FePt UL thickness. For a 5-nm FePtCu:C nanocomposite thin film with a 2-nm FePt UL, the coercivity is 6.5 KOe, the correlation length is 59nm, the desired face-centred-tetragonal (fct) ordered structure [L10 phase] is formed and the c axis normal to the film plane [(001) texture] is obtained. These results indicate that the better orientation and magnetic properties of the films can be tuned by decreasing the thickness of the FePt UL.

  15. Two Liquid Phases Separation of Fe-Cu-B and Fe-Cu-Ag-B systems at 1873 and 1523 K

    Science.gov (United States)

    Ono-Nakazato, Hideki; Yamaguchi, Katsuhiro; Agawa, Shingo; Taguchi, Kenji; Usui, Tateo

    In recycling of steel scraps, the accumulation of tramp element in steel has been one of serious problems. Because copper in steel causes hot-shortness, the copper content of steel scraps is strictly adjusted under the upper limiting value in steelmaking process. In addition, recycling of steel scrap is necessary for energy savings and to realize a recycling-oriented society. In the present study,it was found that addition of boron could separate a single liquid in Fe-Cu system into Fe-rich and Cu-rich phases. Equilibrium experiments in Fe-Cu-B ternary system at 1873 and 1523 K showed that the copper content in Fe-rich phase decreased to 4.3 mass%. Subsequently, equilibrium experiments in Fe-Cu-Ag-B system were carried out and the copper was observed to be distributed between Fe-B and Ag phases. The distribution ratio of [mass%Cu](in Ag) / [mass%Cu](in Fe) was about 6 at 1873 K, regardless of copper content. It was found that the copper content of iron could be decreased by using silver as the solvent.

  16. Simultaneously degradation of 2,4-dichlorophenol and EDTA in aqueous solution by the bimetallic Cu-Fe/O₂ system.

    Science.gov (United States)

    Liu, Xin; Fan, Jin-Hong; Ma, Lu-Ming

    2015-01-01

    Oxidative degradation of aqueous organic contaminants 2,4-dichlorophenol (2,4-DCP) using ethylenediaminetetraacetic acid (EDTA)-enhanced bimetallic Cu-Fe system in the presence of dissolved oxygen was investigated. The proposed process was applied for the pH range of 3~7 with the degradation efficiency of 2,4-DCP and EDTA varying within 10 %, and achieved at 100 % degradation of 40 mg L(-1) 2,4-DCP in 1 h, at the initial pH of 3, 25 g L(-1) of bimetallic Fe-Cu powder (WCu/WFe = 0.01289) and initial EDTA of 0.57 mM. However, the removal efficiency of 2,4-DCP in control tests were 7.52 % (Cu-Fe/O2 system) and 84.32 % (EDTA-enhanced Fe/O2 process), respectively, after 3 h, reaction. The proposed main mechanism, involves the in situ generation of H2O2 by the electron transfer from Fe(0) to O2 which was enhanced by ethylenediaminetetraacetic acid (EDTA), and the in situ generation of ·OH via advanced oxidation reaction. Accordingly, 2,4-DCP was attacked by ·OH to achieve complete dechlorination and low molecular weight organic acids, even mineralized. Systematic studies on the effects of initial EDTA and 2,4-DCP concentration, Cu-Fe dosing, Cu content, and pH revealed that these effects need to be optimized to avoid the excessive consumption of ·OH and new EDTA and heavy metal Cu pollution.

  17. Stress impedance effect of FeCoSiB/Cu/FeCoSiB sandwich layers on flexible substrate

    Energy Technology Data Exchange (ETDEWEB)

    Peng, B., E-mail: bpeng@uestc.edu.c [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Zhang, W.L.; Liu, J.D.; Zhang, W.X. [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

    2011-06-15

    FeCoSiB/Cu/FeCoSiB sandwich layers were deposited on flexible substrate to develop flexible stress/strain sensors. The influence of stress on the impedance of the multilayers is reported. The results show that the variation of the impedance increases with the increase in deflection of the free end of the cantilever. A relative change in impedance of 6.4% is obtained in the FeCoSiB(1.5 {mu}m)/Cu(0.25 {mu}m)/FeCoSiB(1.5 {mu}m) sandwich layers at 1 MHz with deflection of 2 mm. The stress impedance effects are sensitive to the frequency of the current and the thickness of both FeCoSiB and Cu layers. The stress impedance effect increases with the increase in the thickness of FeCoSiB or Cu layers. The stress impedance effect increases slightly with the increase in frequency and decreases with the further increase in frequency, which can be understood by the stress and frequency-dependent permeability of magnetic films. - Research highlights: We deposited FeCoSiB/Cu/FeCoSiB multilayer on flexible substrate. We studied the stress impedance effect of FeCoSiB/Cu/FeCoSiB multilayer. Stress impedance effect increases with thickness of both FeCoSiB and Cu layer. Stress impedance effect is dependent on current frequency. Results are understood using stress and frequency-dependent permeability.

  18. Revisited abundance diagnostics in quasars: Fe II/Mg II ratios

    CERN Document Server

    Verner, E M; Verner, D A; Johansson, S; Gull, T R

    2003-01-01

    Both the Fe II UV emission in the 2000- 3000 A region [Fe II (UV)] and resonance emission line complex of Mg II at 2800 A are prominent features in quasar spectra. The observed Fe II UV/ Mg II emission ratios have been proposed as means to measure the buildup of the Fe abundance relative to that of the alpha-elements C, N, O, Ne and Mg as a function of redshift. The current observed ratios show large scatter and no obvious dependence on redshift. Thus, it remains unresolved whether a dependence on redshift exists and whether the observed Fe II UV/ Mg II ratios represent a real nucleosynthesis diagnostic. We have used our new 830-level model atom for Fe+ in photoionization calculations, reproducing the physical conditions in the broad line regions of quasars. This modeling reveals that interpretations of high values of Fe II UV/ Mg II are sensitive not only to Fe and Mg abundance, but also to other factors such as microturbulence, density, and properties of the radiation field. We find that the Fe II UV/ Mg II...

  19. Pressure-Induced Electronic Spin Transition of Iron in Magnesiow?stite-(Mg,Fe)O

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J F; Gavriliuk, A G; Struzhkin, V V; Jacobsen, S D; Sturhahn, W; Hu, M Y; Chow, P; Yoo, C S

    2005-10-05

    An electronic transition of iron in magnesiowuestite has been studied with synchrotron Moessbauer and X-ray emission spectroscopies under high pressures. Synchrotron Moessbauer studies show that the quadrupole splitting disappears and the isomer shift drops significantly across the spin-paring transition of iron in (Mg{sub 0.75},Fe{sub 0.25})O between 62 and 70 GPa, whereas X-ray emission spectroscopy of the Fe-K{sub {beta}} fluorescence lines in dilute (Mg{sub 0.95},Fe{sub 0.05})O also confirms that a high-spin to low-spin transition occurs between 46 GPa and 55 GPa. Based upon current results and percolation theory, we reexamine the high-pressure phase diagram of (Mg,Fe)O and find that iron-iron exchange interaction plays an important role in stabilizing the high-spin state of iron in FeO-rich (Mg,Fe)O.

  20. Large magnetic anisotropy in strained Fe/Co multilayers on AuCu and the effect of carbon doping

    Directory of Open Access Journals (Sweden)

    G. Giannopoulos

    2015-04-01

    Full Text Available A tetragonally distorted FeCo structure is obtained in Fe/Co multilayers epitaxially grown on Au50Cu50 buffer using MgO single crystal substrates as a result of the lattice mismatch between the buffer and the FeCo ferromagnetic layer. The presence of large magnetic anisotropy energy (MAE of the order of 1 MJ/m3 has been confirmed by ferromagnetic resonance. Furthermore, the effect of carbon (C doping to maintain the tetragonal distortion throughout the thickness of 3 nm FeCo has been investigated. Our study shows that FeCo alloys maintain large magnetic moment and possess high MAE properties that are required for designing permanent magnets.

  1. THE ROLE OF MAGNESIUM IN Al-Li-Cu-Mg-Zr ALLOYS

    OpenAIRE

    S Harris; Noble, B.; Dinsdale, K.

    1987-01-01

    Within the UK, research has concentrated on alloys of composition Al-2.5%Li-1.2%Cu-0.7%Mg-0.12%Zr (8090) which is a medium strength replacement for 2014. Ageing this lithium-containing alloy at an elevated temperature produces a mixture of phases which are, in order of importance, δ'(Al3Li), S(Al2CuMg) and T1(Al2CuLi). Changing the magnesium content of the alloy changes the relative proportions of the latter two phases, and also influences the volume fraction of δ' that is produced. A systema...

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

    Directory of Open Access Journals (Sweden)

    Aparecida M. S. Mimura

    2016-06-01

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

  3. Cu-induced localization in the Fe-based superconductor FeTe0.5Se0.5

    Science.gov (United States)

    Wen, Jinsheng; Xu, Zhijun; Zhang, Cheng; Matsuda, Masa; Sobolev, Oleg; Park, Jitae; Bourret, Edith; Lee, Dunghai; Li, Qiang; Gu, Genda; Xu, Guangyong; Tranquada, John; Birgeneau, Robert

    2013-03-01

    We report neutron scattering and resistivity results on the Cu-substitution effects in FeTe0.5Se0.5 with a Tc of ~15 K. With a 2 % Cu substitution, the Tc is reduced to 8 K, and for Fe0.9Cu0.1Te0.5Se0.5, it is not superconducting. In Fe0.9Cu0.1Te0.5Se0.5, the low-energy magnetic excitations around the in-plane wave vector (0.5, 0.5) is greatly enhanced. Upon heating, the magnetic scattering is weakened, which is different from the temperature dependences of the Cu-free and 2 % Cu-doped sample. The spectral weight reduction upon warming decreases with increasing energy in the 10 % Cu-doped sample. We take these as evidences that Cu drives the system towards localization, which is confirmed by our resistivity data. These observations probably explain why superconductivity is absent in the Cu-doped BaFe2As2 system and demonstrate the inadequacy of the rigid-band shift model on the substitution effects of the 3 d transition metals. The work is supported by the U.S. Department of Energy.

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

    DEFF Research Database (Denmark)

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

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Donoso, E.

    2014-07-01

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

  6. Study on effects of powder and flake chemistry and morphology on the properties of Al-Cu-Mg-X-X-X powder metallurgy advanced aluminum alloys

    Science.gov (United States)

    Meschter, P. J.; Lederich, R. J.; Oneal, J. E.

    1986-01-01

    A study was conducted: (1) to develop rapid solidification processed (RSP) dispersoid-containing Al-3Cu-2Li-1Mg-0.2Zr alloys as substitutes for titanium alloys and commercial 2XXX aluminum alloys for service to at least 150 C; and (2) to develop RSP Al-4Li-Cu-Mg-Zr alloys as substitutes for high-strength commercial 7XXX alloys in ambient-temperature applications. RSP Al-3Cu-2Li-1Mg-0.2Zr alloys have density-normalized yield stresses at 150 C up to 52% larger than that of 2124-T851 and up to 30% larger than that of Ti-6Al-4V. Strength at 150 C in these alloys is provided by thermally stable delta' (Al3Li), T1 (Al2LiCu), and S' (Al2CuMg) precipitates. Density-normalized yield stresses of RSP Al-3Cu-2Li-1Mg-0.2Zr alloys are up to 100% larger than that of 2124-T851 and equivalent to that of Al-8Fe-4Ce at 260 C. Strength in the RSP alloys at 260 C is provided by incoherent dispersoids and subboundary constituent particles such as T1 and S. The RSP alloys are attractive substitutes in less than or = 100-h exposures for 2xxx and Al-4Fe-Ce alloys up to 260 C and for titanium alloys up to 150 C. RSP Al-4Li-Cu-Mg-Zr alloys have ambient-temperature yield and ultimate tensile stresses similar to that of 7050-T7651, and are 14% less dense. RSP Al-4Li-0.5Cu-1.5Mg-0.2Zr has a 20% higher specific yield stress, 40% higher specific elastic modulus, and superior corrosion resistance compared to the properties of 7050-T7651. Strength in the Al-4Li-Cu-Mg-Zr alloy class is primarily provided by the substructure and delta' precipitates and is independent of Cu:Mg ratio. Improvements in fracture toughness and transverse-orientation properties in both alloy classes depend on improved melt practices to eliminate oxide inclusions which are incorporated into the consolidated forms.

  7. Comparison of microstructure and corrosion properties of Al-Zn-Mg-Cu alloys 7150 and 7010

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-chang; FAN Xi-gang; REN Shi-yu; ZHANG Xin-mei; ZHANG Bao-you

    2006-01-01

    The influence of coarse Cu-bearing particles, matrix and subgrain boundary precipitates on the stress corrosion susceptibility of the Al-Zn-Mg-Cu alloys was investigated. The strength of 7150 alloy is about 15 MPa higher than that of 7010 alloy.The 7010 alloy exhibits higher resistance to stress corrosion cracking as compared with the 7150 alloy. The coarse Cu-bearing particles are detrimental to the resistance to stress corrosion cracking. The increase of size of matrix and subgrain boundary precipitates decreases the susceptibility of stress corrosion. The anodic dissolution and hydrogen embrittlement govern the cracking process. The severity of stress corrosion cracking is shown to be related to the coarse Cu-bearing particles, matrix and subgrain precipitates in Al-Zn-Mg-Cu alloys.

  8. Comparison of characteristics of LiF:Mg,Ti e LiF:Mg,Cu,P thermoluminescent dosemeters; Comparacao das caracteristicas dos dosimetros termoluminescentes LiF:Mg,Ti e LiF:Mg,Cu,P

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, M.S.; Filipov, D., E-mail: dfilipov@utfpr.edu.br [Universidade Tecnologica Federal do Parana (UTFPR/DAFIS), Curitiba, PR (Brazil). Departamento Academicao de Fisica; Schelin, H.R. [Instituto de Pesquisa Pele Pequeno Principe (IPPPP), Curitiba, PR (Brazil)

    2014-07-01

    The aim of the current study was to compare the thermoluminescent dosimeters LiF:Mg,Ti (TLD-100) and LiF:Mg,Cu,P (MCP) data, which were acquired by the Federal Technological University - Parana. Tests were realized, for this purpose, such as: sensitivity (only one MCP TLD did not present results within the limit range), linearity (whose MCP result was better than the TLD-100 one), energy dependence (TLD-100 presented lower variation than MCP TLD) and reproducibility (whose TLD-100 results were better than the MCP ones). The results from both dosimeters show that these TLDs attend radiodiagnostic dosimetry criteria, however MCP had more satisfactory results. (author)

  9. Effect of γ-rays irradiation on the structural, magnetic, and electrical properties of Mg-Cu-Zn and Ni-Cu-Zn ferrites

    Science.gov (United States)

    Assar, S. T.; Abosheiasha, H. F.; El Sayed, A. R.

    2017-01-01

    Nanoparticles of Ni0.35Cu0.15Zn0.5Fe2O4 and Mg0.35Cu0.15Zn0.5Fe2O4, have been synthesized by citrate precursor method. Then some of the prepared samples have been irradiated by γ-rays of 60Co radioactive source at room temperature with doses of 1 Mrad and 2 Mrad, at a dose rate of 0.1 Mrad/h to study the effect of γ-rays irradiation on some structural, magnetic and electrical properties of the samples. The X-ray diffraction analysis (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometer measurements have been used to investigate the samples. The XRD results show that the irradiation has caused a decrease in the crystallite size and the measured density and an increase in the porosity, specific surface area, and microstrain in the case of Ni-Cu-Zn ferrite whereas in the case of Mg-Cu-Zn ferrite the reverse trend has been noticed. The lattice constant of the investigated samples has been increased with the increase of irradiation due to the conversion of Fe3+ (0.67 Å) to Fe2+ (0.76 Å). The magnetization results show an increase in saturation and remnant magnetizations for the two prepared ferrites after γ-rays irradiation. The main reason of this behavior is most probably due to the redistribution of the cations between A and B sites. The cation distribution has been proposed such that the values of theoretical and experimental magnetic moment are identical and increase as the magnetization increases. Moreover, a theoretical estimation of the lattice constant has been calculated on the basis of the proposed cation distribution for each sample and compared with the corresponding experimental values obtained by XRD analysis; where they have been found in a good agreement with each other. This can be considered as another confirmation of the validity of the cation distribution. Moreover, the cation distribution is thought to play an important role in increasing the values of dc conductivity of all samples

  10. The effect of Mn and Zr additions on Fe impurities and the corrosion performance of Mg

    OpenAIRE

    Gandel, Darren Samuel

    2017-01-01

    Manganese (Mn) and zirconium (Zr) are two common alloying additions in magnesium (Mg) alloys. Both of these elements, while having low solubilities in Mg, each serve a specific purpose when added to Mg. Mn is often added to improve the extrudability and formability of Mg alloys and in aluminium (Al) containing Mg alloys to produce the Al8(Mn,Fe)5 phase which is able to remove iron (Fe) impurities to dramatically improve the corrosion resistance. Zr is incorporated in Mg mainly due to its uniq...

  11. Magneto-optical response of Cu/NiFe/Cu nanostructure under surface plasmon resonance

    Science.gov (United States)

    Mahmoodi, S.; Moradi, M.; Mohseni, S. M.

    2016-12-01

    In this paper, we present theoretical and experimental studies about the surface plasmon resonance effects on the magneto-optical activity of Cu/NiFe/Cu nanostructures as a function of layers thickness and light incident angle. Device fabrication was done by an oblique deposition technique with RF magnetron sputtering to carefully cover fine step thickness variation of all constituted layers. Angular dependent transverse Kerr response of samples was measured in the Kretschmann configuration at a fixed wavelength of 632 nm. At an optimum layer thickness and incident angle, significant amplification of the transverse Kerr effect was observed. Enhancement in the transverse Kerr effect can be realized by hybridization of surface plasmon excitation and cavity resonance in the plasmonic nanostructure. Experimental results were in qualitative agreement with modeling based on the 4×4 transfer matrix formalism.

  12. Mechanically strong nanocrystalline Fe-Si-B-P-Cu soft magnetic powder cores utilizing magnetic metallic glass as a binder

    Directory of Open Access Journals (Sweden)

    Jian Luan

    2016-05-01

    Full Text Available We report on the fabrication and properties of soft magnetic powder cores with superior mechanical strength as well as low core loss (W. Development of such cores is important for applications in automobiles/devices operating in motion. High saturation magnetic flux density (Bs Fe-Si-B-P-Cu powder was sintered with Fe55C10B5P10Ni15Mo5 metallic glass (MG powder in its supercooled liquid state by spark plasma sintering. The sintered cores are made from the nanocrystalline powder particles of Fe-Si-B-P-Cu alloy, which are separated through a magnetic Fe55C10B5P10Ni15Mo5 MG alloy. Low W of ∼ 2.2 W/kg (at 1T and 50 Hz, and high fracture strength (yielding stress ∼500 MPa, which is an order of magnitude higher than the conventional powder cores, were obtained. Stronger metal-metal bonding and magnetic nature of MG binder (which is very different than the conventional polymer based binders are responsible for the superior mechanical and magnetic properties. The MG binder not only helps in improving the mechanical properties but it also enhances the overall Bs of the core.

  13. Spin-dependent electrical transport in Fe-MgO-Fe heterostructures

    Directory of Open Access Journals (Sweden)

    A A Shokri

    2016-09-01

    Full Text Available In this paper, spin-dependent electrical transport properties are investigated in a single-crystal magnetic tunnel junction (MTJ which consists of two ferromagnetic Fe electrodes separated by an MgO insulating barrier. These properties contain electric current, spin polarization and tunnel magnetoresistance (TMR. For this purpose, spin-dependent Hamiltonian is described for Δ1 and Δ5 bands in the transport direction. The transmission is calculated by Green's function formalism based on a single-band tight-binding approximation. The transport properties are investigated as a function of the barrier thickness in the limit of coherent tunneling. We have demonstrated that dependence of the TMR on the applied voltage and barrier thickness. Our numerical results may be useful for designing of spintronic devices. The numerical results may be useful in designing of spintronic devices.

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

    Directory of Open Access Journals (Sweden)

    Anabil Gayen

    2013-01-01

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

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

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

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

  16. Microstructure and magnetic properties of FePt/MgO multilayers deposited by RF magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Xiaoli Li; Fang Wang; Fengxian Jiang; Xiaohong Xu; Haishun Wu

    2008-01-01

    FePt (50 rim) and [FePt(a nm)/MgO(b nm)]5/glass (a=1, 2, 3; b=1, 2, 3)films Were prepared by radio frequency (RF) magnetron sputtering technique, and then were annealed at 600℃ for 30 min. The effect of MgO layer thickness on the structures and magnetic properties of the FePt/MgO multilayers was investigated. The coercivities and inter-grain interactions of the FePt/MgO films were decreased, yet the degree of (001) texturing drastically increased with the increase in MgO layer thickness when the FePt layer thickness was fixed. Thus, the FePt/MgO films with appropriate coercivities, high perpendicular anisotropy, and weak inter- grain interactions were obtained by controlling the MgO layer thickness. Overall, these results indicate that the FePt/MgO nanos- tructured films are promising candidates for future high-density perpendicular recording media. C 2008 University of Science and Technology Beijing. All fights reserved.

  17. Fe and Cu stable isotopes in archeological human bones and their relationship to sex.

    Science.gov (United States)

    Jaouen, Klervia; Balter, Vincent; Herrscher, Estelle; Lamboux, Aline; Telouk, Philippe; Albarède, Francis

    2012-07-01

    Accurate sex assignment of ancient human remains usually relies on the availability of coxal bones or well-preserved DNA. Iron (Fe) and copper (Cu) stable isotope compositions ((56)Fe/(54)Fe and (65)Cu/(63)Cu, respectively) were recently measured in modern human blood, and an unexpected result was the discovery of a (56)Fe-depletion and a (65)Cu-enrichment in men's blood compared to women's blood. Bones, being pervasively irrigated by blood, are expected to retain the (56)Fe/(54)Fe and (65)Cu/(63)Cu signature of blood, which in turn is useful for determining the sex of ancient bones. Here, we report the (56)Fe/(54)Fe, (65)Cu/(63)Cu, and (66)Zn/(64)Zn ratios from a suite of well-preserved phalanxes (n = 43) belonging to individuals buried in the 17th and 18th centuries at the necropolis of Saint-Laurent de Grenoble, France, and for which the sex was independently estimated from pelvic bone morphology. The metals were purified from the bone matrix by liquid chromatography on ion exchange resin and the isotope compositions were measured by multiple-collector inductively coupled plasma mass spectrometry. The results show that, as expected from literature data on blood, male bone iron is depleted in (56)Fe and enriched in (65)Cu relative to female. No sex difference is found in the (66)Zn/(64)Zn ratios of bone. The concentration and isotopic data show no evidence of soil contamination. Four samples of five (77%) can be assigned their correct sex, a result comparable to sex assignment using Fe and Cu isotopes in blood (81%). Isotopic analysis of metals may therefore represent a valid method of sex assignment applicable to incomplete human remains.

  18. The Influence of Composition on the Clustering and Precipitation Behavior of Al-Mg-Si-Cu Alloys

    Science.gov (United States)

    Jia, Zhihong; Ding, Lipeng; Cao, Lingfei; Sanders, Robert; Li, Shichen; Liu, Qing

    2017-01-01

    The natural aging (NA) and artificial aging (AA) behavior of Al-Mg-Si-Cu alloys with different Mg/Si ratios and Cu additions were systematically investigated by means of hardness test, atom probe tomography, transmission electron microscopy, and Monte Carlo simulation. The Si-rich low-Cu alloys displayed higher hardness compared to the Mg-rich equivalents because Si atoms play a dominant role in clustering of solute atoms during both natural and artificial aging. In the high-Cu alloys, Cu did not obviously change the cluster distribution during NA, but significantly refines the clusters and precipitates due to the strong interaction of Cu atoms with Mg atoms during AA. In contrast to the low-Cu alloys, the Mg-rich high-Cu alloys exhibit higher hardness in the early and over-aged stages of artificial aging, with similar or slightly higher hardness in the peak aging condition compared to their Si-rich counterparts. Three types of precipitates ( β″, Q', and L) are favored in the high-Cu alloys. The Mg-rich high-Cu alloy has more L phase, while the Si-rich variant is abundant in Q' phase. The negative effect of NA on subsequent AA behavior is less dependent on Mg/Si ratio in the high-Cu alloys due to a synergistic action of the residual Si and Cu atoms, but is closely related to Mg/Si ratio in low-Cu alloys.

  19. Stripe-to-bubble transition of magnetic domains at the spin reorientation of (Fe/Ni)/Cu/Ni/Cu(001)

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.; Choi, J.; Won, C.; Wu, Y. Z.; Scholl, A.; Doran, A.; Hwang, Chanyong; Qiu, Z.

    2010-06-09

    Magnetic domain evolution at the spin reorientation transition (SRT) of (Fe/Ni)/Cu/Ni/Cu(001) is investigated using photoemission electron microscopy. While the (Fe/Ni) layer exhibits the SRT, the interlayer coupling of the perpendicularly magnetized Ni layer to the (Fe/Ni) layer serves as a virtual perpendicular magnetic field exerted on the (Fe/Ni) layer. We find that the perpendicular virtual magnetic field breaks the up-down symmetry of the (Fe/Ni) stripe domains to induce a net magnetization in the normal direction of the film. Moreover, as the virtual magnetic field increases to exceed a critical field, the stripe domain phase evolves into a bubble domain phase. Although the critical field depends on the Fe film thickness, we show that the area fraction of the minority domain exhibits a universal value that determines the stripe-to-bubble phase transition.

  20. Computation assisted design of favored composition for ternary Mg-Cu-Y metallic glass formation.

    Science.gov (United States)

    Wang, Q; Li, J H; Liu, B X

    2015-06-14

    With the aid of ab initio calculations, a realistic interatomic potential was constructed for the Mg-Cu-Y ternary system under the proposed formalism of smoothed and long-range second-moment approximation of tight-binding. Taking the potential as the starting base, an atomistic computation/simulation route was developed for designing favored and optimized compositions for Mg-Cu-Y metallic glass formation. Simulations revealed that the physical origin of metallic glass formation is the collapse of crystalline lattice when solute concentration exceeds a critical value, thus leading to predict a hexagonal region in the Mg-Cu-Y composition triangle, within which metallic glass formation is energetically favored. It is proposed that the hexagonal region can be defined as the intrinsic glass formation region, or quantitative glass formation ability of the system. Inside the hexagonal region, the driving force for formation of each specific glassy alloy was further calculated and correlated with its forming ability in practice. Calculations pinpointed the optimized stoichiometry in the Mg-Cu-Y system to be Mg64Cu16Y20, at which the formation driving force reaches its maximum, suggesting that metallic glasses designed to have compositions around Mg64Cu16Y20 are most stable or easiest to obtain. The predictions derived directly from the atomistic simulations are supported by experimental observations reported so far in the literature. Furthermore, Honeycutt-Anderson analysis indicated that pentagonal bipyramids (although not aggregating to form icosahedra) dominate in the local structure of the Mg-Cu-Y metallic glasses. A microscopic picture of the medium-range packing can then be described as an extended network of the pentagonal bipyramids, entangled with the fourfold and sixfold disclination lines, jointly fulfilling the space of the metallic glasses.

  1. Determination of Cu, Zn, Ca, Mg and Fe in Human Hair by ICP-AES%电感耦合等离子体原子发射光谱(ICP-AES)法测定人发中铜、锌、钙、镁、铁

    Institute of Scientific and Technical Information of China (English)

    王生进; 张琳; 刘春虎; 董龙腾; 韩夫强

    2016-01-01

    样品经硝酸-高氯酸消化溶解,高氯酸冒烟,盐酸溶解盐类后,在盐酸(5%)介质中,在选定的测定条件下,用电感耦合等离子体原子发射光谱(ICP-AES)法测定人发中微量元素铜、锌、铁、镁、钙.选择Cu 327.3、Zn 206.2、Fe 238.2、Mg 279.5、Ca 315.8 nm分别作为铜、锌、铁、镁、钙的分析线与混合标准溶液同时测定;方法加标回收率为98.6%~101%,铜、锌、铁、镁、钙的精密度(RSD,n=8)为0.37%~2%,准确度(RE)为-3.4%~1.15%,检出限分别为0.002 3、0.001 6、0.004 6、0.003 0、0.001 4 μg/mL.方法克服了分光光度法和原子吸收光谱法操作繁琐、周期长、成本高、灵敏度低等缺点.用于测定人发样品中的铜、锌、铁、镁、钙元素,测定结果与原子吸收光谱法测定值基本一致.经GB-WO7061标准物质和自制标样分析验证,测定值与标准值吻合,结果准确可靠.

  2. Friction behavior of Al-Cu-Fe-B polycrystalline quasicrystals

    Institute of Scientific and Technical Information of China (English)

    周细应; 李培耀; 罗军明; 钱士强; 童建华

    2004-01-01

    Dry sliding friction between the polycrystalline Al59 Cu25.5 Fe12.5 B3 quasicrystals(QCs) and coating of thediamond-like carbon(DLC) was carried out by self-made tribometer under different conditions. The influences of four parameters(temperature, sliding velocity, applied load, atmosphere) on friction of quasicrystal surface were studied. Microstructure of quasicrystal, morphology of worn surface, and wear debris were observed by scanning electron microscope(SEM). The results show that for QCs, the friction coefficient and the roughness of worn surface is influenced by the parameters, especially greatly by the temperature. With increasing the applied load and sliding velocity, the friction coefficient decreases. The dominant wear mechanism at 350 ℃ is delamination for QCs. The cracks forms on the worn surface during friction. Moreover, phase transformation is not observed on worn surface of QCs at 350 ℃.

  3. Melting relations in the system FeCO3-MgCO3 and thermodynamic modelling of Fe-Mg carbonate melts

    Science.gov (United States)

    Kang, Nathan; Schmidt, Max W.; Poli, Stefano; Connolly, James A. D.; Franzolin, Ettore

    2016-09-01

    To constrain the thermodynamics and melting relations of the siderite-magnesite (FeCO3-MgCO3) system, 27 piston cylinder experiments were conducted at 3.5 GPa and 1170-1575 °C. Fe-rich compositions were also investigated with 13 multi-anvil experiments at 10, 13.6 and 20 GPa, 1500-1890 °C. At 3.5 GPa, the solid solution siderite-magnesite coexists with melt over a compositional range of X Mg (=Mg/(Mg + Fetot)) = 0.38-1.0, while at ≥10 GPa solid solution appears to be complete. At 3.5 GPa, the system is pseudo-binary because of the limited stability of siderite or liquid FeCO3, Fe-rich carbonates decomposing at subsolidus conditions to magnetite-magnesioferrite solid solution, graphite and CO2. Similar reactions also occur with liquid FeCO3 resulting in melt species with ferric iron components, but the decomposition of the liquid decreases in importance with pressure. At 3.5 GPa, the metastable melting temperature of pure siderite is located at 1264 °C, whereas pure magnesite melts at 1629 °C. The melting loop is non-ideal on the Fe side where the dissociation reaction resulting in Fe3+ in the melt depresses melting temperatures and causes a minimum. Over the pressure range of 3.5-20 GPa, this minimum is 20-35 °C lower than the (metastable) siderite melting temperature. By merging all present and previous experimental data, standard state (298.15 K, 1 bar) thermodynamic properties of the magnesite melt (MgCO3L) end member are calculated and the properties of (Fe,Mg)CO3 melt fit by a regular solution model with an interaction parameter of -7600 J/mol. The solution model reproduces the asymmetric melting loop and predicts the thermal minimum at 1240 °C near the siderite side at X Mg = 0.2 (3.5 GPa). The solution model is applicable to pressures reaching to the bottom of the upper mantle and allows calculation of phase relations in the FeO-MgO-O2-C system.

  4. Atomic Structure of Ca40+xMg25Cu35-x Metallic Glasses (Postprint)

    Science.gov (United States)

    2012-06-21

    arrangements very similar to the competing Mg2Cu ( Laves phase ) and YCu2 crystals. Simi- lar comparison of coordination polyhedra in the amorphous structure of...hexagonal Laves phase (space group P63/mmc, space group number 194) with lattice parameters a¼ 5.170 Å and c¼ 8.50 Å. This crystal structure contains three...centered (0,0,12,4) Friauf polyhedron containing 12 Mg and 4 Ca atoms in the first shell. Cu2Mg is a cubic Laves phase (space group is Fd-3 m, space group

  5. Effect of MgO on Oxidation Process of Fe3 O4 in Pellets

    Institute of Scientific and Technical Information of China (English)

    Qiang-jian GAO; Yan-song SHEN; Xin JIANG; Hai-yan ZHENG; Feng-man SHEN; Chang-sheng LIU

    2016-01-01

    Induration process of oxidized pellets involves the oxidation of Fe3 O4 and re-crystallization of Fe2 O3 .The oxidation process of Fe3 O4 is significant for pellets to obtain better ambient strength.Thus,the effect of MgO on oxidation process of Fe3 O4 was investigated.The unreacted core model was applied to analyze the oxidizing indura-tion process of pellets.The experimental results show that MgO plays a negative role in the oxidation process of Fe3 O4 .The oxidation rate of Fe3 O4 in MgO-fluxed pellets (95.0% Fe3 O4+5.0% MgO)is slower than that in standard acid pellets (100% Fe3 O4 ).The relation between oxidation ratio of Fe3 O4 and time was calculated based on the unreacted core model for both MgO-fluxed pellets and standard acid pellets.According to verification experi-ments,the values calculated by model coincide well with the experimental values.Therefore,the unreacted core model could be applied to describe the oxidizing induration process of pellets.

  6. Phase separation and rapid solidification of liquid Cu60Fe30Co10 ternary peritectic alloy

    Institute of Scientific and Technical Information of China (English)

    DAI FuPing; CAO ChongDe; WEI BingBo

    2007-01-01

    The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two separated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respectively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) droplets with the same size.

  7. Phase separation and rapid solidification of liquid Cu60Fe30Co10 ternary peritectic alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two sepa- rated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respec- tively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) drop- lets with the same size.

  8. Ferromagnetic resonance in 80NiFe/Cu/Co multilayer films

    Science.gov (United States)

    Koizumi, H.; Ando, Y.; Miyazaki, T.

    1996-12-01

    Trilayers and multilayers containing ferromagnetic 80NiFe,Co layers separated by nonmagnetic Cu layers were fabricated using the magnetron sputtering method. For 80NiFe(60 Å)/Cu (d Cu)/ Co(60 Å) trilayer films, the MR ratio and the exchange coupling strength oscillated with increasing dCu. For 80NiFe(60 Å)/Cu (d Cu)/ Co(60 Å)/Cu (d Cu)/ 80NiFe(60 Å) multilayer films, however, the exchange coupling between the bottom 80NiFe and the Co layers oscillated, while that between the Co and the top 80NiFe layers decreased monotonously with increasing dCu. Consequently, antiferromagnetic exchange coupling was not achieved between the Co(60 Å) and the top magnetic layer. The reason for the nonexistence of antiferromagnetic exchange coupling is discussed by taking into account the rougher surface of the Co(60 Å) layer caused by the growth of the different crystalline structures.

  9. Cytotoxic, Genotoxic, and Neurotoxic Effects of Mg, Pb, and Fe on Pheochromocytoma (PC-12) Cells

    Science.gov (United States)

    Sanders, Talia; Liu, Yi-Ming; Tchounwou, Paul B.

    2014-01-01

    Metals such as lead (Pb), magnesium (Mg), and iron (Fe) are ubiquitous in the environment as a result of natural occurrence and anthropogenic activities. Although Mg, Fe and others are considered essential elements, high level of exposure has been associated with severe adverse health effects including cardiovascular, hematological, nephrotoxic, hepatotoxic, and neurologic abnormalities in humans. In the present study we hypothesized that Mg, Pb, and Fe are cytotoxic, genotoxic and neurotoxic, and their toxicity is mediated through oxidative stress and alteration in protein expression. To test the hypothesis, we used the pheochromocytoma (PC-12) cell line as a neuro cell model and performed the LDH assay for cell viability, Comet assay for DNA damage, Western blot for oxidative stress, and HPLC-MS to assess the concentration levels of neurological biomarkers such as glutamate, dopamine (DA), and 3-methoxytyramine (3-MT). The results of this study clearly show that Mg, Pb, and Fe, respectively in the form of MgSO4, Pb(NO3)2, FeCl2, and FeCl3 induce cytotoxicity, oxidative stress, and genotoxicity in PC-12 cells. In addition, exposure to these metallic compounds caused significant changes in the concentration levels of glutamate, dopamine, and 3-MT in PC-12 cells. Taken together the findings suggest that MgSO4, Pb(NO3)2, FeCl2, and FeCl3 have the potential to induce substantial toxicity to PC-12 cells. PMID:24942330

  10. Novel Oscillation Period of the Interlayer Exchange Coupling in Fe/Cr/Fe Due to MgO Capping

    Science.gov (United States)

    Halley, D.; Bengone, O.; Boukari, S.; Weber, W.

    2009-01-01

    A novel period of the interlayer exchange coupling as a function of Cr thickness is observed in epitaxial Fe/Cr/Fe (001) sandwiches capped with MgO. This additional period, equal to 3 chromium atomic layers, vanishes when the capping is Cr. A strong oscillation of the magnetic coupling is also observed as a function of the thickness of the Fe layer next to the MgO capping layer. This effect is attributed to the formation of quantum well states in this Fe layer. It is believed that this confinement modifies the reflection coefficient at the Cr/Fe interface for electrons of a particular symmetry and leads to the new coupling period which is linked to the Fermi surface topology of chromium.

  11. Production of sulfate radical from peroxymonosulfate induced by a magnetically separable CuFe2O4 spinel in water: Efficiency, stability, and mechanism

    KAUST Repository

    Zhang, Tao

    2013-03-19

    A simple, nonhazardous, efficient and low energy-consuming process is desirable to generate powerful radicals from peroxymonosulfate (PMS) for recalcitrant pollutant removal. In this work, the production of radical species from PMS induced by a magnetic CuFe2O4 spinel was studied. Iopromide, a recalcitrant model pollutant, was used to investigate the efficiency of this process. CuFe2O4 showed higher activity and 30 times lower Cu2+ leaching (1.5 μg L-1 per 100 mg L-1) than a well-crystallized CuO at the same dosage. CuFe 2O4 maintained its activity and crystallinity during repeated batch experiments. In comparison, the activity of CuO declined significantly, which was ascribed to the deterioration in its degree of crystallinity. The efficiency of the PMS/CuFe2O4 was highest at neutral pH and decreased at acidic and alkaline pHs. Sulfate radical was the primary radical species responsible for the iopromide degradation. On the basis of the stoichiometry of oxalate degradation in the PMS/CuFe 2O4, the radical production yield from PMS was determined to be near 1 mol/mol. The PMS decomposition involved an inner-sphere complexation with the oxide\\'s surface Cu(II) sites. In situ characterization of the oxide surface with ATR-FTIR and Raman during the PMS decomposition suggested that surface Cu(II)-Cu(III)-Cu(II) redox cycle was responsible for the efficient sulfate radical generation from PMS. © 2013 American Chemical Society.

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

    Science.gov (United States)

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

  13. A comparison study of Co and Cu doped MgO diluted magnetic thin films

    Science.gov (United States)

    Sarıtaş, S.; ćakıcı, T.; Muǧlu, G. Merhan; Kundakcı, M.; Yıldırım, M.

    2017-02-01

    Transition metal-doped MgO diluted magnetic thin films are appropriate candidates for spintronic applications and designing magnetic devices and sensors. Therefore, MgO:Co and MgO:Cu films were deposited on glass substrates by Chemical Spray Pyrolysis (CSP) method different thin film deposition parameters. Deposited different transition metal doped MgO thin films were compared in terms of optic and structural properties. Comparison optic analysis of the films was investigated spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. Comparison structural analysis of the thin films was examined by using XRD, Raman Analysis, SEM, EDX and AFM techniques. The transition metal-doped; MgO:Co and MgO:Cu thin films maybe have potential applications in spintronics and magnetic data storage.

  14. Quality and Cost Assessment of Treatment with SiMg and NiCuMg Master Alloys vs Cored Wire in Production of Ductile Iron

    Directory of Open Access Journals (Sweden)

    E. Guzik

    2007-07-01

    Full Text Available The results of studies on the use of magnesium alloy in modern cored wire injection method for production of nodular and vermicular graphite cast irons were described. The injection of Mg cored wire length is a treatment method which can be used to process high sulphur cupola iron held in ladles or iron melted in an electric induction furnace. This paper describes the results of using a high-magnesium ferrosilicon alloy in cored wire (Mg recovery 47-70% for the production of vermicular and nodular graphite cast irons at Ścinawka Foundry, and for the production of nodular graphite iron at the following foundries: GZUT, KRAKODLEW, Centrozap - DEFKA, EE Zawiercie, WSK–Rzeszów, FWM PRZYSUCHA, HSW Stalowa Wola and PIOMA. The results of calculations and experiments have indicated the length of the cored wire to be injected basing on the initial sulfur content and weight of the treated melt. The results of numerous trials have shown that the magnesium cored wire process can produce high quality nodular and vermicular graphite irons under the specific industrial conditions of the above mentioned foundries. It has also been proved that in the manufacture of nodular graphite iron, the cost of the nodulariser in the form of elastic cored wire is lower than the cost of the FeSiMg or NiCuMg master alloys.

  15. Kinetic behavior of LiFeMgPO 4 cathode material for Li-ion batteries

    Science.gov (United States)

    Hong, Jian; Wang, Chunsheng; Kasavajjula, Uday

    LiFe 0.9Mg 0.1PO 4 material was prepared by mechanical milling method, followed by heat treatment. The equilibrium potential-composition isotherm of LiFe 0.9Mg 0.1PO 4 and charge-discharge kinetics of LiFe 0.9Mg 0.1PO 4 were measured using galvanostatic intermittent titration technique (GITT), potential-step chronoamperometry (PSCA), and electrochemical impedance spectroscopy (EIS). The rate performance of the cathode is controlled by the charge-transfer kinetics, electronic conductivity, Li-ion diffusion capability, and phase transformation rate. Since LiFe 0.9Mg 0.1PO 4 has a fast charge-transfer reaction and high electronic and ionic diffusivity, the phase transformation between LiFe 0.9Mg 0.1PO 4 and Li 0.1Fe 0.9Mg 0.1PO 4 begins to play a more important role in the charge-discharge process, as is evident by an inductive loop induced by the phase transformation in the low frequency region of EIS. The phase purity and morphology of LiFe 0.9Mg 0.1PO 4 were also observed using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  16. Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process

    Directory of Open Access Journals (Sweden)

    Saikawa S.

    2015-06-01

    Full Text Available High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC and Y-block shaped metal mold(Permanent mold Casting; PC C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of the two-step aged SC alloys were 353-387 MPa and about 0.4% respectively. This low tensile properties of the SC alloys might be caused by remaining of undissolved crystallized phase such as Al2CuM, MgZn2 and Al-Fe-Cu system compounds. However, good tensile properties were obtained from PC alloys, tensile strength and 0.2% proof stress and elongation were 503-537 MPa, 474-519 MPa and 1.3-3.3%.

  17. Giant Magneto-Impedance Effect in Sandwiched FeSiB/Cu/FeSiB Films

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yong; YANG Chun-Sheng; YU Jin-Qiang; ZHAO Xiao-Lin; MAO Hai-Ping

    2000-01-01

    Giant magneto-impedance (GMI) effect has been realized in the sandwiched FeSiB/Cu/FeSiB films. With magnetic field Ha and ac current applied along the longitudinal direction of the sample, the GMI ratio increases with the increasing Ha, reaching a positive maximum, value, and then decreases to negative values with further increase of magnetic field. Field dependence of the GMI ratio also indicates that the magnetic field corresponding to the maximum GMI ratio is different for various frequencies. The positive maximum GMI ratio is 17.2% for Ha=1600 A/m and frequency of 3 MHz. In addition, the films display a large negative GMI ratio with a magnetic field applied along the transverse direction and the value of the GMI ratio is about -13.4% for Ha=5600A/m and frequency of 3 MHz.

  18. Tunable Magnetic Properties in CuCr2- x Fe x O4 Ceramics by Doping of Fe

    Science.gov (United States)

    Zhu, C. M.; Wang, L. G.; Bao, D. L. G. C.; Luo, H.; Tian, Z. M.; Yuan, S. L.

    2016-08-01

    CuCr2- x Fe x O4 ceramics have been successfully synthesized using the sol-gel method for the first time. With pure formation, material structure has been characterized by x-ray diffraction. The samples have been identified as having the spinel structure with formulae CuCr2- x Fe x O4. Micrographs obtained by scanning electron microscopy show the dense microstructure of the samples. The stoichiometric ratio of the ceramics has been measured through energy dispersive spectra. Magnetic properties of CuCr2- x Fe x O4 ceramics have been discussed. Temperature dependence of magnetization presents the gradually increasing irreversible temperature as the content of Fe element increases from x = 0 to 1. Coercive field ( H C), remanent magnetization ( M r), and saturation magnetization ( M S) respectively display the monotonous variation phenomena with increasing content of Fe. The increasing M r, M S and the decreasing H C can be attributed to the change of magnetic exchange interaction because of the doped Fe. It also proves that the magnetic properties of CuCr2- x Fe x O4 ceramics can be effectively tuned by the doping content of Fe.

  19. Non-isothermal precipitation behaviors of Al-Mg-Si-Cu alloys with different Zn contents

    Energy Technology Data Exchange (ETDEWEB)

    Guo, M.X., E-mail: mingxingguo@skl.ustb.edu.cn; Zhang, Y.; Zhang, X.K.; Zhang, J.S.; Zhuang, L.Z.

    2016-07-04

    The non-isothermal precipitation behaviors of Al–Mg–Si–Cu alloys with different Zn contents were investigated by differential scanning calorimetry (DSC) analysis, hardness measurement and high resolution transmission electron microscope characterization. The results show that Zn addition has a significant effect on the GP zone dissolution and precipitation of Al-Mg-Si-Cu alloys. And their activation energies change with the changes of Zn content and aging conditions. Precipitation kinetics can be improved by adding 0.5 wt% or 3.0 wt%Zn, while be suppressed after adding 1.5 wt%Zn. The Mg-Si precipitates (GP zones and β″) are still the main precipitates in the Al-Mg-Si-Cu alloys after heated up to 250 °C, and no Mg-Zn precipitates are observed in the Zn-added alloy due to the occurrence of Mg-Zn precipitates reversion. The measured age-hardening responses of the alloys are corresponding to the predicted results by the established precipitation kinetic equations. Additionally, a double-hump phenomenon of hardness appears in the artificial aging of pre-aged alloy with 3.0 wt% Zn addition, which resulted from the formation of pre-β″ and β″ precipitates. Finally, the precipitation mechanism of Al-Mg-Si-Cu alloys with different Zn contents was proposed based on the microstructure evolution and interaction forces between Mg, Si and Zn atoms.

  20. Corrosion and protection of heterogeneous cast Al-Si (356) and Al-Si-Cu-Fe (380) alloys by chromate adn cerium inhibitors

    Science.gov (United States)

    Jain, Syadwad

    In this study, the localized corrosion and conversion coating on cast alloys 356 (Al-7.0Si-0.3Mg) and 380 (Al-8.5Si-3.5Cu-1.6Fe) were characterized. The intermetallic phases presence in the permanent mold cast alloy 356 are primary-Si, Al5FeSi, Al8Si6Mg3Fe and Mg2Si. The die cast alloy 380 is rich in Cu and Fe elements. These alloying elements result in formation of the intermetallic phases Al 5FeSi, Al2Cu and Al(FeCuCr) along with primary-Si. The Cu- and Fe-rich IMPS are cathodic with respect to the matrix phase and strongly govern the corrosion behavior of the two cast alloys in an aggressive environment due to formation of local electrochemical cell in their vicinity. Results have shown that corrosion behavior of permanent mould cast alloy 356 is significantly better than the die cast aluminum alloy 380, primarily due to high content of Cu- and Fe-rich phases such as Al2Cu and Al 5FeSi in the latter. The IMPS also alter the protection mechanism of the cast alloys in the presence of inhibitors in an environment. The presence of chromate in the solution results in reduced cathodic activity on all the phases. Chromate provides some anodic inhibition by increasing pitting potentials and altering corrosion potentials for the phases. Results have shown that performance of CCC was much better on 356 than on 380, primarily due to inhomogeneous and incomplete coating deposition on Cu- and Fe- phases present in alloy 380. XPS and Raman were used to characterize coating deposition on intermetallics. Results show evidence of cyanide complex formation on the intermetallic phases. The presence of this complex is speculated to locally suppress CCC formation. Formation and breakdown of cerium conversion coatings on 356 and 380 was also analyzed. Results showed that deposition of cerium hydroxide started with heavy precipitation on intermetallic particles with the coatings growing outwards onto the matrix. Electrochemical analysis of synthesized intermetallics compounds in the

  1. Optical Property of LiNbO3 Crystal Codoped with In, Mg and Fe

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In2O3, MgO and Fe2O3 were doped in LiNbO3 and Czochralski method was used to grow In:Mg:Fe:LiNbO3 crystals. The OH- extension transmission spectra, light scattering resistance ability, two wave coupled diffraction efficiency and response time of the crystal were measured. Codoping In and Mg in crystal will improve its light scattering resistance ability and response time. Doping In can increase the ability to replace antisite Nb and decrease the doping quantity of Mg. All these are propitious to improve the optical homogeneity of crystal. Doping Fe can improve the photorefractive sensitivity for LiNbO3 crystal. We discussed the site of In, Mg and Fe in LiNbO3 crystals and the influence of the absorption peak of OH- transmission spectra on photorefractive property for LiNbO3 crystal.

  2. Microstructure and Wear Behavior Of as Cast Al-25mg2si-2cu-2ni Alloy

    Directory of Open Access Journals (Sweden)

    1Geetanjali.S.Guggari ,

    2015-09-01

    Full Text Available The remarkable feature of the Aluminium is its low density and ability to withstand corrosion effect due to phenomenon of passivation. Structural components made from Aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The oxides and sulphate are useful compounds of Aluminium based on its weight. In this work, an attempt has been made to utilize the combined effect of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg2Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys.

  3. Evidence of Charge Transfer and Orbital Magnetic Moment in Multiferroic CuFeO2

    Science.gov (United States)

    Narumi, Yasuo; Nakamura, Tetsuya; Ikeno, Hidekazu; Terada, Noriki; Morioka, Takayuki; Saito, Kota; Kitazawa, Hideaki; Kindo, Koichi; Nojiri, Hiroyuki

    2016-11-01

    Soft X-ray absorption spectra (XAS) and magnetic circular dichroism (XMCD) of Fe and Cu L2,3 edges have been measured on the triangular lattice antiferromagnet CuFeO2. By applying sum rule analysis to the XMCD of Fe, the ratio of the orbital to spin magnetic moments is determined to be -0.071. Because the nominal valence of Fe in CuFeO2 was Fe3+ (3d5), the orbital magnetic moment was considered to be zero in the past. However, the present research demonstrates that the orbital magnetic moment of Fe takes a finite value and it is possibly due to Fe4+ (3d4), which is considered to be responsible for the strong magnetic anisotropy and the ferroelectricity. We compare the experimental results with the results of ab initio multiplet calculations based on the configuration interaction theory and discuss the anomalous electronic structures of Fe and Cu ions in CuFeO2.

  4. Co-Cu-Mg-Al四元类水滑石的合成与表征%Synthesis and Characterization of CoCuMgAl Hydrotalcite-like Compounds

    Institute of Scientific and Technical Information of China (English)

    刘炳华

    2006-01-01

    以共沉淀法合成了1.5Co/0.5Cu/Al, 1.25Co/0.25Cu/0.5Mg/Al, Co/0.5Cu/0.5Mg/Al和Co/Cu/Al等样品,采用TG-DSC和XRD进行了表征.结果表明,1.5Co/0.5Cu/Al,1.25Co/0.25Cu/0.5Mg/Al和Co/0.5Cu/0.5Mg/Al样品都形成类水滑石(HTLcs),而Co/Cu/Al样品因Jahn-Teller效应未能形成HTLcs.

  5. Effect of Cu doping on the structure and phase transition of directly synthesized FePt nanoparticles

    Science.gov (United States)

    Wang, Hanbin; Li, Yang; Chen, Xu; Shu, Dan; Liu, Xiang; Wang, Xina; Zhang, Jun; Wang, Hao; Wang, Yi; Ruterana, Pierre

    2017-01-01

    In this work, ternary Cu doped FePt nanoparticles were prepared in hexadecylamine at 320 °C by choosing FeCl2 as the Fe source. The experimental results showed that without Cu doping the as-prepared FePt nanoparticles possessed fcc structure and gradually exhibited typical fct diffraction peaks after increasing the Cu doping concentration. TEM images showed that the FePt nanoparticles had larger size and wider size distribution after introducing Cu additive. Magnetic property measurement showed that a coercivity of 4800 Oe was obtained when the composition of the ternary nanoparticles reached Fe35Pt45Cu20, in which the content of Fe+Cu was higher than Pt. The research indicates that Cu doping promotes the phase transition of FePt nanoparticles at temperature as low as 320 °C.

  6. Synchrotron X—Ray Study on Structures of Ni80Fe20/Cu Superlattices

    Institute of Scientific and Technical Information of China (English)

    杨涛; 麦振洪; 赖武彦; 吴忠华; 王德武; XUMing; 罗光明; 柴春林

    2001-01-01

    We have shown that,in contrast to the results in the literature,the Bragg peak intensity of Ni80Fe20/Cu superlattices is enhanced at the incident x-ray energy slightly higher than the absorption edge of the heavier element(Cu).The atomic density at Ni80Fe20/Cu interface was analysed by the diffraction anomalous fine structure technology with the incident angle of x-ray fixed at the first Bragg peak.Our results demonstrate the epitaxy growth of Ni80Fe20/Cu superlattices.Upon annealing,the epitaxity of Ni80Fe20/Cu multilayers becomes poor but the local crystallinity in each layer is improved.

  7. The Dissolution Kinetics of MgO into CaO-MgO-Fe2O3 Slag

    Science.gov (United States)

    Wei, Ruirui; Lv, Xuewei; Yue, Zhiwen; Xiang, Shenglin

    2017-02-01

    Calcium ferrite is the main binding phase for high-basicity sinter. The production and structure of calcium ferrite greatly influence the quality of the sinter. With the change in gangue composition, MgO becomes an important factor in the generation of calcium ferrite. In this study, the rotating cylinder method was used to study the dissolution kinetics of MgO into CaO-MgO-Fe2O3 melt. The experimental variables included the temperature, the initial composition of the melt, the Fe2O3/CaO mass ratio, the rotation time, and the rotation speed. The results indicate that the dissolution rate increases with increasing dissolution time, temperature, and rotation speed but decreases with increasing MgO content and Fe2O3/CaO mass ratio in the initial slag. The dissolution rate was observed to increase and then decrease with the addition of SiO2 in the initial slag. The activation energy and diffusion coefficient for MgO dissolution were found to range from 117.31 to 234.24 kJ mol-1 and from 1.03 × 10-6 to 1.18 × 10-5 cm2 s-1, respectively. The concentration difference between the solid and liquid phases is the main driving force for dissolution, but the viscosity and magnesium ion diffusivity of the melt also affect the process.

  8. Direct Measurement of the Metastable Liquid Miscibility Gap in Fe-Co-Cu Ternary Alloy System

    Institute of Scientific and Technical Information of China (English)

    CAO Chong-De; Georg P.G(O)RLER

    2005-01-01

    @@ The metastable liquid-liquid phase separation in undercooled Fe-Co-Cu ternary alloy melts (XCu = 0.10-0.84;XCo:XFe = 1:3,1:1 and 3:1) is investigated by differential thermal analysis in combination with glass fluxing technique. In almost every case, the undercooling of the homogeneous alloy melt was sufficient to reach the boundary line of the submerged miscibility gap. The differential-thermal-analysis signals indicate that this separation into a (Fe, Co)-rich liquid phase L1 and a Cu-rich liquid L2 is exothermic and proceeds until the rapid solidification of the L1 phase occurs. At a given Cu concentration and with the increase of Co content, the phase separation temperatures decrease monotonically between the corresponding values of the boundary systems Fe-Cu and Co-Cu. The boundary lines of the miscibility gap, which are determined for the three quasi-binary cross-sections of the (Fe, Co)-Cu alloy system, show remarkably flat domes. The occurrence of the liquid phase separation shows an evident influence on the subsequent γ-Fe(Co, Cu)→α-Fe(Co, Cu) solid phase transformation.

  9. Hydrogen storage in Mg-LiBH4 composites catalyzed by FeF3

    Science.gov (United States)

    Puszkiel, Julián; Gennari, Fabiana C.; Arneodo Larochette, Pierre; Troiani, Horacio E.; Karimi, Fahim; Pistidda, Claudio; Gosalawit-Utke, Rapee; Jepsen, Julian; Jensen, Torben R.; Gundlach, Carsten; Tolkiehn, Martin; Bellosta von Colbe, José; Klassen, Thomas; Dornheim, Martin

    2014-12-01

    Mg-10 mol% LiBH4 composite plus small amounts of FeF3 is investigated in the present work. The presence of LiBH4 during the milling process noticeably modifies the size and morphology of the Mg agglomerates, leading to faster hydrogenation and reaching almost the theoretical hydrogen capacity owing to enhanced hydrogen diffusion mechanism. However, the dehydrogenation of the system at low temperatures (≤300 °C) is still slow. Thus, FeF3 addition is proposed to improve the dehydrogenation kinetic behavior. From experimental results, it is found that the presence of FeF3 results in an additional size reduction of the Mg agglomerates between ∼10 and ∼100 μm and the formation of stable phases such as MgF2, LiF and FeB. The FeB species might have a catalytic effect upon the MgH2 decomposition. As a further result of the FeF3 addition, the Mg-10 mol%LiBH4-5 mol% FeF3 material shows improved dehydrogenation properties: reduced dehydrogenation activation energy, faster hydrogen desorption rate and reversible hydrogen capacities of about 5 wt% at 275 °C.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-15

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

  11. Structural evolutions of the mechanically alloyed Al70Cu20Fe10 powders

    Indian Academy of Sciences (India)

    Musa Göğebakan; Bariş Avar

    2011-10-01

    Elemental mixtures of Al, Cu, Fe powders with the nominal composition of Al70Cu20Fe10 were mechanically alloyed in a planetary ball mill for 80 h. Subsequent annealing of the as-milled powders were performed at 600–800°C temperature range for 4 h. Structural characteristics of the mechanically alloyed Al70Cu20Fe10 powders with the milling time and the heat treatment were investigated by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and differential thermal analysis (DTA). Mechanical alloying of the Al70Cu20Fe10 did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation of -Al(Cu,Fe) solid solution phase (-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The -phase was one of the major phases in the Al70Cu20Fe10 alloy. The w-Al7Cu2Fe1 phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled samples. The present investigation indicated that a suitable technique to obtain a large amount of quasicrystalline powders is to use a combination of short-time milling and subsequent annealing.

  12. Thick CoFeB with perpendicular magnetic anisotropy in CoFeB-MgO based magnetic tunnel junction

    Directory of Open Access Journals (Sweden)

    V. B. Naik

    2012-12-01

    Full Text Available We have investigated the effect of an ultra-thin Ta insertion in the CoFeB (CoFeB/Ta/CoFeB free layer (FL on magnetic and tunneling magnetoresistance (TMR properties of a CoFeB-MgO system with perpendicular magnetic anisotropy (PMA. It is found that the critical thickness (tc to sustain PMA is doubled (tc = 2.6 nm in Ta-inserted CoFeB FL as compared to single CoFeB layer (tc = 1.3 nm. While the effective magnetic anisotropy is found to increase with Ta insertion, the saturation magnetization showed a slight reduction. As the CoFeB thickness increasing, the thermal stability of Ta inserted structure is significantly increased by a factor of 2.5 for total CoFeB thickness less than 2 nm. We have observed a reasonable value of TMR for a much thicker CoFeB FL (thickness = 2-2.6 nm with Ta insertion, and without significant increment in resistance-area product. Our results reveal that an ultra-thin Ta insertion in CoFeB might pay the way towards developing the high-density memory devices with enhanced thermal stability.

  13. S, Zn, Cr, Cu and Fe changes during fluvial sediments oxidation Transformaciones del S, Zn, Cr, Cu y Fe en sedimentos fluviales durante el proceso de secado

    Directory of Open Access Journals (Sweden)

    María Pía Di Nanno

    2009-12-01

    Full Text Available Acidification of dredged sediments which have been disposed on land is highly dependent on redox shifts. The aim of the present work was to assess changes in sulphur, metal speciation (Zn, Fe, Cr y Cu and acidity caused by a polluted sediment oxidation event. Sediments were dessicated under controlled conditions and sulphide compounds (acid volatile sulphides-AVS- and sulphate, pH and neutralization potential were measured through time during 36 days. Zinc, Cu, Cr and Fe speciation (BCR metal sequential extraction procedure were measured at the beginning of the experiment and at day 22. An acid-base equilibrium method based on the BCR procedure was employed to assess the sediment acidification risk. Some of the re-suspension experiments were inoculated with an Acidithiobacillus ferrooxidans strain to assess biological catalysis on sulphide oxidation. Acid-base equilibrium results indicated the sediment sample had a significant acidification potential. Oxidation increased sulphate levels (56 to 2300 mg S kg-¹ in the desiccation experiment with a temporal evolution adjusted by a logistic model, and a 2100 to 3000 mg SO4 -² L-¹ increase for the resuspension experiments. Sulphide oxidation rates varied between 0 to 3.1.10-9 mg O2 kg-¹ s-¹ for the drying sediment. Zinc changes could be explained partially by ZnS conversion to ZnSO4 during oxidation. Iron reduction could be attributed to an increase in Fe oxides crystallinity. Acid-base equilibrium for the sample indicated it was a potentially acid-generating material. Zinc increased its bioavailability during drying and was the only metal that appeared in significant amounts in solution during re-suspension. Land-filling with dredged sediments could present increased metals bioavailability problems despite having an important and effective neutralization potential.La evaluación de los riesgos de acidificación por deposición de sedimentos dragados en superficie es muy dependiente de los

  14. First-principles calculations of perpendicular magnetic anisotropy in Fe1-x Co x /MgO(001) thin films.

    Science.gov (United States)

    Cai, Guanzhi; Wu, Zhiming; Guo, Fei; Wu, Yaping; Li, Heng; Liu, Qianwen; Fu, Mingming; Chen, Ting; Kang, Junyong

    2015-01-01

    The perpendicular magnetic anisotropy (PMA) of Fe1-x Co x thin films on MgO(001) was investigated via first-principles density-functional calculations. Four different configurations were considered based on their ground states: Fe/MgO, Fe12Co4/MgO, Fe10Co6/MgO, and Fe8Co8/MgO. As the Co composition increases, the amplitude of PMA increases first from Fe/MgO to Fe12Co4/MgO, and then decreases in Fe10Co6/MgO; finally, the magnetic anisotropy becomes horizontal in Fe8Co8/MgO. Analysis based on the second-order perturbation of the spin-orbit interaction was carried out to illustrate the contributions from Fe and Co atoms to PMA, and the differential charge density was calculated to give an intuitive comparison of 3d orbital occupancy. The enhanced PMA in Fe12Co4/MgO is ascribed to the optimized combination of occupied and unoccupied 3d states around the Fermi energy from both interface Fe and Co atoms, while the weaker PMA in Fe10Co6/MgO is mainly attributed to the modulation of the interface Co-d xy orbital around the Fermi energy. By adjusting the Co composition in Fe1-x Co x , the density of states of transitional metal atoms will be modulated to optimize PMA for future high-density memory application.

  15. Structure and stress in Cu/Au and Fe/Au systems: A molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Zientarski, Tomasz, E-mail: martom@dyzio.umcs.lublin.pl [Department for the Modelling of Physico-Chemical Processes, Maria Curie-Skłodowska University, ul. Gliniana 33, 20-614 Lublin (Poland); Chocyk, Dariusz [Department of Applied Physics, Lublin University of Technology, ul. Nadbystrzycka 38, 20-618 Lublin (Poland)

    2014-07-01

    Growth of Fe and Cu thin films on Au substrate and stress evolution were modeled using molecular dynamics simulation. The interactions in the system are described by embedded atom method. The kinematical theory of scattering is performed to identify the structure obtained from simulations. The gold layers undergo reconstruction before deposition. The deposited copper atoms do not disturb the atoms in the reconstructed gold layer, but the deposited iron atoms cause the disappearance of the reconstructed gold surfaces. In both systems Cu/Au and Fe/Au, in the early stage of growth one observes compressive stress. Next, Cu/Au systems have the compressive stress, while in the case of Fe/Au the tensile stress is observed. In the Fe/Au system, the body-centered cubic lattice of Fe changes its orientation relative to the Au layer. In the Fe/Au system we observed a larger diffusion of Au atoms than in Cu/Au systems. - Highlights: • The kinematical theory of scattering is performed to identify the structure. • The correlation between the stress and the deformation is observed. • The relaxation of the stress depends on the orientation of layers. • The lattice of Fe changes its orientation relative to the Au layer in the Fe/Au system. • The Cu layer continues the lattice of Au in the Cu/Au system.

  16. Isolation and characterization of a new Cu-Fe protein from Desulfovibrio aminophilus DSM12254.

    Science.gov (United States)

    Rivas, Maria G; Mota, Cristiano S; Pauleta, Sofia R; Carepo, Marta S P; Folgosa, Filipe; Andrade, Susana L A; Fauque, Guy; Pereira, Alice S; Tavares, Pedro; Calvete, Juan J; Moura, Isabel; Moura, José J G

    2009-10-01

    The isolation and characterization of a new metalloprotein containing Cu and Fe atoms is reported. The as-isolated Cu-Fe protein shows an UV-visible spectrum with absorption bands at 320 nm, 409 nm and 615 nm. Molecular mass of the native protein along with denaturating electrophoresis and mass spectrometry data show that this protein is a multimer consisting of 14+/-1 subunits of 15254.3+/-7.6 Da. Mössbauer spectroscopy data of the as-isolated Cu-Fe protein is consistent with the presence of [2Fe-2S](2+) centers. Data interpretation of the dithionite reduced protein suggest that the metallic cluster could be constituted by two ferromagnetically coupled [2Fe-2S](+) spin delocalized pairs. The biochemical properties of the Cu-Fe protein are similar to the recently reported molybdenum resistance associated protein from Desulfovibrio, D. alaskensis. Furthermore, a BLAST search from the DNA deduced amino acid sequence shows that the Cu-Fe protein has homology with proteins annotated as zinc resistance associated proteins from Desulfovibrio, D. alaskensis, D. vulgaris Hildenborough, D. piger ATCC 29098. These facts suggest a possible role of the Cu-Fe protein in metal tolerance.

  17. Grain growth of Al-4Cu-Mg alloy during isothermal heat treatment

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure of an Al-4Cu-Mg alloy during isothermal heat treatment in the Strain Induced Melt Activation (SIMA)process was investigated and the kinetics of grain growth was analyzed. The grain growth during isothermal heat treatment of the Al4Cu-Mg alloy coincided with the Ostwald ripening theory. During isothermal heat treatment, both grain shape and the high volume fraction of solid phase have significant effects on grain growth. Therefore, a new grain growth model based on the Ostwald ripening theory was proposed taking into consideration the grain shape and the volume fraction of solid phase. By comparing the calculated results with the experimental results, it was confirmed that the present model could be applied to grain growth during isothermal heat treatment of the Al-4Cu-Mg alloy in the SIMA process.

  18. Novel Fluorescent Chemosensors Based on Tryptophan Unit for Cu2+ and Fe3+ in Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    CHENG Peng-fei; XU Kuo-xi; YAO Wen-yong; KONG Hua-jie; KOU Li; MA Xiao-dan; WANG Chao-jie

    2013-01-01

    We reported four fluorescent chemosensors containing tryptophan units.The fluorescence spectrum titration experiments suggest that chemosensors 1,2,3 and 4 are highly selective for Cu2+ and Fe3+ over Li+,Na+,K+,Co2+,Zn2+,Ni2+,Hg2+ and Cr3+ via forming complexes with Cu2+ or Fe3+,which is confirmed by dramatical quench of fluoreseence in aqueous solution at pH 7.4,thus making all the chemosensors suitable for Cu2+ and Fe3+ fluorescent sensors.

  19. 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.

  20. Structure and electromagnetic properties of FeSiAl particles coated by MgO

    Science.gov (United States)

    Zhang, Yu; Zhou, Ting-dong

    2017-03-01

    FeSiAl particles with a layer of MgO surface coating have excellent soft magnetic and electromagnetic properties. In order to obtain the FeSiAl/MgO composites, Mg(OH)2 sol prepared by sol-gel process was well-mixed with FeSiAl flake particles, and then treated by calcination at 823 K in vacuum. The microstructural, morphological and electromagnetic parameters of FeSiAl/MgO particles were tested. Accordingly, the electromagnetic wave reflection loss in the frequency range of 0.5-18 GHz was calculated. The results show that the surface coating increases coercivity Hc and decreases complex permittivity, leading to a good impedance matching. When the coating amount was 7.5%, reflection loss of the composite particles can reach to -33 dB.

  1. ADSORPSI ION CU(II MENGGUNAKAN PASIR LAUT TERAKTIVASI H2SO4 DAN TERSALUT Fe2O3

    Directory of Open Access Journals (Sweden)

    DS Pambudi

    2014-11-01

    Full Text Available Pasir laut merupakan bahan alam yang melimpah. Selain digunakan sebagai bahan bangunan, pasir dapat dimanfaatkan sebagai penjerap ion logam berat mengingat 30% lebih dari volumenya adalah pori-pori. Tujuan penelitian adalah untuk mengetahui kapasitas adsorpsi ion logam Cu(II menggunakan pasir laut kontrol, pasir laut teraktivasi H2SO4, pasir laut tersalut Fe2O3, serta pasir laut teraktivasi H2SO4 dan tersalut Fe2O3. Ada dua macam pasir laut yang digunakan, yaitu pasir hitam dan pasir putih. Kajian yang dilakukan meliputi optimasi adsorben pada variasi pH, konsentrasi ion logam, dan waktu kontak. Optimasi pH diperoleh pada pH 7, optimasi konsentasi ion logam diperoleh 250 ppm untuk pasir hitam dan 200 ppm untuk pasir putih, dan optimasi waktu diperoleh 60 menit untuk pasir hitam dan 90 menit untuk pasir putih. Kapasitas adsorpsi pasir laut teraktivasi H2SO4 dan tersalut Fe2O3 dalam menyerap ion logam tembaga sebesar 24,8634 mg/g untuk pasir hitam dan 19,8854 mg/g untuk pasir putih. Sebanyak 6,5 g pasir hitam teraktivasi H2SO4 dan tersalut Fe2O3 digunakan untuk menyerap limbah pada konsentrasi Cu(II sebesar 2960,32 ppm dengan persentase teradsorpsi sebesar 94,70%. Sedangkan pada pasir putih teraktivasi H2SO4 dan tersalut Fe2O3, sebanyak 8 g pasir digunakan untuk menyerap limbah dengan konsentrasi Cu(II sebesar 2984,13 ppm, hasilnya menunjukkan 92,56% ion logam Cu(II teradsorp. Sea sand is abundant natural materials. In addition to be used as a building material, sand can be utilized as heavy metal ion adsorbent, because it has quite a lot of pores, i.e 30% more than its volume. The purpose of this study was to determine the adsorption capacity of Cu(II ions using sea sand alone as control, H2SO4-activated sea sand, Fe2O3-coated sea sand, as well as H2SO4-activated and Fe2O3-coated sea sand. Two kinds of sea sand have been used in the research, i.e the black sand and the white sand. Studies were performed to examine the optimization of the

  2. Synthesis and structural analysis of a regular Cu-Mg-Al hydrotalcite-like compound

    OpenAIRE

    WU, Jian-Song; XIAO, Ying-Kai; Liu, Yu-ping; XU, Wan-Bang

    2011-01-01

    A fine-quality, regular Cu-Mg-Al hydrotalcite-like compound was synthesized via the glycothermal method using CuCl2 \\cdot 2H2O, MgCl2 \\cdot 6H2O, AlCl3 \\cdot 6H2O, and Na2CO3 as raw materials and sodium hydroxide as the precipitant. Hydrotalcite samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric-differential thermal analysis, and Brunauer-Emmett-Teller N2 surface ar...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-05

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

  4. Conversion of syngas to higher alcohols over Cu-Fe-Zr catalysts induced by ethanol

    Institute of Scientific and Technical Information of China (English)

    Hongtao Zhang; Xiaomei Yang; Lipeng Zhou; Yunlai Su; Zhongmin Liu

    2009-01-01

    Ethanol induced method was applied to prepare Cu-Fe-Zr catalysts for conversion of syngas to higher alcohols. The catalytic performance of the catalysts induced by ethanol was superior to that of the catalyst prepared by the conventional precipitation method. Among various procedures for ethanol induced method,it was found that incorporation of ethanol in the precipitation process was the better. After incorporation of ethanol,the crystal size of CuO decreased and the reduction of copper species became easier. The better activity of Cu-Fe-Zr catalysts prepared by ethanol induced procedures was probably caused by the higher dispersion of Cu species.

  5. Coverage Effects on the Magnetism of Fe/MgO(001) Ultrathin Films

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Boubeta, C.

    2004-11-04

    Different aspects of the structure-magnetism and morphology-magnetism correlation in the ultrathin limit are studied in epitaxial Fe films grown on MgO(001). In the initial stages of growth the presence of substrate steps, intrinsically higher than an Fe atomic layer, prevent connection between Fe islands and hence the formation of large volume magnetic regions. This is proposed as an explanation to the superparamagnetic nature of ultrathin Fe films grown on MgO in addition to the usually considered islanded, or Vollmer-Weber, growth. Using this model, we explain the observed transition from superparamagnetism to ferromagnetism for Fe coverages above 3 monolayers (ML). However, even though ferromagnetism and magnetocrystalline anisotropy are observed for 4ML, complete coverage of the MgO substrate by the Fe ultrathin films only occurs around 6 ML as determined by polar Kerr spectra and simulations that consider different coverage situations. In annealed 3.5 ML Fe films, shape or configurational anisotropy dominates the intrinsic magnetocrystalline anisotropy, due to an annealing induced continuous to islanded morphological transition. A small interface anisotropy in thicker films is observed, probably due to dislocations observed at the Fe/MgO(001) interface.

  6. Magnetic properties of epitaxial Fe/MgO structures on Si(100)

    Science.gov (United States)

    Jo, Jeong Hong; Shin, Eun Jeong; Kim, Hyung-jun; Lim, Sang Ho

    2017-01-01

    The magnetic properties of epitaxial Fe/MgO structures on Si(100) substrates are investigated over an Fe thickness range of 2-20 nm. Superparamagnetic behavior is observed at an Fe thickness of 2 nm, indicating that no continuous Fe thin film is formed. At Fe thicknesses of 5 nm and higher, a continuous two-dimensional layered structure is formed, which has a dominant epitaxial relationship of Fe[010](100)//MgO [ 01 1 bar ] (100)//Si [ 01 1 bar ] (100) and a minor portion of Fe[010](100)//MgO[010](100)//Si [ 01 1 bar ] (100). This structural feature is echoed by a four-fold magnetic anisotropy in the film plane, and this tendency increases with increasing Fe thickness. The strength of the first-order cubic magnetocrystalline anisotropy, which can only be extracted from the structures, is in the range of 3.87×105-4.04×105 erg/cm3, weaker than that of bulk Fe (4.8×105 erg/cm3).

  7. Local environment analysis of Fe ions in BaMgSiO4

    Science.gov (United States)

    Kase, Junya; Shingaki, Yoshihiro; Inaba, Yuta; Meguro, Kazune; Murata, Hidenobu; Okajima, Toshihiro; Yamamoto, Tomoyuki

    2016-08-01

    Polycrystalline Fe-doped BaMgSiO4 is synthesized by the conventional solid state reaction method, which shows strong photochromism. Photochromic property of the synthesized specimens is investigated by measuring the diffuse reflectance spectrum. Local environment of doped Fe ions in BaMgSiO4 has been studied by the analysis of the X-ray absorption near-edge structure (XANES) spectrum with the aid of the first-principles calculations.

  8. Study on Mg/Fe Mixed Oxides Derived from Hydrotalcite as De-SOx Catalyst

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel class of desulfurization agent derived from hydrotalcite has been developed and its activity for Sox uptake have been investigated. The results showed that the Mg/Fe mixed oxide having high Sox uptake ability at a broad reaction temperature (e.g. 673K ~ 973K). The Mg/Fe ratio of the mixed oxide strongly affect the desulfurization role of the material and it can be used repeatly without much loss of Sox uptake ability.

  9. On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

    CERN Document Server

    Obryk, Barbara; de Barros, Vinicius S; Guzzo, Pedro L; Bilski, Paweł

    2013-01-01

    LiF:Mg,Ti and LiF:Mg,Cu,P are well known thermoluminescence (TL) dosimetry materials since many years. A few years ago their properties seemed well known and it was widely believed that they are not suitable for the measurement of doses above the saturation level of the TL signal, which for both materials occur at about 1 kGy. The high-dose high-temperature TL emission of LiF:Mg,Cu,P observed at the IFJ in 2006, which above 30 kGy takes the form of the so-called TL peak B, opened the way to use this material for measuring the dose in the high and ultra-high range, in particular for the monitoring of ionizing radiation around the essential electronic elements of high-energy accelerators, also fission and fusion facilities, as well as for emergency dosimetry. This discovery initiated studies of high and ultra-high dose characteristics of both of these phosphors, which turned out to be significantly different in many aspects. These studies not only strive to refine the method for measuring high doses based on th...

  10. Application of Fe-Cu binary oxide nanoparticles for the removal of hexavalent chromium from aqueous solution.

    Science.gov (United States)

    Khan, Saif Ullah; Zaidi, Rumman; Hassan, Saeikh Z; Farooqi, I H; Azam, Ameer

    2016-01-01

    The adsorption process has been used as an effective technique for the removal of metal ions from aqueous solutions. Groundwater remediation by nanoparticles has received interest in recent years. In the present study, a binary metal oxide of Fe-Cu was prepared and used for the removal of hexavalent chromium from aqueous solution. Batch experiments were performed to investigate the effects of initial Cr (VI) concentration, dose of adsorbent, and pH of solution on the removal efficiency of Cr (VI). The prepared nanostructured Fe-Cu binary oxides were able to reduce the concentration of Cr (VI) in aqueous solution. Binary metal oxides nanoparticle exhibited an outstanding ability to remove Cr (VI) due to high surface area, low particle size, and high inherent activity. The percentage removal efficiency of Cr (VI) increased with nanoparticles doses (0.1 g L(-1)-2.5 g L(-1)), whereas it decreased with initial Cr (VI) concentration (1 mg L(-1)-25 mg L(-1)) and with pH (3-9). The Freundlich model was found to be the better fit for adsorption isotherm. The prepared nanomaterial was characterized using powder X-ray diffraction, scanning electron microscopy (SEM), and ultraviolet (UV)-visible spectroscopy. It showed that the Fe-Cu binary oxides were formed in single phase. SEM micrograph showed aggregates with many nano-sized particles. UV-visible spectroscopy showed quantum confinement effect.

  11. EXAFS STUDY OF THE SHORT RANGE STRUCTURE OF NANOCRYSTALLINE BCC-Fe80Cu20 SOLID SOLUTION

    Institute of Scientific and Technical Information of China (English)

    Y.Z. Yang; X.J. Bai; T.C. Kuang; G.M. Wang; S. Q. Wei

    2002-01-01

    The structure of bcc-Fe80 Cu2o solid solution produced by mechanical alloying of theelemental bcc-Fe and fcc-Cu powders has been studied using X-ray diffraction and theextended X-ray absorption fine structure (EXAFS) techniques. The disappearance ofelemental Fe and Cu X-ray diffraction (XRD) peaks and the presence of bcc structuralXRD peaks illustrate the formation of a nanocrystalline single-phase bcc-Fe80 Gu20solid solution. From the EXAFS results, the clear observation of Cu atoms taking onbcc coordination in the solid solution and Fe atoms remaining bcc structure furtherverifies the reality of atomic alloying between Fe and Cu atoms and the lattice changeof Cu from fcc to bcc. However, the supersaturated bcc solid solution is not chemicallyuniform, i.e., some regions are rich in Fe atoms and other regions rich in Cu atoms.

  12. TEM Nanostructural Study of Al-6Si-3Cu-Mg Melt-Spun Ribbons

    Directory of Open Access Journals (Sweden)

    Ismeli Alfonso López

    2008-01-01

    Full Text Available Three quaternary Al-6Si-3Cu-xMg (x = 0.59, 3.80, and 6.78 wt.% alloys were produced by melt-spun and characterized using X-ray diffractometry (XRD, transmission electron microscopy (TEM, and microhardness techniques. Obtained second phases were Al2Cu( for the alloy with 0.59% Mg and Al5Cu2Mg8Si6 (Q for the alloys with 3.80 and 6.78% Mg. These phases are present as 30–50 nm or as 5–10 nm nanoparticles. Alloying elements content in solid solution increased, mainly for Si and Mg. The high alloying elements content in solid solution and the small -Al cell size for melt-spun alloys leads to microhardness values about 2 times higher than those of ingot counterparts. The microhardness increase for melt-spun alloys with 3.80 and 6.78% Mg depends on Mg content in solid solution.

  13. Creep behaviour of a casting titanium carbide reinforced AlSi12CuNiMg piston alloy at elevated temperatures; Hochtemperaturkriechverhalten der schmelzmetallurgisch hergestellten dispersionsverstaerkten Kolbenlegierung AlSi12CuNiMg

    Energy Technology Data Exchange (ETDEWEB)

    Michel, S.; Scholz, A. [Zentrum fuer Konstruktionswerkstoffe, TU Darmstadt (Germany); Tonn, B. [Institut fuer Metallurgie, TU Clausthal (Germany); Zak, H.

    2012-03-15

    This paper deals with the creep behaviour of the titanium carbide reinforced AlSi12CuNiMg piston alloy at 350 C and its comparison to the conventional AlSi12Cu4Ni2MgTiZr piston alloy. With only 0,02 vol-% TiC reinforcement the creep strength and creep rupture strength of the AlSi12CuNiMg piston alloy are significantly improved and reach the level of the expensive AlSi12Cu4Ni2MgTiZr alloy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Thermally robust Mo/CoFeB/MgO trilayers with strong perpendicular magnetic anisotropy.

    Science.gov (United States)

    Liu, T; Zhang, Y; Cai, J W; Pan, H Y

    2014-07-31

    The recent discovery of perpendicular magnetic anisotropy (PMA) at the CoFeB/MgO interface has accelerated the development of next generation high-density non-volatile memories by utilizing perpendicular magnetic tunnel junctions (p-MTJs). However, the insufficient interfacial PMA in the typical Ta/CoFeB/MgO system will not only complicate the p-MTJ optimization, but also limit the device density scalability. Moreover, the rapid decreases of PMA in Ta/CoFeB/MgO films with annealing temperature higher than 300°C will make the compatibility with CMOS integrated circuits a big problem. By replacing the Ta buffer layer with a thin Mo film, we have increased the PMA in the Ta/CoFeB/MgO structure by 20%. More importantly, the thermal stability of the perpendicularly magnetized (001)CoFeB/MgO films is greatly increased from 300°C to 425°C, making the Mo/CoFeB/MgO films attractive for a practical p-MTJ application.

  15. Superparamagnetic mesoporous Mg-Fe bi-metal oxides as efficient magnetic solid-base catalysts for Knoevenagel condensations.

    Science.gov (United States)

    Gao, Zhe; Zhou, Jian; Cui, Fangming; Zhu, Yan; Hua, Zile; Shi, Jianlin

    2010-12-14

    Superparamagnetic mesoporous Mg-Fe bi-metal oxides with varied Mg-Fe atomic ratios have been successfully synthesized as solid base catalysts. The M2F-400 catalyst with Mg/Fe atomic ratio = 2 showed extraordinarily high activities for Knoevenagel reactions even at room temperature. It could be magnetically separated, recycled, and reused for at least five cycles.

  16. Incidence of in situ annealing on the nanoscale topographical/electrical properties of the tunnel barrier in sputtered epitaxial Fe/MgO/Fe multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D J; Arabski, J; Da Costa, V Da; Schmerber, G; Bowen, M; Boukari, S; Beaurepaire, E, E-mail: dong-jik.kim@ipcms.u-strasbg.f, E-mail: eric.beaurepaire@ipcms.u-strasbg.f [IPCMS UMR 7504 CNRS, Universite de Strasbourg, 23 Rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France)

    2010-06-02

    Technological improvements in the magnetotransport performance of Fe/MgO/Fe stacks require nanoscale control over the topographical and electrical properties of the ultrathin MgO barrier. We have statistically investigated the incidence of in situ annealing of the lower Fe layer on the nanoscale topographical/electrical properties of Fe/MgO bilayers and the structural and magnetic properties of Fe/MgO/Fe/Co multilayers prepared by sputtering. This annealing step improves the crystal quality of both the lower Fe and the upper Fe/Co layers, leading to an enhanced saturated magnetic moment. Finally, this annealing step substantially mitigates the presence of nanohills on the lower Fe layer and improves the uniformity of the height and/or the thickness of the MgO tunnel barrier. Our results pave the way for studies of nanoscale transport on micrometre-sized devices through a better understanding of, and control over, nanoscale hotspots in the tunnel barrier.

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

    Science.gov (United States)

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

    2015-06-01

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

  18. Effect of Applied Current Density on Morphological and Structural Properties of Electrodeposited Fe-Cu Films

    Institute of Scientific and Technical Information of China (English)

    Umut Sarac; M. Celalettin Baykul

    2012-01-01

    A detailed study has been carried out to investigate the effect of applied current density on the composition, crystallographic structure, grain size, and surface morphology of Fe-Cu films. X-ray diffraction (XRD) results show that the films consist of a mixture of face-centered cubic (fcc) Cu and body centered cubic (bcc) ~-Fe phases. The average crystalline size of both Fe and Cu particles decreases as the applied current density becomes more negative. Compositional analysis of Fe-Cu films indicates that the Fe content within the films increases with decreasing current density towards more negative values. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to investigate the surface morphology of Fe-Cu films. It is observed that the surface morphology of the films changes from dendritic structure to a cauliflower structure as the applied current density becomes more negative. The surface roughness and grain size of the Fe-Cu films decrease with decreasing applied current density towards more negative values.

  19. Thermal Spraying of CuAlFe Powder on Cu5Sn Alloy

    Science.gov (United States)

    Roata, I. C.; Pascu, A.; Croitoru, C.; Stanciu, E. M.; Pop, M. A.

    2017-06-01

    To improve the corrosion and wear resistance of copper and its alloys, flame spraying has been employed to obtain a relatively homogenous Cu/Al/Fe-based coating. To minimize the defects that usually occur by using this method, a post-coating annealing step has been employed, by using concentrated solar energy as means of thermal surface treatment. Scanning electron micrographs have indicated a reduction in the cracks/pores density and accelerated corrosion testing have indicated a higher performance of the solar-annealed sample, in comparison with the initial reference material. The coating approach mentioned in this paper could be successfully applied to restore several worn tools and instruments, and could also be of use in the renewable energy field (IR-absorbent coatings) or in advanced oxidation processes, such as photocatalysis.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-09-01

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

  1. Influence of aluminium on the properties of the Mg/sub 2/Cu-H/sub 2/ system

    Energy Technology Data Exchange (ETDEWEB)

    Biris, A.; Lupu, D.; Bucur, R.V.; Indrea, E.; Borodi, G.; Bogdan, M.

    1982-01-01

    The addition of aluminium to a mixture of Mg-Cu (2:1 atomic ratio) leads by melting to the formation of increasing amounts of Mg(Cu,Al)/sub 2/ where aluminium substitutes for copper atoms in the MgCu/sub 2/ lattice, raising the lattice parameter. The hydrogen absorbed in this phase is strongly bounded, as proved by desorption isotherms and nuclear magnetic resonance data.

  2. Corrosion mechanism of mechanically alloyed Mg50Ni50 and Mg45Cu5Ni50 alloys

    Institute of Scientific and Technical Information of China (English)

    张耀; 李寿权; 陈立新; 雷永泉; 王启东

    2002-01-01

    As the loss of active material Mg may affect electrode's discharge capacity and the cycling stability,a more refined mechanism study on cycling capacity degradation should be made.The present investigation is based on the supposition that the capacity degradation of the binary Mg50Ni50 alloy and ternary Mg45Cu5Ni50 alloy electrodes is solely due to the corrosion of Mg,the active hydrogen storage element.That means amount of capacity degradation is determined by the corrosion current time,which is also the time of operation.The corrosion current J corr dependence on cycling time was deduced.A mathematic relation between the cycling capacity retention CN / C 1 (%) and the duration of operation was also deduced.The data calculated from the equations deduced agree well with those of the experiment result.The loss of the active hydrogen-absorbing element Mg is proved to be the main cause for cycling capacity deterioration in the present investigation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-15

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

  4. Spin-Orbit Effects in CoFeB/MgO Heterostructures with Heavy Metal Underlayers

    Science.gov (United States)

    Torrejon, Jacob; Kim, Junyeon; Sinha, Jaivardhan; Hayashi, Masamitsu

    2016-10-01

    We study effects originating from the strong spin-orbit coupling in CoFeB/MgO heterostructures with heavy metal (HM) underlayers. The perpendicular magnetic anisotropy at the CoFeB/MgO interface, the spin Hall angle of the heavy metal layer, current induced torques and the Dzyaloshinskii-Moriya interaction at the HM/CoFeB interfaces are studied for films in which the early 5d transition metals are used as the HM underlayer. We show how the choice of the HM layer influences these intricate spin-orbit effects that emerge within the bulk and at interfaces of the heterostructures.

  5. Phase-transformation in iron oxide and formation of Cu/γ-Fe2O3 nanocomposite using radio-frequency sputtering with metal chips on an α-Fe2O3 target

    Science.gov (United States)

    Abe, Seishi; Watanabe, Masato

    2017-07-01

    A simple technique that uses radio-frequency sputtering with a functional element on a hematite (α-Fe2O3) target is presented for the production of maghemite (γ-Fe2O3) thin films. These films are prepared on water-cooled glass substrates in an Ar atmosphere. Investigations are done with Ti, Si, Al, Cu, Mo, and Zn, with γ-Fe2O3 being obtained only in the presence of Cu, indicating that phase transition occurs only for this metal. Mössbauer spectra and magnetization analysis reveal that the quality of the obtained γ-Fe2O3 films is higher than that of the film produced using Mg, which was reported in our previous work. High-angle annular dark-field scanning tunneling electron microscopy and electron energy-loss spectroscopy reveal that the added Cu remains in a metallic state (without oxidization), forming a Cu/γ-Fe2O3 phase-mixture in the as-deposited film. The Cu/γ-Fe2O3 composite film exhibits negative magnetoresistance (MR), with a MR ratio of approximately 0.6% at room temperature in an applied field of 10 kOe, and a negative Faraday rotation of -5708 deg cm-1 at 830 nm.

  6. Preparation Behavior of the Mg-Fe Hydrotalcite by Urea Method and Its Cr(VI) Sorption Property.

    Science.gov (United States)

    Xu, Sheng; Liao, MengChen; Zeng, HongYan; Liu, XiaoJun; Zhu, PeiHan; Chen, ChaoRong; Duan, HengZhi

    2016-03-01

    The hydrotalcite of Mg6Fe2(OH)16CO3 x 4.5H2O were synthesized using urea method by adjusting the initial pH and urea amount in the reaction solution. The results showed that the co-precipitation of Mg2+ with Fe3+ cations formed Mg-Fe LDH occurring at pH 8.48-9.35. The pH played a crucial role in the Mg-Fe LDH precipitation by controlling urea/Fe3+ molar ratio in the reaction solution at 105 degrees C. The optimized urea/Fe3+ molar ratio was 12.0, where the relative yield of the Mg-Fe LDH was 80.0% and the Mg-Fe LDH was highly crystalline with small particle sizes (1-2 μm). The affinity of the Mg-Fe mixed oxide (Mg-Fe LDO) with Cr(VI) was studied as a function of contact time, initial pH, temperature of the solutions and calcined time of Mg-Fe LDH. The adsorption conditions were optimized using response surface methodology. The maximum adsorption capacity of 38.86 mg/g was achieved at 85 min with the conditions of initial pH 5.5, temperature 55 degrees C and calcined time 4 h. It was concluded that the Mg-Fe LDO can be used as an adsorbent to removal Cr(VI) in aqueous solutions.

  7. Photocatalytic Characterization of Fe- and Cu-Doped ZnO Nanorods Synthesized by Cohydrolysis

    Directory of Open Access Journals (Sweden)

    Young Rang Uhm

    2013-01-01

    Full Text Available Fe- and Cu-doped ZnO nanorods have been synthesized by a novel process employing a hydrolysis of metal powders. Zn, Fe, and Cu nanopowders were used as starting materials and incorporated into distilled water. The solution was refluxed at 60°C for 24 h to obtain the precipitates from the hydrolysis of Zn and dopants (Cu and Fe. The TEM results for ZnO with and without metal doping showed that the produced powders had a rod-like shape. The rod shape was attributable to the zinc oxide from the hydrolysis of Zn. With an increasing doping content, the UV-vis spectra were shifted to a long wavelength and this result indicates that the band gap was changed by the metal doping. The values of phenol degrading Fe- and Cu-doped ZnO by a solar simulator were measured to be 60 and 75%, respectively.

  8. The electrical conductivity characteristics of Fe/Cu nano-scale multilayer materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A mathematical model for describing the relationship betweenelectrical conductivity and the thickness of bilayer, ratio of sublayer thickness of a nano-scale multilayer material (MLM) is presented. Fe/Cu MLM was synthesized by electron beam physical vapor deposition (EB-PVD) technique, and the dependence of electrical conductivity of Fe/Cu MLM on the bilayer thickness and ratio of sublayer thickness were investigated. It is shown that the electrical conductivity of Fe/Cu MLM with fixed ratio of sublayer thickness decreases sharply when the thickness of bilayer becomes thinner than 30 nm. When the bilayer thickness is kept constant, the electrical conductivity linearly decreases with the increasing ratio of sublayer thickness. The values of parameters in the model were obtained by fitting the measured results of electrical conductivity of Fe/Cu MLM with fixed ratio of sublayer thickness. It is found that the calculated values agree well with measured ones.

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

    CSIR Research Space (South Africa)

    Makgwane, PR

    2015-03-01

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

  10. ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY

    Science.gov (United States)

    Tian, N.; Fan, X. D.; Wang, J. W.; You, C. Y.; Lu, Z. X.; Ge, L. L.

    2013-07-01

    High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α-Fe possesses a high saturation magnetization. Fe-B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α-Fe simultaneously. In this work, we made nanocrystalline powders of Fe82B17Cu1, mainly consisting of α-Fe and Fe2B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe82B17Cu1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.

  11. Direct observation of atomic-scale origins of local dissolution in Al-Cu-Mg alloys

    Science.gov (United States)

    Zhang, B.; Wang, J.; Wu, B.; Oguzie, E. E.; Luo, K.; Ma, X. L.

    2016-12-01

    Atomistic chemical inhomogeneities are anticipated to induce dissimilarities in surface potentials, which control corrosion initiation of alloys at the atomic scale. Precise understanding of corrosion is therefore hampered by lack of definite information describing how atomistic heterogeneities regulate the process. Here, using high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) and electron energy loss spectroscopy (EELS) techniques, we systematically analyzed the Al20Cu2Mn3 second phase of 2024Al and successfully observed that atomic-scale segregation of Cu at defect sites induced preferential dissolution of the adjacent zones. We define an “atomic-scale galvanic cell”, composed of zones rich in Cu and its surrounding matrix. Our findings provide vital information linking atomic-scale microstructure and pitting mechanism, particularly for Al-Cu-Mg alloys. The resolution achieved also enables understanding of dealloying mechanisms and further streamlines our comprehension of the concept of general corrosion.

  12. Morphology, magnetic and resonance properties of Fe/MgO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Garcia, A; Algarabel, P A; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC 50009 Zaragoza (Spain); Vovk, A [Centro de Fisica da Materia Condensada Unversidade de Lisboa, Campo Grande Ed. C8, 1749-016, Lisboa (Portugal); Strichovanec, P; Pardo, J A; Magen, C [Instituto de Nanociencia de Aragon, Universidad de Zaragoza 50018 Zaragoza (Spain); Golub, V; Salyuk, O, E-mail: ayvovk@fc.ul.pt [Institute of Magnetism NAS of Ukraine, 36-b Vernnadsky blvd., 03142, Kyiv (Ukraine)

    2011-07-06

    Magnetic, resonance and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers prepared by pulsed laser deposition were investigated. Comparison of the data allows conclusions on Fe layers morphology. For t<0.61 nm typical features of granular cermet films in dielectric regime are observed, i.e. high electrical resistance, isotropic magnetoresistance and strong temperature dependence of magnetization. For higher t coalescence of Fe granules occurs and metallic percolation cluster is formed at t{approx}0.81 nm. This is manifested by rapid decrease of films resistance and formation of multipeak ferromagnetic resonance spectra. For t>1.25 nm a continuous coverage of MgO by Fe takes place. However, the morphology of Fe layers is rough. This causes the appearance of magnetostatic resonance modes analogous to those observed for continuous films deposited on embossed surfaces.

  13. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO.

    Science.gov (United States)

    Baumann, S; Donati, F; Stepanow, S; Rusponi, S; Paul, W; Gangopadhyay, S; Rau, I G; Pacchioni, G E; Gragnaniello, L; Pivetta, M; Dreiser, J; Piamonteze, C; Lutz, C P; Macfarlane, R M; Jones, B A; Gambardella, P; Heinrich, A J; Brune, H

    2015-12-04

    We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0±0.3  meV/atom. This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

  14. Origin of Perpendicular Magnetic Anisotropy and Large Orbital Moment in Fe Atoms on MgO

    Science.gov (United States)

    Baumann, S.; Donati, F.; Stepanow, S.; Rusponi, S.; Paul, W.; Gangopadhyay, S.; Rau, I. G.; Pacchioni, G. E.; Gragnaniello, L.; Pivetta, M.; Dreiser, J.; Piamonteze, C.; Lutz, C. P.; Macfarlane, R. M.; Jones, B. A.; Gambardella, P.; Heinrich, A. J.; Brune, H.

    2015-12-01

    We report on the magnetic properties of individual Fe atoms deposited on MgO(100) thin films probed by x-ray magnetic circular dichroism and scanning tunneling spectroscopy. We show that the Fe atoms have strong perpendicular magnetic anisotropy with a zero-field splitting of 14.0 ±0.3 meV /atom . This is a factor of 10 larger than the interface anisotropy of epitaxial Fe layers on MgO and the largest value reported for Fe atoms adsorbed on surfaces. The interplay between the ligand field at the O adsorption sites and spin-orbit coupling is analyzed by density functional theory and multiplet calculations, providing a comprehensive model of the magnetic properties of Fe atoms in a low-symmetry bonding environment.

  15. Evaporation Mechanism of Cu from Liquid Fe Containing C and S

    Science.gov (United States)

    Jung, Sung-Hoon; Kang, Youn-Bae

    2016-08-01

    A number of liquid-gas experiments were carried out in order to elucidate evaporation mechanism of Cu from liquid Fe containing C and S. Rate of Cu evaporation in liquid Fe droplets at 1873 K (1600 °C) was determined using electromagnetic levitation equipment. Evaporation rate of the Cu under various conditions (flow rate of gas mixtures, initial C, and S concentrations) was examined. It was found from a series of kinetic analyses of the experimental data that Cu evaporates in forms of Cu(g) and CuS(g). As was reported for the Sn evaporation from liquid iron (Jung et al. Met. Mater. Trans. 46B, 250-258, 2014), S plays two roles for the evaporation of Cu: accelerating the rate by forming CuS(g) and decelerating the rate by blocking evaporation sites. As a result of these combinatorial effects, the evaporation of Cu is decelerated at low S content, but is accelerated at high S content. Based on the elucidated mechanism, an evaporation model equation for Cu was developed in the present study, which takes into account (1) evaporation of Cu in the two forms (Cu(g) and CuS(g)), (2) surface blocking by S using ideal Langmuir adsorption, and (3) effect of C. The obtained rate constant of a reaction Cu i + S i = CuS i (g), k CuS R , is 1.37 × 10-9 m4 mol-1 s-1, and the residual rate constant, k CuS r , is 4.11 × 10-10 m4 mol-1 s-1 at 1873 K (1600 °C). Both of them were found to be one order lower than those for Sn evaporation.

  16. Synthesis and crystal structure of NaMgFe(MoO43

    Directory of Open Access Journals (Sweden)

    Manel Mhiri

    2016-06-01

    Full Text Available The iron molybdate NaMgFe(MoO43 {sodium magnesium iron(III tris[molybdate(VI]} has been synthesized by the flux method. This compound is isostructural with α-NaFe2(MoO43 and crystallizes in the triclinic space group P-1. Its structure is built up from [Mg,Fe]2O10 units of edge-sharing [Mg,Fe]O6 octahedra which are linked to each other through the common corners of [MoO4] tetrahedra. The resulting anionic three-dimensional framework leads to the formation of channels along the [101] direction in which the Na+ cations are located.

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

    KAUST Repository

    Ma, Hongbin

    2016-01-01

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

  18. Mechanical properties and microstructure of laser treated Al-Cu-Mg alloys

    NARCIS (Netherlands)

    Hosson, J.Th.M. De; Noordhuis, J.

    1993-01-01

    The mechanical properties and microstructural features of Al-Cu-Mg alloys were investigated, as exposed to laser treatments at various scan velocities. As far as the mechanical property is concerned a striking observation is a minimum in the hardness value at a laser scan velocity of 1/2 cm/s. Usual

  19. Effect of solution heat treatment time on a rheocast Al-Zn-Mg-Cu alloy

    CSIR Research Space (South Africa)

    Mazibuko, NE

    2011-06-01

    Full Text Available During rheo-high pressure die casting (R-HPDC) of Al-Zn-Mg-Cu alloys a coarse eutectic phase is formed. This eutectic phase is difficult to take into solution because of its size and it would require longer solution heat treatment times...

  20. Mechanical properties and microstructure of laser treated Al-Cu-Mg alloys

    NARCIS (Netherlands)

    Hosson, J.Th.M. De; Noordhuis, J.

    1993-01-01

    The mechanical properties and microstructural features of Al-Cu-Mg alloys were investigated, as exposed to laser treatments at various scan velocities. As far as the mechanical property is concerned a striking observation is a minimum in the hardness value at a laser scan velocity of 1/2 cm/s.

  1. Study on the thermal storage properties of Al-Si-Cu-Mg alloy

    Science.gov (United States)

    XIE, Yi; WAN, Ke-yang; XIE, Guo-sheng; HU, Jia-rui; YIN, Fu-cheng; GONG, Jing

    2017-04-01

    Based on thermodynamic calculation technology, the thermodynamic data of six alloys (inc. Al-Si and Al-Si-Cu-Mg systems) was calculated. The microstructure, phase transformation temperature and latent heat of the Al-4%Cu-12%Mg-7%Si alloy and Al-13%Si alloy were also verified by X-ray diffraction(XRD), scanning electron microscopy/Energy-dispersive system (SEM/EDS) and Differential scanning calorimetry (DSC). The results show that The enthalpy change value of Al-Si-Cu-Mg alloy is larger than that of Al-Si alloy from 800 °C to 400 °C, while its phase transformation temperature is lower. In particular, the enthalpy value of Al-4%Cu-12%Mg-7%Si alloy is 85% higher than that of Al-13%Si near eutectic alloy, and its initial temperature of phase transformation is about 74 °C lower. The former has relatively low phase transformation temperature and over-dimensioned latent heat of phase transformation, displaying the excellent thermal storage property. Therefore, the alloy is a good potential solar energy thermal storage material. The results in the paper also indicated that thermodynamic calculation is of value in seeking new potential solar energy thermal storage materials for solar thermal power generation system.

  2. The influence of chemical composition on the properties and structure Al-Si-Cu(Mg alloys

    Directory of Open Access Journals (Sweden)

    M. Kaczorowski

    2007-04-01

    Full Text Available The mechanical properties of different chemical composition AlSiCuMg type cast alloys after precipitation hardening are presented. The aim of the study was to find out how much the changes in chemistry of aluminum cast alloys permissible by EN-PN standards may influence the mechanical properties of these alloys. Eight AlSi5Cu3(Mg type cast alloys of different content alloying elements were selected for the study. The specimens cut form test castings were subjected to precipitation hardening heat treatment. The age hardened specimens were evaluated using tensile test, hardness measurements and impact test. Moreover, the structure investigation were carried out using either conventional light Metallography and scanning (SEM and transmission (TEM electron microscopy. The two last methods were used for fractography observations and precipitation process observations respectively. It was concluded that the changes in chemical composition which can reach even 2,5wt.% cause essential differences of the structure and mechanical properties of the alloys. As followed from quantitative evaluation and as could be predicted theoretically, copper and silicon mostly influenced the mechanical properties of AlSi5Cu3(Mg type cast alloys. Moreover it was showed that the total concentration of alloying elements accelerated and intensifies the process of decomposition of supersaturated solid solution. The increase of Cu and Mg concentration increased the density of precipitates. It increases of strength properties of the alloys which are accompanied with decreasing in ductility.

  3. Understanding Active Metal Reaction Kinetis with Cu-Mg Replacement Reaction

    Indian Academy of Sciences (India)

    Ilhami Ceyhun; Zafer Karagolge

    2017-02-01

    Metal substitution reactions are simple redox reactions. Thesereactions demonstrate the relative activity and the electrochemicalseries of metals. In particular, the purpose of thisstudy is to help students comprehend the displacement reactionamong, Mg metal and solutions containing Cu$^{+2}$, Ni$^{+2}$,Pb$^{+2}$, Cd$^{+2}$, Co$^{+2}$. This study is an important experiment towardsunderstanding reaction kinetics.

  4. Structural and magnetic properties of Cu-alloyed FePd films

    Energy Technology Data Exchange (ETDEWEB)

    Polit, A., E-mail: aleksander.polit@gmail.com [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Makarov, D., E-mail: d.makarov@ifw-dresden.de [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Brombacher, C., E-mail: Christoph.Brombacher@vacuumschmelze.com [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Krupinski, M., E-mail: michal.krupinski@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Perzanowski, M., E-mail: marcin.perzanowski@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Zabila, Y., E-mail: yevhen.zabila@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland); Albrecht, M., E-mail: manfred.albrecht@physik.uni-augsburg.de [Chemnitz University of Technology, Institute of Physics, D-09107 Chemnitz (Germany); Marszałek, M., E-mail: marta.marszalek@ifj.edu.pl [The H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-348 Krakow (Poland)

    2015-05-01

    Multilayer films [Cu(d Å)/Fe(9 Å)/Pd(11 Å)]{sub 5} were deposited at room temperature on Si(001)/SiO{sub 2}(400 nm) substrates. In order to induce chemical L1{sub 0} ordering, the as-deposited samples were post-annealed by rapid thermal annealing (RTA) at 600 °C for 90 s followed additionally by heating in ultra-high vacuum (UHV) at 700 °C up to several hours. In this study the impact of post-annealing on the structural and magnetic properties of FePdCu alloy films in dependence on the Cu content was investigated. It was found that the addition of Cu to the FePd alloy has a strong influence on the chemical ordering process and the (001) texture formation. After the RTA treatment only an isotropic distribution of the easy axis of magnetization with coercive fields in the range of a few hundred mT was observed. In contrast, samples which were additionally heated for 1 h at 700 °C revealed an out-of-plane easy axis of magnetization with an effective magnetic anisotropy of about 2×10{sup 5} J/m{sup 3} for the sample containing 10 at% of Cu. - Highlights: • Fabrication by two-step annealing of FePdCu thin alloy films. • The impact of post-annealing on the structural and magnetic properties of FePdCu alloy films. • The addition of Cu to the FePd alloy has a strong influence on the chemical ordering process and the (001) texture formation. • Importance of texture in polycrystalline L1{sub 0} FePdCu alloy for perpendicular magnetic anisotropy.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  6. PLA/MgAlCu-LDH复合材料的制备、表征及性能研究%Fabrication, Characterization and Properties of PLA/MgAlCu-LDH Composites Materials

    Institute of Scientific and Technical Information of China (English)

    张红梅; 朱同贺

    2015-01-01

    用溶液插层法制备了PLA/MgAlCu-LDH共混溶液,通过涂膜法制备了不同MgAlCu-LDH含量的PLA/MgAlCu-LDH复合膜,采用扫描电镜(SEM)、红外光谱(FTIR)、X射线衍射(XRD)、力学性能测试仪器对制备的复合膜的形貌、结构及性能进行测试表征.结果表明:部分PLA分子链插入到MgAlCu-LDH片层间隙中,使得MgAlCu-LDH层间距变大,MgAlCu-LDH作为插层剂对整个共混聚合物的韧性和强度有明显的影响;PLA/MgAl-Cu-LDH复合材料的杨氏模量随MgAlCu-LDH含量的增加而增加,加入少量MgAlCu-LDH时PLA/MgAlCu-LDH复合材料的抗拉强度、屈服强度和断裂伸长率均增加,在室温下拉伸时,PLA/MgAlCu-LDH 3%(质量分数)复合材料的抗拉强度、屈服强度和断裂伸长率分别比PLA提高14.5%、11.5%和23.7%.

  7. Microstructure and properties of hot extruded Mg-3Zn-Y-xCu (x = 0, 1, 3, 5) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bao-sheng; Kuang, Ya-fei; Fang, Da-qing; Chai, Yue-sheng [Taiyuan Univ. of Science and Technology (China). College of Materials Science and Engineering; Taiyuan Univ. of Science and Technology (China). Engineering Research Center for Magnesium Alloys of Shanxi Province; Zhang, Yue-zhong [Taiyuan Univ. of Science and Technology (China). Engineering Research Center for Magnesium Alloys of Shanxi Province; Taiyuan Univ. of Science and Technology (China). College of Chemical and Biological Engineering

    2017-04-15

    In petroleum drilling engineering, materials with high strength and rapid degradation are required for degradable fracturing ball applications. In this work, the microstructure, mechanical properties, and corrosion behavior of extruded Mg-3Zn-Y-xCu (x = 0, 1, 3, 5 weight percent) alloys are investigated using optical microscopy, scanning electronic microscopy equipped with energy dispersive X-ray spectroscopy, X-ray diffraction, transmission electronic microscopy, compression tests, electrochemical measurements, and hydrogen evolution tests, to explore their potential as excellent candidate alloys for degradable fracturing ball applications. It is found that the Mg-3Zn-Y alloy is mainly composed of α-Mg, Mg{sub 3}Zn{sub 3}Y{sub 2}, and Mg{sub 3}Zn{sub 6}Y phases. After Cu addition, a new MgZnCu phase is formed, while the Mg{sub 3}Zn{sub 3}Y{sub 2} phase disappears. The Mg-3Zn-Y-3Cu alloy shows the highest compressive strength (473 MPa) and yield strength (402 MPa), mainly attributed to the combined effect of the fine-grain and dispersed precipitation of Mg{sub 3}Zn{sub 6}Y and MgZnCu. The corrosion rate of Mg-3Zn-Y-3Cu reaches 0.41 mm day{sup -1} in 3.5 wt.% KCl solution. Consequently, Mg-3Zn-Y-3Cu alloy is a suitable degradable fracturing ball-seat material.

  8. Structural, electronic, and elastic properties of CuFeS2: first-principles study

    Science.gov (United States)

    Zhou, Meng; Gao, Xiang; Cheng, Yan; Chen, Xiangrong; Cai, Lingcang

    2015-03-01

    The structural, electronic, and elastic properties of CuFeS2 have been investigated by using the generalized gradient approximation (GGA), GGA + U (on-site Coulomb repulsion energy), the local density approximation (LDA), and the LDA + U approach in the frame of density functional theory. It is shown that when the GGA + U formalism is selected with a U value of 3 eV for the 3d state of Fe, the calculated lattice constants agree well with the available experimental and other theoretical data. Our GGA + U calculations indicate that CuFeS2 is a semiconductor with a band gap of 0.552 eV and with a magnetic moment of 3.64 µB per Fe atom, which are well consistent with the experimental results. Combined with the density of states, the band structure characteristics of CuFeS2 have been analyzed and their origins have been specified, which reveals a hybridization existing between Fe-3d, Cu-3s, and S-3p, respectively. The charge and Mulliken population analyses indicate that CuFeS2 is a covalent crystal. Moreover, the calculated elastic constants prove that CuFeS2 is mechanically stable but anisotropic. The bulk modulus obtained from elastic constants is 87.1 GPa, which agrees well with the experimental value of 91 ± 15 GPa and better than the theoretical bulk modulus 74 GPa obtained from GGA method by Lazewski et al. The obtained shear modulus and Debye temperature are 21.0 GPa and 287 K, respectively, and the latter accords well with the available experimental value. It is expected that our work can provide useful information to further investigate CuFeS2 from both the experimental and theoretical sides.

  9. A Comparative Kinetics Study between Cu/SSZ-13 and Fe/SSZ-13 SCR Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Feng; Wang, Yilin; Kollar, Marton; Washton, Nancy M.; Szanyi, Janos; Peden, Charles HF

    2015-11-09

    Cu- and Fe/SSZ-13 catalysts with the same Cu(Fe)/Al ratios are synthesized using the same parent SSZ-13 starting material. The catalytic performance for both fresh and hydrothermally aged catalysts is tested with NO and NH3 oxidation, and standard SCR reactions under steady-state conditions, and standard and fast SCR under temperature-programmed conditions. For standard SCR, Cu/SSZ-13 shows much better low-temperature performance which can be explained by NH3-inhibition of Fe/SSZ-13. During hydrothermal aging, both catalysts undergo dealumination but Fe/SSZ-13 dealuminates more severely. For aged catalysts, Cu/SSZ-13 gains oxidation activities due to formation of CuOx. However, Fe/SSZ-13 loses oxidation activities although formation of FeOx clusters and FeAlOx species also occur. Because of such physical properties differences, aged Cu/SSZ-13 loses while Fe/SSZ-13 maintains high-temperature SCR selectivities. A physical mixture of aged catalysts provides stable SCR performance in a wide temperature range and is able to decrease N2O formation at high reaction temperatures. This suggests that Fe/SSZ-13 can be used as a cocatalyst for Cu/SSZ-13 for transportation applications. During temperature-programmed SCR reactions, weak hysteresis is found during standard SCR due to NH3 inhibition. For fast SCR, hysteresis caused by NH4NO3 inhibition is much more significant. NH4NO3 deposition is greatly enhanced by Brønsted and Lewis acidity of the catalysts.

  10. Stability of the post irradiation traps in LiF: Mg, Cu, P; Estabilidad de las trampas posradiacion en LiF: Mg, Cu, P

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P.R. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Furetta, C. [Physics Department, Rome University ' ' La Sapienza' ' , Rome (Italy); Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico)

    2004-07-01

    In this work the results of the study of the stability of the traps are presented in dosemeters Tl of LiF: Mg,Cu,P, irradiated with gamma radiation of {sup 60} Co. The studied dosemeters were of LiF: Mg,Cu,P + Ptfe, developed in the ININ, taking like reference to the commercial dosemeter GR200A of Chinese manufacture. Before being exposed to the radiation, the dosemeters received their standard treatment from having erased, two hours after the irradiation they took the initial readings. The dosemeters faded again and they were irradiated to the same dose, soon after they stayed under normal conditions, protected of the light, later on they were taken their readings periodically during six months. The readings taken Tl the same day of the irradiation presented four peaks whose energy, determined by the deconvolution method were; 1.30 {+-} 0.01 eV, 1.50 {+-} 0.01 eV, 1.70 {+-} 0.01 eV and 2.58 {+-} 0.02 eV, for LiF: Mg,Cu,P + Ptfe, while GR200A stops the energy they were: 1.33 {+-} 0.11 eV, 1.58 {+-} 0.11 eV, 1.73 {+-} 0.11 eV and 2.60 {+-} 0.03 eV. In both cases the peak 1, with the energy but it lowers, it disappears completely after some later hours to the irradiation, while the peak 2, it disappears completely after 122 days for the local dosemeter and after 94 days for the commercial dosemeter. The energy of the peaks 3 and 4 that remained visible during the whole period of study it was: 1.38 {+-} 0.01 eV and 2.65 {+-} 0.01 eV, for LiF: Mg,Cu,P + Ptfe respectively, in the same order for GR200A, the energies were: 1.51 {+-} 0.02 eV and 2.64 {+-} 0.03 eV. In all the cases the peaks with energy below 2 eV, showed tendency to the drop, while the main peak, showed certain tendency to increase, as they show it the results. (Author)

  11. Comparison of serum Concentration of Se, Pb, Mg, Cu, Zn, between MS patients and healthy controls

    Science.gov (United States)

    Alizadeh, Anahita; Mehrpour, Omid; Nikkhah, Karim; Bayat, Golnaz; Espandani, Mahsa; Golzari, Alireza; Jarahi, Lida; Foroughipour, Mohsen

    2016-01-01

    Introduction Multiple Sclerosis (MS) is defined as one of the inflammatory autoimmune disorders and is common. Its exact etiology is unclear. There are some evidences on the role of environmental factors in susceptible genetics. The aim of this study is to evaluate the possible role of Selenium, Zinc, Copper, Lead and Magnesium metals in Multiple Sclerosis patients. Methods In the present analytical cross-sectional study, 56 individuals including 26 patients and 30 healthy controls were enrolled in the evaluation. The serum level of Se, Zn, Cu, Pb were quantified in graphite furnace conditions and flame conditions by utilizing an atomic absorption Perkin Elmer spectrophotometer 3030. The serum levels of Mg were measured by auto analyzer 1500 BT. The mean level of minerals (Zn, Pb, Cu, Mg, Se) in serum samples were compared in both cases and controls. The mean level of minerals (Zn, Pb, Cu, Mg, Se) in serum samples were compared in both cases and controls by using independent-samples t-test for normal distribution and Mann-Whitney U test as a non-parametric test. All statistical analyses were carried out using SPSS 11.0. Results As well as the Zn, Cu, and Se, there was no significant difference between MS patients and healthy individuals in Pb concentrations (p-value = 0.11, 0.14, 0.32, 0.20 respectively) but the level of Mg was significantly different (p= 0.001). Conclusion All serum concentrations of Zn, Pb, Se, Cu in both groups were in normal ranges and there was no difference in MS patients compared with the healthy group who were matched in genetics. Blood level of Mg was significantly lower in MS patients. But it should be noted that even with the low level of serum magnesium in MS patients, this value is still in the normal range. PMID:27757186

  12. Study of CoFeB thickness and composition dependence in a modified CoFeB/MgO/CoFeB perpendicular magnetic tunnel junction

    Science.gov (United States)

    Zhu, M.; Chong, H.; Vu, Q. B.; Brooks, R.; Stamper, H.; Bennett, S.

    2016-02-01

    We studied the CoFeB thickness and composition dependence of tunneling magnetoresistance (TMR) and resistance-area product (RA) in a modified CoFeB/MgO/CoFeB perpendicular magnetic tunnel junction (MTJ), in which the bottom CoFeB is coupled to an in-plane exchange biased magnetic layer. This stack structure allows us to measure TMR and RA of the MTJs in sheet film format without patterning them, using current-in-plane-tunneling (CIPT) technique. The thickness ranges for both top and bottom CoFeB to exhibit perpendicular magnetic anisotropy are similar to what are seen in each single magnetic film stack. However, CIPT measurement revealed that there exists an optimal thickness for both top and bottom CoFeB to achieve the highest TMR value. Magnetic hysteresis loops also suggest the thickness-dependent coupling between the top and bottom CoFeB layers. We studied MTJs with two CoFeB compositions (Co40Fe40B20 and Co20Fe60B20) and found that Co20Fe60B20 MTJs give higher TMR and also wider perpendicular thickness range when used at the top layer.

  13. Preparation of hydrogen by methanol decomposition over Fe/MgO, Co/MgO and Ni/MgO catalysts%甲醇在Fe/MgO、Co/MgO和Ni/MgO催化剂上裂解制备氢气

    Institute of Scientific and Technical Information of China (English)

    朱刚; 焦宝娟

    2012-01-01

    The catalysts of Fe, Co and Ni supported on MgO were prepared by the means of impregnation. Methanol decomposition over Fe/MgO, Co/MgO and Ni/MgO catalysts were systematically investigated at 600℃. The results indicated that the production of H2 by methanol decomposition could be realized over these catalysts and carbon nano-tubes were produced at the same time. Ni/MgO was the best one among the three catalysts.%采用浸渍法制备出3种MgO负载型过渡金属催化剂Fe/MgO、Co/MgO和Ni/MgO,系统研究了甲醇在3种催化剂上于600℃下的裂解产物.结果表明,3种催化剂均能催化甲醇裂解产生富氢气体,同时产生碳纳米管.其中,Ni/MgO具有最佳的催化效果.

  14. Fe and Co nanostructures embedded into the Cu(100) surface: Self-Organization and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kolesnikov, S. V., E-mail: kolesnikov@physics.msu.ru; Klavsyuk, A. L.; Saletsky, A. M. [Moscow State University, Faculty of Physics (Russian Federation)

    2015-10-15

    The self-organization and magnetic properties of small iron and cobalt nanostructures embedded into the first layer of a Cu(100) surface are investigated using the self-learning kinetic Monte Carlo method and density functional theory. The similarities and differences between the Fe/Cu(100) and the Co/Cu(100) are underlined. The time evolution of magnetic properties of a copper monolayer with embedded magnetic atoms at 380 K is discussed.

  15. Giant strain control of magnetoelectric effect in Ta|Fe|MgO.

    Science.gov (United States)

    Odkhuu, Dorj

    2016-09-06

    The exploration of electric field controlled magnetism has come under scrutiny for its intriguing magnetoelectric phenomenon as well as technological advances in spintronics. Herein, the tremendous effect of an epitaxial strain on voltage-controlled perpendicular magnetic anisotropy (VPMA) is demonstrated in a transition-metal|ferromagnet|MgO (TM|FM|MgO) heterostructure from first-principles electronic structure computation. By tuning the epitaxial strain in Ta|Fe|MgO as a model system of TM|FM|MgO, we find distinctly different behaviours of VPMA from V- to Λ-shape trends with a substantially large magnetoelectric coefficient, up to an order of 10(3) fJV(-1)m(-1). We further reveal that the VPMA modulation under strain is mainly governed by the inherently large spin-orbit coupling of Ta 5d-Fe 3d hybridized orbitals at the TM|FM interface, although the Fe 3d-O 2p hybridization at the FM|MgO interface is partly responsible in determining the PMA of Ta|Fe|MgO. These results suggest that the control of epitaxial strain enables the engineering of VPMA, and provides physical insights for the divergent behaviors of VPMA and magnetoelectric coefficients found in TM|FM|MgO experiments.

  16. Giant strain control of magnetoelectric effect in Ta|Fe|MgO

    Science.gov (United States)

    Odkhuu, Dorj

    2016-09-01

    The exploration of electric field controlled magnetism has come under scrutiny for its intriguing magnetoelectric phenomenon as well as technological advances in spintronics. Herein, the tremendous effect of an epitaxial strain on voltage-controlled perpendicular magnetic anisotropy (VPMA) is demonstrated in a transition-metal|ferromagnet|MgO (TM|FM|MgO) heterostructure from first-principles electronic structure computation. By tuning the epitaxial strain in Ta|Fe|MgO as a model system of TM|FM|MgO, we find distinctly different behaviours of VPMA from V- to Λ-shape trends with a substantially large magnetoelectric coefficient, up to an order of 103 fJV‑1m‑1. We further reveal that the VPMA modulation under strain is mainly governed by the inherently large spin-orbit coupling of Ta 5d–Fe 3d hybridized orbitals at the TM|FM interface, although the Fe 3d–O 2p hybridization at the FM|MgO interface is partly responsible in determining the PMA of Ta|Fe|MgO. These results suggest that the control of epitaxial strain enables the engineering of VPMA, and provides physical insights for the divergent behaviors of VPMA and magnetoelectric coefficients found in TM|FM|MgO experiments.

  17. Structural and hydrogen storage capacity evolution of Mg2FeH6 hydride synthesized by reactive mechanical alloying

    Institute of Scientific and Technical Information of China (English)

    LI Song-lin(李松林); R.A.Varin

    2004-01-01

    Mg-based metal hydrides are promising as hydrogen storage materials for fuel cell application. In this work, Mg2 FeH6 complex hydride phase was synthesized by controlled reactive ball milling of 2Mg-Fe (atomic ratio)powder mixture in H2. Mg2 FeH6 is confirmed to be formed via the following three stages: formation of MgH2 via the reaction of Mg with H2, incubation stage and formation of Mg2 FeH6 by reaction of fully refined MgH2 and Fe.The incubation stage is characterized by no traces of Mg or hydride crystalline phase by XRD. On the other hand,Mg is observed uniformly distributed in the milled powder by SEM-EDS. Also, almost the same amount of H2 as the first stage is detected stored in the powders of the second stage by DSC and TGA.

  18. Perpendicular magnetic anisotropy in Ta|Co40Fe40B20|MgAl2O4 structures and perpendicular CoFeB|MgAl2O4|CoFeB magnetic tunnel junction

    KAUST Repository

    Tao, B. S.

    2014-09-08

    Magnetic properties of Co40Fe40B20(CoFeB) thin films sandwiched between Ta and MgAl2O4layers have been systematically studied. For as-grown state, Ta/CoFeB/MgAl2O4structures exhibit good perpendicular magnetic anisotropy (PMA) with interface anisotropy Ki=1.22erg/cm2, which further increases to 1.30erg/cm2after annealing, while MgAl2O4/CoFeB/Ta multilayer shows in-plane magnetic anisotropy and must be annealed in order to achieve PMA. For bottom CoFeB layer, the thickness window for PMA is from 0.6 to 1.0nm, while that for top CoFeB layer is between 0.8 and 1.4nm. Perpendicular magnetic tunnel junctions (p-MTJs) with a core structure of CoFeB/MgAl2O4/CoFeB have also been fabricated and tunneling magnetoresistance ratio of about 36% at room temperature and 63% at low temperature have been obtained. The intrinsic excitations in the p-MTJs have been identified by inelastic electron-tunneling spectroscopy.

  19. The CorA Mg2+ transporter does not transport Fe2+.

    Science.gov (United States)

    Papp, Krisztina M; Maguire, Michael E

    2004-11-01

    corA encodes the constitutively expressed primary Mg2+ uptake system of most eubacteria and many archaea. Recently, a mutation in corA was reported to make Salmonella enterica serovar Typhimurium markedly resistant to Fe2+-mediated toxicity. Mechanistically, this was hypothesized to be from an ability of CorA to mediate the influx of Fe2+. Consequently, we directly examined Fe2+ transport and toxicity in wild-type versus corA cells. As determined by direct transport assay, CorA cannot transport Fe2+ and Fe2+ does not potently inhibit CorA transport of 63Ni2+. Mg2+ can, relatively weakly, inhibit Fe2+ uptake, but inhibition is not dependent on the presence of a functional corA allele. Although excess Fe2+ was slightly toxic to S. enterica serovar Typhimurium, we were unable to elicit a significant differential sensitivity in a wild-type versus a corA strain. We conclude that CorA does not transport Fe2+ and that the relationship, if any, between iron toxicity and corA is indirect.

  20. Geomaterials related to photovoltaics: a nanostructured Fe-bearing kuramite, Cu3SnS4

    Science.gov (United States)

    Di Benedetto, Francesco; Bencistà, Ilaria; D'Acapito, Francesco; Frizzera, Silvia; Caneschi, Andrea; Innocenti, Massimo; Lavacchi, Alessandro; Montegrossi, Giordano; Oberhauser, Werner; Romanelli, Maurizio; Dittrich, Herbert; Pardi, Luca A.; Tippelt, Gerold; Amthauer, Georg

    2016-09-01

    The successful synthesis of nanoparticles of Fe-bearing kuramite, (Cu,Fe)3SnS4, is reported in this study. Nanocrystalline powders were obtained through a mild, environmentally friendly and scalable solvothermal approach, in a single run. The sample was the object of a multidisciplinary investigation, including X-ray diffraction and absorption, scanning electron microscopy and microanalysis, electron paramagnetic resonance, diffuse reflectance and Mössbauer spectroscopy as well as SQUID magnetometry. The nanoparticles consist of pure Fe-bearing kuramite, exhibiting tetragonal structure. The valence state of the metal cations was assessed to be Cu+, Sn4+ and Fe3+. The material presents a band gap value of 1.6 eV, which is fully compatible with solar cell applications. The uptake of Fe by nanokuramite opens a compositional field where the physical properties can be tuned. We thus foster the application of Fe-bearing nanokuramite for photovoltaics and energy storage purposes.

  1. Enhancement of voltage-controlled magnetic anisotropy through precise control of Mg insertion thickness at CoFeB|MgO interface

    Science.gov (United States)

    Li, Xiang; Fitzell, Kevin; Wu, Di; Karaba, C. Ty; Buditama, Abraham; Yu, Guoqiang; Wong, Kin L.; Altieri, Nicholas; Grezes, Cecile; Kioussis, Nicholas; Tolbert, Sarah; Zhang, Zongzhi; Chang, Jane P.; Khalili Amiri, Pedram; Wang, Kang L.

    2017-01-01

    We studied the impact of different insertion layers (Ta, Pt, and Mg) at the CoFeB|MgO interface on voltage-controlled magnetic anisotropy (VCMA) effect and other magnetic properties. Inserting a very thin Mg layer of 0.1-0.3 nm yielded a VCMA coefficient of 100 fJ/V-m, more than 3 times higher than the average values of around 30 fJ/V-m reported in Ta|CoFeB|MgO-based structures. Ta and Pt insertion layers also showed a small improvement, yielding VCMA coefficients around 40 fJ/V-m. Electrical, magnetic, and X-ray diffraction results reveal that a Mg insertion layer of around 1.2 nm gives rise to the highest perpendicular magnetic anisotropy, saturation magnetization, as well as the best CoFe and MgO crystallinity. Other Mg insertion thicknesses give rise to either under- or over-oxidation of the CoFe|MgO interface; a strong over-oxidation of the CoFe layer leads to the maximum VCMA effect. These results show that precise control over the Mg insertion thickness and CoFe oxidation level at the CoFeB|MgO interface is crucial for the development of electric-field-controlled perpendicular magnetic tunnel junctions with low write voltage.

  2. Self-healing of deformation damage in underaged Al-Cu-Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hautakangas, S. [Faculty of Applied Physics, Section NPM2, Delft University of Technology, Mekelweg 15, NL-2629JB Delft (Netherlands)], E-mail: h.schut@tudelft.nl; Schut, H. [Faculty of Applied Physics, Section NPM2, Delft University of Technology, Mekelweg 15, NL-2629JB Delft (Netherlands); Dijk, N.H. van [Faculty of Applied Physics, Section FAME, Delft University of Technology, Mekelweg 15, NL-2629JB Delft (Netherlands); Rivera Diaz del Castillo, P.E.J.; Zwaag, S. van der [Faculty of Aerospace Engineering, Section Fundamentals of Advanced Materials, Delft University of Technology, Kluyverweg 1, NL-2629HS Delft (Netherlands)

    2008-05-15

    The generation and evolution of open volume defects in underaged and T3 Al-Cu-Mg alloy is studied with positron annihilation spectroscopy. During room temperature ageing the positron lifetime in plastically deformed, underaged material approaches the saturation lifetime of the undeformed material. Doppler-broadening results indicate that this behaviour can be attributed to diffusion and clustering of retained solute Cu atoms at the deformation defects, a process of relevance for the introduction of a self-healing mechanism in age-hardenable aluminium alloys.

  3. Spin-Polarized Electron Injection in Co/Cu/Fe Sandwich Structure

    Institute of Scientific and Technical Information of China (English)

    WANG Shou-Guo; CHEN Yan-Xue; WANG Zhi-He; CHEN Qiang; XIE Shi-Jie; MEI Liang-Mo

    2000-01-01

    A material asymmetry Co/Cu/Fe junction structure has been prepared for studying the spin-polarized electron injection at 77K. The sample performance was demonstrated to be analogous to that of a bipolar transistor. The maximal value of the output pulse voltage between Cu and Fe layers could reach the order of severalμV when the bias current between Co and Cu layers was 10μA. The interface roughness, photograph of material, magnetic loop and injection characteristic curves have been measured. Some important points on this topic have been discussed.

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

    Science.gov (United States)

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

    2008-03-01

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

  5. Ultrathin W space layer-enabled thermal stability enhancement in a perpendicular MgO/CoFeB/W/CoFeB/MgO recording frame.

    Science.gov (United States)

    Kim, Jae-Hong; Lee, Ja-Bin; An, Gwang-Guk; Yang, Seung-Mo; Chung, Woo-Seong; Park, Hae-Soo; Hong, Jin-Pyo

    2015-11-20

    Perpendicularly magnetized tunnel junctions (p-MTJs) show promise as reliable candidates for next-generation memory due to their outstanding features. However, several key challenges remain that affect CoFeB/MgO-based p-MTJ performance. One significant issue is the low thermal stability (Δ) due to the rapid perpendicular magnetic anisotropy (PMA) degradation during annealing at temperatures greater than 300 °C. Thus, the ability to provide thermally robust PMA characteristics is a key steps towards extending the use of these materials. Here, we examine the influence of a W spacer on double MgO/CoFeB/W/CoFeB/MgO frames as a generic alternative layer to ensure thermally-robust PMAs at temperatures up to 425 °C. The thickness-dependent magnetic features of the W layer were evaluated at various annealing temperatures to confirm the presence of strong ferromagnetic interlayer coupling at an optimized 0.55 nm W spacer thickness. Using this W layer we achieved a higher Δ of 78 for an approximately circular 20 nm diameter free layer device.

  6. Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu-substitution in single-crystalline FePt thin films

    Directory of Open Access Journals (Sweden)

    Takuya Ono

    2016-05-01

    Full Text Available In L10 (fct-FePt thin films, both tuning Fe and Pt concentrations and substitution with third-metal were studied for magnetic characteristic optimization. We investigated single-crystalline FePt-X (X = Mn, Ni, Cu thin films grown epitaxially on MgO(001 substrates at a substrate temperature of 350  °C by changing Fe, Pt, and X contents, and explored the effects of off-stoichiometry and 3d-metal-substitution. The magnetic moment per atom (m of FePt-X films as a function of the effective number of valence electrons (neff in 3d metal sites follows the Slater-Pauling-type trend, by which m decreases by the neff deviation from neff = 8, independently of the X metal and the Pt concentration. The magnetic anisotropy (Ku exhibits neff dependence similar to m. This trend was almost independent of the Pt concentration after compensation using the theoretical prediction on the relation between Ku and Fe/Pt concentrations. Such a trend has been proved for stoichiometric FePt-X films, but it was clarified as robust against off-stoichiometry. The compensated Ku ( K u comp of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the K u comp of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation.

  7. Experimental investigation of off-stoichiometry and 3d transition metal (Mn, Ni, Cu)-substitution in single-crystalline FePt thin films

    Science.gov (United States)

    Ono, Takuya; Nakata, Hitoshi; Moriya, Tomohiro; Kikuchi, Nobuaki; Okamoto, Satoshi; Kitakami, Osamu; Shimatsu, Takehito

    2016-05-01

    In L10 (fct)-FePt thin films, both tuning Fe and Pt concentrations and substitution with third-metal were studied for magnetic characteristic optimization. We investigated single-crystalline FePt-X (X = Mn, Ni, Cu) thin films grown epitaxially on MgO(001) substrates at a substrate temperature of 350 °C by changing Fe, Pt, and X contents, and explored the effects of off-stoichiometry and 3d-metal-substitution. The magnetic moment per atom (m) of FePt-X films as a function of the effective number of valence electrons (neff) in 3d metal sites follows the Slater-Pauling-type trend, by which m decreases by the neff deviation from neff = 8, independently of the X metal and the Pt concentration. The magnetic anisotropy (Ku) exhibits neff dependence similar to m. This trend was almost independent of the Pt concentration after compensation using the theoretical prediction on the relation between Ku and Fe/Pt concentrations. Such a trend has been proved for stoichiometric FePt-X films, but it was clarified as robust against off-stoichiometry. The compensated Ku ( Ku comp ) of FePt-Mn and FePt-Cu followed a similar trend to that predicted by the rigid-band model, although the Ku comp of the FePt-Mn thin films dropped more rapidly than the rigid band calculation. However, it followed the recent first-principles calculation.

  8. A novel reusable nanocomposite adsorbent, xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide, for removing Cu(II) from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinshui, E-mail: jsliu@sina.com; Liu, Wenxiu; Wang, Yiru; Xu, Meijiao; Wang, Bin

    2016-03-30

    Graphical abstract: - Highlights: • Xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide (xanthated Fe{sub 3}O{sub 4}-CS-GO) was synthesized. • Xanthated Fe{sub 3}O{sub 4}-CS-GO demonstrates the high affinity to Cu(II) ions. • The adsorbent can be effectively reused to remove Cu(II) ions. - Abstract: Novel nanocomposites of xanthated Fe{sub 3}O{sub 4}-chitosan grafted onto graphene oxide (xanthated Fe{sub 3}O{sub 4}-CS-GO) were successfully synthesized for the first time using an amidation reaction. The xanthated Fe{sub 3}O{sub 4}-CS-GO was used to remove Cu(II) from aqueous solutions. The xanthated Fe{sub 3}O{sub 4}-CS-GO was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometry, and energy dispersive X-ray spectroscopy. The Cu(II) adsorption isotherms for the xanthated Fe{sub 3}O{sub 4}-CS-GO fitted the Langmuir isotherm model. The maximum Cu(II) adsorption capacity of the xanthated Fe{sub 3}O{sub 4}-CS-GO was 426.8 mg g{sup −1}, which is much higher than the maximum adsorption capacities of other adsorbents that have been described in the literature. This was attributed to xanthated Fe{sub 3}O{sub 4}-CS-GO having abundant functional groups. The xanthated Fe{sub 3}O{sub 4}-CS-GO could be regenerated using ethylene diamine tetraacetic acid, and could easily be removed from a liquid using an external magnetic field. These features would allow secondary pollution of the environment to be avoided more easily than is the case for other adsorbents. Cu(II) was adsorbed from aqueous solutions quickly and efficiently by the xanthated Fe{sub 3}O{sub 4}-CS-GO complex, suggesting that xanthated Fe{sub 3}O{sub 4}-CS-GO may be an ideal candidate for removing Cu(II) from wastewater.

  9. Microstructural and Kinetic Evolution of Fe Doped MgH2 during H2 Cycling

    Directory of Open Access Journals (Sweden)

    Annalisa Aurora

    2012-09-01

    Full Text Available The effect of extended H2 sorption cycles on the structure and on the hydrogen storage performances of MgH2 powders with 5 wt% of Fe particle catalyst is reported. MgH2 powders with and without Fe have been ball milled under Argon, the doped MgH2 nanocomposite has been cycled under hydrogen pressure up to a maximum of 47 desorption and absorption cycles at 300 °C. After acceleration during the first 10 cycles, the kinetics behavior of doped MgH2 is constant after extended cycling, in terms of maximum storage capacity and rate of sorption. The major effect of cycling on particle morphology is the progressive extraction of Mg from the MgO shell surrounding the powder particles. The Mg extraction from the MgO shell leaves the catalyst particles inside the hydride particles. Many empty MgO shells are observed in the pure ball milled MgH2 upon cycling at higher temperature, suggesting that this enhancement of the extraction efficiency is related to the higher operating temperature which favors Mg diffusivity with respect to the H ion one.

  10. Determination of the percolation threshold in Fe/MgO magnetic granular multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-GarcIa, A; Algarabel, P A; De Teresa, J M; Morellon, L; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, 50009-Zaragoza (Spain); Vovk, A; Strichovanec, P; Pardo, J A; Magen, C, E-mail: vovk@imag.kiev.u [Instituto de Nanociencia de Aragon, Universidad de Zaragoza, 50018-Zaragoza (Spain)

    2010-02-10

    The evolution of the morphology, magnetic and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers with respect to the nominal metallic layer thickness was investigated. A comparison with existing experimental data on discontinuous metal-insulator multilayers, ultrathin epitaxial Fe films on MgO substrates and granular cermet films is made. It is confirmed that the deposition conditions and the material composition play a crucial role in the percolation process. Nominal thicknesses of Fe layers at which an infinite metallic cluster is formed and the conditions for continuous Fe coverage were determined. Different methods of percolation threshold detection were analysed. We show that investigation of the temperature dependence of resistance in nanostructures could lead to an overestimation of the percolation threshold value, while magnetic measurements alone could lead to its underestimation.

  11. Anatomy of electric field control of perpendicular magnetic anisotropy at Fe/MgO interfaces

    Science.gov (United States)

    Ibrahim, F.; Yang, H. X.; Hallal, A.; Dieny, B.; Chshiev, M.

    2016-01-01

    The charge-mediated effect of electric field on the perpendicular magnetic anisotropy (PMA) of Fe/MgO interfaces is investigated using first-principles calculations. We present an approach by discussing this effect in relation to the intrinsic dipole field existing at the Fe/MgO interface. A firm correlation between the PMA and the interfacial dipole is established and further verified in the absence of an applied electric field. The on-site projected PMA analysis not only elucidates that the effect of electric field on the PMA extends beyond the interfacial Fe layer, but also shows that the second Fe layer carries the largest contribution to the effect. This observation is interpreted in relation to the orbital hybridization changes induced by applying an electric field.

  12. Structural, optical and room-temperature ferromagnetic properties of Fe-doped CuO nanostructures

    Science.gov (United States)

    Mohamed Basith, N.; Judith Vijaya, J.; John Kennedy, L.; Bououdina, M.

    2013-09-01

    Pure CuO and Fe-doped CuO nanostructures with different weight ratios (0.5, 1.0, 1.5, and 2.0 at wt% of Fe) were synthesized via the microwave combustion method. The synthesized samples were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometry (VSM). XRD patterns refined by the Rietveld method indicated the formation of single-phase monoclinic structure and also confirmed that Fe ions successfully incorporated into CuO crystal lattice by occupying Cu ionic sites. Interestingly, the morphology was found to change considerably from nanoflowers to nano-rod and disk-shaped then to nanoparticles with the variation of Fe content. The optical band gap calculated using DRS was found to be 2.8 eV for pure CuO and increases up to 3.4 eV with increasing ‘Fe’ content. Photoluminescence measurements also confirm these results. The magnetic measurements indicated that the obtained nanostructures are found to be room temperature ferromagnetism (RTF) with an optimum value of saturation magnetization at 2.0 wt% of Fe-doped CuO, i.e. 1.2960×10-3 emu/g.

  13. Preparation and oxygen permeation properties of SrFe(Cu)O3-δ dense ceramic membranes

    Institute of Scientific and Technical Information of China (English)

    Heng Zhang; Tingting Wang; Xinfa Dong; Weiming Lin

    2009-01-01

    Mixed oxygen-ionic and electronic conducting membranes of SrFe(Cu)O3-δ were prepared by solid-state reaction method.The crystal structure,oxygen nonstoichiometry,and phase stability of the materials were studied by TGA and XRD.Oxygen permeation fluxes through these membranes were studied at operating temperature ranging from 750 to 950 ℃.Results showed that doping Cu in SrFeO3-δ compound had a significant effect on the formation of single-phased perovskite structure.For SrFe1-xCuxO3-δ series materials,the oxygen nonstoichiometry and the oxygen permeation flux increased considerably with the increase of Cu-doping content (x = 0.1-0.3).The sintering property of the membrane decreased significantly when the Cu substitution amount reached 40%.SrFe0.7CU0.3O3-δ showed high oxygen permeation flux,but SrCuO2 and Sr2Fe2O5 phases formed in the compound after oxygen permeation test induced cracks in the membrane.

  14. PREPARATION OF NANO-CRYSTALLINE Fe-Cu THIN FILMS AND THEIR MAGNETIC PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    X.F.Bi; S.K.Gong; H.B.Xu; K.I.Arai

    2002-01-01

    Fe-Cu thin films of 0.2μm in thickness with different Cu contents were prepared byusing r.f. magnetron sputtering onto glass substrate. The effect of sputtering param-eters, including Ar gas pressure and input rf power, on the structure and magneticproperties was investigated. It was found that when the power is lower than 70W,the structure of the films remained single bcc-Fe phase with Cu solubility of up to50at.%. TEM observations for the bcc-Fe phase showed that the grain size was inthe nanometer range of less than 20nm. The coercivity of Fe-Cu films was largelyaffected by not only Ar gas pressure but also rf power, and reached about 2.5Oe in thepressure of 0.67-6.67Pa and in the power of less than 100W. In addition, saturationmagnetization, with Cu content less than 60at.%, was about proportional to the con-tent of bcc-Fe. When Cu content was at 60at.%, however, saturation magnetizationwas much smaller than its calculation value.

  15. Preparation of nanometer FeCuP alloy and its application in decomposition of PH3

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new ternary Fe-based alloy catalyst FeCuP applied to decompose PH3 was prepared with low-cost material by chemical reduction deposition method. The properties of it were characterized by XRD, ICP and SEM. Its catalytic activity on the decomposition of PH3 and the decomposition conditions were studied. FeCuP alloy exhibits high thermal stabilities and high catalytic activity. Using it as catalyst, the decomposition temperature of phosphine decreases from over 800 ℃ to 400-500 ℃. The decomposition rate of phosphine achieved 100%.

  16. Atomic-partial vibrational density of states of i-AlCuFe quasicrystals

    CERN Document Server

    Parshin, P P; Brand, R A; Dianoux, A J; Calvayrac, Y

    2002-01-01

    We present new results on the separation of the atomic-partial vibrational density of states for the ternary quasicrystal i-Al sub 6 sub 2 Cu sub 2 sub 5 sub . sub 5 Fe sub 1 sub 2 sub . sub 5. The decomposition into three atomic-partial functions, Al-, Cu- and Fe-g(E), has been performed self-consistently with the calculation of the multi-phonon contributions. The results show the surprising result that both Cu- and Fe-g(E) are strongly peaked. The low-energy regions of Al- and Cu-g(E) show strong deviations from Debye behaviour due to the presence of non-propagating low-energy vibrational states. (orig.)

  17. Study of the effect of silver in the mechanical properties and electrical conductivity of duralumins (Al-4%Cu-0.5%Mg

    Directory of Open Access Journals (Sweden)

    Reinaldo Correa-Avendaño

    2014-01-01

    Full Text Available En este trabajo se evalúa el efecto del contenido de plata de las aleaciones base Al-Cu en la microestructura, la resistencia a la tracción, la resistencia eléctrica y el incremento de la temperatura con el paso de la corriente eléctrica (efecto Joule. Para tal fin, fueron evaluadas las aleaciones Al-4%Cu-0,5%Mg con contenidos de plata en proporciones del 1,5%, 2,5% y 3,5%. El endurecimiento por precipitación se llevó a cabo mediante tratamientos térmicos de homogenización por solución sólida. El análisis de la microestructura se realizó mediante el microscopio óptico y SEM, además, se realizó análisis de dureza Vickers, ensayos de resistencia a la tracción y pruebas de conductividad eléctrica, las cual se compararon con la aleación A356-T6. Los resultados de esta investigación muestran que el aumento de la plata en la aleación aumenta la resistencia la tracción y disminuye su resistividad. Mediante el análisis del SEM y EDS se observó la fase ɵ (CuAl2, Al6(Cu, Fe y Al7Cu2Fe.

  18. Giant strain control of magnetoelectric effect in Ta/Fe/MgO

    CERN Document Server

    Odkhuu, Dorj

    2016-01-01

    The exploration of electric field controlled magnetism has come under scrutiny for its intriguing magnetoelectric phenomenon as well as technological advances in spintronics. Herein, the tremendous effect of an epitaxial strain on voltage-controlled perpendicular magnetic anisotropy (VPMA) is demonstrated in a transition-metal/ferromagnet/MgO (TM/FM/MgO) heterostructure from first-principles electronic structure computation. By tuning the epitaxial strain in Ta/Fe/MgO as a model system of TM/FM/MgO, we find distinctly different behaviours of VPMA from V- to {\\Lambda}-shape trends with a substantially large magnetoelectric coefficient, up to an order of 1000 fJ/Vm. We further reveal that the VPMA modulation under strain is mainly governed by the inherently large spin-orbit coupling of Ta 5d-Fe 3d hybridized orbitals at the TM/FM interface, although the Fe 3d-O 2p hybridization at the FM/MgO is partly responsible in determining the PMA of Ta/Fe/MgO. These results suggest that the control of epitaxial strain ena...

  19. Interface study of FeMgOFe magnetic tunnel junctions using 3D Atom Probe

    CERN Document Server

    Mazumder, B; Vella, A; Vurpillot, F; Deconihout, B

    2011-01-01

    A detailed interface study was conducted on a Fe/MgO/Fe system using laser assisted 3D atom probe. It exhibits an additional oxide formation at the second interface of the multilayer structure independent of laser wavelength, laser fluence and the thickness of the tunnel barrier. We have shown with the help of simulation that this phenomena is caused by the field evaporation of two layers having two different evaporation

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

    CERN Document Server

    Becquart, C S

    2003-01-01

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

  1. Magnetic and catalytic properties of inverse spinel CuFe2O4 nanoparticles

    Science.gov (United States)

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

    2017-06-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

  3. Preparation and characterization of Mn/MgAlFe as transfer catalyst for SOx abatement

    Institute of Scientific and Technical Information of China (English)

    Ruiyu Jiang; Honghong Shan; Chunyi Li; Chaohe Yang

    2011-01-01

    A series of manganese-promoted MgAlFe mixed oxides,used as sulfur transfer catalysts,were prepared by acid-processed gelatin method and characterized by TGA-DTA,XRD,N2 adsorption-desorption and FT-IR techniques.It was found that the sulfur transfer catalysts with 0.5-3.0 wt% manganese showed its good dispersion in the precursor.The novel Mn/MgAlFe catalysts with 0.5-5.0 wt% manganese oxide showed a high oxidative adsorption rate and sulfur adsorption capacity,and 5.0 wt% Mn/MgAlFe sample was superior to the others for SO2 removal.Moreover,the presence of CO had no obvious effect on the adsorption activity of sulfur transfer catalysts for SO2 uptake.

  4. Tunnel anisotropic magnetoresistance in CoFeB|MgO|Ta junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hatanaka, S.; Miwa, S., E-mail: miwa@mp.es.osaka-u.ac.jp; Matsuda, K.; Nawaoka, K.; Tanaka, K.; Morishita, H.; Goto, M.; Mizuochi, N.; Shinjo, T.; Suzuki, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2015-08-24

    We found that CoFeB|MgO|Ta tunnel junctions exhibit tunnel anisotropic magnetoresistance (TAMR) at room temperature. The tunnel junctions exhibit positive magnetoresistance with the application of a magnetic field normal to the film plane. The dependencies on the applied magnetic field angle and MgO thickness reveal that the magnetoresistance originates from the TAMR, caused by the spin polarization and the spin-orbit interaction at the CoFeB|MgO interface. We also found that the TAMR can be used to detect ferromagnetic resonance in the CoFeB. This detection method could be useful for the characterization of nanomagnets that are free from the spin-transfer effect and the stray field of a reference layer, unlike conventional magnetic tunnel junctions.

  5. The Effect of Increasing Sn Content on High-Temperature Mechanical Deformation of an Mg-3%Cu-1%Ca Alloy

    Directory of Open Access Journals (Sweden)

    Georgios S.E. Antipas

    2013-11-01

    Full Text Available Chill casting of magnesium alloy samples with secondary alloying elements of Cu, Ca and Sn at % w.t. concentrations in the range 1–5, 0.1–5 and 0.1–3 respectively, gave rise to appreciably enhanced resistance to high-temperature creep, while maintaining good heat conductivity. The latter was considered to be driven by Cu and Mg-Cu intermetallics while it was clear that Sn mediated the high-temperature performance, mainly via networks of Mg2Sn and MgCaSn precipitates along the Mg matrix grain boundaries. It was postulated that Sn formed intermetallics by preferential substitution of Ca atoms and, thus, did not degrade the heat conductivity by retaining Cu. The % w.t. stoichiometry with the optimum combination of heat conductivity and resistance to high-temperature creep was found to be Mg-3Cu-1Ca-0.1Sn.

  6. Gradual solution heat treatment of AlSiCuMg cast alloys

    Institute of Scientific and Technical Information of China (English)

    WANG Guiqing; BIAN Xiufang; ZHANG Junyan

    2003-01-01

    The microstmcture characteristics of AlSiCuMg cast alloys were studied with different Cu content and the gradual solution treatment by DSC, SEM, TEM and mechanical method. The melting point of α(Al) + Si decreases and polynary eutectic phases with low melting point form with increase of Cu content. Gradual solution treatment includes two steps:solution treating near the melting point of polynary eutectic phase to take it dissolve first, and then increasing solution temperature to take the remainder copper intermetallics dissolved into o(Al). Grain boundaries melting can be avoided by gradual solution treatment, even the maximum solution temperature is above final solidification point, and the age hardening response increases correspondingly.

  7. Positron lifetime evolution during room temperature ageing in Al-Zn-Mg-(Cu)

    Energy Technology Data Exchange (ETDEWEB)

    Ferragut, R.; Moia, F. [LNESS, Department of Physics, Politecnico di Milano, Como (Italy); Liddicoat, P.; Ringer, S.P. [Australian Key Centre for Microscopy and Microanalysis, ARC Centre of Excellence for Design in Light Metals, University of Sydney, NSW (Australia); Dupasquier, A.

    2009-11-15

    The effect on the formation of vacancy-solute clusters by the addition of small percentages of Cu to Al-Zn-Mg has been studied by positron annihilation lifetime spectroscopy. The results document the ability of Cu to increase the number of vacancies retained after quenching, by forming an additional population of vacancy-solute clusters in competition with pure Zn clusters. It has also been shown that Cu accelerates the decomposition of the alloy at 150 , thereby leaving a reduced supersaturation of the matrix after an early interruption. An unexpected result is that the curve positron lifetime vs, ageing time at RT displays the symptoms of a change in the nature of the coherent aggregates that occurs in about 10 hours of RT exposure. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures.

    Science.gov (United States)

    Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L; Zhang, Qianfan; Zhao, Weisheng

    2015-12-11

    Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.

  9. Origin of interfacial perpendicular magnetic anisotropy in MgO/CoFe/metallic capping layer structures

    Science.gov (United States)

    Peng, Shouzhong; Wang, Mengxing; Yang, Hongxin; Zeng, Lang; Nan, Jiang; Zhou, Jiaqi; Zhang, Youguang; Hallal, Ali; Chshiev, Mairbek; Wang, Kang L.; Zhang, Qianfan; Zhao, Weisheng

    2015-12-01

    Spin-transfer-torque magnetic random access memory (STT-MRAM) attracts extensive attentions due to its non-volatility, high density and low power consumption. The core device in STT-MRAM is CoFeB/MgO-based magnetic tunnel junction (MTJ), which possesses a high tunnel magnetoresistance ratio as well as a large value of perpendicular magnetic anisotropy (PMA). It has been experimentally proven that a capping layer coating on CoFeB layer is essential to obtain a strong PMA. However, the physical mechanism of such effect remains unclear. In this paper, we investigate the origin of the PMA in MgO/CoFe/metallic capping layer structures by using a first-principles computation scheme. The trend of PMA variation with different capping materials agrees well with experimental results. We find that interfacial PMA in the three-layer structures comes from both the MgO/CoFe and CoFe/capping layer interfaces, which can be analyzed separately. Furthermore, the PMAs in the CoFe/capping layer interfaces are analyzed through resolving the magnetic anisotropy energy by layer and orbital. The variation of PMA with different capping materials is attributed to the different hybridizations of both d and p orbitals via spin-orbit coupling. This work can significantly benefit the research and development of nanoscale STT-MRAM.

  10. Critical Analysis on the Structural and Magnetic Properties of Bulk and Nanocrystalline Cu-Fe-O

    Directory of Open Access Journals (Sweden)

    D. Paul Joseph

    2010-01-01

    Full Text Available Nanocrystalline and bulk samples of “Fe”-doped CuO were prepared by coprecipitation and ceramic methods. Structural and compositional analyses were performed using X-ray diffraction, SEM, and EDAX. Traces of secondary phases such as CuFe2O4, Fe3O4, and α-Fe2O3 having peaks very close to that of the host CuO were identified from the Rietveld profile analysis and the SAED pattern of bulk and nanocrystalline Cu0.98Fe0.02O samples. Vibrating Sample Magnetometer (VSM measurements show hysteresis at 300 K for all the samples. The ferrimagnetic Neel transition temperature ( was found to be around 465°C irrespective of the content of “Fe”, which is close to the value of cubic CuFe2O4. High-pressure X-Ray diffraction studies were performed on 2% “Fe”-doped bulk CuO using synchrotron radiation. From the absence of any strong new peaks at high pressure, it is evident that the secondary phases if present could be less than the level of detection. Cu2O, which is diamagnetic by nature, was also doped with 1% of “Fe” and was found to show paramagnetic behavior in contrast to the “Fe” doped CuO. Hence the possibility of intrinsic magnetization of “Fe”-doped CuO apart from the secondary phases is discussed based on the magnetization and charge state of “Fe” and the host into which it is substituted.

  11. Chelation of Cu(II, Zn(II, and Fe(II by Tannin Constituents of Selected Edible Nuts

    Directory of Open Access Journals (Sweden)

    Magdalena Karamać

    2009-12-01

    Full Text Available The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II and Zn(II was determined by the reaction with tetramethylmurexide, whereas for Fe(II, ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II. The Fe(II complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II by ~90%. The capacity to chelate Zn(II was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II, whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II chelation took place at the levels tested.

  12. Moessbauer spectroscopy of Mg(0.9)Fe(0.1)SiO3 perovskite

    Science.gov (United States)

    Jeanloz, Raymond; O'Neill, Bridget; Pasternak, Moshe P.; Taylor, R. D.; Bohlen, Steven R.

    1992-01-01

    Ambient pressure Moessbauer spectra of Mg(0.9)Fe-57(0.1)SiO3 perovskite synthesized at pressure-temperature conditions of about 50 GPa and 1700 K show that the iron is entirely high-spin Fe(2+) and appears to be primarily located in the octahedral site within the crystal structure. We observe broad Moessbauer lines, suggesting a distribution of electric-field gradients caused by disorder associated with the Fe ions. Also, the perovskite exhibits magnetic ordering at temperatures lower than 5 K, implying that there is a magnetic contribution to the absolute ('third-law') entropy of this phase.

  13. The CorA Mg2+ Transporter Does Not Transport Fe2+

    OpenAIRE

    Papp, Krisztina M.; Maguire, Michael E.

    2004-01-01

    corA encodes the constitutively expressed primary Mg2+ uptake system of most eubacteria and many archaea. Recently, a mutation in corA was reported to make Salmonella enterica serovar Typhimurium markedly resistant to Fe2+-mediated toxicity. Mechanistically, this was hypothesized to be from an ability of CorA to mediate the influx of Fe2+. Consequently, we directly examined Fe2+ transport and toxicity in wild-type versus corA cells. As determined by direct transport assay, CorA cannot transpo...

  14. Ethylbenzene dehydrogenation over FeOx/(Mg,Zn)(Al)O catalysts derived from hydrotalcites: Role of MgO as basic sites

    KAUST Repository

    Balasamy, Rabindran J.

    2011-05-01

    A series of Mg3-xZnxFe0.5Al0.5 mixed oxide catalysts derived from hydrotalcites were tested in the ethylbenzene dehydrogenation to styrene in He atmosphere at 550 °C. The catalysts were prepared by coprecipitation from the nitrates of metal components followed by calcination to mixed oxides at 550 °C. A part of Mg2+ in Mg 3Fe0.5Al0.5 mixed oxide was replaced with Zn2+ to test the effect of MgO as the support. The mixed oxides were composed of periclase and spinel-type compounds with a high surface area of 100-180m2gcat-1. Mössbauer and XPS measurements indicated the presence of Fe3+ on the catalysts and H2-TPR measurement suggested that the dehydrogenation reaction is catalyzed by the reduction-oxidation between Fe3+/Fe2+. The activity of Mg3-xZnxFe0.5Al0.5 mixed oxide decreased with increasing x, indicating an important role of MgO on the activity. Both CO2-TPD measurements as well as IR measurements of adsorbed CO2 clearly indicated the presence of basic sites of Mg 2+O2- on the catalysts. It seems that the combination of Mg2+O2- and Fe3+ was essential for the catalytic activity. It is concluded that the surface base sites generated on O2- bound Mg2+ near Fe3+ sites are responsible for H+-abstraction; the dehydrogenation of ethylbenzene was initiated by the H+ abstraction on Mg2+O2- basic sites, and accelerated by the reduction-oxidation of Fe3+/Fe2+ active species. © 2011 Elsevier B.V.

  15. First-principles investigation of Fe-doped MgSiO{sub 3}-ilmenite

    Energy Technology Data Exchange (ETDEWEB)

    Stashans, Arvids, E-mail: arvids@utpl.edu.ec [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Rivera, Krupskaya [Grupo de Fisicoquimica de Materiales, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Escuela de Geologia y Minas, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador); Pinto, Henry P. [Interdisciplinary Center for Nanotoxicity, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217-0510 (United States)

    2012-06-15

    First principles density functional theory and generalised gradient approximation (GGA) have been exploited to investigate Fe-doped ilmenite-type MgSiO{sub 3} mineral. Strong electron correlation effects not included in a density-functional formalism are described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach). Microstructure of equilibrium geometries, electronic band structures as well as magnetic properties are computed and discussed in detail. Hartree-Fock methodology is used as an extra tool to study optical properties of the same system. For equilibrium state of the doped mineral we find zigzag-type atomic rearrangements around the Fe impurity. The inclusion of correlation effects leads to an improved description of the electronic properties. In particular, it is discovered that Fe incorporation produces local energy levels within the band-gap of the material. Using {Delta}SCF method optical absorption energies are found to be equal to 2.2 and 2.6 eV leading to light absorption at longer wavelengths compared to the undoped MgSiO{sub 3}. Our results provide evidence on the occurrence of local magnetic moment in the region surrounding iron dopant. According to the outcomes, the Fe Rightwards-Double-Arrow Mg reaction can be described as substitutionally labile with Fe{sup 2+} complex being found in the high-spin state at low pressure MgSiO{sub 3}-ilmenite conditions.

  16. Giant interfacial perpendicular magnetic anisotropy in MgO/CoFe/capping layer structures

    Science.gov (United States)

    Peng, Shouzhong; Zhao, Weisheng; Qiao, Junfeng; Su, Li; Zhou, Jiaqi; Yang, Hongxin; Zhang, Qianfan; Zhang, Youguang; Grezes, Cecile; Amiri, Pedram Khalili; Wang, Kang L.

    2017-02-01

    Magnetic tunnel junction based on the CoFeB/MgO/CoFeB structures is of great interest due to its application in the spin-transfer-torque magnetic random access memory (STT-MRAM). Large interfacial perpendicular magnetic anisotropy (PMA) is required to achieve high thermal stability. Here, we use the first-principles calculations to investigate the magnetic anisotropy energy (MAE) of the MgO/CoFe/capping layer structures, where the capping materials include 5d metals Hf, Ta, Re, Os, Ir, Pt, and Au and 6p metals Tl, Pb, and Bi. We demonstrate that it is feasible to enhance PMA by using proper capping materials. Relatively large PMA is found in the structures with the capping materials of Hf, Ta, Os, Ir, and Pb. More importantly, the MgO/CoFe/Bi structure gives rise to giant PMA (6.09 mJ/m2), which is about three times larger than that of the MgO/CoFe/Ta structure. The origin of the MAE is elucidated by examining the contributions to MAE from each atomic layer and orbital. These findings provide a comprehensive understanding of the PMA and point towards the possibility to achieve the advanced-node STT-MRAM with high thermal stability.

  17. Tunneling magnetoresistance in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Tao, L. L.; Liang, S. H.; Liu, D. P.; Wei, H. X.; Han, X. F., E-mail: xfhan@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Jian [Department of Physics and the Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong (China)

    2014-04-28

    We present a theoretical study of the tunneling magnetoresistance (TMR) and spin-polarized transport in Fe{sub 3}Si/MgO/Fe{sub 3}Si(001) magnetic tunnel junction (MTJ). It is found that the spin-polarized conductance and bias-dependent TMR ratios are rather sensitive to the structure of Fe{sub 3}Si electrode. From the symmetry analysis of the band structures, we found that there is no spin-polarized Δ{sub 1} symmetry bands crossing the Fermi level for the cubic Fe{sub 3}Si. In contrast, the tetragonal Fe{sub 3}Si driven by in-plane strain reveals half-metal nature in terms of Δ{sub 1} state. The giant TMR ratios are predicted for both MTJs with cubic and tetragonal Fe{sub 3}Si electrodes under zero bias. However, the giant TMR ratio resulting from interface resonant transmission for the former decreases rapidly with the bias. For the latter, the giant TMR ratio can maintain up to larger bias due to coherent transmission through the majority-spin Δ{sub 1} channel.

  18. Biocompatibility Assessment of Novel Bioresorbable Alloys Mg-Zn-Se and Mg-Zn-Cu for Endovascular Applications: In- Vitro Studies

    OpenAIRE

    Persaud-Sharma, Dharam; Budiansky, Noah; McGoron, Anthony J

    2013-01-01

    Previous studies have shown that using biodegradable magnesium alloys such as Mg-Zn and Mg-Zn-Al possess the appropriate mechanical properties and biocompatibility to serve in a multitude of biological applications ranging from endovascular to orthopedic and fixation devices. The objective of this study was to evaluate the biocompatibility of novel as-cast magnesium alloys Mg-1Zn-1Cu wt.% and Mg-1Zn-1Se wt.% as potential implantable biomedical materials, and compare their biologically effecti...

  19. The Formation of Fe/Mg Smectite Under Mildly Acidic Conditions on Early Mars

    Science.gov (United States)

    Sutter, Brad; Golden, D. C.; Ming, Douglas W.; Niles, P. B.

    2011-01-01

    The detection of Fe/Mg smectites and carbonate in Noachian and early Hesperian terrain of Mars has been used to suggest that neutral to mildly alkaline conditions prevailed during the early history of Mars. However, if early Mars was neutral to moderately alkaline with a denser CO2 atmosphere than today, then large carbonates deposits should be more widely detected in Noachian terrain. The critical question is: Why have so few carbonate deposits been detected compared to Fe/Mg smectites? We suggest that Fe/Mg smectites on early Mars formed under mildly acidic conditions, which would inhibit the extensive formation of carbonate deposits. The goal of this work is to evaluate the formation of Fe/Mg smectites under mildly acidic conditions. The stability of smectites under mildly acidic conditions is attributed to elevated Fe/Mg activities that inhibit smectite dissolution. Beidelite and saponite have been shown to form from hydrothermal alteration of basaltic glass at pH 3.5-4.0 in seawater solutions. Nontronite is also known to be stable in mildly acidic systems associated with mafic and ultramafic rock. Nontronite was shown to form in acid sulfate soils in the Bangkok Plain, Thailand due to oxidation of Fe-sulfides that transformed saponite to nontronite. Smectite is known to transform to kaolinite in naturally acid soils due to selective leaching of Mg. However, if Mg removal is limited, then based on equilibrium relationships, the dissolution of smectite should be minimized. If Fe and Mg solution activities are sufficiently high, such as might be found in a low water/rock ratio system that is poorly drained, smectite could form and remain stable under mildly acidic conditions on Mars. The sources of mild acidity on early Mars includes elevated atmospheric CO2 levels, Fe-hydrolysis reactions, and the presence of volcanic SO2 aerosols. Equilibrium calculations dictate that water equilibrated with an early Mars CO2 atmosphere at 1 to 4 bar yields a pH of 3.6 to 3

  20. The Formation of Fe/Mg Smectite Under Mildly Acidic Conditions on Early Mars

    Science.gov (United States)

    Sutter, B.; Golden, D. C.; Ming, D.; Niles, P. B.

    2011-12-01

    The detection of Fe/Mg smectites and carbonate in Noachian and early Hesperian terrain of Mars has been used to suggest that neutral to mildly alkaline conditions prevailed during the early history of Mars. However, if early Mars was neutral to moderately alkaline with a denser CO2 atmosphere than today, then "large" carbonates deposits should be more widely detected in Noachian terrain. The critical question is: Why have so few carbonate deposits been detected compared to Fe/Mg smectites? We suggest that Fe/Mg smectites on early Mars formed under mildly acidic conditions, which would inhibit the extensive formation of carbonate deposits. The goal of this work is to evaluate the formation of Fe/Mg smectites under mildly acidic conditions. The stability of smectites under mildly acidic conditions is attributed to elevated Fe/Mg activities that inhibit smectite dissolution. Beidelite and saponite have been shown to form from hydrothermal alteration of basaltic glass at pH 3.5-4.0 in seawater solutions. Nontronite is also known to be stable in mildly acidic systems associated with mafic and ultramafic rock. Nontronite was shown to form in acid sulfate soils in the Bangkok Plain, Thailand due to oxidation of Fe-sulfides that transformed saponite to nontronite. Smectite is known to transform to kaolinite in naturally acid soils due to selective leaching of Mg. However, if Mg removal is limited, then based on equilibrium relationships, the dissolution of smectite should be minimized. If Fe and Mg solution activities are sufficiently high, such as might be found in a low water/rock ratio system that is poorly drained, smectite could form and remain stable under mildly acidic conditions on Mars. The sources of mild acidity on early Mars includes elevated atmospheric CO2 levels, Fe-hydrolysis reactions, and the presence of volcanic SO2 aerosols. Equilibrium calculations dictate that water equilibrated with an early Mars CO2 atmosphere at 1 to 4 bar yields a pH of 3.6 to 3

  1. One-pot solvent free synthesis of dihydropyrimidinones using calcined Mg/Fe hydrotalcite catalyst

    Directory of Open Access Journals (Sweden)

    Vijay V Dabholkar

    2017-02-01

    Full Text Available The Mg/Fe = 3 hydrotalcite as reusable solid catalyst was found to be an excellent heterogeneous base catalyst for the synthesis of 3,4-dihydropyrimidinones/thiones, a multicomponent reaction using substituted aromatic aldehyde, ethyl acetoacetate and urea/thiourea. The work has been carried out under thermal solvent free conditions. Mg/Fe = 3 hydrotalcite heterogeneous solid catalyst offers simple means of recovery and the isolated catalyst was reused for number of times without significant loss of catalytic activity.

  2. Magnetic properties of soft layer/FePt-MgO exchange coupled composite Perpendicular recording media

    Institute of Scientific and Technical Information of China (English)

    Yin Jin-Hua; Takao Suzuki; Pan Li-Qing

    2008-01-01

    The magnetic properties of exchange coupled composite(ECC)media that are composed of perpendicular magnetic recording media FePt-MgO and two kinds of soft layers have been studied by using an x-ray diffractometer,a polar Kerr magneto-optical system(PMOKE)and a vibrating sample magnetometer(VSM).The results show that ECC media can reduce the coercivities of perpendicular magnetic recording media FePt-MgO.The ECC media with granular-type soft layers have weaker exchange couplings between magnetic grains and the magnetization process,for ECC media of this kind mainly follow the Stoner-Wohlfarth model.

  3. Supercondcuting properties in MgB2/Fe wires prepared by PIT method

    Institute of Scientific and Technical Information of China (English)

    YAN Guo; FENG Yong; FU Baoquan; LIU Chunfang; JI Ping; ZHANG Pingxiang; ZHOU Lian

    2003-01-01

    The MgB2 formation was analyzed physically and chemically and the MgB2/Fe wires were fabricated by powder in tube (PIT) technology. The microstructureof MgB2 in wires was studied by the scanning electrical microscope (SEM), whichshows a good connection of grains and the size of MgB2 grain is 1-3μm. The results of Jc measured by the standard four probes method show that Jc value reaches 6.1×104 A/cm2 at 20 K in self field.

  4. Combustion synthesized copper-ion substituted FeAl2O4 (Cu0.1Fe0.9Al2O4): A superior catalyst for methanol steam reforming compared to its impregnated analogue

    Science.gov (United States)

    Maiti, Sayantani; Llorca, Jordi; Dominguez, Montserrat; Colussi, Sara; Trovarelli, Alessandro; Priolkar, Kaustubh R.; Aquilanti, Giuliana; Gayen, Arup

    2016-02-01

    A series of copper ion substituted MAl2O4 (M = Mg, Mn, Fe and Zn) spinels is prepared by a single step solution combustion synthesis (SCS) and tested for methanol steam reforming (MSR). The copper ion substituted Cu0.1Fe0.9Al2O4 appears to be the most active, showing ∼98% methanol conversion at 300 °C with ∼5% CO selectivity at GHSV = 30,000 h-1 and H2O:CH3OH = 1.1. The analogous impregnated catalyst, CuO (10 at%)/FeAl2O4, is found to be much less active. These materials are characterized by XRD, H2-TPR, BET, HRTEM, XPS and XANES analyses. Spinel phase formation is highly facilitated upon Cu-ion substitution and Cu loading beyond 10 at% leads to the formation of CuO as an additional phase. The ionic substitution of copper in FeAl2O4 leads to the highly crystalline SCS catalyst containing Cu2+ ion sites that are shown to be more active than the dispersed CuO nano-crystallites on the FeAl2O4 impregnated catalyst, despite its lower surface area. The as prepared SCS catalyst contains also a portion of copper as Cu1+ that increases when subjected to reforming atmosphere. The MSR activity of the SCS catalyst decreases with time-on-stream due to the sintering of catalyst crystallites as established from XPS and HRTEM analyses.

  5. Oxidation of two ternary Fe-Cu-5Al alloys in 1×105 Pa pure oxygen at 700 ℃

    Institute of Scientific and Technical Information of China (English)

    XIANG Jun-huai; NIU Yan; WU Wei-tao; LIU Guo-dong

    2006-01-01

    The oxidation of two two-phase ternary Fe-Cu-Al alloys containing about 5% Al(mole fraction),one Fe-rich and one Cu-rich,were studied at 700 ℃ in 1×105 Pa pure oxygen. The Fe-rich alloy (Fe-15Cu-5Al) shows two quasi-parabolic stages,with a large increase of the parabolic rate constant after about 4 h. The presence of 5% Al does not change greatly the oxidation rate of Fe-15Cu-5Al with respect to a binary Fe-Cu alloy of similar composition,which was quite different from the situation of the same alloys oxidized at 800 ℃. Oxidation of Fe-15Cu-5Al at 700 ℃ produced an outer layer of iron oxides and an inner layer containing a mixture of copper metal,iron and aluminium oxide. On the contrary,the Cu-rich Fe-85Cu-5Al alloy presents a rather irregular kinetic behavior,with formation of an inner continuous alumina thin layer and a rather irregular outer layer. The outer layer with a rather irregular thickness was mainly composed of a matrix of copper oxides plus some aluminium and iron oxides presenting in the deep part of the layer at certain locations. As a result of the formation of a protective alumina layer,the presence of 5% Al greatly reduced the oxidation rate of Fe-85Cu-5Al with respect to a binary Fe-Cu alloy of similar composition,which was also quite different from the situation of the same alloys oxidized at 800 ℃. Moreover,the oxidation rate at 700 ℃ of the Fe-85Cu-5Al alloy was much lower than that of Fe-15Cu-5Al alloy due to the same reason..

  6. Flow Stress Behavior and Processing Map of Al-Cu-Mg-Ag Alloy during Hot Compression

    Institute of Scientific and Technical Information of China (English)

    YANG Sheng; YI Danqing; ZHANG Hong; YAO Sujuan

    2008-01-01

    The hot deformation behavior of Al-Cu-Mg-Ag was studied by isothermal hot compression tests in the temperature range of 573-773 K and strain rate range of 0.001-1 s-1 on a Gleeble 1500 D thermal mechanical simulator. The results show the flow stress of Al-Cu-Mg-Ag alloy increases with strain rate and decreases after a peak value, indicating dynamic recovery and recrystallization. A hyperbolic sine relationship is found to correlate well the flow stress with the strain rate and temperature, the flow stress equation is estimated to illustrate the relation of strain rate and stress and temperature during high temperature deformation process. The processing maps exhibit two domains as optimum fields for hot deformation at different strains, including the high strain rate domain in 623-773 K and the low strain rate domain in 573-673 K.

  7. Low Cycle Mechanical and Fatigue Properties of AlZnMgCu Alloy

    Directory of Open Access Journals (Sweden)

    Pysz S.

    2016-03-01

    Full Text Available The article presents the analysis of properties of the high-strength AlZnMgCu (abbr AlZn aluminium alloy and estimates possibilities of its application for responsible structures with reduced weight as an alternative to iron alloy castings. The aim of the conducted studies was to develop and select the best heat treatment regime for a 7xx casting alloy based on high-strength materials for plastic working from the 7xxx series. For analysis, wrought AlZnMgCu alloy (7075 was selected. Its potential of the estimated as-cast mechanical properties indicates a broad spectrum of possible applications for automotive parts and in the armaments industry. The resulting tensile and fatigue properties support the thesis adopted, while the design works further confirm these assumptions.

  8. Selective oxidation of cyclohexane on a novel catalyst Mg-Cu/SBA-15 by molecular oxygen.

    Science.gov (United States)

    Duan, Xiaogang; Liu, Weimin; Yue, Lumin; Fu, Wei; Ha, Minh Ngoc; Li, Jun; Lu, Guanzhong

    2015-10-21

    The novel catalysts xMg-2.3Cu/SBA-15 with copper and magnesium oxide co-supported on mesoporous silica were synthesized by an impregnation method. The newly synthesized catalysts were characterized using a series of techniques such as BET, XRD, H2-TPR, UV-vis, XPS, EDS and TEM. The catalytic performance was evaluated by using selective oxidation of cyclohexane with molecular oxygen as the oxidant in a solvent free system. The incorporation of magnesium improved the dispersion of copper oxide and prevented the deep oxidation of cyclohexanol and cyclohexanone. The selectivity of K/A oil was up to 99.3% with 12% conversion of cyclohexane over the 1.2Mg-2.3Cu/SBA-15 catalyst. To our knowledge, this is the best result for the heterogeneous oxidation of cyclohexane by O2.

  9. Heating rate effect on thermoluminescence glow curves of LiF:Mg,Cu,P+PTFE phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Cruz-Zaragoza, E. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, A.P. 70-543, Mexico D.F. 04510 (Mexico); Gonzalez, P.R., E-mail: pedro.gonzalez@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Carretera Mexico-Toluca S/N, C.P. 52750, Ocoyoacac, Estado de Mexico (Mexico); Azorin, J. [Universidad Autonoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, 09340 Mexico D.F. (Mexico); Furetta, C. [Touro University Rome, Division of Touro College New York, Circne Gianicolense 15-17, 00153 Rome (Italy)

    2011-10-15

    The influence of heating rate on the thermoluminescence (TL) property of LiF:Mg,Cu,P+PTFE was analyzed. The activation energy and the frequency factor as a function of the heating rate were determined. The kinetic parameters and their dependence on the heating rate were evaluated using the sequential quadratic programming glow curve deconvolution (SQPGCD). The results showed that as the heating rate increases, the peak intensity at the maximum (I{sub M}) decreases and shifts to higher temperature; similar behavior of the kinetics parameters was observed. - Highlights: >Heating rate influence on the thermoluminescence (TL) property of LiF:Mg,Cu,P was analyzed. > The kinetic parameters, activation energy and frequency factor were evaluated using the sequential quadratic programming glow curve deconvolution. > The peak intensity at the maximum (I{sub M}) of the glow curves decreases. > Shifts to higher temperature were observed as the heating rate increased. > Similar behavior of the kinetics parameters was noticed.

  10. Assessment of retrogression and re-aging treatment on microstructural and mechanical properties of Al-Zn-Mg-Cu P/M alloy

    Energy Technology Data Exchange (ETDEWEB)

    Naeem, Haider T. [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia); College of Engineering, Al-Muthanna University, South Baghdad (Iraq); Mohammad, Kahtan S.; Hussin, Kamarudin; Tan, T. Qing; Idris, M. Sobri [School of Materials Engineering, Universiti Malaysia Perlis, Taman Muhibbah, 02600 Jejawi, Perlis (Malaysia)

    2015-05-15

    In order to understand the importance of the retrogression and re-aging as a heat treatment for improving microstructural and mechanical properties of the Al-Zn-Mg-Cu powder metallurgy alloys, Al-Zn-Mg-Cu-Fe-Cr alloys were fabricated from the elemental powders. Green compacts are compressed under compaction pressure about 370 MPa. The sintering process carried out for the samples of aluminum alloys at temperature was 650°C under argon atmosphere for two hours. The sintered compacts were subjected into homogenizing condition at 470°C for 1.5 hours and then aged at 120°C for 24 hours (T6 temper) after that it carried out the retrogressed at 180°C for 30 min., and then re-aged at 120°C for 24 hours (RRA). Observations microstructures were examined using optical, scanning electron microscopy coupled with energy dispersive spectroscopy and X-ray diffraction. Density and porosity content was conducted for the samples of alloys. The result showing that the highest Vickers hardness exhibited for an Al-Zn-Mg-Cu alloy after underwent the retrogression and reaging treatment. Increasing in hardness was because of the precipitation hardening through precipitate the (Mg Zn) and (Mg{sub 2}Zn{sub 11}) phases during matrix of aluminum-alloy.

  11. Investigation of Pb, Cd, Cu and Mg Concentrations in Groundwater Resources of Razan Plain

    OpenAIRE

    S. Sobhan Ardakani; M. Maanijou; Asadi, H.

    2015-01-01

    Introduction & Objective: Iran is located in the dry and semi dry regions, thus almost 90% of the required fresh water is exploited from groundwater resources. Due to the increasing pol-lution of water resources, the purpose of this study was evaluation of Pb, Cd, Cu and Mg concentrations in groundwater resources of Razan Plain and preparing the zoning map using GIS. Materials & Methods: Groundwater samples were collected from 20 selected stations during two seasons in 2012. The samples were ...

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

    Directory of Open Access Journals (Sweden)

    Zhenchao Wen

    2016-05-01

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

  13. Optical Properties of Mg, Fe, Co-Doped Near-Stoichiometric LiTaO3 Single Crystals

    Directory of Open Access Journals (Sweden)

    Chung Wen Lan

    2012-01-01

    Full Text Available Mg, Fe co-doped near-stoichiometric lithium tantalite (SLT single crystals were grown by employing the zone-leveling Czochralski (ZLCz technique. The optical properties, holographic parameters, as well as the composition of the grown crystals were measured. It was found that the Li/Ta ratio decreased with the doping of Mg and Fe ions. A red shift was observed in absorption spectrum for the Mg, Fe co-doped crystals compared to the undoped and Mg-doped ones. The effect of the iron ions (Fe2+ and Fe3+ was further discussed based on the specified absorption bands. Moreover, the occupation mechanism for the defects was discussed by using the IR absorption spectrum, which was attributed to the FeTa3− defects in the highly Fe-doped crystal. In addition, the holographic parameters were also found to be improved with a higher Fe/Ta ratio in the crystals.

  14. First principles calculation of stable structure and adhesive strength of plated Ni/Fe(100) or Cu/Fe(100) interfaces

    Institute of Scientific and Technical Information of China (English)

    Ryota NAKANISHI; Koji SUEOKA; Seiji SHIBA; Makoto HINO; Koji MURAKAMI; Ken MURAOKA

    2009-01-01

    A study the with first principles calculation of the interfaces of the Ni layer or Cu layer on the Fe(100) surface formed with metal plating was performed. Ni or Cu atoms were shown to adopt the corresponding position to the bcc structure of the Fe(100) substrate. Other calculations showed that the interfaces of Ni (5 atomic layers)/Fe(100) (5 layers) or Cu (5 atomic layers)/Fe(100) (5 layers) had square lattices. The orientation relationship of Ni/Fe(100) interface corresponds to fcc-Ni(100)//bcc-Fe(100), Ni[011]//Fe[010], and Similar results were obtained for Cu/Fe(100) interfaces. This structure was supported by TEM analysis of plated Ni layer on Fe(100) surfaces. The adhesion strength of the Ni/Fe(100) interface evaluated by first principles calculation was higher than that of the Cu/Fe(100) interface. The experimental results of Hull cell iron plated with Ni or Cu supported the results of the calculation. These results indicate that the first principles calculation, which deals with the ideal interface at the atomic scale, has the potential to evaluate the adhesion strength of metallic material interfaces.

  15. Metabolismo del Mg, Cu, Zn, Cr, Mn, y Ni en la diabetes melitus

    OpenAIRE

    1995-01-01

    En los últimos años, a los elementos traza y al mg se las ha implicado en la patologenesis de las complicaciones crónicas de la diabetes mellitus (dm). Las alteraciones del estado mineral asociadas a la dm podrían estar influidas, entre otros factores, por el grado de control metabólico y la asociación, o no, de otras patologías metabólicas como la hipertensión arterial (hta), la dislipemia y la obesidad. A pesar de que el mg, cu, zn, cr, mn y ni son cationes de localización principalmente in...

  16. Influence of Mg Addition on Crystallisation Kinetics and Structure of the Zn-Al-Cu Alloy

    Directory of Open Access Journals (Sweden)

    Krupiński M.

    2016-06-01

    Full Text Available In this work the effect of Mg addition on structure as well as kinetics of crystallisation of Zn-Al-Cu cast alloy was presented. To the zinc alloy was added 0.1% mass of Mg. The alloy was cast into a metal mould. Thermo-derivative analysis was performed using the UMSA platform (Universal Metallurgical Simulator and Analyzer. The investigated alloys were freely cooled down with a rate of 0.1°C s-1. For the structure analysis were used results obtained using light microscopy, scanning and transmission electron microscopy.

  17. Resolving the stellar sources of isotopically rare presolar silicate grains through Mg and Fe isotopic analyses

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ann N.; Messenger, Scott, E-mail: lan-anh.n.nguyen@nasa.gov [Robert M. Walker Laboratory for Space Science, Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058 (United States)

    2014-04-01

    We conducted multi-element isotopic analyses of 11 presolar silicate grains from the Acfer 094 meteorite having unusual O isotopic compositions. Eight grains are {sup 18}O-rich, one is {sup 16}O-rich, and two are extremely {sup 17}O-rich. We constrained the grains' stellar sources by measuring their Si and Mg isotopic ratios, and also the {sup 54}Fe/{sup 56}Fe and {sup 57}Fe/{sup 56}Fe ratios for five grains. The Mg and Fe isotopic measurements were conducted after surrounding matrix grains were removed for more accurate ratios. Most of the {sup 18}O-rich silicates had anomalous Mg isotopic ratios, and their combined isotopic constraints are consistent with origins in low-mass Type II supernovae (SNe II) rather than high-metallicity stars. The isotopic ratios of the {sup 16}O-rich silicate are also consistent with an SN origin. Mixing small amounts of interior stellar material with the stellar envelope replicated all measured isotopic ratios except for {sup 29}Si/{sup 28}Si and {sup 54}Fe/{sup 56}Fe in some grains. The {sup 29}Si/{sup 28}Si ratios of all SN-derived grains are matched by doubling the {sup 29}Si yield in the Ne- and Si-burning zones. The {sup 54}Fe/{sup 56}Fe ratios of the grains imply elemental fractionation in the Si/S zone, or introduction of isotopically solar Fe by secondary processing. The two highly {sup 17}O-rich silicates exhibited significant {sup 25}Mg and/or {sup 26}Mg enrichments and their isotopic ratios are best explained by strong dilution of 1.15 M {sub ☉} CO nova matter. We estimate that ∼12% and 1% of presolar silicates have SN and nova origins, respectively, similar to presolar SiC and oxides. This implies that asymptotic giant branch stars are the dominant dust producers in the galaxy.

  18. Effect of Mg substitution on electromagnetic properties of NiCuZn ferrite

    Science.gov (United States)

    Sujatha, Ch.; Venugopal Reddy, K.; Sowri Babu, K.; RamaChandra Reddy, A.; Buchi Suresh, M.; Rao, K. H.

    2013-08-01

    Mg substituted NiCuZn ferrites were prepared through sol-gel method using polyvinyl alcohol (PVA) as a chelating agent. The samples after annealing at 500 °C to remove PVA were sintered at 950 °C for 1 h. The structural and electromagnetic properties of the samples were investigated. All the samples showed single phase spinel structure with increased lattice constant as a function of Mg concentration. The morphology reveals polyhedral shaped grains with increased grain size as a function of Mg composition. Dielectric parameters showed low values at higher frequencies. The initial permeability increased with Mg substitution in place of Ni in accordance with the microstructure. The samples sintered at low temperature having low dielectric losses and improved permeability along with the high frequency stability of permeability find applications in multilayer chip inductors.

  19. Synthesis and characterization studies of MgO:CuO nanocrystals by wet-chemical method

    Science.gov (United States)

    Kaviyarasu, K.; Maria Magdalane, C.; Anand, K.; Manikandan, E.; Maaza, M.

    2015-05-01

    In this report, we examine the progress in adapting these nanomaterials for several predominantly photonics device fabrication by wet-chemical method. Nanocomposite of magnesium oxide (MgO) with copper oxide (CuO) doped nanoparticles were characterized by X-ray powder diffraction (XRD) and the observed peaks are quite agreeable with the pure phase cubic structure. High-resolution transmission electron microscopic (HR-TEM) results reveal that the resultant nanopowders are porous and agglomerated with polycrystalline nano-entities. Field emission of selected-area electron diffraction (SAED) studies showed that the average size of the nanoparticles were 20 nm. Photoluminescence spectra of MgO:CuO were investigated, showing emission peaks around 375 nm relating to new energy levels induced by defects or defect levels generation and confocal micro-Raman images indicated that the chemical molecular vibrational band structure and morphology of the product which is spherical shaped nanoparticles with an average particle size of ∼25 nm with standard deviation. The electrochemical response of MgO:CuO which is proves that the nano-copper/magnesium has high functionality due to the small size and it has higher electrochemical activity without any modifications.

  20. Preparation and Properties of Mg-Cu-Y-Al bulk Amorphous Alloys

    DEFF Research Database (Denmark)

    Pryds, Nini; Eldrup, Morten Mostgaard; Ohnuma, M.

    2000-01-01

    Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial and tempo......Bulk amorphous (Mg(1-gamma)Al(gamma))(60)CU(30)Y(10) alloys were prepared using a relatively simple technique of rapid cooling of the melt in a copper wedge mould. The temperature vs, time was recorded during the cooling and solidification process of the melt and compared with a spacial......-ray diffraction (XRD) and differential scanning calorimetry (DSC) for different alloy compositions and annealing temperatures. On annealing into the supercooled liquid state (441 K), specimens with no Al content remain basically amorphous while nanoparticles are formed and remain stable also at higher...... temperatures in specimens containing a few percent Al. The alloy with no Al crystallises apparently without the formation of nanoparticles. The critical cooling rate for the formation of an amorphous Mg(60)CU(30)Y(10) specimen was determined experimentally by a combination of DSC data and temperature vs, time...

  1. Auto-combustion synthesis and characterization of Mg doped CuAlO2 nanoparticles

    Science.gov (United States)

    Agrawal, Shraddha; Parveen, Azra; Naqvi, A. H.

    2015-06-01

    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO2nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO2 sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO2 has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  2. Deformation and microstructure characterization during semi-solid extrusion of Al-4Cu-Mg alloy

    Institute of Scientific and Technical Information of China (English)

    LU Ya-lin; LI Miao-quan; LI Xing-cheng

    2006-01-01

    Effects of the process parameters, including deformation temperature, punch velocity and extrusion ratio, on the deformation and microstructure characterization during the semi-solid extrusion of Al-4Cu-Mg alloy, were investigated. The experimental results show that the load decreases with an increase of deformation temperature and/or a decrease of punch velocity.When the displacement is more than 4 mm, the load decreases significantly with an increase of the deformation temperature, which is related to the high liquid fraction. The microstructure varies with the process parameters and deformation regions. It can be found that the dynamic recovery occurs during the semi-solid extrusion of Al-4Cu-Mg alloy at lower deformation temperature.Subsequently, the microstructure elongated gradually polygonizes with an increase of deformation temperature. So, the higher deformation temperature should be chosen during the semi-solid extrusion of Al-4Cu-Mg alloy because the grains polygonized and high liquid fractions are beneficial to deformation.

  3. Auto-combustion synthesis and characterization of Mg doped CuAlO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Agrawal, Shraddha, E-mail: shraddhaa32@gmail.com; Parveen, Azra; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg.& Technology, Aligarh Muslim University, Aligarh-202002 (India)

    2015-06-24

    The synthesis of pure and Mg doped Copper aluminumoxide CuAlO{sub 2}nanoparticles, a promising p-type TCO (transparent conducting oxide) have been done bysol gel auto combustion method using NaOH as a fuel, calcinated at 600°C. The structural properties were examined by XRD and SEM techniques. The optical absorption spectra of CuAlO{sub 2} sample recorded by UV-VIS spectrophotometer in the range of 200 to 800 nm have been presented. The crystallite size was determined by powder X-ray diffraction technique. The electrical behavior of pure and Mg doped CuAlO{sub 2} has been studied over a wide range of frequencies by using complex impedance spectroscopy.The variation of a.c. conductivity has been studied as function of frequency and temperature. The data taken together conclude that doping causes decreases in the ac conductivity of the nanoparticles as compared with the pure nanoparticles. Mg doping affects the optical properties and band gap.

  4. High strain rate tensile behavior of Al-4.8Cu-1.2Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Bobbili, Ravindranadh, E-mail: ravindranadh@dmrl.drdo.in; Paman, Ashish; Madhu, V.

    2016-01-10

    The purpose of the current study is to perform quasi static and high strain rate tensile tests on Al-4.8Cu-1.2Mg alloy under different strain rates ranging from 0.01–3500/s and also at temperatures of 25,100, 200 and 300 °C. The combined effect of strain rate, temperature and stress triaxiality on the material behavior is studied by testing both smooth and notched specimens. Johnson–Cook (J–C) constitutive and fracture models are established based on high strain rate tensile data obtained from Split hopkinson tension bar (SHTB) and quasi-static tests. By modifying the strain hardening and strain rate hardening terms in the Johnson–Cook (J–C) constitutive model, a new J–C constitutive model of Al-4.8Cu-1.2Mg alloy was obtained. The improved Johnson–Cook constitutive model matched the experiment results very well. With the Johnson–Cook constitutive and fracture models, numerical simulations of tensile tests at different conditions for Al-4.8Cu-1.2Mg alloy were conducted. Numerical simulations are performed using a non-linear explicit finite element code autodyn. Good agreement is obtained between the numerical simulation results and the experiment results. The fracture surfaces of specimens tested under various strain rates and temperatures were studied under scanning electron microscopy (SEM).

  5. Recrystallization Behavior of CoCrCuFeNi High-Entropy Alloy

    Science.gov (United States)

    Park, Nokeun; Watanabe, Ikuto; Terada, Daisuke; Yokoyama, Yoshihiko; Liaw, Peter K.; Tsuji, Nobuhiro

    2015-04-01

    We investigated the recrystallization behavior of a cold-rolled CoCrCuFeNi high-entropy alloy (HEA). Two different face-centered cubic phases having different chemical compositions and lattice constants in the as-cast specimen have different chemical compositions: One phase was the Cu-lean matrix and the other was the Cu-rich second phase. The second phase remained even after a heat treatment at 1373 K (1100 °C) and Cu enriched more in the Cu-rich second phase. The calculated mixing enthalpies of both Cu-lean and Cu-rich phases in the as-cast and heat-treated specimens explained that Cu partitioning during the heat treatment decreased the mixing enthalpy in both phases. In the specimens 90 pct cold rolled and annealed at 923 K, 973 K, and 1073 K (650 °C, 700 °C, and 800 °C), recrystallization proceeded with increasing the annealing temperature, and ultrafine recrystallized grains with grain sizes around 1 μm could be obtained. The microhardness tended to decrease with increasing the fraction recrystallized, but it was found that the microhardness values of partially recrystallized specimens were much higher than those expected by a simple rule of mixture between the initial and cold-rolled specimens. The reason for the higher hardness was discussed based on the ultrafine grain size, sluggish diffusion expected in HEAs, and two-phase structure in the CoCrCuFeNi alloy.

  6. Elaboration of pellets of LiF: Mg, Cu, P and its dosimetric properties; Elaboracion de pastillas de LiF: Mg, Cu, P y sus propiedades dosimetricas

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez C, A.; Gonzalez M, P.R.; Azorin N, J

    1991-03-15

    The LiF: Mg, Cu, P is at the moment in the entire world one of the TL materials of more interest, by its equivalence with the tissue, as well as for its high sensitivity, which is 25 to 35 times greater than of the TLD-100 of Harshaw (USA). In our laboratory dosemeters of this material have been developed in form of sinterized pellets. The importance of these new dosemeters in pellet form is due to that in this form its manipulation is facilitated. Due to its high sensitivity, these dosemeters result to be those but appropriate to measure the ionizing radiations, in intervals of extremely low dose. In this report the method of elaboration of the pellets, as well as its main dosimetric characteristics are presented. (Author)

  7. Dosimetry of beta particles using Li:Mg, Cu, P + Ptfe; Dosimetria de particulas beta usando Li: Mg, Cu, P + Ptfe

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, L.; Azorin, J.; Rivera, T. [Depto. de Fisica, UAM-I, 09340 Mexico D.F. (Mexico)

    2003-07-01

    This paper presents the experimental results of determining the thermoluminescence (Tl) response of LiF: Mg, Cu, P + Ptfe pellets excited with {sup 90}Sr/{sup 90}Y beta radiation. The glow curve exhibited three peaks which appear at 121 C, 178 C and 217 C . Its relative sensitivity is 49 with respect to that of the TLD-100 dosemeter taken as a reference. The minimal dose that could be measured was 750 mGy. The Tl response as a function of dose was linear in the range of 0.7 mGy to 22.5 mGy. The study of the repeatability of the information contained in the pellets showed a standard deviation of 2 %. (Author)

  8. Dosimetric characterization of a Tl new material of LiF: Mg, Cu, P; Caracterizacion dosimetrica de un nuevo material TL de LiF: Mg, Cu, P

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, P.R.; Avila, O. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Quiroz, C. [UAEM, Facultad de Medicina, 50180, Toluca, Estado de Mexico (Mexico); Azorin, J. [UAM-I, 09340 Mexico D.F. (Mexico)

    2004-07-01

    In this work the method of preparation of a new material T L is described of LiF: Mg, Cu, P and the preliminary results of the tests corresponding to their dosimetric characterization are reported. The carried out tests were: detection threshold, sensitivity, dissipation of the sign T L, answer T L in function of the dose of radiation gamma, among others. The results showed that this material when receiving the one thermal treatment of having erased of 280 C by 10 min, followed by 100 C for two hours, he/she has a detection threshold ten times but I lower that that of the TLD-100, is 21 times but sensitive that that of reference and the dissipation of the sign T L during two months was null. This new material T L overcomes in many aspects to the commercial dosemeters of its type. (Author)

  9. AI-Si-Cu-Mg(-Er)铸造铝合金的低周疲劳行为%Low-Cycle Fatigue Behavior of Cast AI-Si-Cu-Mg(-Er) Aluminum Alloy

    Institute of Scientific and Technical Information of China (English)

    车欣; 徐志军; 陈立佳; 徐海健; 李锋

    2011-01-01

    对金属型铸造Al-Si-Cu-Mg和Al-Si-Cu-Mg-Er铝合金进行了疲劳试验,并研究了其室温下的低周疲劳行为.试验结果表明:金属型铸造Al-Si-Cu-Mg和Al-Si-Cu-Mg-Er铝合金表现为循环应变硬化和循环稳定,主要取决于外加总应变的高低;稀土元素Er的加入可提高金属型铸造Al-Si-Cu-Mg合金的循环变形抗力和疲劳寿命;金属型铸造Al-Si-Cu-Mg合金的塑性应变、弹性应变与断裂时的载荷反向次数之间呈直线关系,Al-Si-Cu-Mg-Er合金的弹性应变与疲劳断裂时的载荷反向次数之间也呈直线关系,但其塑性应变与疲劳断裂时的载荷反向次数之间则呈双线性关系.%Through the strain-controlled fatigue experiments, the low-cycle fatigue behavior of permanent-mold cast Al-Si-Cu-Mg and Al-Si-Cu-Mg-Er alloys at room temperature was investigated.The experimental results show that the Al-Si-Cu-Mg and Al-Si-Cu-Mg-Er alloys exhibit the cyclic strain hardening and cyclic stability, mainly depending on the imposed total strain amplitude. For the permanent-mold cast Al-Si-Cu-Mg alloy, the addition of Er can effectively enhance both cyclic deformation resistance and fatigue life of the alloys. A single-slope linear relation between plastic strain amplitude, elastic strain amplitude and reversals to failure is observed for permanent-mold cast Al-Si-Cu-Mg alloy. However, a two-slope linear relation between plastic strain amplitude and reversals to failure is noted for the Al-Si-Cu-Mg-Er alloy, although the corresponding relation between elastic strain amplitude and reversals to failure is linear.

  10. Radio-photoluminescence of highly irradiated LiF:Mg,Ti and LiF:Mg,Cu,P detectors

    CERN Document Server

    Mrozik, Anna; Marczewska, Barbara; Obryk, Barbara; Hodyr, Krzysztof; Gieszczyk, Wojciech

    2014-01-01

    The radio-photoluminescent (RPL) characteristics of LiF:Mg,Ti (MTS) and LiF:Mg,Cu,P (MCP) thermoluminescent detectors, routinely used in radiation protection dosimetry, were investigated after irradiation with ultra-high electron doses ranging up to 1 MGy. The photoluminescence of both types of LiF detectors was stimulated by a blue light (460 nm) and measured within a spectral window around 530 nm. The RPL dose response was found to be linear up to 50 kGy and sublinear in the range of 50 kGy to 1 MGy for MCP detectors and linear up to 3 kGy and next sublinear in the range from 5 kGy to 1 MGy for MTS detectors. For both type of LiF detectors RPL signal is saturated for doses higher than 100 kGy. The observed differences between MCP and MTS may suggest, that the RPL effect in LiF is not entirely governed by intrinsic defects (F2 and F3+ centers), but impurities may also have a significant influence. Due to the non-destructive character of the RPL measurement, it is suggested to apply combined RPL/TL readouts, ...

  11. TPR and TPD studies of effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts

    Indian Academy of Sciences (India)

    Olusola O James; Biswajit Chowdhury; Sudip Maity

    2013-05-01

    Temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) were used to study the effects of Cu and Ca promotion on Fe-Zn-based Fischer-Tropsch catalysts. The reduction temperature for Fe2O3 → Fe3O4 was unaffected by Ca addition but decreased when promoted with Cu. Fe-Zn promoted with Cu and Ca showed even much lower reduction temperature for Fe2O3→Fe3O4. Ca promotion enhances carburization and increases surface acidity and basicity of the Fe-Zn oxide precursor. While Cu inhibits carburization and decreases the surface acidity and basicity of the Fe-Zn oxide precursor. The implications of these effects on the application of catalysts for FT are discussed.

  12. Magnetic order tuned by Cu substitution in Fe1.1-zCuzTe

    Science.gov (United States)

    Wen, Jinsheng; Xu, Zhijun; Xu, Guangyong; Lumsden, M. D.; Valdivia, P. N.; Bourret-Courchesne, E.; Gu, Genda; Lee, Dung-Hai; Tranquada, J. M.; Birgeneau, R. J.

    2012-07-01

    We study the effects of Cu substitution in Fe1.1Te, the nonsuperconducting parent compound of the iron-based superconductor, Fe1+yTe1-xSex, utilizing neutron scattering techniques. It is found that the structural and magnetic transitions, which occur at ˜60 K without Cu, are monotonically depressed with increasing Cu content. By 10% Cu for Fe, the structural transition is hardly detectable, and the system becomes a spin glass below 22 K, with a slightly incommensurate ordering wave vector of (0.5-δ, 0, 0.5) with δ being the incommensurability of 0.02, and correlation length of 12 Å along the a axis and 9 Å along the c axis. With 4% Cu, both transition temperatures are at 41 K, though short-range incommensurate order at (0.42, 0, 0.5) is present at 60 K. With further cooling, the incommensurability decreases linearly with temperature down to 37 K, below which there is a first-order transition to a long-range almost-commensurate antiferromagnetic structure. A spin anisotropy gap of 4.5 meV is also observed in this compound. Our results show that the weakly magnetic Cu has a large effect on the magnetic correlations; it is suggested that this is caused by the frustration of the exchange interactions between the coupled Fe spins.

  13. Magnetic orders tuned by Cu substitution in Fe1.1 zCuzTe

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Jinsheng [University of California, Berkeley; Xu, Zhijun [Brookhaven National Laboratory (BNL); Xu, Guangyong [Brookhaven National Laboratory (BNL); Lumsden, Mark D [ORNL; Valdivia, P. N. [University of California, Berkeley; Bourret-Courchesne, E. D. [Lawrence Berkeley National Laboratory (LBNL); Gu, Genda [Brookhaven National Laboratory (BNL); Lee, Dunghai [University of California, Berkeley & LBNL; Tranquada, John M. [Brookhaven National Laboratory (BNL); Birgeneau, R. J. [University of California, Berkeley

    2012-01-01

    We study the effects of Cu substitution in Fe1.1Te, the non-superconducting parent compound of the iron-based superconductor, Fe1+yTe1 xSex, utilizing neutron scattering techniques. It is found that the structural and magnetic transitions, which occur at 60 K without Cu, are monotonically depressed with increasing Cu content. By 10% Cu for Fe, the structural transition is hardly detectable, and the system becomes a spin glass below 22 K, with a slightly incommensurate ordering wave vector of (0.48, 0, 0.5), and correlation length of 12 A along the a axis and 9 A along the c axis. With 4% Cu, both transition temperatures are at 41 K, though short-range incommensurate order at (0.42, 0, 0.5) is present at 60 K. With further cooling, the incommensurability decreases linearly with temperature down to 37 K, below which there is a first order transition to a longrange almost-commensurate antiferromagnetic structure. A spin anisotropy gap of 4.5 meV is also observed in this compound. Our results show that the weakly magnetic Cu has large effects on the magnetic correlations; it is suggested that this is caused by the frustration of the exchange interactions between the coupled Fe spins.

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

    Science.gov (United States)

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

    2017-10-01

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

  15. Room temperature ferromagnetism in Fe-doped CuO nanoparticles.

    Science.gov (United States)

    Layek, Samar; Verma, H C

    2013-03-01

    The pure and Fe-doped CuO nanoparticles of the series Cu(1-x)Fe(x)O (x = 0.00, 0.02, 0.04, 0.06 and 0.08) were successfully prepared by a simple low temperature sol-gel method using metal nitrates and citric acid. Rietveld refinement of the X-ray diffraction data showed that all the samples were single phase crystallized in monoclinic structure of space group C2/c with average crystallite size of about 25 nm and unit cell volume decreases with increasing iron doping concentration. TEM micrograph showed nearly spherical shaped agglomerated particles of 4% Fe-doped CuO with average diameter 26 nm. Pure CuO showed weak ferromagnetic behavior at room temperature with coercive field of 67 Oe. The ferromagnetic properties were greatly enhanced with Fe-doping in the CuO matrix. All the doped samples showed ferromagnetism at room temperature with a noticeable coercive field. Saturation magnetization increases with increasing Fe-doping, becomes highest for 4% doping then decreases for further doping which confirms that the ferromagnetism in these nanoparticles are intrinsic and are not resulting from any impurity phases. The ZFC and FC branches of the temperature dependent magnetization (measured in the range of 10-350 K by SQUID magnetometer) look like typical ferromagnetic nanoparticles and indicates that the ferromagnetic Curie temperature is above 350 K.

  16. Microstructure and corrosion resistance of AlCrFeCuCo high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Xing-Wu, E-mail: qiuxingwu@126.com [School of Material Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China); Department of Materials Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China); Zhang, Yun-Peng; He, Li [School of Material Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China); Liu, Chun-ge [Department of Transportation and Municipal Engineering, Sichuan College of Architectural Technology, Deyang 618000 (China)

    2013-02-05

    Highlights: Black-Right-Pointing-Pointer We use a new method (laser cladding) to prepare high-entropy alloy. Black-Right-Pointing-Pointer We gained small microstructure under rapid solidification condition. Black-Right-Pointing-Pointer We studied corrosion resistance of AlCrFeCuCo high-entropy alloy in two different liquids. - Abstract: The AlCrFeCuCo high-entropy alloys were prepared by the laser cladding method. The microstructure and corrosion resistance property of AlCrFeCuCo high-entropy alloy were researched by scanning electron microscopy, X-ray diffraction and electrochemical workstation. The results show that, under the rapid solidification small microstructure gained, the morphology of AlCrFeCuCo high entropy alloy is simple, the phase mainly compose of FCC and BCC; elements segregated in the alloys; the alloy shows excellent corrosion resistance, along with the increase of the scanning speed, alloy corrosion resistance performance shows a enhancement in the first and then weakened trend. The corrosion resistance performance of AlCrFeCuCo high-entropy alloys in 1 mol/L NaCl solution is better than in 0.5 mol/L H{sub 2}SO{sub 4} solution.

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

    Science.gov (United States)

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

    2016-03-01

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

  18. Simple electrodepositing of CoFe/Cu multilayers: Effect of ferromagnetic layer thicknesses

    Science.gov (United States)

    Tekgül, Atakan; Alper, Mürsel; Kockar, Hakan

    2017-01-01

    The CoFe/Cu magnetic multilayers were produced by changing CoFe ferromagnetic layers from 3 nm to 10 nm using electrodeposition. By now, the thinnest Cu (0.5 nm) layer thicknesses were used to see whether the GMR effect in the multilayers can be obtained or not since the pinning of non-magnetic layer between the ferromagnetic layers is required. For the proper depositions, the cyclic voltammograms was used, and the current-time transients were obtained. The Cu and CoFe layers were deposited at a cathode potential of -0.3 and -1.5 V with respect to saturated calomel electrode, respectively. From the XRD patterns, the multilayers were shown to be fcc crystal structures. For the magnetization measurements, saturation magnetization increases from 160 to 600 kA/m from 3 to 8 nm ferromagnetic layer thicknesses. And, the coercivity values increase until the 8 nm of the CoFe layer thickness. It is seen that the thin Cu layer (fixed at 0.5 nm) and pinholes support the random magnetization orientation and thus all multilayers exhibited the giant magnetoresistance (GMR) effect, and the highest GMR value was observed about 5.5%. And, the variation of GMR field sensitivity was calculated. The results show that the GMR and GMR sensitivity are compatible among the multilayers. The CoFe/Cu magnetic multilayers having GMR properties are used in GMR sensors and hard disk drive of the nano-technological devices.

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

    Directory of Open Access Journals (Sweden)

    Alipour Hossein

    2016-06-01

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

  20. Influence of structural parameters on magnetoresistive properties of CuFeNi melt spun ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Cazottes, S., E-mail: sophie.cazottes@etu.univ-rouen.fr [Groupe de Physique des Materiaux (GPM), Universite de Rouen, UMR CNRS 6634, Site Universitaire du Madrillet, Avenue de l' Universite, BP 12, 76801 Saint-Etienne du Rouvray Cedex (France); Danoix, F.; Fnidiki, A.; Lemarchand, D. [Groupe de Physique des Materiaux (GPM), Universite de Rouen, UMR CNRS 6634, Site Universitaire du Madrillet, Avenue de l' Universite, BP 12, 76801 Saint-Etienne du Rouvray Cedex (France); Baricco, M. [Dipartimento di Chimica IFM and NIS/INSTM, Universita' di Torino, Via P. Giuria 9, 10125 Torino (Italy)

    2009-04-15

    The microstructure of Cu{sub 80}Fe{sub 10}Ni{sub 10} (at%) granular ribbon was investigated by means of atom probe tomography (APT). A granular system is composed of magnetic precipitates embedded in a non-magnetic matrix. In this ribbon, the magnetic precipitates have a diameter smaller than 5 nm in the as-spun state, and their crystallographic structure is very similar to the one of the matrix, which makes it difficult to characterize them using conventional techniques. Those data are of great importance to understand the magnetic and the transport behaviour of these ribbons. Using atom probe tomography, a 3D reconstruction of the microstructure of the as-spun and annealed ribbons was achieved and a precise characterization of the compositions of the two phases and of the composition profile at interfaces was carried out. In the as-spun state the composition of the matrix is Cu{sub 89}Fe{sub 3}Ni{sub 8}, the one of the precipitates is Cu{sub 30}Fe{sub 40}Ni{sub 30}. Upon annealing, the precipitates get enriched in iron. After annealing at 600 {sup o}C for 24 h, the measured compositions are close to the one predicted by Thermocalc, with Cu{sub 94}Fe{sub 1}Ni{sub 5} for the matrix and Cu{sub 5}Fe{sub 64}Ni{sub 31} for the precipitates.

  1. Influence of structural parameters on magnetoresistive properties of CuFeNi melt spun ribbons.

    Science.gov (United States)

    Cazottes, S; Danoix, F; Fnidiki, A; Lemarchand, D; Baricco, M

    2009-04-01

    The microstructure of Cu(80)Fe(10)Ni(10) (at%) granular ribbon was investigated by means of atom probe tomography (APT). A granular system is composed of magnetic precipitates embedded in a non-magnetic matrix. In this ribbon, the magnetic precipitates have a diameter smaller than 5nm in the as-spun state, and their crystallographic structure is very similar to the one of the matrix, which makes it difficult to characterize them using conventional techniques. Those data are of great importance to understand the magnetic and the transport behaviour of these ribbons. Using atom probe tomography, a 3D reconstruction of the microstructure of the as-spun and annealed ribbons was achieved and a precise characterization of the compositions of the two phases and of the composition profile at interfaces was carried out. In the as-spun state the composition of the matrix is Cu(89)Fe(3)Ni(8), the one of the precipitates is Cu(30)Fe(40)Ni(30). Upon annealing, the precipitates get enriched in iron. After annealing at 600 degrees C for 24h, the measured compositions are close to the one predicted by Thermocalc, with Cu(94)Fe(1)Ni(5) for the matrix and Cu(5)Fe(64)Ni(31) for the precipitates.

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

    Science.gov (United States)

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

    2010-03-01

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

  3. Atomic structure of glassy Mg60Cu30Y10 investigated with EXAFS, x-ray and neutron diffraction, and reverse Monte Carlo simulations

    DEFF Research Database (Denmark)

    Jovari, P.; Saksl, K.; Pryds, Nini;

    2007-01-01

    Short range order of amorphous Mg60Cu30Y10 was investigated by x-ray and neutron diffraction, Cu and Y K-edge x-ray absorption fine structure measurements, and the reverse Monte Carlo simulation technique. We found that Mg-Mg and Mg-Cu nearest neighbor distances are very similar to values found i...

  4. High resolution electron microscopy study of a high Cu variant of Weldalite (tm) 049 and a high strength Al-Cu-Ag-Mg-Zr alloy

    Science.gov (United States)

    Herring, R. A.; Gayle, Frank W.; Pickens, Joseph R.

    1991-01-01

    Weldalite (trademark) 049 is an Al-Cu-Li-Ag-Mg alloy that is strengthened in artificially aged tempers primarily by very thin plate-like precipitates lying on the set of (111) matrix planes. This precipitate might be expected to be the T(sub 1) phase, Al2CuLi, which has been observed in Al-Cu-Li alloys. However, in several ways this precipitate is similar to the omega phase which also appears as the set of (111) planes plates and is found in Al-Cu-Ag-Mg alloys. The study was undertaken to identify the set of (111) planes precipitate or precipitates in Weldalite (trademark) 049 in the T8 (stretched and artificially aged) temper, and to determine whether T(sub 1), omega, or some other phase is primarily responsible for the high strength (i.e., 700 MPa tensile strength) in this Al-Cu-Li-Ag-Mg alloy.

  5. Optimization of the tunnel magnetoresistance of CoFeB/ MgO/ CoFeB - based magnetic tunnel junctions (MTJs) with e-beam evaporation barriers

    Energy Technology Data Exchange (ETDEWEB)

    Zbarskyy, Vladyslav; Walter, Marvin; Eilers, Gerrit; Muenzenberg, Markus [I. Physikalisches Institut, Georg-August-Universitaet Goettingen, 37077 Goettingen (Germany); Peretzki, Patrick; Seibt, Michael [IV. Physikalisches Institut, Georg-August-Universitaet Goettingen, 37077 Goettingen (Germany)

    2010-07-01

    The investigation of MTJs with a high tunnel magnetoresistance (TMR) is very important for the production of MRAM devices. All our CoFeB layers are prepared via magnetron sputtering and MgO barriers via e-beam evaporation. We investigate the magnetic switching properties of CoFeB/MgO/CoFeB MTJs with measurements of hysteresis curves - using the magneto-optical Kerr effect - and TMR curves, optimizing the thickness of the CoFeB layers. Another parameter we change to optimize the ferromagnetic CoFeB electrodes is the annealing temperature. Both influence the solid state epitaxy leading to crystallization directly at the MgO/CoFeB interface. The optimization of MgO barrier properties is also necessary for the quality of our devices. In this context we study the TMR behaviour with the variation of the sample temperature during the e-beam evaporation of MgO barrier.

  6. Interfacial tension studies between Fe-Cu-Ni sulfide and halo-norilsk basalt slag system

    Institute of Scientific and Technical Information of China (English)

    SU Shangguo; Jim Mungall; WANG Jian; GENG Ke

    2005-01-01

    The interfacial tension of the matte/halo-Norilsk basalt slag systems of FeS-Cu2S-Ni3S2 and FeO-FeS were investigated using the sessile drop technique. The results indicate that interfacial tension decreases with increasing copper and nickel contents in the matte of FeS-Cu2S-Ni3S2 system while it increases with increasing oxygen content in the matte of FeO-FeS system. It is inferred from these results that two conditions are critical for the formation of giant Cu-Ni sulfide deposits. One is that mafic-ultramafic parent magma of sulfide deposits should be rich in copper and nickel where due to the low interfacial tension, it is difficult to form sulfide droplet in the early stage of magma evolution. In other words, sulfide liquid conglomeration occurs more difficultly. The other condition is that the magma emplacement should be shallow; and a lot of faults occur in the magma emplacement field. Since oxygen content is high in the environment, interfacial tension is high, which helps sulfide liquid conglomeration and consequently Cu-Ni sulfide deposits form.

  7. Synthesis of a clinoptilolite-Fe system with high Cu sorption capacity.

    Science.gov (United States)

    Doula, Maria K

    2007-03-01

    An iron oxide-clinoptilolite system was synthesized by adding natural clinoptilolite in an iron nitrate solution under strongly basic condition. The newly synthesized material has a red-brown color. A combination of XRD, FTIR and EPR spectroscopies, as well as specific surface area measurements and TG/DSC thermal analyses provided information on the type of Fe species located on the zeolite surface. Clinoptilolite seems to maintain its structure, while Fe(3+) species are in a symmetric environment (Th or Oh). The new material has a noteworthy high value of specific surface area (151 m(2)g(-1)) and is fully iron exchanged (Fe/Al=1.23). Differences in FTIR and TG/DSC spectrograms between the Fe-Clin system and untreated Clin were reported and explained. According to Cu adsorption/desorption experiments, carried out after the synthesis and characterization procedures, the Fe-Clin system is a promising new material since it adsorbs significantly larger Cu concentrations than clinoptilolite. This fact is owed to its high specific surface area and to its high negative surface charge. Desorption of Cu was also examined and it was observed that the Fe-Clin system desorbs smaller Cu amounts than untreated clinoptilolite.

  8. Evaluation of the relative thermoluminescence efficiency of LiF:Mg,Ti and LiF:Mg,Cu,P TL detectors to low-energy heavy ions

    DEFF Research Database (Denmark)

    Gieszczyk, W.; Bilski, P.; Olko, P.

    2013-01-01

    The most popular types of LiF-based thermoluminescent (TL) detectors, LiF:Mg,Ti (MTS-N) and LiF:Mg,Cu,P (MCP-N), have been investigated, with respect to their dose (fluence) response and relative TL efficiency to different ion species. The detectors were irradiated using the nitrogen, iron, krypt...

  9. The bulk-Moon MgO/FeO ratio: A highlands perspective

    Science.gov (United States)

    Warren, P. H.

    1984-01-01

    Compositional data for nonmare (highlands) samples suggest that the Moon's mg ratio (MgO/FeO) is higher than general estimates. Geochemically representative highlands soils have mg ratios of 0.66 (Apollo 16), 0.69 (Luna 20) and 0.73 (ALHA81005). These soils are mixtures of unrelated pristine nonmare rocks, of which there are at least three groups: Mg-rich rocks, ferroan anorthosites, and KREEP. Other than Mg-rich rocks, virtually all pristine rocks have mg 0.65. Thus, assuming the mixing process that sampled Mg-rich materials was random, the average mg of Mg-rich parent magmas was probably at least 0.70. More direct evidence can be derived from the Mg-rich rocks themselves. Nine of them have bulk-rock mg 0.87. Two (15445 A and 67435 PST) contain Fo(92) olivine. Production of melts that crystallized Fo(92) olivine implies that the mg ratios of source regions in lunar mantle were commensurably high. A quantification of this constraint is developed assuming that the parent melts formed by equilibrium (batch) partial melting. Implications of the model are discussed.

  10. Epitaxial Fe3Pt/FePt nanocomposites on MgO and SrTiO3

    Science.gov (United States)

    Casoli, F.; Lupo, P.; Nasi, L.; Cabassi, R.; Fabbrici, S.; Bolzoni, F.; Ranzieri, P.; Albertini, F.

    2015-02-01

    We have exploited the pseudomorphic growth of the magnetically soft Fe3Pt phase on top of L10-FePt to obtain fully epitaxial soft/hard nanocomposites on both MgO(100) and SrTiO3(100). The magnetic properties of this new nanocomposite system, driven by the soft/hard exchange-coupling, can be tailored by varying soft phase thickness, soft phase magnetic anisotropy and substrate. Coercivity is strongly reduced by the addition of the soft phase, a reduction which is definitely affected by the nominal composition of the soft phase and by the substrate choice; similarly is the magnetic phase diagram of the composite system. Coercive field decreases down to 21% of the hard layer value for Fe3Pt(5 nm)/FePt(3.55 nm) nanocomposites on SrTiO3; this maximum coercivity reduction was obtained with a nominal atomic content of Fe in the soft phase of 80%.

  11. Preparation and characterization of epitaxial thin films and patterned nanostructures of Ni/Cu and Fe/Cu

    OpenAIRE

    Corredor, Edna C.

    2012-01-01

    El objetivo del trabajo realizado en esta tesis titulada: Preparation and magnetic characterization of epitaxial thin films and patterned nanostructures of Ni/Cu and Fe/Cu es establecer relaciones entre las propiedades magnéticas de sistemas nanoestructurados y sus dimensiones físicas o factores estructurales que aparecen al reducirse la dimensión espacial a dos, en el caso de películas delgadas, y a una en el caso de elementos patronados. Los sistemas objeto de estudio se caracterizan por se...

  12. Preparation and characterization of epitaxial thin films and patterned nanostructures of Ni/Cu and Fe/Cu

    OpenAIRE

    Corredor Vega, Edna Consuelo; Ciria Remacha, Miguel Ángel; Arnaudas Pontaque, José Ignacio

    2013-01-01

    El objetivo del trabajo realizado en esta tesis titulada: Preparation and magnetic characterization of epitaxial thin films and patterned nanostructures of Ni/Cu and Fe/Cu es establecer relaciones entre las propiedades magnéticas de sistemas nanoestructurados y sus dimensiones físicas o factores estructurales que aparecen al reducirse la dimensión espacial a dos, en el caso de películas delgadas, y a una en el caso de elementos patronados. Los sistemas objeto de estudio se caracterizan por se...

  13. Magnetic ordering of Fe atoms in the YBa2(Cu/0. 95/Fe/0. 05/)3O(7. 01) superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Liubutin, I.S.; Terziev, V.G.; Morozov, O.N. (Institut Kristallografii, Moscow (USSR))

    1990-11-01

    Moessbauer spectroscopy detected the magnetic ordering of Fe atoms in YBa2(Cu/0.95/Fe/0.05/)3O(y) in both the superconducting and the nonsuperconducting states. It is shown that, in the superconducting sample, the superconductivity coexists with magnetic ordering of the Fe atoms in Cu1 nodes. In the nonsuperconducting sample, the Fe atoms in the Cu1 nodes have a magnetic-ordering point (20 K) which is reduced by 10 K upon transition to the superconducting state. 15 refs.

  14. Comparison of Tunneling in Fe-based Superconductors with Multi-band MgB2

    Science.gov (United States)

    Zasadzinski, John; Iavarone, Maria

    MgB2 is an s-wave, phonon coupled, multiband superconductor that exhibits novel tunneling spectra including a subtle dip feature due to quasiparticle transfer between bands. Since this feature mimics the above-gap spectral dip feature observed in Fe-based superconductors, typically attributed to a strong coupling boson, it is worthwhile to consider whether quasiparticle transfer is relevant. We first show that the dip in MgB2 appears in the π-band, DOS (Δ = 2.4 meV) and is due to quasiparticle transfer to the σ-band with Δ = 7.2 meV. Reviewing the spectral dip in Fe-based superconductors, including new data on FeSe crystals, there are inconsistencies with quasiparticle transfer as the origin. The conclusion is that the spectral dip is more likely due to a boson, the resonance spin excitation, as found in cuprate superconductors.

  15. Magnetic phase transitions in Ta/CoFeB/MgO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Barsukov, I.; Safranski, C.; Chen, Y.-J.; Youngblood, B.; Krivorotov, I. N. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Fu, Yu [INAC/CEA, Grenoble, 17 Avenue des Martyrs, 38054 Grenoble (France); Gonçalves, A. M. [Physics and Astronomy, University of California, Irvine, California 92697 (United States); Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud, 150, Rio de Janeiro 22.290-180, RJ (Brazil); Spasova, M.; Farle, M. [Fakultät für Physik and Center for Nanointegration (CeNIDE), Universität Duisburg-Essen, 47048 Duisburg (Germany); Katine, J. A. [HGST Research Center, San Jose, California 95135 (United States); Kuo, C. C. [Components Research, Intel, Hillsboro, Oregon 97124 (United States)

    2015-05-11

    We study thin films and magnetic tunnel junction nanopillars based on Ta/Co{sub 20}Fe{sub 60}B{sub 20}/MgO multilayers by electrical transport and magnetometry measurements. These measurements suggest that an ultrathin magnetic oxide layer forms at the Co{sub 20}Fe{sub 60}B{sub 20}/MgO interface. At approximately 160 K, the oxide undergoes a phase transition from an insulating antiferromagnet at low temperatures to a conductive weak ferromagnet at high temperatures. This interfacial magnetic oxide is expected to have significant impact on the magnetic properties of CoFeB-based multilayers used in spin torque memories.

  16. Influence of Cu content on the mechanical properties and corrosion resistance of Mg-Zn-Ca bulk metallic glasses

    Science.gov (United States)

    Zhao, Yan-feng; Zhu, Jian; Chang, Li; Song, Jing-guo; Chen, Xiao-hua; Hui, Xi-dong

    2014-05-01

    (Mg66.2Zn28.8Ca5)100- x Cu x (at%, x = 0, 1, 3, and 5) bulk metallic glasses (BMGs) of 2 mm in diameter were prepared by the conventional copper mold injection casting method. Besides, the influence of Cu content on the microstructure, thermal stability, mechanical properties, and corrosion behavior of Mg-Zn-Ca BMGs was investigated. It is found that the addition of Cu decreases the glass-forming ability of Mg-Zn-Ca BMGs. Crystalline phases are precipitated at a higher Cu content, larger than 3at%. The compressive fracture strength of Mg-Zn-Ca BMGs is enhanced by the addition of Cu. With the formation of in-situ composites, the compressive strength of the Mg-Zn-Ca alloy with 3at% Cu reaches 979 MPa, which is the highest strength among the Mg-Zn-Ca alloys. Furthermore, the addition of Cu also results in the increase of corrosion potential and the decrease of corrosion current density in Mg-Zn-Ca BMGs, thereby delaying their biodegradability.

  17. FeO and MgO in plagioclase of lunar anorthosites: Igneous or metamorphic?

    Science.gov (United States)

    Phinney, W. C.

    1994-01-01

    The combined evidence from terrestrial anorthosites and experimental laboratory studies strongly implies that lunar anorthosites have been subjected to high-grade metamorphic events that have erased the igneous signatures of FeO and MgO in their plagioclases. Arguments to the contrary have, to this point, been more hopeful than rigorous.

  18. High-pressure synthesis of Mg{sub 2}FeH{sub 6} complex hydride

    Energy Technology Data Exchange (ETDEWEB)

    Retuerto, M.; Sanchez-Benitez, J.; Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco E-28049 Madrid (Spain); Rodriguez-Canas, E. [Servicio Interdepartamental de Investigacion, Facultad de Ciencias, Universidad Autonoma de Madrid, Cantoblanco E-28049 Madrid (Spain); Serafini, D. [Departamento de Fisica, Facultad de Ciencias, Universidad de Santiago de Chile and Center for Interdisciplinary Research in Materials, CIMAT, Av. Lib. Bernardo O' Higgins 3363, Santiago (Chile)

    2010-08-15

    We have designed a new synthesis method for the ternary metal hydride Mg{sub 2}FeH{sub 6} based on the direct reaction of simple hydrides under high-pressure conditions. Well-crystallized samples were prepared in a piston-cylinder hydrostatic press at 2 GPa and temperatures around 750 C from mixtures of MgH{sub 2} and Fe enclosed in gold or platinum capsules. Seven different samples have been prepared under different conditions. X-ray powder diffraction analysis was used to identify and assess the purity of the samples, through Rietveld analyses of the crystal structure (K{sub 2}PtCl{sub 6}-type). Mg{sub 2}FeH{sub 6} shows a cubic symmetry with space group Fm-3m. SEM images show an average particle size of 1-2 {mu}m for Mg{sub 2}FeH{sub 6}; the microcrystals present well-grown faces and display a high homogeneity of shapes and sizes. Thermogravimetric analysis has been carried out to determine not only the hydrogen desorption temperature but also the hydrogen contents. (author)

  19. Compositional effects on the vibrational properties of (Mg,Fe)O

    Science.gov (United States)

    Steinhardt, W.; Jackson, J. M.; Wicks, J. K.; Sturhahn, W.

    2010-12-01

    One of the main constituents of Earth's lower mantle is (Mg,Fe)O periclase. Iron-poor (Mg1-xFex), with xLamb-Mössbauer factor (fLM), vibrational specific heat per atom at constant volume (cV), the vibrational entropy per atom (Svib), the mean force constant (D), and the vibrational kinetic energy (EK) of the 57Fe nucleus. We will discuss these parameters in the context of previous NRIXS results for (Mg,Fe)O. We find that our NRIXS results from (Mg0.5Fe0.5)O complement the parameters determined for iron-rich (Struzhkin et al. 2001; Wicks et al. 2010) and iron-poor (Lin et al. 2006; Chen et al. 2010) periclase samples. References: Chen, B. et al. (2010), Fall AGU. Irifune, T (1994), Nature, 370, 131-133. Jacobsen, S., et al. (2004), PNAS, 101, 5867-5871. Labrosse, S., et al. (2007), Nature, 450, 866-869. Lin, J.-F. et al. (2006), GRL 33, L22304. Sakai, T., et al. (2010), PCM, 37, 487-496. Struzhkin, V. V., et al. (2001), PRL, 87, 255501. Wicks, J. K. et al. (2010), GRL, 37, L15304.

  20. Cap-Induced Magnetic Anisotropy in Ultra-thin Fe/MgO(001) Films

    Science.gov (United States)

    Brown-Heft, Tobias; Pendharkar, Mihir; Lee, Elizabeth; Palmstrom, Chris

    Magnetic anisotropy plays an important role in the design of spintronic devices. Perpendicular magnetic anisotropy (PMA) is preferred for magnetic tunnel junctions because the resulting energy barrier between magnetization states can be very high and this allows enhanced device scalability suitable for magnetic random access memory applications. Interface induced anisotropy is often used to control magnetic easy axes. For example, the Fe/MgO(001) system has been predicted to exhibit PMA in the ultrathin Fe limit. We have used in-situ magneto optic Kerr effect and ex-situ SQUID to study the changes in anisotropy constants between bare Fe/MgO(001) films and those capped with MgO, Pt, and Ta. In some cases in-plane anisotropy terms reverse sign after capping. We also observe transitions from superparamagnetic to ferromagnetic behavior induced by capping layers. Perpendicular anisotropy is observed for Pt/Fe/MgO(001) films after annealing to 300°C. These effects are characterized and incorporated into a magnetic simulation that accurately reproduces the behavior of the films. This work was supported in part by the Semiconductor Research Corporation programs (1) MSR-Intel, and (2) C-SPIN.

  1. Magnetic and transport properties of epitaxial thin film MgFe2O4 grown on MgO (100) by molecular beam epitaxy.

    Science.gov (United States)

    Wu, Han-Chun; Mauit, Ozhet; Coileáin, Cormac Ó; Syrlybekov, Askar; Khalid, Abbas; Mouti, Anas; Abid, Mourad; Zhang, Hong-Zhou; Abid, Mohamed; Shvets, Igor V

    2014-11-12

    Magnesium ferrite is a very important magnetic material due to its interesting magnetic and electrical properties and its chemical and thermal stability. Here we report on the magnetic and transport properties of epitaxial MgFe2O4 thin films grown on MgO (001) by molecular beam epitaxy. The structural properties and chemical composition of the MgFe2O4 films were characterized by X-Ray diffraction and X-Ray photoelectron spectroscopy, respectively. The nonsaturation of the magnetization in high magnetic fields observed for M (H) measurements and the linear negative magnetoresistance (MR) curves indicate the presence of anti-phase boundaries (APBs) in MgFe2O4. The presence of APBs was confirmed by transmission electron microscopy. Moreover, post annealing decreases the resistance and enhances the MR of the film, suggesting migration of the APBs. Our results may be valuable for the application of MgFe2O4 in spintronics.

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

    Science.gov (United States)

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

    2015-03-28

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

  3. In-situ grazing incidence X-ray diffraction measurements of relaxation in Fe/MgO/Fe epitaxial magnetic tunnel junctions during annealing

    Science.gov (United States)

    Eastwood, D. S.; Ali, M.; Hickey, B. J.; Tanner, B. K.

    2013-12-01

    The relaxation of Fe/MgO/Fe tunnel junctions grown epitaxially on (001) MgO substrates has been measured by in-situ grazing incidence in-plane X-ray diffraction during the thermal annealing cycle. We find that the Fe layers are fully relaxed and that there are no irreversible changes during annealing. The MgO tunnel barrier is initially strained towards the Fe but on annealing, relaxes and expands towards the bulk MgO value. The strain dispersion is reduced in the MgO by about 40% above 480 K post-annealing. There is no significant change in the "twist" mosaic. Our results indicate that the final annealing stage of device fabrication, crucial to attainment of high TMR, induces substantial strain relaxation at the MgO barrier/lower Fe electrode interface.

  4. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    Science.gov (United States)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  5. Isotopic Fractionation of Mg2+(aq), Ca2+(aq), and Fe2+(aq) with Carbonate Minerals

    Energy Technology Data Exchange (ETDEWEB)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-15

    Density functional electronic structure calculations are used to compute the equilibrium constant (the isotope fractionation factor) for 26Mg/24Mg and 44Ca/40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 103ln(K) at 25 °C, of -5.3, -1.1, and +1.1 for 26Mg/24Mg exchange between calcite (CaCO3), magnesite (MgCO3), and dolomite (Ca0.5Mg0.5CO3), respectively, and Mg2+(aq), with positive values indicating enrichment in the mineral phase. For 44Ca/40Ca exchange between calcite and Ca2+(aq), the calculations predict values of +1.5 for Ca2+(aq) in six-fold coordination and +4.1 for Ca2+(aq) in seven-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO3)610- and M2+(H2O)6 embedded in a set of fixed atoms representing the 2nd shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using 2 the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe3+-hematite and Fe2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe3+(aq) and Fe2+(aq) species.

  6. Facile synthesis of Fe-incorporated CuO nanoarrays with enhanced electrochemical performance for lithium ion full batteries

    Energy Technology Data Exchange (ETDEWEB)

    Heng, Bojun [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China); Department of Applied Physics, Wuhan University of Science and Technology, Wuhan, 430065 (China); Qing, Chen; Wang, Hai; Sun, Daming; Wang, Bixiao [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China); Tang, Yiwen, E-mail: ywtang@phy.ccnu.edu.cn [Institute of Nano-science and Technology, Central-China Normal University, Wuhan, 430079 (China)

    2015-11-15

    CuO nanoarrays (CNAs) and Fe-incorporated CuO nanoarrays (FCNAs) were fabricated by hydrothermal method. Addition of Fe salt to the reaction mixture allowed the introduction of iron oxide onto the CNAs surface, which was characterized by XPS and HRTEM. Introducing Fe ion into reaction precursor significantly affected not only the morphologies of as-prepared products but also their electrochemical performance as anode for lithium ion full battery. The FCNAs electrodes showed higher specific capacity and better capacity retention at different current densities than that of CNAs. - Highlights: • Fe-incorporated CuO nanoarrays were fabricated by hydrothermal method. • Fe salt in reaction mixture leads to iron oxides forming on the surface of CuO. • Fe-incorporating improves the lithium ion battery performance of CuO anodes.

  7. Sub-micron-sized polyethylenimine-modified polystyrene/Fe3O4/chitosan magnetic composites for the efficient and recyclable adsorption of Cu(II) ions

    Science.gov (United States)

    Xiao, Changwei; Liu, Xijian; Mao, Shimin; Zhang, Lijuan; Lu, Jie

    2017-02-01

    A sub-micron-sized polyethylenimine(PEI)-modified polystyrene/Fe3O4/chitosan magnetic composite (PS/Fe3O4/CS-PEI) was developed as a novel adsorbent for the removal of Cu(II) ions from aqueous solutions. The PS/Fe3O4/CS-PEI microspheres with a diameter of ∼300 nm can be highly monodisperse and conveniently separated from suspensions by a magnet due to their excellent magnetism. When the PS/Fe3O4/CS-PEI microspheres were used as an absorbent for the absorption of Cu(II) ions, the adsorption isotherms and adsorption kinetics well fitted the Langmuir model and the pseudo-second-order model, respectively. The maximum adsorption capacity was about 204.6 mg g-1, which was higher than those of other chitosan adsorbents reported recently. The adsorption was considerably fast, reaching the equilibrium within 15 min. In addition, the adsorbed Cu(II) ions could be effectively desorbed using 0.1 mol L-1 NaOH solution, and the regeneration study proved that the composite microspheres could be repeatedly utilized without significant capacity loss after six cycles. All the results demonstrated that the synthesized sub-micron-sized magnetic PS/Fe3O4/CS-PEI composites can be used as an ideal adsorbent of Cu(II) ions for environmental cleanup applications.

  8. Interfacial electronic structure-modulated magnetic anisotropy in Ta/CoFeB/MgO/Ta multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi; Jiang, Shao Long; Yang, Guang; Liu, Yang; Teng, Jiao; Yu, Guang Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Kai You [SKLSM, Institute of Semiconductors, CAS, P. O. Box 912, Beijing 100083 (China); Wu, Zheng Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China)

    2014-09-01

    We have observed several unexpected phenomena when a trace amount of Fe atoms is deposited onto the CoFeB/MgO interface in Ta/CoFeB/MgO/Ta multilayers. With the nominal thickness of the introduced Fe atoms (t{sub Fe}) varying from 0 to 0.1 Å, the effective magnetic anisotropy energy (K{sub eff}) of annealed multilayers is remarkably enhanced from 1.28 × 10{sup 6 }erg/cm{sup 3} to 2.14 × 10{sup 6 }erg/cm{sup 3}. As t{sub Fe} further increasing, the K{sub eff} decreases and even becomes negative when t{sub Fe} > 1 Å, indicating the change from perpendicular magnetic anisotropy to in-plane magnetic anisotropy. The analysis by X-ray photoelectron spectrometer reveals that the Fe atoms at annealed CoFeB/MgO interface show different electronic structures as t{sub Fe} increasing, which combine with O atoms to form FeO{sub x} (x < 1), Fe{sub 2}O{sub 3}, and Fe{sub 3}O{sub 4}, respectively, leading to modulation of Fe 3d-O 2p orbital hybridization and thus the K{sub eff}. On the other hand, we find that the introduction of Fe atoms also helps to reduce the multilayers' magnetic damping.

  9. XPS analyses of Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films

    Energy Technology Data Exchange (ETDEWEB)

    Li Minghua, E-mail: mhli@ustb.edu.cn [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Han Gang; Liu Yang; Feng Chun; Wang Haicheng; Teng Jiao; Yu Guanghua [Department of Material Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. Black-Right-Pointing-Pointer The chemical states of Ta and MgO{sub x} at the interface of the NiFe/MgO{sub x}/Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). Black-Right-Pointing-Pointer The AMR of Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films is related to the chemical states of MgO{sub x}. These states were produced under different technical conditions and influence the film properties. - Abstract: Ta/MgO{sub x}/Ni{sub 81}Fe{sub 19}/MgO{sub x}/Ta films were prepared by magnetron sputtering. The anisotropic magnetoresistance (AMR) increases dramatically after annealing. The chemical states of Ta and MgO{sub x} at the interface of the NiFe/MgO{sub x}/Ta films, which were prepared at the different technological conditions, were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that the AMR of the films is related to the chemical states of MgO{sub x}. The chemical states of Mg are different when MgO{sub x} is prepared at different technological conditions. Therefore, increasing the AMR is beneficial when more Mg{sup 2+} ions are present in the MgO{sub x} films.

  10. The Influence of the East Pacific Rise Hydrothermal Field on the Distributions of Dissolved Fe, Mn, Zn, Cu and Cd in the South Pacific

    Science.gov (United States)

    Roshan, S.; Wu, J.

    2014-12-01

    East Pacific Rise (EPR) hosts the largest hydrothermal field in the world. The concentrations of dissolved key trace metals (Fe, Zn, Cu and Cd) were determined in the seawater samples collected from EPR to Tahiti in the South Pacific along 10-15 ºS during U. S. GEOTRACES 2013 by means of Mg(OH)2 co-precipitation isotope dilution method using ICP-MS. Dissolved Mn was determined in these samples using a new method combining Mg(OH)2 co-precipitation with calibration with external standards of 57Fe, 52Cr and 59Co. The results show substantial mid-depth maxima of Fe and Mn extended from EPR. These hydrothermally-enriched Fe and Mn show long-distance westward transportation to the central South Pacific. The mid-depth enrichment of Zn was also observed at stations close to EPR. In contrast, Cu and Cd show depletions around the hydrothermal vent near EPR. Overall the results suggest that hydrothermal activity is a source for Fe, Mn and Zn and a sink for Cu and Cd.

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    Cu/TiO2, Fe/TiO2 and heteropoly acid promoted Cu/TiO2, Fe/TiO2 catalysts were prepared and characterized by N2 physisorption, XRPD, NH3-TPD, H2-TPR and EPR. The catalysts exhibited only crystalline TiO2 phases with the active metals and promoters in highly dispersed state. The acidic properties...... activity and acidity was lower for promoted catalysts than for unpromoted catalysts. In the heteropoly acid promoted catalysts the SCR active Cu and Fe metals were protected from potassium poisons by bonding of the potassium to the Brønsted acid centres. Thus heteropoly acid promoted catalysts might...... were studied and compared with the catalytic activity for the selective catalytic reduction (SCR) of NO with ammonia. The SCR activities and acidity values of heteropoly acid promoted catalysts were found to be much higher than unpromoted catalysts. The influence of potassium poisons on the SCR...

  12. Synthesis of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of Congo Red from aqueous solution

    Indian Academy of Sciences (India)

    Zhigang Jia; Shengbiao Li; Jianhong Liu; Qi Qin; Rongsun Zhu

    2015-12-01

    MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres were prepared by urea-hydrolysed hydrothermal reaction and the subsequent calcinations. The morphology and structure of the products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscope and Fourier transformed infrared. The adsorption performance of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for the removal of an anionic dye (Congo Red, CR) from aqueous solution was investigated. The results showed that MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres are particularly efficient in removing CR. The adsorption follows a pseudo-second-order kinetic model and best fits the Langmuir isotherm model. The maximum adsorption capacities of MgAl-LDH/CoFe2O4 and MgAl-CLDH/CoFe2O4 nanofibres for CR were found to be 213.2 and 49.8 mg g−1, respectively. The both adsorption processes were found to be spontaneous and exothermic in nature.

  13. Feasibility of dispersive liquid–liquid microextraction for extraction and preconcentration of Cu and Fe in red and white wine and determination by flame atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Tassia S.; Rosa, Francisco C.; Bizzi, Cezar A.; Dressler, Valderi L.; Flores, Erico M.M.; Duarte, Fabio A., E-mail: fabioand@gmail.com

    2015-03-01

    A method for extraction and preconcentration of Cu and Fe in red and white wines using dispersive liquid–liquid microextraction (DLLME) and determination by flame atomic absorption spectrometry (F AAS) was developed. Extraction was performed using sodium diethyldithiocarbamate as chelating agent and a mixture of 40 μL of 1,2-dichlorobenzene (extraction solvent) and 900 μL of methanol (dispersive solvent). Some parameters that influencing the extraction efficiency such as pH (2 to 5), concentration of chelating agent (0 to 2%), effect of salt addition (0 to 10%), number of washing steps (1 to 4) and centrifugation time (0 to 15 min) were studied. Accuracy was evaluated after microwave-assisted digestion in closed vessels and analytes were determined by inductively coupled plasma optical emission spectrometry. Agreement with the proposed method ranged from 91 to 110 and from 89 to 113% for Cu and Fe, respectively. Calibration of F AAS instrument was performed using analyte addition method and limits of detection were 6.3 and 2.4 μg L{sup −1} for Cu and Fe, respectively. The proposed method was applied for the determination of Cu and Fe in five samples of red wine and three samples of white wine, with concentration ranging from 21 to 178 μg L{sup −1} and from 1.38 to 3.74 mg L{sup −1}, respectively. - Highlights: • Determination of Cu and Fe in wine using DLLME and F AAS • High preconcentration factors and low LODs were achieved. • Alternative method for the determination of Cu and Fe in wine for routine analysis.

  14. Structure and Properties of Mg-Cu-(Y,Ca Bulk Metallic Glasses / Struktura I Własności Masywnych Szkieł Metalicznych Mg-Cu-(Y,Ca

    Directory of Open Access Journals (Sweden)

    Babilas R.

    2015-12-01

    Full Text Available The work presents preparation methods, structure characterization and mechanical properties analysis of Mg-based bulk metallic glasses in as-cast state and after crystallization process. The studies were performed on Mg60Cu30Y10 and Mg37Cu36Ca27 glassy alloys in the form of plates and rods. The X-ray diffraction investigations revealed that the tested samples with different thicknesses and shapes were amorphous. The characteristics of the fractured surfaces showed mixed fractures with the “river” and “mirror” patterns, which are characteristic for the glassy materials and some “smooth” areas. The samples of Mg37Cu36Ca27 alloy presented a two-stage crystallization process, but addition of Y caused a single stage crystallization behavior. Qualitative phase analysis from the X-ray data of examined alloys annealed at 473 K enabled the identification of Mg, Mg2Cu, Cu2Mg and CaCu crystalline phases. The changes of compressive strength as a function of annealing temperature for studied rods were stated. The best mechanical properties including microhardness and compressive strength were obtained for the alloy with the addition of Y in as-cast state.

  15. EPR and optical absorption studies of Cu 2+ doped bis (glycinato) Mg (II) monohydrate single crystals

    Science.gov (United States)

    Dwivedi, Prashant; kripal, Ram

    2010-02-01

    Electron paramagnetic resonance (EPR) study of Cu 2+ doped bis (glycinato) Mg (II) monohydrate single crystals is carried out at room temperature. Copper enters the lattice substitutionally and is trapped at two magnetically inequivalent sites. The observed spectra are fitted to a spin-Hamiltonian of rhombic symmetry with the following values of the parameters: Cu 2+ (I), gx = 2.1577 ± 0.0002, gy = 2.2018 ± 0.0002, gz = 2.3259 ± 0.0002, Ax = (87 ± 2) × 10 -4 cm -1, Ay = (107 ± 2) × 10 -4 cm -1, Az = (141 ± 2) × 10 -4 cm -1; Cu 2+ (II), gx = 2.1108 ± 0.0002, gy = 2.1622 ± 0.0002, gz = 2.2971 ± 0.0002, Ax = (69 ± 2) × 10 -4 cm -1, Ay = (117 ± 2) × 10 -4 cm -1and Az = (134 ± 2) × 10 -4 cm -1. The ground state wave function of the Cu 2+ ion in this lattice is evaluated to be predominantly | x2 - y2lbond2 . The g-factor anisotropy is also calculated and compared with the experimental value. With the help of the optical absorption study, the nature of bonding in the complex is discussed.

  16. Taming the resistive switching in Fe/MgO/V/Fe magnetic tunnel junctions: An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar-Hualde, J.M. [IPhT, CEA/Saclay, Orme des Merisiers, 91190 Gif-sur-Yvette Cedex (France); Alouani, M. [IPCMS, UMR 7504 CNRS-UdS, 23 rue du Loess, Strasbourg 67034 (France)

    2014-12-15

    A possible mechanism for the resistive switching observed experimentally in Fe/MgO/V/Fe junctions is presented. Ab initio total energy calculations within the local density approximation and pseudopotential theory shows that by moving the oxygen ions across the MgO/V interface one obtains a metastable state. It is argued that this state can be reached by applying an electric field across the interface. In addition, the ground state and the metastable state show different electric conductances. The latter results are discussed in terms of the changes of the density of states at the Fermi level and the charge transfer at the interface due to the oxygen ion motion. - Highlights: • Local minima are found for oxygen near the interface with at least one oxygen moved. • Relaxation of a small unit cell preserves this result and lowers energy barrier. • V on the top of Mg exhibits the minimum and a reasonable energy barrier. • Sense of switching: experimental evidence of the configuration (V on O or V on Mg). • Sense of switching can be understood in terms of charge oscillations induced by the O.

  17. Optical switching properties and durability of a Mg-Fe alloy based thin film hydrogen sensor

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Marc K.; Haas, Gunther; Portz, Andre; Laufer, Andreas; Polity, Angelika; Meyer, Bruno K. [I. Physikalisches Institut, Giessen (Germany)

    2011-07-01

    Mg-Fe alloy based hydrogen gas sensors were produced by a RF sputtering process. By exposure to a hydrogen containing gas mixture the Mg-metal alloy switches from the metal phase into a hydride phase, thereby the optical reflection shows a change. A Pd top layer acts as hydrogen catalyst. The degradation of the hydrogenation speed (sensor reaction) and the switching durability are well known problems of such Mg-metal based switching mirrors. Furthermore, there is a delay of sensor reaction after some weeks of storage (in air). In order to solve these problems, we added a Ti buffer layer between MgFe and Pd layer. The buffer layer inserted sensor system featured an improvement of sensor reaction and switching durability. A polytetrafluoroethylene (PTFE) covering coat was added and reduced the sensor degeneration after the storage. Furthermore, there was an additional improvement of switching durability. Samples of PTFE/Pd/Ti/MgFe achieved over 1000 switching cycles (with 4 % hydrogen in air) without a significant performance reduction.

  18. Electromagnetic properties of nanocrystalline Al$^{3+}$ substituted MgCuMn ferrites synthesized by microwave hydrothermal method

    Indian Academy of Sciences (India)

    T RAMESH; S R MURTHY

    2016-10-01

    The effect of Al$^{3+}$ substitution on electromagnetic properties has been studied for nanocrystalline Mg$_{0.8}$Cu$_{0.2}Mn$_{0.05}$Al$_x$Fe$_{1.95−x}$O$_4$ ferrites, wherein $x$ varies from 0 to 0.4 in steps of 0.1. These ferrites were synthesizedby using microwave hydrothermal method and then characterized using X-ray diffractometer (XRD), Fourier transform infrared and transmission electron microscopy. The synthesized powders were densified using microwavesintering method at 950◦C/50 min. Structural and surface morphology of sintered samples were characterized using XRD and atomic force microscopy, respectively. The complex permittivity and permeability properties were measuredover a frequency range 100 Hz–1.8 GHz. The temperature variation of magnetic properties were measured in the temperature range of 300–650 K. The electrical and magnetization studies inferred that the values of d.c. resistivity increases by 27%, whereas saturation magnetization decreases linearly from 38.6 to 23.0 emu g$^{−1}$ and Curie temperature was found to be decreased from 628 to 513 K with an increase of Al$^{3+}$ ions. The low dielectric, magnetic losses, moderate saturation magnetization and high-temperature stability properties exhibited by Al$^{3+}$ substituted MgCuMn ferrites make them find applications in microwave devices, such as circulators and isolators etc. The applicability of present samples formicrowave devices has been tested by the measurement of ferromagnetic resonance linewidth at K$_a$ band.

  19. Comparison of hydrogen-storage properties of Mg-14Ni-3Fe2O3-3Ti and Mg-14Ni-2Fe2O3-2Ti-2Fe

    Science.gov (United States)

    Kwak, Young Jun; Park, Hye Ryoung; Song, Myoung Youp

    2013-05-01

    Magnesium with oxides or transition elements prepared by mechanical grinding under H2 (reactive mechanical grinding) showed relatively high hydriding and dehydriding rates when the content of additives was about 20 wt%. Ni, Fe2O3, and Fe were chosen as the oxides or transition elements to be added. Ti was also selected since it was considered to increase the hydriding and dehydriding rates by forming Ti hydride. Samples Mg-14Ni-3Fe2O3-3Ti (Sample A) and Mg-14Ni-2Fe2O3-2Ti-2Fe (Sample B) were prepared by reactive mechanical grinding, and their hydrogen storage properties were compared. The activated Sample A had a little smaller hydriding rate than the activated Sample B, but a higher dehydriding rate than the activated Sample B. Sample A exhibits quite a larger dehydriding rate and quantity of hydrogen desorbed for 60 min than any other Mg-xNi-yFe2O3-zM (M=transition metals) samples. An addition of a relatively larger amount of Ti is considered to lead to quite a high hydriding rate and a high dehydriding rate of Sample A.

  20. Mechanisms of age-hardening in two Al-Cu-Mg alloys studied by positron annihilation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ferragut, R. [Univ. Nacional del Centro de la Provincia de Buenos Aires, Tandil (Argentina). IFIMAT; INFM and Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Somoza, A. [Univ. Nacional del Centro de la Provincia de Buenos Aires, Tandil (Argentina). IFIMAT; Dupasquier, A. [INFM and Dipt. di Fisica, Politecnico di Milano, Milano (Italy); Polmear, I.J. [Monash Univ., School of Physics and Materials Engineering, Melbourne (Australia)

    2002-07-01

    Age-hardening at 150 C has been studied in an Al-Cu-Mg alloy microalloyed with 0.1 at.% Ag and the commercial alloy 2024. Positron annihilation lifetime spectroscopy (PALS) was combined with measurements of microhardness changes during ageing at 150 C. Both alloys are known to harden in two stages separated by an extended plateau. Combined PALS and hardness data shows that the effect of Ag is to enhance vacancy trapping at Mg atoms in competition with the formation of mobile vacancy-Cu pairs. Thus, the addition of Ag gives a reduction of Cu atoms mobility, leading to slower initial hardening in comparison with a silver-free alloy with similar Cu:Mg ratio. In both alloys, the second stage of hardening begins before increases occur in positron lifetimes that indicate the formation of misfit interfaces (i.e. semi-coherent precipitates). This observation supports the view that this second stage of hardening in alloys based on the Al-Cu-Mg system is associated mainly with the growth and transformation of coherent GP(Cu,Mg) zones. The PALS data are consistent with the hypothesis that the X' phase, previously observed to be present in Al-Cu-Mg-Ag at peak ageing, develops misfit interfaces with the matrix. (orig.)

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

    Science.gov (United States)

    Taddee, Chutirat; Kamwanna, Teerasak; Amornkitbamrung, Vittaya

    2016-09-01

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

  2. Influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers, Fe/Cr/Fe- and Fe/MgO/Fe multilayers; Untersuchung der Morphologie und magnetische Eigenschaften von ionenstrahl-gesputterten Eisen-Einzelschichten, Fe/Cr/Fe- und Fe/MgO/Fe-Schichtsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Steeb, Alexandra

    2007-04-05

    In this PhD Thesis, the influence of the surface topography, morphology and structure on magnetic properties of ion beam sputtered iron layers on GaAs is examined. To analyze the structure of the produced iron films, low energy electron diffraction and scanning tunneling microscopy is employed. The utilized methods to investigate the magnetic properties are Kerr- and SQUID-magnetometry and ferromagnetic resonance. It is demonstrated that on untreated as well as on presputtered and heated GaAs substrates the sputtered iron films grow epitaxially. The least surface roughness of 1 A exhibit iron films grown on untreated GaAs, while iron films on heated GaAs have the highest roughness of 30 A. The largest crystal anisotropy constant is found for the presputtered GaAs/Fe-System. For this preparation method, two monolayers of iron are determined to be magnetically dead layers. At a film thickness of 100 A, 83% of the value for saturation magnetization of bulk iron are achieved. The small observed FMR-linewidths confirm the good bulk properties of the ion beam sputtered iron. Furthermore, an antiferromagnetic interlayer exchange coupling in sputtered Fe/Cr/Fe-films was achieved. For a thickness of 12 to 17 A of the chrome interlayer, a coupling strength up to 0.2 mJ/m{sup 2} is found. To account for the small coupling strength, a strong intermixing at the interface is assumed. Finally, epitaxial Fe/MgO/Fe/FeMn multilayers are deposited on GaAs. After the structuring, it is possible to detect tunneling processes in the tunneling contacts with current-voltage measurements. The tunnel magneto resistance values of 2% are small, which can be explained by the absence of sharp, well-defined interfaces between the Fe/FeMn and the Fe/MgO interfaces. These results demonstrate, that analog to MBE the ion beam sputtering method realizes good magnetic bulk properties. However, interface sensitive phenomena are weakened because of a strong intermixing at the interfaces. (orig.)

  3. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr and Cu compounds

    Indian Academy of Sciences (India)

    U Turgut

    2004-11-01

    Chemical effects on the K shell fluorescence yields of Fe, Mn, Co, Cr and Cu compounds were investigated. Samples were excited using 59.5 keV energy photons from a 241Am radioisotope source. K X-rays emitted by samples were counted by a Si(Li) detector with a resolution 160 eV at 5.9 keV. Chemical effects on the K shell fluorescence yields (K) for Fe, Mn, Co, Cr and Cu compounds were observed. The values are compared with theoretical, semiempirical fit and experimental ones for the pure elements.

  4. Modeling and analysis of soybean (Glycine max. L Cu/Zn, Mn and Fe superoxide dismutases

    Directory of Open Access Journals (Sweden)

    V. Ramana Gopavajhula

    2013-01-01

    Full Text Available Superoxide dismutase (SOD, EC 1.15.1.1 is an important metal-containing antioxidant enzyme that provides the first line of defense against toxic superoxide radicals by catalyzing their dismutation to oxygen and hydrogen peroxide. SOD is classified into four metalloprotein isoforms, namely, Cu/Zn SOD, Mn SOD, Ni SOD and Fe SOD. The structural models of soybean SOD isoforms have not yet been solved. In this study, we describe structural models for soybean Cu/Zn SOD, Mn SOD and Fe SOD and provide insights into the molecular function of this metal-binding enzyme in improving tolerance to oxidative stress in plants.

  5. Microstructure and Tribological Behaviour of CrCuFeNiTi High Entropy Alloys

    OpenAIRE

    Sobiyi Kehinde; Bodunrin Michael; Akinlabi Esther; Obadele Babatunde

    2016-01-01

    The microstructure, hardness and wear performance of CrCuFeTiNi high entropy alloy were evaluated. The alloy was produced by mixing constituent elements, consolidated and melted using vacuum arc furnace. The X-ray diffraction analysis confirmed that the alloy is composed of FCC and BCC simple phases. The microstructure contains three regions that were rich in Cu, Cr and Fe which resulted from segregation of constituent elements. The Vickers micro hardness of the alloy was determined as HV0.5 ...

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

    OpenAIRE

    Milla González, Miguel

    2013-01-01

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

  7. Layered Double Hydroxides with Hydrotalcite—type Structure Containing Fe3+,Al3+ and Mg2+

    Institute of Scientific and Technical Information of China (English)

    GUOXiong-hua; LIShu-ping; HOUWan-guo; HANShu-hua; HUJi-fan; LIDong-qing

    2003-01-01

    Layered double hydroxides(LDHs)with hydrotalcite-type structure containing Fe3+,Al3+ and Mg2+ were prepared by means of a coprecipitation method.The products were characterized by element analysis, X-ray powder diffraction and transmission electron microscopy.It was found that even if the molar ratio of n(Fe+Al)/n(Fe+Al+Mg)>0.33,yet a pure hydrotalcite-like compound(HTlc)phase was gained when n(Fe)/n(Al+Mg+Fe)≤0.30 and n(Al+Mg+Fe)≤0.30;the Al(OH)3 phase appeared in the products when n(Al)/n(Al+Mg+Fe)>0.30;and an amorphous phase emerged when n(Fe)/n(Al+Mg+Fe)>0.33.These results show that there is no concentration superposition effect between Fe3+ and Al3+ on the crystalline state of the produced samples.In our previous work,the concentration superposition effect between Zn2+ and Mg2+ in the synthesis of Zn-Mg-Al-LDHs was found.For the prepared Fe-Al-Mg-LDHs samples,the value of lattice parameter a is between 0.30-0.32nm;and the value of lattice parameter c is between 2.30-2.47nm,the bassl spacing is in the range of 0.76-0.83nm.When the ratio of n(Fe)/n(Al)is a constant,the values of a and c increase with the increase of the Mg2+ content of the produced samples.The mean particle size and the mean crystal grain were determined by virtue of a particle-size instrument,XRD-Scherrer formulsa and TEM method,respectively.

  8. Brazing characteristics of a Zr-Ti-Cu-Fe eutectic alloy filler metal for Zircaloy-4

    Science.gov (United States)

    Lee, Jung G.; Lim, C. H.; Kim, K. H.; Park, S. S.; Lee, M. K.; Rhee, C. K.

    2013-10-01

    A Zr-Ti-Cu-Fe quaternary eutectic alloy was employed as a new Be-free brazing filler metal for Zircaloy-4 to supersede physically vapor-deposited Be coatings used conventionally with several disadvantages. The quaternary eutectic composition of Zr58Ti16Cu10Fe16 (at.%) showing a low melting temperature range from 832 °C to 853 °C was designed by a partial substitution of Zr with Ti based on a Zr-Cu-Fe ternary eutectic system. By applying an alloy ribbon with the determined composition, a highly reliable joint was obtained with a homogeneous formation of predominantly grown α-Zr phases owing to a complete isothermal solidification, exhibiting strength higher than that of Zircaloy-4. The homogenization of the joint was rate-controlled by the diffusion of the filler elements (Ti, Cu, and Fe) into the Zircaloy-4 base metal, and the detrimental segregation of the Zr2Fe phase in the central zone was completely eliminated by an isothermal holding at a brazing temperature of 920 °C for 10 min.

  9. L10 ordered structures in Al-Cu-(Mg alloys at the early stages of elevated temperature aging

    Directory of Open Access Journals (Sweden)

    Fuzhong, Xia

    2016-09-01

    Full Text Available This study concerns the precipitation structures of Al-3Cu and Al-3Cu-1.78Mg (wt. % alloys at the early stages of elevated temperature aging. The Al-3Cu and Al-3Cu-1.78 Mg alloys were solution treated at 540 °C and 500 °C for 2 h, respectively, and then aged at 190 °C for 2 min. The precipitation structures in aged Al-3Cu-(1.78Mg alloys were characterized by Transmission Electron Microscopy (TEM and High Resolution Transmission Electron Microscopy (HTREM. 001 zone axis Selected area electron diffraction patterns indicate that L10 ordered structures are formed in the two aged alloys. HRTEM experiments reveal the partial dislocations on the interfaces of L10 ordered structures. From comparing experimental results with that in the literature, it is concluded that the L10 ordered structures in aged Al-3Cu alloy consist of Al and Cu atoms, and they are comprised by Al, Cu and Mg atoms together in the aged Al-3Cu-1.78Mg alloy. On the basis of precipitate growing thermodynamics, it is thought the L10 ordered structures act as nuclei for GP zones in Al-Cu-(Mg alloys during aging.En este trabajo se estudian las estructuras de precipitación en Al-3Cu y Al-3Cu-1,78Mg (% en peso en los estados iniciales de envejecimiento a temperatura elevada. Las aleaciones Al-3Cu y Al-3Cu-1.78 Mg fueron sometidas a un tratamiento térmico de solución de 2 h a 540 °C y 500 °C, respectivamente, y posteriormente envejecidas 2 min a 190 °C. Las estructuras de precipitación en Al-3Cu-(1.78Mg envejecido fueron caracterizadas por microscopía electrónica de transmisión (TEM y por microscopía electrónica de transmisión de alta resolución (HTREM. Los diagramas de difracción de electrones de área seleccionada indican que se forman estructuras ordenadas L10 en las dos aleaciones envejecidas. Experimentos de HRTEM revelan la presencia de dislocaciones parciales en las intercaras de las estructuras L10 ordenadas. Comparando estos resultados experimentales con la

  10. Dielectric behaviour of MgFe2O4 prepared from chemically beneficiated iron ore rejects

    Indian Academy of Sciences (India)

    K S Rane; V M S Verenkar; P Y Sawant

    2001-06-01

    Chemically beneficiated high silica/alumina iron ore rejects (27–76% Fe2O3) were used to synthesize iron oxides of purity 96–98% with SiO2/Al2O3 ratio reduced to 0.03. The major impurities on chemical beneficiations were Al, Si, and Mn in the range 2–3%. A 99.73% purity Fe2O3 was also prepared by solvent extraction method using methyl isobutyl ketone (MIBK) from the acid extracts of the ore rejects. The magnesium ferrite, MgFe2O4, prepared from these synthetic iron oxides showed high resistivity of ∼ 108 ohm cm. All ferrites showed saturation magnetization, 4s, in the narrow range of 900–1200 Gauss and the Curie temperature, c, of all these fell within a small limit of 670 ± 30 K. All ferrites had low dielectric constants ('), 12–15, and low dielectric loss, tan , which decreased with the increase in frequency indicating a normal dielectric dispersion found in ferrites. The presence of insignificant amount of polarizable Fe2+ ions can be attributed to their high resistances and low dielectric constants. Impurities inherent in the samples had no marked influence on the electrical properties of the ferrites prepared from the iron ore rejects, suggesting the possibility of formation of ferrite of constant composition, MgFe2O4, of low magnetic and dielectric losses at lower temperatures of 1000°C by ceramic technique.

  11. The effects of Mg addition on the microstructure and mechanical properties of thixoformed Al–5%Si–Cu alloys

    Energy Technology Data Exchange (ETDEWEB)

    Salleh, M.S., E-mail: shukor@utem.edu.my [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Selangor (Malaysia); Department of Manufacturing Process, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Omar, M.Z., E-mail: zaidi@eng.ukm.my [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Selangor (Malaysia); Syarif, J., E-mail: syarif@eng.ukm.my [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Selangor (Malaysia)

    2015-02-05

    Highlights: • The average globule size of α-Al decreased when Mg amount is increased. • T6 heat treatment has increased the strength of the thixoformed alloys. • The elongation after T6 heat treatment is even significantly improved. • Thixoformed alloy with high Mg content shows a brittle type fracture. • Thixoformed alloy in T6 condition shows a ductile type fracture. - Abstract: In this study, the effects of different amounts of magnesium (Mg) on the microstructures and tensile properties of thixoformed Al–5%Si–Cu alloys were investigated. Three different alloys containing various amounts of Mg (0.5, 0.8 and 1.2 wt%) were prepared through the cooling slope casting technique, before they were thixoformed using a compression press. Several of the thixoformed samples were then treated with a T6 heat treatment, that is, solution treatment at 525 °C for 8 h, quenching in warm water at 60 °C, followed by aging at 155 °C for 4 h. All of the samples were then characterised by optical microscopy (OM), scanning electron microscopy (SEM) energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis as well as by tensile tests. The results revealed that magnesium was able to refine the size of α-Al globules and the eutectic silicon in the samples. It was also observed that a compact π-Al{sub 9}FeMg{sub 3}Si{sub 5} phase was formed when the magnesium content was 0.8 wt% and 1.2 wt%. The mechanical properties of the thixoformed alloys improved significantly after the T6 heat treatment. The highest attainment was recorded by the latter alloy (i.e. with 1.2 wt%Mg) with its ultimate tensile strength (UTS) as high as 306 MPa, yield strength (YS), 264 MPa, and elongation to fracture of 1.8%. The fracture of thixoformed alloy with a low Mg content (0.5 wt%) showed a combination of dimple and cleavage fracture, whereas in the alloy that contained the highest Mg content (1.2 wt%), cleavage fracture was observed.

  12. Effects of Cu Layer Width on the Giant Magneto-impedance Effect in Sandwich FeCuNbCrSiB/Cu/FeCuNbCrSiB Films With a Meander Line Structure%Cu层宽度对弯曲型三明治结构FeCuNbCrSiB/Cu/FeCuNbCrSiB多层膜巨磁阻抗效应的影响

    Institute of Scientific and Technical Information of China (English)

    张亚民; 陈吉安; 周勇; 丁文; 王明军; 高孝裕; 周志敏

    2005-01-01

    采用射频磁控溅射方法和微细加工工艺制备了不同Cu层宽度的弯曲型三明治结构的FeCuNbCrSiB/Cu/FeCuNbCrSiB多层膜,在频率1~40MHz下研究了Cu层宽度对多层膜的纵向和横向巨磁阻抗效应的影响.结果表明,弯曲型三明治结构多层膜的巨磁阻抗率随Cu层宽度的变化具有显著的变化,在频率10MHz、磁场12kA/m下,当Cu层宽度为0.4mm时,纵向、横向巨磁阻抗率分别达-57%、-65%.

  13. Mg-Fe-mixed oxides derived from layered double hydroxides: A study of the surface properties

    Directory of Open Access Journals (Sweden)

    Marinković-Nedučin Radmila P.

    2011-01-01

    Full Text Available The influence of surface properties on the selectivity of the synthesized catalysts was studied, considering that their selectivity towards particular hydrocarbons is crucial for their overall activity in the chosen Fischer- -Tropsch reaction. Magnesium- and iron-containing layered double hydroxides (LDH, with the general formula: [Mg1-xFex(OH2](CO3x/2?mH2O, x = = n(Fe/(n(Mg+n(Fe, synthesized with different Mg/Fe ratio and their thermally derived mixed oxides were investigated. Magnesium was chosen because of its basic properties, whereas iron was selected due to its well-known high Fischer-Tropsch activity, redox properties and the ability to form specific active sites in the layered LDH structure required for catalytic application. The thermally less stable multiphase system (synthesized outside the optimal single LDH phase range with additional Fe-phase, having a lower content of surface acid and base active sites, a lower surface area and smaller fraction of smaller mesopores, showed higher selectivity in the Fischer-Tropsch reaction. The results of this study imply that the metastability of derived multiphase oxides structure has a greater influence on the formation of specific catalyst surface sites than other investigated surface properties.

  14. Perpendicular magnetic anisotropy in composite MgO/CoFeB/Ta/[Co/Pd]n structures

    Science.gov (United States)

    Garcia-Vazquez, Valentin; Chang, Yao-Jen; Canizo-Cabrera, A.; Garzon-Roman, Abel; Wu, Te-ho

    2016-02-01

    The impact of a non-magnetic Ta spacer layer on the perpendicular magnetic anisotropy (PMA) of composite magnetic structures constituted by ultra-thin Co/Pd multilayers (MLs) and MgO/CoFeB was studied. Composite structures lacking a Ta layer present in-plane magnetic anisotropy. The strong perpendicular anisotropy observed in sole Co/Pd MLs is not sufficient to pull the magnetic moment out of the film plane, not even after annealing at 300 or 350 °C. PMA with squareness values close to unity and annealing stability up to 350 °C is observed after the insertion of an ultra-thin Ta layer. Our study demonstrates that Ta layer is essential for obtaining perpendicular magnetic axis in MgO/CoFeB/Ta/[Co/Pd]6. The exchange coupling between the MgO/CoFeB bilayer and the Co/Pd MLs is ferromagnetic with sharp switching characteristics. Perpendicular composite structures with sharp magnetization reversal and annealing stability are relevant in perpendicular CoFeB-based magnetic tunnel junctions for the development of gigabit-scale nonvolatile memory.

  15. Biocompatibility Assessment of Novel Bioresorbable Alloys Mg-Zn-Se and Mg-Zn-Cu for Endovascular Applications: In- Vitro Studies

    Science.gov (United States)

    Budiansky, Noah; McGoron, Anthony J.

    2013-01-01

    Previous studies have shown that using biodegradable magnesium alloys such as Mg-Zn and Mg-Zn-Al possess the appropriate mechanical properties and biocompatibility to serve in a multitude of biological applications ranging from endovascular to orthopedic and fixation devices. The objective of this study was to evaluate the biocompatibility of novel as-cast magnesium alloys Mg-1Zn-1Cu wt.% and Mg-1Zn-1Se wt.% as potential implantable biomedical materials, and compare their biologically effective properties to a binary Mg-Zn alloy. The cytotoxicity of these experimental alloys was evaluated using a tetrazolium based- MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and a lactate dehydrogenase membrane integrity assay (LDH). The MTS assay was performed on extract solutions obtained from a 30-day period of alloy immersion and agitation in simulated body fluid to evaluate the major degradation products eluted from the alloy materials. Human foreskin fibroblast cell growth on the experimental magnesium alloys was evaluated for a 72 hour period, and cell death was quantified by measuring lactate dehydrogenase concentrations. Both Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. The Mg-Zn-Cu alloy was found to completely degrade within 72 hours, resulting in lower human foreskin fibroblast cell viability. The Mg-Zn-Se alloy was shown to be less cytotoxic than both the Mg-Zn-Cu and Mg-Zn alloys. PMID:24058329

  16. Biocompatibility Assessment of Novel Bioresorbable Alloys Mg-Zn-Se and Mg-Zn-Cu for Endovascular Applications: In- Vitro Studies.

    Science.gov (United States)

    Persaud-Sharma, Dharam; Budiansky, Noah; McGoron, Anthony J

    2013-01-01

    Previous studies have shown that using biodegradable magnesium alloys such as Mg-Zn and Mg-Zn-Al possess the appropriate mechanical properties and biocompatibility to serve in a multitude of biological applications ranging from endovascular to orthopedic and fixation devices. The objective of this study was to evaluate the biocompatibility of novel as-cast magnesium alloys Mg-1Zn-1Cu wt.% and Mg-1Zn-1Se wt.% as potential implantable biomedical materials, and compare their biologically effective properties to a binary Mg-Zn alloy. The cytotoxicity of these experimental alloys was evaluated using a tetrazolium based- MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and a lactate dehydrogenase membrane integrity assay (LDH). The MTS assay was performed on extract solutions obtained from a 30-day period of alloy immersion and agitation in simulated body fluid to evaluate the major degradation products eluted from the alloy materials. Human foreskin fibroblast cell growth on the experimental magnesium alloys was evaluated for a 72 hour period, and cell death was quantified by measuring lactate dehydrogenase concentrations. Both Mg-Zn-Se and Mg-Zn-Cu alloys exhibit low cytotoxicity levels which are suitable for biomaterial applications. The Mg-Zn-Cu alloy was found to completely degrade within 72 hours, resulting in lower human foreskin fibroblast cell viability. The Mg-Zn-Se alloy was shown to be less cytotoxic than both the Mg-Zn-Cu and Mg-Zn alloys.

  17. Ultrasonic assisted-Fenton-like degradation of nitrobenzene at neutral pH using nanosized oxides of Fe and Cu.

    Science.gov (United States)

    ElShafei, Gamal M S; Yehia, F Z; Dimitry, O I H; Badawi, A M; Eshaq, Gh

    2014-07-01

    Ultrasonic-assisted heterogeneous Fenton reaction was used for degradation of nitrobenzene (NB) at neutral pH conditions. Nano-sized oxides of α-Fe2O3 and CuO were prepared, characterized and tested in degradation of NB (10 mg L(-1)) under sonication of 20 kHz at 25 °C. Complete degradation of NB was effected at pH 7 in presence of 10 mM H2O2 after 10 min of sonication in presence of α-Fe2O3 (1.0 g L(-1)), (k=0.58 min(-1)) and after 25 min in case of CuO (k=0.126 min(-1)). α-Fe2O3 showed also effective degradation under the conditions of 0.1 g L(-1) oxide and 5.0 mM of H2O2, even though with a lower rate constant (0.346 min(-1)). Sonication plays a major role in enhancing the production of hydroxyl radicals in presence of solid oxides. Hydroxyl radicals-degradation pathway is suggested and adopted to explain the differences noted in rate constants recorded on using different oxides. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Crystal structure of the quaternary compounds CuFe2AlSe4 and CuFe2GaSe4 from X-ray powder diffraction

    Indian Academy of Sciences (India)

    G E Delgado; A J Mora; P Grima-Gallardo; M Muñoz; S Durán; M Quintero; J M Briceño

    2015-08-01

    The crystal structure of the quaternary compounds CuFe2AlSe4 and CuFe2GaSe4, belonging to the system I–II2–III–VI4, were characterized using X-ray powder diffraction data. Both compounds crystallize in the tetragonal space group I42m (No. 121), = 2, with unit cell parameters = 5.609(1) Å, = 10.963(2) Å for CuFe2AlSe4 and = 5.6165(3) Å, = 11.075(1) Å for CuFe2GaSe4. These compounds are isostructural with CuFe2InSe4, and have a normal adamantane stannite structure.

  19. Determination of P, K, Ca, Mg, Mn, Fe, Cu, Na, Zn and Al in compound fertilizers by X-ray fluorescence spectrometry with fused glass disc sample preparation%熔融制样-X射线荧光光谱法快速测定复合肥中的磷、钾、钙、镁、锰、铁、铜、钠、锌和铝

    Institute of Scientific and Technical Information of China (English)

    任春生; 廖海平; 鲍惠君; 朱迪琦; 何阳

    2011-01-01

    为实现复合肥样品中多元素的同时分析,采用熔融片法制样,有效地消除了试样的粒度效应,用X射线荧光光谱法测定复合肥样品中磷、钾、钙、镁、锰、铁、铜、钠、锌和铝10个元素,对仪器工作条件进行了试验并选定最佳条件,使各元素测定所要求的灵敏度和准确度得到满足,以8个合成的样品作为校准样品,采用固定理论α影响系数进行回归及基体效应校正,方法精密度(RSD,n=8)≤1.36%,分析结果与化学法进行对照基本一致.%A method for the determination of including P, K, Ca, Mg, Mn, Fe, Cu, Na, Zn and Al in compound fertilizers by X-ray fluorescence spectrometry with fused glass disc sample preparation was reported in this paper.The granularity effect in the analysis was eliminated by the fusion method of sam pie-dissolution.The working conditions of the instrument were also studied and optimized to meet with the requirements of sensitivity and accuracy of determination.Eight composed samples were used as the calibration standards.The matrix effect was corrected with fixed theoretical alpha coefficient method.The precision of the method was RSD≤1.36% (n =8).The results were in agreement with those by chemical methods.

  20. Induced Ferromagnetism at BiFeO3/YBa2Cu3O7 Interfaces

    OpenAIRE

    Zhu, Jian-Xin; WEN, XIAO-DONG; Haraldsen, J. T.; He, Mi; C. Panagopoulos; Chia, Elbert E. M.

    2014-01-01

    Transition metal oxides (TMOs) exhibit many emergent phenomena ranging from high-temperature superconductivity and giant magnetoresistance to magnetism and ferroelectricity. In addition, when TMOs are interfaced with each other, new functionalities can arise, which are absent in individual components. Here, we report results from first-principles calculations on the magnetism at the BiFeO3/YBa2Cu3O7 interfaces. By comparing the total energy for various magnetic spin configurations inside BiFe...

  1. 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)

  2. Structural and magnetic properties of FeMnx chains (x =1 -6 ) supported on Cu2N /Cu (100)

    Science.gov (United States)

    Choi, Deung-Jang; Robles, Roberto; Gauyacq, Jean-Pierre; Ternes, Markus; Loth, Sebastian; Lorente, Nicolás

    2016-08-01

    Heterogeneous atomic magnetic chains are built by atom manipulation on a Cu2N /Cu (100) substrate. Their magnetic properties are studied and rationalized by a combined scanning tunneling microscopy (STM) and density functional theory (DFT) work completed by model Hamiltonian studies. The chains are built using Fe and Mn atoms ontop of the Cu atoms along the N rows of the Cu2N surface. Here, we present results for FeMnx chains (x =1 -6 ) emphasizing the evolution of the geometrical, electronic, and magnetic properties with chain size. By fitting our results to a Heisenberg Hamiltonian we have studied the exchange-coupling matrix elements J for different chains. For the shorter chains, x ≤2 , we have included spin-orbit effects in the DFT calculations, extracting the magnetic anisotropy energy. Our results are also fitted to a simple anisotropic spin Hamiltonian and we have extracted values for the longitudinal-anisotropy D and transversal-anisotropy E constants. These parameters together with the values for J allow us to compute the magnetic excitation energies of the system and to compare them with the experimental data.

  3. CaO+SiO2+Al2O3+MgO+FeO五元渣系中FeO活度的研究%Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags

    Institute of Scientific and Technical Information of China (English)

    吕庆; 赵丽树; 王成立; 张淑会; 李福民; 刘增勋

    2008-01-01

    Activities of FeO in CaO-SiO2-Al2O3-MgO-FeO slags were determined at 1673 K by electrochemical measurements of the solid electrolyte cell: Mo |Mo+MoO2[ZrO2(MgO)[Fe+(CaO-SiO2-Al2O3-MgO-FeO)+Ag|Fe. The influences of slag compositions and basicity on FeO activities were analyzed. The results reveal that, for slags of fixed (%CaO)/(%SiO2) ratio, MgO and Al2O3 content, there was an increase of FeO activities with increase of FeO content. For slags with constant {(%CaO)+ (%MgO)}/(%SiO2) ratio, fixed FeO and Al,2O3 content, FeO activities decreased when MgO content increased from 5% to 10%, and increased with the increase of MgO content when it was over 10%. The FeO activities increased when (%CaO)/(%SiO2) ratio changed from 1.03 to 1.30 in the slags of constant MgO, FeO and Al2O3 content.

  4. 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.

  5. MgO/Cu2O Superlattices: Growth of Epitaxial Two-Dimensional Nanostructures

    Science.gov (United States)

    Yang, M. J.; Wadekar, P. V.; Hsieh, W. C.; Huang, H. C.; Lin, C. W.; Chou, J. W.; Liao, C. H.; Chang, C. F.; Seo, H. W.; You, S. T.; Tu, L. W.; Lo, I. K.; Ho, N. J.; Yeh, S. W.; Liao, H. H.; Chen, Q. Y.; Chu, W. K.

    2016-12-01

    Alternated stacking of dissimilar layers can produce novel superlattice materials with multiple functionalities. The majority of such work reported in literature on epitaxial superlattices has been on alternating layers with the same space group (SG) and crystal structure (CS), whereas superlattices with the same CS but different SG have not been studied as much. We have grown superlattices with two well-known oxide materials, viz. cuprite (Cu2O, CS = cubic and SG = Pn bar{3} m) and magnesium oxide (MgO, CS = cubic, SG = Fm bar{3} m). An MgO buffer layer grown near 650°C at the film-substrate interface was found to be essential to achieving reasonable long-range atomic order. Grazing-angle x-ray diffraction, x-ray reflectivity, and electron diffraction analyses as well as transmission electron microscopy were used to investigate the interface abruptness, smoothness, and general crystallinity of the individual layers. Interdiffusion between MgO and Cu2O near interfacial regions places a limit of 250°C on the growth temperature for fabrication of superlattices with reasonably sharp interfaces.

  6. Building of CoFe2/CoFe2O4/MgO architectures: Structure, magnetism and surface functionalized by TiO2

    Science.gov (United States)

    Wang, M.; Ma, Y. Q.; Sun, X.; Geng, B. Q.; Wu, M. Z.; Zheng, G. H.; Dai, Z. X.

    2017-01-01

    Well-dispersed uniform CoFe2O4 nanoparticles were prepared and then coated by MgO through thermal decomposition of a metal-organic salt in organic solvent. Then CoFe2O4/MgO were reduced in a H2/N2 mixture gas and subsequently oxidized in an ambient atmosphere in order to build CoFe2/CoFe2O4/MgO architectures with high magnetization, good chemical stability and dispersivity, which are useful in some practical applications. MgO can be dissolved by the HCl solution. The surfaces of CoFe2O4, CoFe2/MgO, CoFe2 and CoFe2/CoFe2O4 magnetic particles were functionalized by TiO2 to prepare the magnetically separable photocatalysts. The rattle-type particles were obtained without the assistance of template and etchant. The photocatalytic activity of these photocatalysts in degradation of methylene blue and the magnetic separability were investigated: The nanosheet-shaped TiO2 and rattle-type particles exhibited good photocatalytic performance; The highest degradation efficiency reaches 93% for the CoFe2/TiO2 sample which has the highest magnetization value of 42 emu/g, beneficial for the recovery of catalyst after degradation.

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

    Science.gov (United States)

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

  8. Studies on the interaction between 9-fluorenylmethyl chloroformate and Fe3+ and Cu2+ ions: Spectroscopic and theoretical calculation approach

    Science.gov (United States)

    Gu, Zhenyan; Lei, Wu; Shi, Wenyan; Hao, Qingli; Si, Weimeng; Xia, Xifeng; Wang, Fengxiang

    2014-11-01

    The interaction between 9-fluorenylmethyl chloroformate (FMOC-Cl) and Fe3+ and Cu2+ ions was investigated using fluorescence, UV/Vis absorption spectroscopies and theoretical calculation. The optical property of FMOC-Cl was studied in detail in absence and presence of various transition metal ions with particular affinity to Fe3+ and Cu2+ ions. With the fluorescence characteristic band centered at 307 and 315 nm for FMOC-Cl, the introduction of Fe3+ or Cu2+ ions leads to the fluorescence quenching of FMOC-Cl with different shift and intensities of two fluorescent bands. It allows us to differentiate between FMOC-Cl and Fe3+ and Cu2+ ions interaction behavior. The study on fluorescent kinetics confirms that the fluorescence quenching of FMOC-Cl with Fe3+ and Cu2+ ions is based on the formation of non-fluorescent material, that is, static quenching. Further analyses of bond lengths, Mulliken atomic charges and the frontier orbital compositions for FMOC-Cl and its complexes with Fe3+ and Cu2+ ions were carried out. The theoretical calculations prove the fluorescence quenching originates from the formation of coordination bonds between the oxygen atom of the carbonyl group of FMOC-Cl and Fe3+ and Cu2+ ions. The commercially available FMOC-Cl can be used as excellent fluorescent probe toward Fe3+ and Cu2+ ions with high sensitivity.

  9. Simulated space weathering of Fe- and Mg-rich aqueously altered minerals using pulsed laser irradiation

    Science.gov (United States)

    Kaluna, H. M.; Ishii, H. A.; Bradley, J. P.; Gillis-Davis, J. J.; Lucey, P. G.

    2017-08-01

    Simulated space weathering experiments on volatile-rich carbonaceous chondrites (CCs) have resulted in contrasting spectral behaviors (e.g. reddening vs bluing). The aim of this work is to investigate the origin of these contrasting trends by simulating space weathering on a subset of minerals found in these meteorites. We use pulsed laser irradiation to simulate micrometeorite impacts on aqueously altered minerals and observe their spectral and physical evolution as a function of irradiation time. Irradiation of the mineral lizardite, a Mg-phyllosilicate, produces a small degree of reddening and darkening, but a pronounced reduction in band depths with increasing irradiation. In comparison, irradiation of an Fe-rich aqueously altered mineral assemblage composed of cronstedtite, pyrite and siderite, produces significant darkening and band depth suppression. The spectral slopes of the Fe-rich assemblage initially redden then become bluer with increasing irradiation time. Post-irradiation analyses of the Fe-rich assemblage using scanning and transmission electron microscopy reveal the presence of micron sized carbon-rich particles that contain notable fractions of nitrogen and oxygen. Radiative transfer modeling of the Fe-rich assemblage suggests that nanometer sized metallic iron (npFe0) particles result in the initial spectral reddening of the samples, but the increasing production of micron sized carbon particles (μpC) results in the subsequent spectral bluing. The presence of npFe0 and the possible catalytic nature of cronstedtite, an Fe-rich phyllosilicate, likely promotes the synthesis of these carbon-rich, organic-like compounds. These experiments indicate that space weathering processes may enable organic synthesis reactions on the surfaces of volatile-rich asteroids. Furthermore, Mg-rich and Fe-rich aqueously altered minerals are dominant at different phases of the aqueous alteration process. Thus, the contrasting spectral slope evolution between the Fe

  10. Effect of Be addition on the precipitation behaviors and mechanical properties in Al-Cu-Li-Mg-Zr-(Ag) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.K. [Dept. of Materials Engineering, Miryang National Univ. (Korea); Chung, D.S. [Dept. of Materials, Ulsan Polytechnic Coll. (Korea); Park, H.S. [Jisung Precision Inc. Ltd, Changwon, Kyungnam (Korea); Enoki, M. [Dept. of Materials Engineering, Univ. of Tokyo (Japan)

    2005-07-01

    The effect of beryllium (Be) on the precipitation behaviors and mechanical properties of Al-Cu-Li-Mg-Zr-(Ag) alloys was investigated. The results show that adding 0.02%Be to Al-Cu-Li-Mg-Zr-(Ag) alloys, the elongation of the alloy increased without significant decrease in strength and the aging response was accelerated. In a Al-Cu-Li-Mg-Zr-(Ag) alloy, G.P. zone was formed at early aging time (2 h) and T{sub 1} and {theta}' phases were formed at peak-aging and over-aging times, while in Al-Cu-Li-Mg-Zr-(Ag)-Be alloys T{sub 1} and {theta}' phases were formed at early aging time (2 h) and the density of {theta}' phase was very low and fine T{sub 1} phases were homogeneously distributed at peak-aging and over-aging times. (orig.)

  11. Grain Refinement and High-Performance of Equal-Channel Angular Pressed Cu-Mg Alloy for Electrical Contact Wire

    Directory of Open Access Journals (Sweden)

    Aibin Ma

    2014-12-01

    Full Text Available Multi-pass equal-channel angular pressing (EACP was applied to produce ultrafine-grained (UFG Cu-0.2wt%Mg alloy contact wire with high mechanical/electric performance, aim to overcome the catenary barrier of high-speed trains by maximizing the tension and improving the power delivery. Microstructure evolution and overall properties of the Cu-Mg alloy after different severe-plastic-deformation (SPD routes were investigated by microscopic observation, tensile and electric tests. The results show that the Cu-Mg alloy after multi-pass ECAP at 473 K obtains ultrafine grains, higher strength and desired conductivity. More passes of ECAP leads to finer grains and higher strength, but increasing ECAP temperature significantly lower the strength increment of the UFG alloy. Grain refinement via continuous SPD processing can endow the Cu-Mg alloy superior strength and good conductivity characteristics, which are advantageous to high-speed electrification railway systems.

  12. Corrosion Behavior of Mg65Cu25-xZnxGd10 (x=0, 5) Metallic Glass

    Institute of Scientific and Technical Information of China (English)

    LI Guoqiang; HUANG Wei; LI Huanxi; ZHENG Lijing; Hashmi M F

    2008-01-01

    The effect of substitutional element Zn on corrosion behavior of Mg65Cu25Gd10 glass was investigated. The amorphous structure of Mg65Cu25-xZnxGd10(x=0, 5) alloys were examined by X-ray diffractometry and differential scanning calorimetry (DSC). The dissolution rates of Mg65Cu25-xZnxGd10(x=0,5) metallic glasses in a 5 wt% NaCl solution with pH value of 7 were determined by a hydrogen evolution testing method. The corrosion behavior of these alloys was characterized using dipping tests with 5 wt% NaCl, in combination with electrochemical measurements and scanning electron microscopy (SEM). Results show that the anti-corrosion ability of Mg65Cu25Gd10 alloy is significantly improved due to the addition of Zn. Possible mechanism responsible for the improvement is discussed.

  13. Aging behavior and fatigue crack propagation of high Zn-containing Al-Zn-Mg-Cu alloys with zinc variation

    National Research Council Canada - National Science Library

    Kai Wen Yunqiang Fan Guojun Wang Longbing Jin Xiwu Li Zhihui Li Yongan Zhang Baiqing Xiong

    2017-01-01

    In the present work, the influence of two-step aging treatments on hardness, electrical conductivity and mechanical properties of two high Zn-containing Al-Zn-Mg-Cu alloys with zinc content variation...

  14. Thermal stability and magnetic properties of MgFe2O4@ZnO nanoparticles

    Science.gov (United States)

    Mallesh, S.; Prabu, D.; Srinivas, V.

    2017-05-01

    Magnesium ferrite, MgFe2O4, (MgFO) nanoparticles (NPs) have been synthesized through sol-gel process. Subsequently, as prepared particles were coated with Zinc-oxide (ZnO) layer(s) through ultrasonication process. Thermal stability, structure and magnetic properties of as-prepared (AP) and annealed samples in the temperature range of 350 °C-1200 °C have been investigated. Structural data suggests that AP MgFO NPs and samples annealed below 500 °C in air exhibit stable ferrite phase. However, α-Fe2O3 and a small fraction of MgO secondary phases appear along with ferrite phase on annealing in the temperatures range 500 °C- 1000 °C. This results in significant changes in magnetic moment for AP NPs 0.77 μB increases to 0.92 μB for 1200 °C air annealed sample. The magnetic properties decreased at intermediate temperatures due to the presence of secondary phases. On the other hand, pure ferrite phase could be stabilized with an optimum amount of ZnO coated MgFO NPs for samples annealed in the temperature range 500 °C-1000 °C with improvement in magnetic behavior compared to that of MgFO samples.

  15. Thermally induced perpendicular magnetic anisotropy in CoFeB/MgO/CoFeB based magnetic tunnel junction

    Science.gov (United States)

    Kulkarni, Prabhanjan D.; Khan, Jakeer; Predeep, P.; Chowdhury, P.

    2016-05-01

    Thin films of CoFeB/MgO/CoFeB based MTJ structure were deposited using UHV magnetron sputtering system and post annealing treatment in the temperature range from 100 to 400 °C has been carried out to understand their magnetic anisotropic properties. Though the as-deposited stack possesses in-plane magnetic anisotropy, the changeover to perpendicular magnetic anisotropy happens at temperature above 200 °C. The PMA is maximum (4.5 x 106 erg/cm3) when annealed at 300°C and the stack retains PMA till 350 °C, which is necessary in CMOS technology. The stack regains in-plane magnetic anisotropy at higher annealing temperatures due to intermixing at interfaces.

  16. Progress in bulk MgCu2-type rare-earth iron magnetostrictive compounds

    Institute of Scientific and Technical Information of China (English)

    Ren Wei-Jun; Zhang Zhi-Dong

    2013-01-01

    Studies of bulk MgCu2-type rare-earth iron compounds with Laves phase are reviewed.The relationship between magnetostriction and structural distortion and the consequent crystallographic method for measuring magnetostriction are introduced at first.Then we review recent progress in understanding bulk magnetostrictive Laves phase materials,especially the magnetostriction and the minimization of the anisotropy of the light rare-earth Pr-and Sm-based compounds.Finally,a summary and outlook for this kind of compounds are presented.

  17. Age-hardening characteristic of an Al-Zn-Mg-Cu alloy produced by spray deposition

    Institute of Scientific and Technical Information of China (English)

    WANG Feng; XIONG Baiqing; ZHANG Yongan; ZHU Baohong; LIU Hongwei; ZHANG Zhihui; WANG Zixing

    2007-01-01

    Al-10.8Zn-2.8Mg-1.9Cu alloy was synthesized by spray atomization and deposition technique. GP zones and age-hardening process in the alloy were investigated using high-resolution electron microscopy (HREM), selected area diffraction (SAD), and differential scanning calorimetry (DSC) analysis. The results indicated that spray deposition process accelerated the aging kinetics of the alloy at an aging temperature of 120℃, thereby reducing the peak aging time to 16 h.GPI and GPⅡ are the two types of zones that are major precipitates for the alloy under peak-aged condition. The precipitation sequence for the alloy is also discussed.

  18. STUDY ON THE HOT DEFORMATION BEHAVIORS OF Al-Zn-Mg-Cu-Cr ALUMINUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    G.Y. Lin; Z.F. Zhang; H. Zhang; D.S. Peng; J. Zhou

    2008-01-01

    The hot deformation behaviors and mierostructures of Al-Zn-Mg-Cu-Cr aluminum alloy have been studied using thermal simulation test, optical microscopy and transmission electron microscopy. As a result, the true stress versus true strain curves and the microstructures under various deformation conditions are obtained. The microstructures gradually incline to dynamic-recrystallization with the deformation temperature rising and the recrystallization grains refine with the decrease of deformation temperature or with raising the strain rates. The quantitative relationship between the Zener-HoUomon parameter (Z) and average recrystallization grain size in the subsequent heat treatment is set up.

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

    Science.gov (United States)

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

    2016-09-01

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

  20. First-Principles Study of the Role of Cu in Improving the Coercivity of Nd-Fe-B Permanent Magnets

    Science.gov (United States)

    Tatetsu, Y.; Tsuneyuki, S.; Gohda, Y.

    2016-12-01

    We study the magnetic and electronic properties of Cu-doped Nd2 Fe14 B /NdOx systems with first-principles calculations in order to understand the roles of Cu in improving the coercivity of Nd-Fe-B permanent magnets. By analyzing the formation energies of several model systems, we find that Cu prefers to be at the interface. We conclude that the Cu addition to Nd-Fe-B magnets is a practical way of not only increasing the anisotropy of Nd atoms at the interface but also of lessening the magnetic coupling between the Nd and Fe atoms. Particularly, substituting Fe at the interface of the main phase with Cu works effectively in terms of improving the magnetic anisotropy in Nd atoms. This may explain the coercivity improvements reported recently.

  1. Anisotropic photoelectric film assembled from mesoporous silica (MS)@CuO@FeS2 composite microspheres for improving photoelectric conversion.

    Science.gov (United States)

    Zong, Jie; Zhu, Yihua; Shen, Jianhua; Yang, Xiaoling; Li, Chunzhong

    2013-07-15

    We report a novel strategy for the fabrication of mesoporous silica (MS)@CuO@FeS2 composite microsphere-based anisotropic films that combine the advantages of the CuO and FeS2 materials to improve photoelectric conversion. This was achieved by aligning MS@CuO@FeS2 composite microspheres in a cross-linked gel under a homogeneous magnetic field. The MS@CuO@FeS2 composite microspheres, which were synthesized by a simple layer-by-layer (LbL) self-assembly technique together with a solvothermal method, can absorb a wide range of light and exhibit ferromagnetic properties. In addition, the resulting MS@CuO@FeS2 composite microsphere-based anisotropic film shows photoelectric anisotropy. Such systems are promising for improving the performance of solar cells.

  2. Adsorption of As(III) from Aqueous Solutions by Novel Fe-Mg Type Hydrotalcite.

    Science.gov (United States)

    Ogata, Fumihiko; Kawasaki, Naohito

    2015-01-01

    Morphological and chemical evaluation of Fe-Mg hydrotalcite (Fe-HT) was performed using scanning electron microscopy, X-ray diffraction analysis, and electron microanalysis for application as an adsorbent for water treatment. The adsorption of arsenic III (As(III)) on Fe-HT was evaluated via examination of the effect of the contact time and analysis of the adsorption isotherm. The amount of As(III) adsorbed increased slightly with increasing temperature. The results of the adsorption isotherm studies suggested that As(III) adsorption can be well described by both the Freundlich and Langmuir equations. The adsorption of As(III) on Fe-HT reached equilibrium within 24 h, and the adsorption kinetic data fit the pseudo-second-order kinetic model better than the pseudo-first-order model. The amount of As(III) present on the surface of Fe-HT increased after As(III) adsorption, and the crystalline structure of Fe-HT was maintained after adsorption of As(III). The (003) and (006) peaks in the X-ray diffraction patterns were attributed to basal reflections, and these peaks shifted from respective 2θ values of 10.86 and 21.94° to 11.12 and 22.52°, indicating exchange of As(III) with chloride ions in Fe-HT with consequent narrowing of the inter-layer spacing. Collectively, these results suggest that Fe-HT is prospectively useful for the adsorption of As(III) from aqueous solutions.

  3. Adsorption of perchlorate from aqueous solution by the calcination product of Mg/(Al-Fe) hydrotalcite-like compounds.

    Science.gov (United States)

    Yang, Yiqiong; Gao, Naiyun; Chu, Wenhai; Zhang, Yongji; Ma, Yan

    2012-03-30

    The calcination products containing Mg(II), Al(III), and Fe(III) in the brucite-like layers with varying Mg/Al/Fe molar ratios at 550°C were used as the adsorbent to remove perchlorate from aqueous solution, while the Mg/(Al-Fe) hydrotalcite compounds were synthesized by co-precipitation method at a constant pH value. The Mg/(Al-Fe) hydrotalcite compounds (HMAF) were characterized by XRD, FT-IR and TG-DTA. The characteristics showed that the layered double hydroxides structures in the HMAF were lost during calcination at 550°C, but were reconstructed subsequent to adsorption of perchlorate, indicating that the 'memory effect' appeared to play an important role in perchlorate adsorption. Batch adsorption studies were conducted under various equilibration conditions, such as molar ratios of Mg/Al/Fe, calcined temperature, different initial solution pH, adsorbent dose, initial perchlorate concentration, and co-existing anions. It was found that the existence of ferric iron in calcined Mg/(Al-Fe) hydrotalcite compound (CHMAF) was favorable to removal of perchlorate from water, and the best ratio of Mg/Al/Fe is 3:0.8:0.2 (CHMAF5%). This study demonstrated that the calcination product of Mg/(Al-Fe) hydrotalcite-like compound was a promising adsorbent for control of the perchlorate pollution in water.

  4. Assessment of heavy metal (Cu, Ni, Fe, Co, Mn, Cr, Zn) pollution in effluent dominated rivulet water and their effect on glycogen metabolism and histology of Mastacembelus armatus

    OpenAIRE

    Javed, Mehjbeen; Usmani, Nazura

    2013-01-01

    The present study was conducted to examine the contamination of rivulet situated at Kasimpur, Aligarh (27.218° N; 79.378° E). It receives the wastewater of Harduaganj Thermal Power Plant (HTPS) containing fly ash and heavy metals. Among the heavy metals estimated in the rivulet water, Fe (8.71 mgL-1) was present in the highest concentration followed by Cu (0.86 mgL-1), Zn (0.30 mgL-1) Mn (0.21 mgL-1), Ni (0.12 mgL-1), Co (0.11 mgL-1) and Cr (0.10 mgL-1). The values for the heavy metals such a...

  5. Effects of ultrasonic field in pulse electrodeposition of NiFe film on Cu substrate

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, R. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Yow, H.K. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia)], E-mail: hkyow@mmu.edu.my; Ong, B.H. [Faculty of Engineering, Multimedia University, Cyberjaya Campus, 63100, Cyberjaya (Malaysia); Manickam, R. [Electronics Faculty, Tyndale Education Group Pte Ltd., 188942 (Singapore); Saaminathan, V. [School of Material Science and Engineering, Nanyang Technological University, 639798 (Singapore); Tan, K.B. [Department of Chemistry, Universiti Putra Malaysia, Serdang, 43400 (Malaysia)

    2009-07-29

    NiFe film was pulse electrodeposited on conductive Cu substrate under galvanostatic mode in the presence of an ultrasonic field. The NiFe film electrodeposited was subjected to structural and surface analyses by X-ray diffraction, energy dispersive X-ray spectroscopy, surface profiling and scanning electron microscopy, respectively. The results show that the ultrasonic field has significantly improved the surface roughness, reduced the spherical grain size in the range from 490-575 nm to 90-150 nm, and increased the Ni content from 76.08% to 79.74% in the NiFe film electrodeposited.

  6. Study of the C-14-contamination potential of C-impurities in CuO and Fe

    NARCIS (Netherlands)

    Vandeputte, K; Moens, L; Dams, R; van der Plicht, Johannes

    1998-01-01

    The carbon concentration in CuO and iron was determined by isolating C. The values were in agreement with results reported in other studies. Contaminating carbon from CuO and Fe was transformed to AMS targets and measured for C-14. C-traces in CuO were shown to be the major contribution to the C-14

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

    Science.gov (United States)

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

    2017-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-01

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

  9. Effect of MgO/Fe Interface Oxidation State on Electric-Field Modulation of Interfacial Magnetic Anisotropy

    Science.gov (United States)

    Guan, X. W.; Cheng, X. M.; Wang, S.; Huang, T.; Xue, K. H.; Miao, X. S.

    2016-06-01

    The impact of the MgO/Fe interface oxidation state on the electric-field-modified magnetic anisotropy in MgO/Fe has been revealed by density functional calculations. It is shown that the influence of the interface oxidation is strong enough to dominate the effect of the electric field on the magnetic anisotropy of MgO/Fe-based films. The magnetoelectric coefficients are calculated to be positive for the ideal and overoxidized MgO/Fe interface, but an abnormal negative value emerges in the underoxidized case. By analyzing the interface states based on density of states and band structures, we demonstrate that the considerably different electronic structures of the three oxidized MgO/Fe interfaces lead to the strong discrepancy in the electric-field modulation of the interfacial magnetic anisotropy. These results are of considerable interest in the area of electric-field-controlled magnetic anisotropy and switching.

  10. Evaluation of Sintering Behavior of Premix Al-Zn-Mg-Cu Alloy Powder

    Directory of Open Access Journals (Sweden)

    Haris Rudianto

    2015-01-01

    Full Text Available Sintering of light aluminium alloys powder has been investigated as a way to substitute steels in automotive and aerospace industries. Premix Al-5.5Zn-2.5Mg-0.5Cu composite powder called Alumix 431D was analyzed in this research. Sintering was carried out under ultra high purity nitrogen gas and before reaching sintering temperature, green samples were delubricated at 400°C for 30 min. The powder possesses high sinterability by reaching 96% relative density at 580°C sintering temperature. Formation of liquid phase seems to support achieving high sintering density. Optimum mechanical properties also were obtained under those conditions. T6 heat treatment was done to improve the mechanical properties by formation of precipitation strengthening, and MgZn2 appears to be dominant strengthening precipitate. X-ray diffraction, optical microscopy, and SEM-EDS were used to characterize powder, and sintered and heat treated samples.

  11. The anodic and cathodic dissolution of Al and Al-Cu-Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mokaddem, M.; Volovitch, P. [Laboratoire de physicochimie des surfaces, UMR7045, Ecole Nationale Superieure de Chimie de Paris, ParisTech, 11, rue Pierre et Marie Curie, Paris (France); Rechou, F.; Oltra, R. [Institut CARNOT de Bourgogne, Electrochimie Interfaciale-Corrosion, UMR5209, Universite de Bourgogne, Dijon (France); Ogle, K., E-mail: kevin-ogle@enscp.f [Laboratoire de physicochimie des surfaces, UMR7045, Ecole Nationale Superieure de Chimie de Paris, ParisTech, 11, rue Pierre et Marie Curie, Paris (France)

    2010-04-15

    Atomic emission spectroelectrochemistry (AESEC) was used to monitor the release of Al from 99.99% aluminum (1199 alloy) and Al, Mg, and Cu from 2024 Al alloy in 30 g/l NaCl electrolyte as a function of pH. The cathodic dissolution of Al was demonstrated and attributed to an increase in the pH at the interface due to the water reduction reaction. The dissolution of Mg was also observed but was a more complex function of current probably depending on the interfacial pH and the Al dissolution rate. The detachment of copper-rich particles was observed as very rapid spectroscopic emission transients (peak width < 10 ms).

  12. Study on strength and fracture toughness of Al-Zn-Mg-Cu-Ti(-Sn alloys

    Directory of Open Access Journals (Sweden)

    Yan A.

    2015-01-01

    Full Text Available The strength and fracture toughness of Al-Zn-Mg-Cu-Ti(-Sn alloys were investigated by performing tensile and plane strain fracture toughness (KIC tests. Detailed observations with optical, scanning electron and transmission electron microscopy were conducted to analyze microstructure and fracture surfaces of the alloys. The results revealed that addition of Sn refined the solution-aging grain size of matrix and reduced coarsening rate of precipitate during aging. Narrower precipitation free zones and more discontinuous distribution of grain boundary precipitates were observed to be displayed in the Sn-containing alloy. Small size second phase particles Mg2Sn were observed to form in the Sn-containing alloy and distribute in the fine dimples of fracture surface. These features of microstructure were believed to impart higher strength and fracture toughness of the Sn-containing alloy on overaging.

  13. Adsorption study of anionic reactive dye from aqueous solution to Mg-Fe-CO3 layered double hydroxide (LDH)

    Science.gov (United States)

    Ahmed, I. M.; Gasser, M. S.

    2012-10-01

    Mg-Fe-Cl Layered double hydroxides (LDHs) have been prepared using a method involving separate nucleation and aging steps with Mg/Fe = 3. The interlayer anions readily replaced by carbonate are characterized by X-ray diffraction (XRD) and FTIR. The effects of different parameters, such as pH, contact time, concentration of dye and temperature on the capacity and adsorption mechanism of Mg-Fe-CO3-LDH in removing an anionic dye (congo red, CR) from aqueous solution were separately investigated. The results show that Mg-Fe-CO3-LDH is particularly efficient in removing CR and the dye removal increases with decreasing pH. The adsorption of CR on Mg-Fe-CO3-LDH reached equilibrium after 15 min where 100 mg/L CR was removed. The equilibrium isotherm indicates that the adsorption of CR onto Mg-Fe-CO3-LDH fits to Langmuir and Freundlich equation as well. The adsorption data obtained from the Langmuir model gave good values of the determination coefficient and the saturated adsorption capacity of Mg-Fe-CO3-LDH for CR was found to be 104.6 mg/g. The regeneration study indicates that the prepared LDH could be used for several cycles. The thermodynamic parameters have been calculated, and the adsorption process was found to be spontaneous, endothermic in nature and follows a pseudo-second-order kinetic model.

  14. The effect of zinc additions on the environmental stability of Alloy 8090 (Al-Li-Cu-Mg-Zr)

    Science.gov (United States)

    Kilmer, Raymond J.; Stoner, G. E.

    1991-01-01

    Stress corrosion cracking (SCC) remains a problem in both Al-Li and conventional Al heat treatable alloys. It has recently been found that relatively small additions (less than or approximately 1 wt-percent) of Zn can dramatically improve the SCC performance of alloy 8090 (Al-Li-Cu-Mg-Zr). Constant load time to failure experiments using cylindrical tensile samples loaded between 30 and 85 percent of TYS indicate improvements of orders of magnitude over the baseline 8090 for the Zn-containing alloys under certain aging conditions. However, the toughnesses of the alloys were noticeably degraded due to the formation of second phase particles which primarily reside on grain and subgrain boundaries. EDS revealed that these intermetallic particles were Cu and Zn rich. The particles were present in the T3 condition and were not found to be the result of quench rate, though their size and distribution were. At 5 hours at 160 C, the alloys displayed the greatest susceptibility to SCC but by 20 hours at 160 C the alloys demonstrated markedly improved TTF lifetimes. Aging past this time did not provide separable TTF results, however, the alloy toughnesses continued to worsen. Initial examination of the alloys microstructures at 5 and 20 hours indicated some changes most notably the S' and delta' distributions. A possible model by which this may occur will be explored. Polarization experiments indicated a change in the trend of E(sub BR) and passive current density at peak aging as compared to the baseline 8090. Initial pitting experiments indicated that the primary pitting mechanism in chloride environments is one occurring at constituent (Al-Fe-Cu) particles and that the Cu and Zn rich boundary precipitates posses a breakaway potential similar to that of the matrix acting neither anodic or cathodic in the first set of aerated 3.5 w/o NaCl experiments. Future work will focus on the identification of the second phase particles, evaluation of K(sub 1SCC) and plateau da/dt via

  15. Stress Corrosion Cracking in Al-Zn-Mg-Cu Aluminum Alloys in Saline Environments

    Science.gov (United States)

    Holroyd, N. J. Henry; Scamans, G. M.

    2013-03-01

    Stress corrosion cracking of Al-Zn-Mg-Cu (AA7xxx) aluminum alloys exposed to saline environments at temperatures ranging from 293 K to 353 K (20 °C to 80 °C) has been reviewed with particular attention to the influences of alloy composition and temper, and bulk and local environmental conditions. Stress corrosion crack (SCC) growth rates at room temperature for peak- and over-aged tempers in saline environments are minimized for Al-Zn-Mg-Cu alloys containing less than ~8 wt pct Zn when Zn/Mg ratios are ranging from 2 to 3, excess magnesium levels are less than 1 wt pct, and copper content is either less than ~0.2 wt pct or ranging from 1.3 to 2 wt pct. A minimum chloride ion concentration of ~0.01 M is required for crack growth rates to exceed those in distilled water, which insures that the local solution pH in crack-tip regions can be maintained at less than 4. Crack growth rates in saline solution without other additions gradually increase with bulk chloride ion concentrations up to around 0.6 M NaCl, whereas in solutions with sufficiently low dichromate (or chromate), inhibitor additions are insensitive to the bulk chloride concentration and are typically at least double those observed without the additions. DCB specimens, fatigue pre-cracked in air before immersion in a saline environment, show an initial period with no detectible crack growth, followed by crack growth at the distilled water rate, and then transition to a higher crack growth rate typical of region 2 crack growth in the saline environment. Time spent in each stage depends on the type of pre-crack ("pop-in" vs fatigue), applied stress intensity factor, alloy chemistry, bulk environment, and, if applied, the external polarization. Apparent activation energies ( E a) for SCC growth in Al-Zn-Mg-Cu alloys exposed to 0.6 M NaCl over the temperatures ranging from 293 K to 353 K (20 °C to 80 °C) for under-, peak-, and over-aged low-copper-containing alloys (alloys (>~0.8 wt pct), they are typically

  16. Microstructural evolution during aging of an Al-Cu-Li-Ag-Mg-Zr alloy

    Science.gov (United States)

    Kumar, K. S.; Brown, S. A.; Pickens, Joseph R.

    1991-01-01

    Alloys in the Al-Cu-Li Ag-Mg subsystem were developed that exhibit desirable combina