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Sample records for cr mn sn

  1. Large magnetic entropy changes and magnetoresistance in Ni45Mn42Cr2Sn11 alloy

    Science.gov (United States)

    Wang, D. H.; Zhang, C. L.; Han, Z. D.; Xuan, H. C.; Gu, B. X.; Du, Y. W.

    2008-02-01

    The magnetic entropy changes and magnetoresistance were studied in Ni45Mn42Cr2Sn11 ferromagnetic shape memory alloy near the martensitic transition temperature. The substitution of Mn by Cr leads to the rapid decrease of the martensitic transition temperature. A large magnetic entropy change, ΔSM, of 15 J/kg K in a magnetic field of 10 kOe and a large negative MR of 45% in a magnetic field up to 50 kOe were observed in this alloy. The temperature and magnetic field induced martensitic transition should be the origin of large ΔSM and MR in Ni45Mn42Cr2Sn11 ferromagnetic shape memory alloy.

  2. Ab initio calculations of structural and magnetic properties of Ni-Co-Mn-Cr-Sn alloys

    Directory of Open Access Journals (Sweden)

    Zagrebin Mikhail

    2015-01-01

    Full Text Available The composition dependences of crystal lattice parameters, bulk modulus, magnetic moments, magnetic exchange parameters in Ni2-yCoyMn1.5-xCrxSn0.5 (y = 0.2, 0.4; 0.0 ≤ x ≤ 0.4 Heusler alloys are investigated with the help of ab initio calculations. Our simulations have shown that crystal lattice parameter firstly increased and then decreased with Cr content (x increasing. The strongest ferromagnetic interaction for Ni1.6Co0.4Mn1.4Cr0.1Sn0.5 is nearest-neighbor interaction between Co and Mn1 (on own sites. The strongest antiferromagnetic interaction is observed between nearest-neighbor Mn1-Cr atoms in the first coordination sphere and it is equal to -15meV. Total magnetic moment of Ni2-yCoyMn1.5-xCrxSn0.5 (y =0.2, 0.4; 0.0 ≤ x ≤ 0.4 takes value in region from 6.1 μB to 6.6 μB.

  3. Theoretical investigations of Co{sub 2}Mn{sub 1-x}Cr{sub x}Sn and Co{sub 2}MnSn{sub 1-y}Si{sub y} pseudo-ternary alloys: First principles calculations

    Energy Technology Data Exchange (ETDEWEB)

    Charifi, Z., E-mail: charifizoulikha@gmail.com [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Hamad, B. [Physics Department, The University of Jordan, Amman 11942 (Jordan); Physics Department, University of Arkansas, 825 W. Dickson St., Fayetteville, AR 72701 (United States); Baaziz, H. [Physics Department, Faculty of Science, University of M' sila, 28000 M' sila (Algeria); Soyalp, F. [Yüzüncü Yıl University, Faculty of Education, Department of Physics, Van 65080 (Turkey)

    2015-11-01

    The electronic and magnetic properties of Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn and Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys are investigated using density functional theory (DFT) within a full-potential linearized augmented-plane-wave (FP-LAPW) method. Amongst the systems under investigation, Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys show half metallicity with 100% spin polarization at the Fermi level, however Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn are found to be pseudo-half metals with few minority states at the Fermi level and high spin polarization. The substitution of Si with Sn keeps the magnetic moment constant in Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys, whereas the substitution of Mn with Cr decreases the magnetic moment and degrade the half-metallicity in Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys. The Curie temperature is calculated and it is found to be about 928 K for all Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys, whereas it decreases linearly with x for Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys. The lattices constants, bulk modulii, energy gaps, polarization ratio and density of states are calculated and their variation versus x or y are discussed. - Highlights: • The band structure calculations show that Co{sub 2}MnSn{sub 1−y}Si{sub y} alloys are half-metallic ferromagnets. • The effect of substituting Sn by Si is a slight change in the position of the Fermi level and an increase in the band gap. • For Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn alloys, the results suggest that there is a finite density of states in the minority-spin d band of manganese. • The Co{sub 2}Mn{sub 1−x}Cr{sub x}Sn compounds cannot be classified as half-metallic ferromagnets. • The substitution of Mn with Cr decreases the magnetic moment per formula unit from 5.0 to 4.0µ{sub B}.

  4. Concentration of heavy metal As, Pb, Mn, Ni, Sn, Zn, Cr, Fe and radon gas in bottom sediment from abandoned tin mines in the Phuket Province

    Directory of Open Access Journals (Sweden)

    Suteerasak, T.

    2006-05-01

    Full Text Available This research is aimed at analyzing the heavy metals: As, Pb, Mn, Ni, Sn, Zn, Cr, Fe, and radon gas emission in bottom sediment from six abandoned tin mines in Phuket Province. Fe, Mn, and Sn were found in higher concentrations (but non-polluting than Cr and Ni. As, Pb, and Zn were polluting at lower levels. The concentration ranges for As, Pb, and Zn were 75.3-169, 98.6-547.5, and 120.4-323.3 mg/kg respectively. The activity of radon gas emission from bottom sediment from an abandoned tin mine in Amphur Muang was in the range of 162-212 Bq/kg., in the Amphur Katoo mine the range was 122-266 Bq/kg. and in the Amphur Talang mine the range was 180-263 Bq/kg. All these sites have higher concentrations of radon gas emissions than other similar sites. The heavy metals and radon gas come from geochemical materials such as soil and granite rock, found around the abandoned tin mines.

  5. Critical behavior near the ferromagnetic-paramagnetic transformation in the austenite phase of Ni43Mn46Sn8X3 (X = In and Cr) Heusler alloys

    Science.gov (United States)

    Nan, W. Z.; Thanh, Tran Dang; Nam, G.; You, T. S.; Piao, H. G.; Pan, L. Q.; Yu, S. C.

    2017-12-01

    In this work, we present a detailed study on the magnetic property and critical behavior in the austenitic phase of Ni43Mn46Sn8X3 alloys with X = Cr and In, which were prepared by an arc-melting method in an argon ambience. The M(T) curve of the Cr sample (X = Cr) exhibits a single magnetic phase transition at the Curie temperature of the ferromagnetic (FM) austenitic phase with TAC = 303 K. In contrast, the In sample (X = In) exhibits multiple magnetic phase transitions, including a magnetic phase transition from a FM state to weakly magnetic state at TMC = 165 K of the martensitic phase, a martensitic transition from the weakly magnetic to the FM austenite phase at TM-A = 259 K, and a magnetic phase transition from the FM to paramagnetic (PM) at TAC = 297 K of the austenite phase. Based on the Landau theory and M(H) data measured at different temperatures, we pointed that the FM-PM phase transitions around TAC in both samples were the second-order phase transition. Our results suggest an existence of the long-range FM interactions in the austenite phase. A small deviation from the mean-field theory of the critical exponents has been also observed pointing out an existence of the inhomogeneous magnetism that could be associated with the presence of the anti-FM interactions in these samples. Besides, their effective exponents βeff(ε) and γeff(ε) have been also calculated.

  6. Large adiabatic temperature change in magnetoelastic transition in Ni{sub 50}Mn{sub 35}Cr{sub 2}Sn{sub 13} Heusler alloy of granular nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, H. R.; Sharma, S. K.; Ram, S., E-mail: prakashhr73@gmail.com [Materials Science Centre, Indian Institute of Technology, Kharagpur-721302 (India); Chatterjee, S. [High Magnetic Field Lab, UGC-DAE Consortium of Scientific Research, Kolkata-700098 (India)

    2016-05-06

    The Ni-Mn-Sn alloys are a pioneering series of magnetocaloric materials of a huge heat-energy exchanger in the martensite transition. A small additive of nearly 2 at% Cr effectively tunes the valence electron density of 8.090 electrons per atom and a large change in the entropy ΔS{sub M←A} = 4.428 J/kg-K (ΔS{sub M→A} = 3.695 J/kg-K in the recycle) at the martensite ← austenite phase transition as it is useful for the magnetic refrigeration and other cooling devices. The Cr additive tempers the tetragonality with the aspect ratio c/a = 0.903 of the martensite phase and exhibits an adiabatic temperature change of 10 K. At room temperature, a hysteresis loop exhibits 48.91 emu/g saturation magnetization and 82.1 Oe coercivity.

  7. Fatigue behaviors and damage mechanism of a Cr-Mn-N austenitic steel

    DEFF Research Database (Denmark)

    Lv, Z.; Cai, P.; Yu, Tianbo

    2017-01-01

    Four-point bending fatigue tests were conducted on a Cr-Mn-N austenitic steel at room temperature, at frequency of 20 Hz and the stress ratio of R = 0.1, in air. The fatigue strength of this Cr-Mn-N austenitic steel was measured to be 503 MPa in the maximum stress from the S-N curve obtained...

  8. Martensitic Transformation in Ni-Mn-Sn-Co Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Alexandre Deltell

    2015-04-01

    Full Text Available Thermal and structural austenite to martensite reversible transition was studied in melt spun ribbons of Ni50Mn40Sn5Co5, Ni50Mn37.5Sn7.5Co5 and Ni50Mn35Sn10Co5 (at. % alloys. Analysis of X-ray diffraction patterns confirms that all alloys have martensitic structure at room temperature: four layered orthorhombic 4O for Ni50Mn40Sn5Co5, four layered orthorhombic 4O and seven-layered monoclinic 14M for Ni50Mn37.5Sn7.5Co5 and seven-layered monoclinic 14M for Ni50Mn35Sn5Co5. Analysis of differential scanning calorimetry scans shows that higher enthalpy and entropy changes are obtained for alloy Ni50Mn37.5Sn7.5Co5, whereas transition temperatures increases as increasing valence electron density.

  9. Magnetic properties of Cr layers in X/Cr/Sn/Cr multilayers (X=V, Fe, Ag) studied through 119Sn Mössbauer spectroscopy

    Science.gov (United States)

    Mibu, K.; Almokhtar, M.; Nakanishi, A.; Kobayashi, T.; Shinjo, T.

    2001-05-01

    The influence of periodically inserted monatomic layers on the magnetic properties of thin Cr films is investigated by applying 119Sn Mössbauer spectroscopy to epitaxial X/Cr/Sn/Cr multilayers, where monatomic X (X=V, Fe, or Ag) and Sn layers are embedded alternately in a Cr(0 0 1) film. The hyperfine field induced at the Sn sites shows a significant dependence on X, indicating that the size of the Cr magnetic moments changes drastically dependent on the sort of inserted metal.

  10. Effect of pressure on the Curie temperature of Mn{sub 2}RuSn and Mn{sub 2}PdSn

    Energy Technology Data Exchange (ETDEWEB)

    Adachi, Y., E-mail: adachy@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, Yonezawa 992-8510 (Japan); Watanabe, T. [Faculty of Engineering, Yamagata University, Yonezawa 992-8510 (Japan); Kanomata, T. [Faculty of Engineering, Tohoku Gakuin University, Tagajo 985-8537 (Japan); Research Institute for Engineering and Technology, Tohoku Gakuin University, 985-8537 (Japan); Hayasaka, M.; Endo, K. [Faculty of Engineering, Tohoku Gakuin University, Tagajo 985-8537 (Japan); Nishihara, H. [Faculty of Science and Technology, Ryukoku University, Otsu 520-2194 (Japan); Xu, X.; Kainuma, R. [Department of Materials Science, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan)

    2017-04-15

    Effect of pressure on the Curie temperature T{sub C} of the Mn-rich Heusler alloys Mn{sub 2}RuSn and Mn{sub 2}PdSn has been investigated by measuring the temperature dependence of initial permeability at various pressures up to 10 kbar. It was found that the Curie temperatures of Mn{sub 2}RuSn and Mn{sub 2}PdSn decrease with increasing pressure. The pressure derivatives of T{sub C} were estimated to be −0.59 K/kbar for Mn{sub 2}RuSn and −0.80 K/kbar for Mn{sub 2}PdSn. On the basis of the experimental results, the relationship between the magnetic transition temperature and the Mn-Mn distance is discussed.

  11. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn ...

    Indian Academy of Sciences (India)

    Unknown

    Mössbauer studies using Sn-119 were carried out to investigate the hyperfine fields present at the Sn site in these alloys. The hyperfine field distribution in these alloys as well as X-ray studies point to the chemical disorder present in both alloys. Co-existence of a paramagnetic portion along with the magnetic hyperfine part.

  12. The 52Cr(p, γ)53Mn reaction

    NARCIS (Netherlands)

    Vuister, P.H.

    The 52Cr(p, γ)53Mn reaction was investigated in the energy region Ep = 1.36–2.26 MeV. The resonance energies, the corresponding 53Mn excitation energies and the resonance strengths of 199 resonances, assigned to this reaction, are reported. The excitation energies and gamma-ray branchings of 13

  13. Giant low-field magnetic entropy changes in Ni45Mn44-xCrxSn11 ferromagnetic shape memory alloys

    Science.gov (United States)

    Zhang, C. L.; Zou, W. Q.; Xuan, H. C.; Han, Z. D.; Wang, D. H.; Gu, B. X.; Du, Y. W.

    2007-12-01

    A series of Ni45Mn44-xCrxSn11 (x = 0, 1, 2) ferromagnetic shape memory alloys were prepared. With slight doping of Cr, the martensitic transition temperatures decrease rapidly. The magnetic entropy changes at a low magnetic field were investigated in these alloys. The maximum value of ΔSM is 23.4 J kg-1 K-1, which was observed in Ni45Mn43CrSn11 alloys. The origin of the magnetic entropy changes in these alloys has been discussed. The giant low-field magnetic entropy changes and low cost make Ni45Mn44-xCrxSn11 alloys a promising candidate for magnetic refrigeration.

  14. The magnetism and electronic transport properties of Mn3Sn1-xSixC

    Science.gov (United States)

    Wen, Yongchun; Wang, Cong; Nie, Man; Sun, Ying

    2015-10-01

    The lattice, magnetic and electronic transport properties of the compounds Mn3Sn1-xSixC (0≤x≤0.4) are investigated. The results have shown that Si-doping in the antiperovskite Mn3SnC induces the decrease of the nearest neighbouring Mn-Mn bond distance of Mn3Sn1-xSixC, and the magnetic structure transforms from ferrimagnetic to antiferromagnetic when x≥0.2. With the increase of Si, the Neel temperature TN rises. The TN of Mn3Sn1-xSixC(x=0.2, 0.3, 0.4) are 217 K, 257 K and 290 K, respectively. However, the magnetovolume effect is quenched. In Mn3SnC and Mn3Sn1-xSixC (x=0.2, 0.3, 0.4) compounds, there exists an anomalous increase in resistivity at a certain temperature that coincides well with their Curie temperature TC or Neel temperature TN. The temperature dependence of the resistivity of Mn3Sn1-xSixC (x=0, 0.2, 0.3, 0.4) exhibits semiconducting-like behavior at low temperature and metallic-like behavior at high temperature.

  15. Magnetoresistance and phase composition of La-Sn-Mn-O systems

    DEFF Research Database (Denmark)

    Li, Z.W.; Morrish, A.H.; Jiang, Jianzhong

    1999-01-01

    The transport properties of the manganites La1 - xSnxMnO3 + delta with x = 0.1-0.5 and of Fe-doped samples have been comprehensively studied using magnetoresistance measurements, Fe-57 and Sn-119 Mossbauer spectroscopy, and x-ray diffraction. At the Sn concentration x = 0.5, La0.5Sn0.5MnO3 + delt...

  16. Magnetic exchange interactions in Mn doped ZnSnAs{sub 2} chalcopyrite

    Energy Technology Data Exchange (ETDEWEB)

    Bouhani-Benziane, H.; Sahnoun, O. [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Sahnoun, M., E-mail: sahnoun_cum@yahoo.fr [Laboratoire de Physique Quantique de la Matière et Modélisation Mathématique (LPQ3M), University of Mascara (Algeria); Department of Chemistry, University of Fribourg (Switzerland); Driz, M. [Laboratoire de Sciences des Matériaux (LSM), University of Sidi Bel Abbes (Algeria); Daul, C. [Department of Chemistry, University of Fribourg (Switzerland)

    2015-12-15

    Accurate ab initio full-potential augmented plane wave (FP-LAPW) electronic calculations within generalized gradient approximation have been performed for Mn doped ZnSnAs{sub 2} chalcopyrites, focusing on their electronic and magnetic properties as a function of the geometry related to low Mn-impurity concentration and the spin magnetic alignment (i.e., ferromagnetic vs antiferromagnetic). As expected, Mn is found to be a source of holes and localized magnetic moments of about 4 µ{sub B} per Mn atom are calculated which are sufficiently large. The defect calculations are firstly performed by replacing a single cation (namely Zn and Sn) with a single Mn atom in the pure chalcopyrite ZnSnAs{sub 2} supercell, and their corresponding formation energies show that the substitution of a Sn atom (rather than Zn) by Mn is strongly favored. Thereafter, a comparison of total energy differences between ferromagnetic (FM) and antiferromagnetic (AFM) are given. Surprisingly, the exchange interaction between a Mn pairs is found to oscillate with the distance between them. Consequently, the AFM alignment is energetically favored in Mn-doped ZnSnAs{sub 2} compounds, except for low impurity concentration associated with lower distances between neighboring Mn impurities, in this case the stabilization of FM increases. Moreover, the ferromagnetic alignment in the Mn-doped ZnSnAs{sub 2} systems behaves half-metallic; the valence band for majority spin orientation is partially filled while there is a gap in the density of states for the minority spin orientation. This semiconducting gap of ~1 eV opened up in the minority channel and is due to the large bonding–antibonding splitting from the p–d hybridization. Our findings suggest that the Mn-doped ZnSnAs{sub 2} chalcopyrites could be a different class of ferromagnetic semiconductors. - Highlights: • ab initio calculations were performed on Mn doped ZnSnAs{sub 2} chalcopyrite. • Substitution of a Sn atom (rather than Zn) by Mn

  17. Corrosion related iron oxides: Cu, Mn and Cr doped hematite

    Directory of Open Access Journals (Sweden)

    Pérez, G.

    2003-12-01

    Full Text Available We have obtained Cu, Mn, and Cr doped hematites, by a thermal treatment of doped goethites at 500 and 880 °C in air for 24 h. The goethites were prepared in the laboratory from iron chloride solutions in the presence of Cu2+, Mn2+, and Cr3+ ions. The samples are characterized by Mössbauer spectroscopy and X-ray diffraction. It is found that at 500 °C all the goethites have transformed into hematites. However, the thermal treatment at 880 °C produces hematites with better crystallinity.

    Hemos obtenido hematitas dopadas con Cu, Mn y Cr, por un tratamiento térmico de goethitas dopadas a 500 y 880 °C en aire durante 24 h. Las goethitas fueron preparadas en el laboratorio a partir de soluciones de cloruro de hierro en presencia de iones de Cu2+, Mn2+ y Cr3+. Las muestras fueron caracterizadas por espectroscopia Mössbauer y difracción de rayos X. Se encontró que a 500 °C todas las goethitas se han transformado a hematitas. Sin embargo, el tratamiento térmico a 880 °C produce hematitas con mejor cristalinidad.

  18. Possible martensitic transformation in Heusler alloy Mn{sub 2}PdSn from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Feng, L., E-mail: author.fenglin@tyut.edu.cn [Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, Computational Condensed Matter Physics Laboratory, Department of Physics, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, X. [Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, Computational Condensed Matter Physics Laboratory, Department of Physics, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, E.K.; Wang, W.H.; Wu, G.H. [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Hu, J.F.; Zhang, W.X. [Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, Computational Condensed Matter Physics Laboratory, Department of Physics, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-12-01

    The tetragonal distortion, electronic structure and magnetic property of Mn{sub 2}PdSn have been systematically investigated by first-principles calculations. The results indicate that the total energy of tetragonal martensitic phase is lower than cubic austenitic phase for Mn{sub 2}PdSn. The corresponding c/a ratio and energy difference are 1.23 and 41.62 meV/f.u., respectively. This suggests that there is a great possibility for martensitic transformation to occur in Mn{sub 2}PdSn with temperature decreasing. The electronic structure shows that there are sharp DOS peaks originating from p–d hybridization in the vicinity of Fermi level in the cubic phase. And these peaks disappear or become more flat in the martensitic phase. - Highlights: • The martensitic transformation is prone to occur with temperature decreasing in Mn{sub 2}PdSn. • Electronic structure and magnetic property of Mn{sub 2}PdSn are investigated. • Both the austenitic and martensitic phases of Mn{sub 2}PdSn are ferrimagnetic.

  19. Electronic, magnetic, and structural properties of the ferrimagnet Mn2CoSn

    Science.gov (United States)

    Winterlik, Jürgen; Fecher, Gerhard H.; Balke, Benjamin; Graf, Tanja; Alijani, Vajiheh; Ksenofontov, Vadim; Jenkins, Catherine A.; Meshcheriakova, Olga; Felser, Claudia; Liu, Guodong; Ueda, Shigenori; Kobayashi, Keisuke; Nakamura, Tetsuya; Wójcik, Marek

    2011-05-01

    The magnetic ground state of the Heusler compound Mn2CoSn was predicted to be nearly half-metallic ferrimagnetic with a high spin polarization by ab initio electronic structure calculations. Mn2CoSn was synthesized, and the magnetic behavior of the compound was studied using a superconducting quantum interference device and x-ray magnetic circular dichroism. The experimental values were found to be in fair accordance with the theoretical predictions. The electronic structure and the crystal structure of Mn2CoSn were characterized comprehensively using x-ray powder diffraction, Sn119 Mössbauer spectroscopy, nuclear magnetic resonance, and hard x-ray photoelectron spectroscopy.

  20. Magnetic analysis of martensitic and austenitic phases in metamagnetic NiMn(In, Sn) alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lázpita, P., E-mail: patricia.lazpita@ehu.es [University of Basque Country (UPV/EHU), Leioa (Spain); Escolar, J. [University of Basque Country (UPV/EHU), Leioa (Spain); Chernenko, V.A. [University of Basque Country (UPV/EHU), Leioa (Spain); BCMaterials, Parque Tecnológico de Bizkaia, Ed. 500, Derio 48160 (Spain); Ikerbasque, Basque Foundation for Science, Bilbao 48013 (Spain); Barandiarán, J.M. [University of Basque Country (UPV/EHU), Leioa (Spain); BCMaterials, Parque Tecnológico de Bizkaia, Ed. 500, Derio 48160 (Spain)

    2015-09-25

    Highlights: • NiMnIn austenite and martensite have similar Ising-type critical exponents. • NiMnIn critical exponents rule out disordered states as spin-glass in martensite. • In NiMnIn alloys, magnetism arises mainly from moments localized at Mn atoms. • NiCoMnSn critical exponents are close to the ones from tricritical mean field model. • NiCoMnSn complex magnetic state results from three different magnetic atoms. - Abstract: Two different metamagnetic shape memory alloys of nominal composition Ni{sub 50}Mn{sub 36}In{sub 14} and Ni{sub 42}Co{sub 8}Mn{sub 39}Sn{sub 11} have been studied by means of modified Arrott plots to give insight into the magnetic states of both the austenitic and martensitic phases. For Ni{sub 50}Mn{sub 36}In{sub 14} alloy, the same critical exponents (β = 0.32 and γ = 2.0) are obtained in austenite and martensite. They suggest that localized moments at Mn atoms are responsible for the magnetism of both phases according to the Ising model. The martensite, however, displays a rather complex behavior because β continuously changes with temperature. In Ni{sub 43}Co{sub 6.5}Mn{sub 39}Sn{sub 11.5}, critical exponents in the austenite are β = 0.27 and γ = 1.0. They are close to the tricritical mean field model, but no reliable fits were obtained in the martensite. The results are discussed in terms of microscopically different magnetic states in two alloys reflecting a complex interplay between the ferromagnetic and antiferromagnetic contributions.

  1. Magnetic properties of Mn-doped chalcopyrites: (BeSn,BeGe,MgGe)N2

    Science.gov (United States)

    Rufinus, Jeff; DeWinter, Jennifer L.

    2008-04-01

    The current interest in the emerging field of semiconductor spintronics is mostly focused on transition metal-doped binary materials. Recently, however, the explorations of transition metal-doped chalcopyrite semiconductors have intensified. Since the chalcopyrites are ternary materials, there are possibilities of having ferromagnetic or antiferromagnetic configurations, depending on which metal site was substituted by the dopant. A density functional theory within generalized gradient approximation study of three thermodynamically stable Mn-doped (II-IV)-N2 chalcopyrites: (BeSn,BeGe,MgGe)N2 was performed. The results show both BeSnN2 and BeGeN2 to be antiferromagnetic for MnII (Mn substitutes II site) and ferromagnetic for MnIV (Mn substitutes IV site.) On the other hand, MgGeN2 was found to be antiferromagnetic, independent of the substitution sites.

  2. Spin glass-like behavior in spin-density-wave CrCoMn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Galkin, Vladimir Yu. E-mail: galkin@magn.ru; Ortiz, Wilson A.; Ali, Naushad

    2003-03-01

    Magnetic susceptibility and magnetization of spin-density-wave (SDW) alloy systems (Cr+3.2%Co){sub 1-x}Mn{sub x} and (Cr+6.5%Co){sub 1-x}Mn{sub x} have been measured with a SQUID magnetometer. Magnetic properties of the studied alloys are compared with those exhibited by binary Cr{sub 1-x}Mn{sub x} and ternary (CrFe){sub 1-x}Mn{sub x} and (CrSi){sub 1-x}Mn{sub x} alloys. All these alloys show spin glass (SG)-like behavior; however, some of their magnetic properties are quite different from those exhibited by conventional metallic spin glasses. Though both Fe and Co produce a local moment in Cr and CrMn, addition of Co to CrMn does not result in suppression of SG-like phase like that in (CrFe){sub 1-x}Mn{sub x}. This seems to be a result of essentially different strengths of Fe-Cr and Co-Cr couplings. All alloys studied show a low-temperature SG-like magnetic hysteresis. Such hysteresis is shifted to negative fields by cooling the alloys in a strong magnetic field through the Neel temperature. This effect is caused by unidirectional anisotropy of Co atoms frozen in the SDW matrix.

  3. Magnetic and magnetocaloric properties of Ni50-xCuxMn39Sn11 alloys

    Science.gov (United States)

    Kaya, Melike; Dincer, Ilker

    2017-11-01

    The effect of Cu substitution on the martensitic transition and magnetocaloric properties of arc-melted Ni50-xCuxMn39Sn11 (x = 6 and 7) Heusler alloys are investigated by differential scanning calorimetry, X-ray powder diffraction, scanning electron microscopy and magnetic measurements. According to XRD patterns, while Ni44Cu6Mn39Sn11 alloy exhibit orthorhombic structure, Ni43Cu7Mn39Sn11 alloy crystallize cubic L21 structure at room temperature. The substitution of Cu for Ni leads to decreasing on the martensitic transition temperatures to lower values. The magnetic entropy changes calculated from M(T) curves, for avoiding hysteresis losses in the vicinity of the martensitic transition region, by using Maxwell relation. The maximum magnetic entropy change, ΔSM is found 11.0 J kg-1 K-1 for Ni43Cu7Mn39Sn11 alloy around the martensitic transition region, which is nearly twice as large as the Ni44Cu6Mn39Sn11 alloy under the magnetic field changing from 0 to 2 T.

  4. Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

    Directory of Open Access Journals (Sweden)

    Anna Behler

    2013-12-01

    Full Text Available A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni50Mn32Sn18 thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase.

  5. Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

    Energy Technology Data Exchange (ETDEWEB)

    Behler, Anna [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Department of Physics, Institute for Solid State Physics, Dresden University of Technology, 01062 Dresden (Germany); Teichert, Niclas; Auge, Alexander; Hütten, Andreas [Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, 33501 Bielefeld (Germany); Dutta, Biswanath; Hickel, Tilmann [Max-Planck Institut für Eisenforschung, 40237 Düsseldorf (Germany); Waske, Anja [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Eckert, Jürgen [IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, 01171 Dresden (Germany); Institute of Materials Science, Dresden University of Technology, 01062 Dresden (Germany)

    2013-12-15

    A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni{sub 50}Mn{sub 32}Sn{sub 18} thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase.

  6. Thickness dependent exchange bias in martensitic epitaxial Ni-Mn-Sn thin films

    Science.gov (United States)

    Behler, Anna; Teichert, Niclas; Dutta, Biswanath; Waske, Anja; Hickel, Tilmann; Auge, Alexander; Hütten, Andreas; Eckert, Jürgen

    2013-12-01

    A thickness dependent exchange bias in the low temperature martensitic state of epitaxial Ni-Mn-Sn thin films is found. The effect can be retained down to very small thicknesses. For a Ni50Mn32Sn18 thin film, which does not undergo a martensitic transformation, no exchange bias is observed. Our results suggest that a significant interplay between ferromagnetic and antiferromagnetic regions, which is the origin for exchange bias, is only present in the martensite. The finding is supported by ab initio calculations showing that the antiferromagnetic order is stabilized in the phase.

  7. type phase LaSr2MnCrO7

    Indian Academy of Sciences (India)

    Administrator

    LaSr2MnCrO7; structure; rietveld XRD analysis; magnetoresistance; ferromagnetic. 1. Introduction. The Ruddlesden–Popper (RP) type ... K2NiF4-type structure with only one layer of corner- sharing BO6 octahedra along the c direction. .... ered manganites exhibit I–M transition at low tem- peratures and the Mn. 3+. /Mn. 4+.

  8. Effect of 3d transition elements substitution for Ni in Ni2Mn1+xSn1-x on the phase stability and magnetic properties: A first principle investigation

    Science.gov (United States)

    Wang, Xu; Shang, Jia-Xiang; Wang, Fu-He; Jiang, Cheng-Bao; Xu, Hui-Bin

    2014-11-01

    In hope of understanding the origin of the 3d-transition elements doping effect on the phase stability and magnetic properties of the ferromagnetic shape memory Heusler alloy Ni-Mn-Sn, the Ni-Z-Mn-Sn system with Z=Ni, Cu, Co, Fe, Mn and Cr is investigated using first-principles calculations. The calculated results show that the energetically favorable magnetic order of the L21 structure is antiferromagnetic for Z=Ni and Cu, and ferromagnetic for the Z=Co, Fe, Mn and Cr. However, for L10 structure, the antiferromagnetic state has an energetical preference for each alloy. Accordingly, a magnetic transition accompanies with the martensite phase transformation and a large change in the magnetic moment can be observed in the alloys with the L21 under the ferromagnetic state, which is mainly dependent on the coupling behaviors of the doped atoms. The weak ferromagnetic coupling between the Ni/Cu and Mn, the strong ferromagnetic coupling between Co/Fe and Mn and the antiferromagnetic coupling between Mn/Cr and Mn play an important role on the magnetic order of L21 structures. Furthermore, the Bethe-Slater model is employed to gain a further understanding and regulation of the coupling behaviors of different doping elements, which is very sensitive to the interatomic distance. These calculated results may help in gaining an insight into the doping behavior of these transition metals and provide some theoretical aid to the material design.

  9. Nonohmic behavior of SnO2.MnO2-based ceramics

    Directory of Open Access Journals (Sweden)

    Marcelo O. Orlandi

    2003-06-01

    Full Text Available The present paper describes the nonohmic behavior of the SnO2.MnO-based system and analyzes the influence of the sintering time and the Nb2O5 concentration on this system's electrical properties. A nonlinear coefficient of ~7 was obtained for a 0.2 mol%-doped Nb2O5 composition, which is comparable to other values reported in the literature for the ternary SnO2-based systems. A recent barrier formation model proposed in the literature to explain the nonlinear electrical behavior of SnO2-based systems is used to clarify the role of the MnO constituent in the formation of the barrier, taking into account the influence of segregated atoms, precipitated phase and oxygen species in the grain boundary region.

  10. Homogenous adsorption of Mn{sub 6}Cr single-molecule-magnets on substrates

    Energy Technology Data Exchange (ETDEWEB)

    Koop, Peter; Gryzia, Aaron; Helmstedt, Andreas; Hachmann, Wiebke; Brechling, Armin; Sacher, Marc; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Hoeke, Veronika; Glaser, Thorsten [Anorganic Chemistry I, Bielefeld University (Germany)

    2010-07-01

    Mn{sub 6}Cr is a single-molecule-magnet (SMM) consisting of two bowl-shaped compounds, each containing three Mn-atoms. These compounds are bound together by a Cr-complex. For charge neutrality, counterions have to be coupled to the SMM. Investigation of separated SMM, the molecule-substrate interaction and/or possible future applications e.g. data storage, requires preparation of monolayers or thin films. This preparation is done by solving Mn{sub 6}Cr in methanol, and dropping few {mu}l of the solution onto a 9 x 9 mm sized substrate. Depending on the choice of substrate Au, SiO{sub 2} (native Oxide, 50 nm Oxide), HOPG, Ru, Mn{sub 6}Cr concentration, the angle of the sample while being prepared and the amount of applied solution Mn{sub 6}Cr yields strongly varying kinds of assembly. On the one hand, clusters emerge in the solution just a moment before the solvent dries, depending on the concentration of Mn{sub 6}Cr in the solution. On the other hand the lateral distribution of the SMM is correlated with the droplet-size, the angle of the sample during preparation and the counterions, e.g. lactate anions cause Mn{sub 6}Cr to create membranes. The samples have been investigated by means of optical microscopy, SEM, surface profilometry and AFM.

  11. Ni-Mn-Sn Heusler: milling and annealing effect on structural and magnetic properties

    Science.gov (United States)

    Popa, Florin; Florin Marinca, Traian; Florin Chicinaş, Horea; Isnard, Olivier; Chicinaş, Ionel

    2017-10-01

    Nanocrystalline Ni51Mn19Sn30 Heusler alloy was prepared in the form of powder by solid state reaction in a planetary ball mill under argon atmosphere. After 10 h of milling the samples exhibit a mixture of two phases: disordered Heusler structure and half-Heusler structure. The stability of the phases was studied and a transformation of the disordered Heusler phase into the ordered Heusler and Ni3Sn2 phase was observed after heat treatment. Magnetic properties strongly depend on the phases promoted during milling and annealing. The phase change after annealing leads to the increase of the sample’s magnetisation.

  12. Direct synthesis of an heterometallic {Mn(II)3Cr(III)4} wheel by decomposition of Reineckes salt.

    Science.gov (United States)

    Semenaka, Valentyna V; Nesterova, Oksana V; Kokozay, Volodymyr N; Zybatyuk, Roman I; Shishkin, Oleg V; Boca, Roman; Shevchenko, Denys V; Huang, Ping; Styring, Stenbjörn

    2010-03-07

    A new heterometallic Mn/Cr molecular wheel complex has been synthesized using zerovalent manganese, Reineckes salt, ammonium thiocyanate and triethanolamine (H(3)tea) as starting materials. The compound [Mn(3)Cr(4)(NCS)(6)(Htea)(6)] (1) has been characterized in terms of its electrochemical, IR and EPR spectroscopic as well as its magnetic properties. The magnetic susceptibility and magnetization data were treated simultaneously during the optimization routine and resulted in J(Mn-Cr) = +0.43 cm(-1), J(Cr-Cr) = -4.75 cm(-1), J(Mn-Mn) = +1.78 cm(-1), g(eff) = 1.878 with the ground state S = 15/2.

  13. Oxidation of CoCrFeMnNi High Entropy Alloys

    Science.gov (United States)

    Holcomb, Gordon R.; Tylczak, Joseph; Carney, Casey

    2015-06-01

    Eight model high entropy alloys (HEAs) in the CoCrFeMnNi family (including one alloy each in the CoCrFeNi and CoFeMnNi subfamilies) were made, prepared, and exposed to laboratory air for 1100 h at 650°C and 750°C. Two commercial alloys, nickel-base superalloy 230 (N06230) and austenitic stainless steel 304H (S30409), were simultaneously exposed for comparison. Mass change oxidation kinetics were measured and cross-sections of exposed samples were observed. Seven of these HEAs contained much more Mn (12-24 wt.%) than is found in commercial heat-resistant stainless steels and superalloys. The oxidation resistance of CoCrFeNi was excellent and comparable to 304H at 650°C and only slightly worse at 750°C. The thin oxide scale on CoCrFeNi was primarily Cr oxide (presumably Cr2O3) with some Mn oxide at the outer part of the scale. The CoCrFeMnNi HEAs all experienced more rapid oxidation than CoCrFeNi and, especially at 750°C, experienced oxide scale spallation. The addition of Y in the alloy to lower S improved the oxidation resistance of these HEAs. Alloy CoFeMnNi, without Cr, experienced much higher oxidation rates and scale spallation than the Cr-containing alloys. A linear regression analysis of the log of the parabolic rate constant, log(kp), as functions of wt.% Cr and Mn found a good correlation for the compositional dependence of the oxidation rate constant, especially at 650°C. Mn was found to be more detrimental increasing log(k p) than Cr was helpful reducing log(k p). If CoCrFeMnNi HEAs are to be used in high temperature oxidizing environments, then examining lower levels of Mn, while maintaining Cr levels, should be pursued.

  14. Magnetic structures of (Mn1-xFex)Sn2 intermetallic compounds

    DEFF Research Database (Denmark)

    Menshikov, A.; Vokhmyanin, A.; Teplykh, A.

    1998-01-01

    With the aim to understand the nature of the antiferromagnetic phase transition at chi similar to 0.8 in the (Mn1-xFex)Sn-2 system, we have performed neutron diffraction measurements for x = 0.2, 0.7, 0.85 and 0.9 between 4.2 and 300 K. The data show that non-collinear magnetic structures exist...

  15. Manganese-mediated ferromagnetism in La 2 Fe Mn 2 Cr O 6 ...

    Indian Academy of Sciences (India)

    We have investigated the structure and magnetic properties of the perovskite oxides of the formula La2Fe1-Mn2Cr1-O6 (0 < < 1.0). For 0 < ≤ 0.5, the members adopt the orthorhombic (Pbnm) structure, where the transition metal atoms are disordered at the 4b sites and the MO6 (M = Fe, Mn, Cr) octahedra become ...

  16. Synthesis of new (Bi, La) 3MSb2O11 phases (M= Cr, Mn, Fe) with ...

    Indian Academy of Sciences (India)

    The magnetic measurements on Bi2LaCrSb2O11 and Bi2LaMnSb2O11 show paramagnetic behaviour with magnetic moments close to the expected spin only magnetic moments of Cr+3 and Mn+3. The UV-Visible diffuse reflectance spectra are broad and indicate that these materials possess a bandgap of ∼ 2 eV.

  17. The investigation of the mechanical properties of Mn doped BaSnO3 nanoparticles

    Science.gov (United States)

    Kazah, I.; Awad, R.

    2017-07-01

    This study investigates the effect of Mn substitution on the structural and mechanical properties of nano BaSnO3 using X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), Scanning electron microscope (SEM) and Vickers microhardness. For this investigation, samples of type BaSn1-xMnxO3 with 0.04 ≤ x ≤ 0.4 were prepared by co-precipitation method. XRD patterns indicate the formation of single phase cubic structure BaSnO3 with space group (Pm3m) for 0 ≤ x ≤ 0.1. BaMnO2 hexagonal phase appears as impurity for x > 0.1. The crystallite size, increases as x increases. Vickers microhardness Hv was carried out at different applied loads varying between 0.98 N and 9.8 N at dwell time 40 seconds. The results show that Hv increases as the Mn-content increases, whereas it decreases as the applied load increase. The Hv results were analysed using Elastic Plastic Deformation and the Modified proportional specimen resistance models. The Vickers microhardness analysis indicates that Modified Proportional Specimen Resistance model is the most suitable one for describing the load independent microhardness region of the investigated samples.

  18. Theoretical approach to the magnetic properties of Mn(II), Cr(III), and ...

    Indian Academy of Sciences (India)

    Srimath

    3+. , and Mn. 2+ ions in the newly reported. 12- and 15-membered macrocyclic complexes are analysed by a theoretical approach. The calculated magnetic ... Cr(III), and Mn(II) ions in 12-membered macrocyclic ligands are 1.98 BM, 3.72 .... and the results of the EPR spectroscopy, one can easily calculate the amount of.

  19. Effects of Cr, Mo, W, Mn and Ni on toughness of 2. 25Cr-Mo-V rotor steel. 2. 25Cr-Mo-V tanko no jinsei ni oyobosu Cr, Mo, W, Mn oyobi Ni no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kadoya, Y. (Mitsubishi Heavy Industries Ltd., Tokyo (Japan). Takasago Research and Development Center); Kitai, T.; Tsuji, I.; Matsuo, A. (Mitsubishi Heavy Industries Ltd., Tokyo (Japan)); Tanaka, Y.; Azuma, T. (The Japan Steel Works Ltd., Tokyo (Japan). Muroran Research Lab.); Ikeda, Y. (The Japan Steel Works Ltd., Tokyo (Japan))

    1993-08-01

    2.25Cr-Mo-V rotor steel is developed and put into practical use as a high and low pressure suitable rotor steel and the gas turbine disk materials. In this study, as a basic component of 2.25Cr-Mo-V steel, 12 kinds of alloys with the additions of Cr, Mo, W, Mn and Ni were made, the impact experiments were carried out, effect of the alloying elements on toughness was examined, and effect of the alloying elements on the precipitation of carbide was investigated. Main results obtained were as follows: Cr, Mo, Mn and Ni additions decreased the Bainite start temperature (Bs) of 2.25Cr-Mo-V steel, Cr and Ni additions decreased Fracture Appearance Transition Temperature (FATT), and Mn addition did not give a significant change on the FATT. Mo addition decreased the FATT, when this addition is more than 1.5%, the FATT was increased. W addition increased the FATT. 17 refs., 12 figs., 2 tabs.

  20. Noncollinear magnetism in Mn{sub 2}RhSn Heusler compound

    Energy Technology Data Exchange (ETDEWEB)

    Meshcheriakova, Olga

    2014-09-15

    Heusler compounds is a large class of materials, which exhibits diverse fundamental phenomena, together with the possibility of their specific tailoring for various engineering demands. Present work discusses the magnetic noncollinearity in the family of noncentrosymmetric ferrimagnetic Mn{sub 2}-based Heusler compounds. Based on the obtained experimental and theoretical results, Mn{sub 2}YZ Heusler family is suspected to provide promising candidates for the formation of the skyrmion lattice. The work is focused on Mn{sub 2}RhSn bulk polycrystalline sample, which serves as a prototype. It crystallizes in the tetragonal noncentrosymmetric structure (No. 119, I anti 4m2), which enables the anisotropic Dzyaloshinskii-Moriya (DM) exchange coupling. Additional short-range modulation, induced by the competing nearest and next-nearest interplanes Heisenberg exchange, is suppressed above the 80 K. This allows to develop the long-range modulations in the ideal ferrimagnetic structure within the ab crystallographic planes, and thus, favors to the occurrence of the skyrmion lattice within the temperature range of (80≤T≤ 270) K. The studies of Mn{sub 2}RhSn were expanded to the broad composition range and continued on thin film samples.

  1. Oxide Transformation in Cr-Mn-Prealloyed Sintered Steels: Thermodynamic and Kinetic Aspects

    Science.gov (United States)

    Hryha, Eduard; Nyborg, Lars

    2014-04-01

    The main obstacle for utilization of Cr and Mn as alloying elements in powder metallurgy is their high oxygen affinity leading to oxidation risk during powder manufacturing, handling, and especially during further consolidation. Despite the high purity of the commercially available Cr- and Mn-prealloyed iron powder grades, the risk of stable oxide formation during the sintering process remains. Thermodynamic and kinetic simulation of the oxide formation/transformation on the former powder surface during heating and sintering stages using thermodynamic modeling tools (Thermo-Calc and HSC Chemistry) was performed. Simulation is based on the results from the analysis of amount, morphology, and composition of the oxide phases inside the inter-particle necks in the specimens from interrupted sintering trials utilizing advanced analysis tools (HRSEM + EDX and XPS). The effect of the processing parameters, such as sintering atmosphere composition, temperature profile as well as graphite addition on the possible scenarios of oxide reduction/formation/transformation for Fe-Cr-Mn-C powder systems, was evaluated. Results indicate that oxide transformation occurs in accordance with the thermodynamic stability of oxides as follows: Fe2O3 → FeO → Fe2MnO4 → Cr2FeO4 → Cr2O3 → MnCr2O4 → MnO/MnSiO x → SiO2. Spinel MnCr2O4 was identified as the most stable oxide phase at applied sintering conditions up to 1393 K (1120 °C). Controlled conditions during the heating stage minimize the formation of stable oxide products and produce oxide-free sintered parts.

  2. Effect of Mn Nanoparticles on Interfacial Intermetallic Compound Growth in Low-Ag Sn-0.3Ag-0.7Cu-xMn Solder Joints

    Science.gov (United States)

    Tang, Y.; Luo, S. M.; Li, G. Y.; Yang, Z.; Chen, R.; Han, Y.; Hou, C. J.

    2017-10-01

    Interfacial intermetallic compound (IMC) growth between Cu substrates and low-Ag Sn-0.3Ag-0.7Cu-xMn (x = 0 wt.%, 0.02 wt.%, 0.05 wt.%, 0.1 wt.%, and 0.15 wt.%) (SAC0307-xMn) solders was investigated under different isothermal aging temperatures of 100°C, 150°C, and 190°C. Scanning electron microscopy (SEM) was employed to observe the microstructural evolution of the solder joints and measure the IMC layer thickness. The IMC phases were identified by energy-dispersive x-ray spectroscopy and x-ray diffraction. The results showed that a Cu6Sn5 IMC layer formed in the as-soldered solder joints, while a duplex structure consisting of a Cu6Sn5 IMC layer near the solder matrix and a Cu3Sn IMC layer was observed after isothermal aging. A considerable drop in the IMC layer thickness was observed when 0.1 wt.% Mn nanoparticles were added. Beyond this amount, the thickness of the IMC layer only slightly increases. Adding Mn nanoparticles can increase the activation energy and thus reduce the interdiffusion rates of the Sn and Cu atoms, which suppresses excessive IMC growth. The solder joint containing 0.1 wt.% Mn nanoparticles has the highest activation energy. SEM images revealed that the number of small particles precipitated in the channels between the Cu6Sn5 IMC layers increases with an increasing proportion of Mn nanoparticles. Based on the microstructural evolution of the solder joints, this study revealed that grain boundary pinning is one of the most important mechanisms for IMC growth inhibition when Mn nanoparticles are added.

  3. Magnetic properties of microwave-synthesized Mn-doped SnO2 nanoparticles

    Science.gov (United States)

    Salah, Numan; Habib, Sami; Azam, Ameer

    2016-11-01

    Semiconductor nanostructures with dilute magnetic property are of great importance for different applications. However, this property depends on several factors including the synthesis route. In this work, manganese (Mn)-doped tin dioxide (SnO2) nanoparticles (NPs) at different concentrations were synthesized by the microwave-assisted synthesis method and evaluated for their magnetic properties. The X-ray diffraction analyses revealed a single-phase rutile-type tetragonal structure, while SEM and TEM images showed fine NPs with average sizes around 10 nm. A considerable increase in value of the energy band gap by around 0.18 eV as a result of Mn doping was observed. This dopant has also increased the lattice d-spacing value, but slightly decreased the lattice constant c. The magnetic measurement result showed that all the microwave-synthesized Mn-doped SnO2 NPs including the pure one have distinctly wide hysteresis loops, indicating that samples have room temperature ferromagnetism (RTFM). RTFM was further enhanced by Mn doping reaching maximum at a concentration of 0.3 mol%. This magnetism could be attributed to the presence of defects at the grain boundaries within the NPs, interfacing sites between the NPs, oxygen or tin vacancies and an optimum level of Mn dopant. The observed wide hysteresis loops in these samples might be due to the use of a surfactant at high concentration that could provide highly compact/tight NPs. These results might be useful for producing nanoscale magnets and magnetic memory devices.

  4. Comparative study of Co, Cr and Al-doped LiMnO2 prepared by ion ...

    Indian Academy of Sciences (India)

    As compared to LiMnO2, Co, Cr and Al-doped LiMnO2 offers higher discharge capacity and better cycling performance. The discharge capacities of Co, Cr and Al-doped LiMnO2 decreases yet the cycling performance improves with the increase of doping concentration. For these doped LiMnO2 at the same doping ...

  5. Structural, magnetic, magnetocaloric and specific heat investigations on Mn doped PrCrO3 orthochromites

    Science.gov (United States)

    Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Kumar, Sandeep; Kholkin, A. L.; Panwar, Neeraj

    2017-05-01

    We have synthesized PrCr0.85Mn0.15O3 (PCMO) chromite and investigated the influence of manganese (Mn) doping at Cr-sites on the structural, magnetic, magnetocaloric and thermal properties of PrCrO3 compound. No structural transition was observed with Mn substitution and the doped compound crystallized into distorted orthorhombic structure with Pnma space group which was confirmed by Rietveld refinement of x-ray powder diffraction patterns. Neel temperature, noticed at 168 K from the temperature variation of magnetization, smaller than that reported for PrCrO3, indicated the influence of Mn3+ substitution in decreasing the antiferromagnetic ordering. Magnetization was almost eight times higher than that reported for undoped sample. Magnetocaloric effect measured via the magnetic entropy change and relative cooling power demonstrated significant values in the temperature range 10-20 K. The values of magnetic entropy change are much superior to that reported for other polycrystalline orthochromites and even at smaller applied field strength. The material exhibited second order magnetic phase transition. The Debye temperature and the density of states at Fermi level were also calculated. The overall results make PrCr0.85Mn0.15O3 chromite a potential candidate to replace the existing materials for low temperature magnetic refrigeration.

  6. Effect of 3d transition elements substitution for Ni in Ni{sub 2}Mn{sub 1+x}Sn{sub 1-x} on the phase stability and magnetic properties: A first principle investigation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xu [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Shang, Jia-Xiang, E-mail: shangjx@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Fu-He [Department of Physics, Capital Normal University, Beijing 100048 (China); Jiang, Cheng-Bao; Xu, Hui-Bin [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2014-11-15

    In hope of understanding the origin of the 3d-transition elements doping effect on the phase stability and magnetic properties of the ferromagnetic shape memory Heusler alloy Ni–Mn–Sn, the Ni–Z–Mn–Sn system with Z=Ni, Cu, Co, Fe, Mn and Cr is investigated using first-principles calculations. The calculated results show that the energetically favorable magnetic order of the L2{sub 1} structure is antiferromagnetic for Z=Ni and Cu, and ferromagnetic for the Z=Co, Fe, Mn and Cr. However, for L1{sub 0} structure, the antiferromagnetic state has an energetical preference for each alloy. Accordingly, a magnetic transition accompanies with the martensite phase transformation and a large change in the magnetic moment can be observed in the alloys with the L2{sub 1} under the ferromagnetic state, which is mainly dependent on the coupling behaviors of the doped atoms. The weak ferromagnetic coupling between the Ni/Cu and Mn, the strong ferromagnetic coupling between Co/Fe and Mn and the antiferromagnetic coupling between Mn/Cr and Mn play an important role on the magnetic order of L2{sub 1} structures. Furthermore, the Bethe–Slater model is employed to gain a further understanding and regulation of the coupling behaviors of different doping elements, which is very sensitive to the interatomic distance. These calculated results may help in gaining an insight into the doping behavior of these transition metals and provide some theoretical aid to the material design. - Highlights: • The magnetic ground state of Ni–Z–Mn–Sn L2{sub 1} is AFM for Z=Ni and Cu, and FM for the Z=Co, Fe, Mn and Cr. • The L1{sub 0} structures of Ni–Z–Mn–Sn are all under AFM state. • A large Δμ caused by metamagnetic transition can be observed in the alloys with Z=Co, Fe, Mn and Cr. • The coupling behaviors of doped atom play an important role on the magnetic properties of the alloys. • The Bethe–Slater curve can be used in understanding the coupling behavior of

  7. Unusual magnetic hysteresis and the weakened transition behavior induced by Sn substitution in Mn{sub 3}SbN

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Ying, E-mail: sunying@buaa.edu.cn [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Guo, Yanfeng; Li, Jun; Wang, Xia [Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Tsujimoto, Yoshihiro [Materials Processing Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan); Wang, Cong [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); Feng, Hai L.; Sathish, Clastin I.; Yamaura, Kazunari, E-mail: yamaura.kazunari@nims.go.jp [Superconducting Properties Unit, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Matsushita, Yoshitaka [Analysis Station, National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan)

    2014-01-28

    Substitution of Sb with Sn was achieved in ferrimagnetic antiperovskite Mn{sub 3}SbN. The experimental results indicate that with an increase in Sn concentration, the magnetization continuously decreases and the crystal structure of Mn{sub 3}Sb{sub 1-x}Sn{sub x}N changes from tetragonal to cubic phase at around x of 0.8. In the doping series, step-like anomaly in the isothermal magnetization was found and this behavior was highlighted at x = 0.4. The anomaly could be attributed to the magnetic frustration, resulting from competition between the multiple spin configurations in the antiperovskite lattice. Meantime, H{sub c} of 18 kOe was observed at x = 0.3, which is probably the highest among those of manganese antiperovskite materials reported so far. With increasing Sn content, the abrupt change of resistivity and the sharp peak of heat capacity in Mn{sub 3}SbN were gradually weakened. The crystal structure refinements indicate the weakened change at the magnetic transition is close related to the change of c/a ratio variation from tetragonal to cubic with Sn content. The results derived from this study indicate that the behavior of Mn{sub 3}Sb{sub 1-x}Sn{sub x}N could potentially enhance its scientific and technical applications, such as spin torque transfer and hard magnets.

  8. Sn-Mn binary metal oxides as non-carbon sorbent for mercury removal in a wide-temperature window.

    Science.gov (United States)

    Xie, Jiangkun; Xu, Haomiao; Qu, Zan; Huang, Wenjun; Chen, Wanmiao; Ma, Yongpeng; Zhao, Songjian; Liu, Ping; Yan, Naiqiang

    2014-08-15

    A series of Sn-Mn binary metal oxides were prepared through co-precipitation method. The sorbents were characterized by powder X-ray diffraction (powder XRD), transmission electronic microscopy (TEM), H2-temperature-programmed reduction (H2-TPR) and NH3-temperature-programmed desorption (NH3-TPD) methods. The capability of the prepared sorbents for mercury adsorption from simulated flue gas was investigated by fixed-bed experiments. Results showed that mercury adsorption on pure SnO2 particles was negligible in the test temperature range, comparatively, mercury capacity on MnOx at low temperature was relative high, but the capacity would decrease significantly when the temperature was elevated. Interestingly, for Sn-Mn binary metal oxide, mercury capacity increased not only at low temperature but also at high temperature. Furthermore, the impact of SO2 on mercury adsorption capability of Sn-Mn binary metal oxides was also investigated and it was noted that the effect at low temperature was different comparing with that of high temperature. The mechanism was investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs). Moreover, a mathematic model was built to calculate mercury desorption activation energy from Sn to Mn binary metal oxides. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. First-principles investigation of competing magnetic interactions in (Mn ,Fe )Ru2Sn Heusler solid solutions

    Science.gov (United States)

    Decolvenaere, Elizabeth; Gordon, Michael; Seshadri, Ram; Van der Ven, Anton

    2017-10-01

    Many Heusler compounds possess magnetic properties well suited for applications as spintronic materials. The pseudobinary Mn0.5Fe0.5Ru2Sn , formed as a solid solution of two full Heuslers, has recently been shown to exhibit exchange hardening suggestive of two magnetic phases, despite existing as a single chemical phase. We have performed a first-principles study of the chemical and magnetic degrees of freedom in the Mn1 -xFexRu2Sn pseudobinary to determine the origin of the unique magnetic behavior responsible for exchange hardening within a single phase. We find a transition from antiferromagnetic (AFM) to ferromagnetic (FM) behavior upon replacement of Mn with Fe, consistent with experimental results. The lowest energy orderings in Mn1 -xFexRu2Sn consist of chemically and magnetically uniform (111) planes, with Fe-rich regions preferring FM ordering and Mn-rich regions preferring AFM ordering, independent of the overall composition. Analysis of the electronic structure suggests that the magnetic behavior of this alloy arises from a competition between AFM-favoring Sn-mediated superexchange and FM-favoring RKKY exchange mediated by spin-polarized conduction electrons. Changes in valency upon replacement of Mn with Fe shifts the balance from superexchange-dominated interactions to RKKY-dominated interactions.

  10. Pressure-induced superconductivity in CrAs and MnP

    Science.gov (United States)

    Cheng, Jinguang; Luo, Jianlin

    2017-09-01

    Transition-metal monopnictides, CrAs and MnP, were studied over 50 years ago due to the presence of interesting magnetic properties: CrAs forms a double-helical magnetic structure below T N  ≈  270 K accompanied by a strong first-order structural transition, while MnP first undergoes a ferromagnetic transition at T C  ≈  290 K and then adopts a similar double-helical order below T s  ≈  50 K. Both compounds are correlated metals and exhibit distinct anomalies at these characteristic magnetic transitions. By using high pressure as a clean tuning knob, we recently observed superconductivity with a maximum superconducting transition temperature of T c  ≈  2 K and 1 K when their helimagnetic orders are suppressed under a critical pressure of P c  ≈  0.8 and 8 GPa for CrAs and MnP, respectively. Despite a relatively low T c, CrAs and MnP are respectively the first superconductor among the Cr- and Mn-based compounds in that the electronic density of states at the Fermi energy are dominated by Cr/Mn-3d electrons. These discoveries, in particular the close proximity of superconductivity to the helimagnetic order reminiscent of many unconventional superconducting systems, have attracted considerable attention in the community of superconductivity. The evolution of the helimagnetic order under pressure and its relationship with superconductivity have been actively investigated recently. Much effort has also been devoted to exploring more novel Cr- or Mn-based superconductors, leading to the discovery of quasi-1D A2Cr3As3 (A  =  K, Rb, Cs) superconductors. In this review article, we will summarize the current progress achieved regarding superconductivity in CrAs and MnP.

  11. Diode-pumped Cr-doped ZnMnSe and ZnMgSe lasers

    Science.gov (United States)

    Říha, A.; Němec, M.; Jelínková, H.; Čech, M.; Vyhlídal, D.; Doroshenko, M. E.; Komar, V. K.; Gerasimenko, A. S.

    2017-12-01

    Chromium ions Cr2+ are known to have good fluorescence properties in the mid-infrared spectral region around the wavelength of 2.5 μm. The aim of this study was the investigation of new laser crystal materials - Zn0.95Mn0.05Se, Zn0.70Mn 0.30Se, and Zn0.75Mg0.25Se doped by Cr2+ ions and comparison of their spectral and laser characteristics. The spectroscopic parameters as absorption and fluorescence spectra as well as lifetimes were measured. As optical pumping the laser diode generating radiation at the wavelength of 1.69 μm (pulse repetition rate 10 Hz, pulse width 2 ms) was used. The longitudinal-pumped resonator was hemispherical with an output coupler radius of curvature 150 mm. The laser emission spectra were investigated and the highest intensity of emitted radiation was achieved at wavelengths 2451 nm, 2469 nm, and 2470 nm from the Cr:Zn0.95Mn0.05Se, Cr:Zn0.70Mn0.30Se, and Cr:Zn0.75Mg0.25Se laser systems, respectively. The input-output characteristics of laser systems were measured; the maximum output peak power 177 mW was obtained for Cr:Zn0.95Mn0.05Se laser system with slope efficiency of 6.3 % with respect to absorbed peak power. The output peak power as well as output beam spatial structure were stable during measurements. For the selection of the lasing wavelength, the single 1.5 mm thick quartz plate was placed at the Brewster angle inside the optical resonator between the output coupler and laser active medium. This element provided the tuning in the wavelength range 2290-2578 nm, 2353-2543 nm, and 2420-2551 nm for Cr:Zn0.95Mn0.05Se, Cr:Zn0.70Mn0.30Se, and Cr:Zn0.75Mg0.25Se, respectively. The obtained spectral FWHM linewidth of the individual output radiation was 10 nm. A comparison with previously measured Cr:ZnSe laser system was added in the end

  12. Chemical shift of Mn and Cr K-edges in X-ray absorption ...

    Indian Academy of Sciences (India)

    Measurements have been carried out at the energy dispersive EXAFS beamline at INDUS-2 Synchrotron Radiation Source at Raja Ramanna Centre for Advanced Technology, Indore. Energy shifts of ∼8–16 eV were observed for Mn K edge in the Mn-compounds while a shift of 13–20 eV was observed for Cr K edge in ...

  13. INFLUENCE OF ANNEALING ON HARDNESS OF Cr-Mn-Ni CAST IRONS

    Directory of Open Access Journals (Sweden)

    V. V. Netrebko

    2015-01-01

    Full Text Available The necessary level of material’s hardness is determined by the exploitation conditions and presence of technological operations during manufacturing of articles. Mechanical edge cutting machining of wear resistant materials is impeded because of their high hardness. It is recommended to apply annealing in order to decrease hardness and improve machinability. The purpose of the work consisted in obtaining of regression dependences of cast iron’s macrohardness on its chemical content after annealing at 730 °С. With the use of mathematical experimental design the regression dependences of cast iron’s macrohardness and structural components’ microhardness on С, Cr, Mn, Ni content have been established. The minimal hardness of 27,6 HRC after annealing at 730 °С is obtained in the cast iron containing: 3,9% С; 11,4% Cr; 0,6% Mn; 0,2% Ni. The maximal hardness of 70,4 HRC is obtained when the content is as follows: 1,1% С; 25,6% Cr; 5,4% Mn; 3,0% Ni. Annealing at 730 °С decreases the cast irons’ hardness containing the minimal amount of Cr, Mn and Ni. Annealing at 730 °С is recommended for cast irons alloyed by Mn and Ni for increasing of hardness.

  14. New type of Schottky diode-based Cu-Al-Mn-Cr shape memory material films

    Science.gov (United States)

    Aksu Canbay, C.; Dere, A.; Mensah-Darkwa, Kwadwo; Al-Ghamdi, Ahmed; Karagoz Genç, Z.; Gupta, R. K.; Yakuphanoglu, F.

    2016-07-01

    Cr-doped CuAlMn shape memory alloys were produced by arc melting method. The effects of Cr content on microstructure and transformation parameters of were investigated. The alloys were characterized by X-ray analysis, optical microscope observations and differential scanning calorimetry measurements. The grain size of the alloys was decreased by the addition of Cr into CuAlMn alloy system. The martensite transformation temperature was shifted both the lower temperature and higher temperature with the addition of chromium. This change was explained on the basis of the change in the thermodynamics such as enthalpy, entropy and activation energy values. The obtained results indicate that the phase transformation temperatures of the CuAlMn alloy system can be controlled by addition of Cr. We fabricated a Schottky barrier diode and observed that ideality factor and barrier height increase with increasing temperature. The diodes exhibited a thermal sensor behavior. This indicates that Schottky diode-based Cu-Al-Mn-Cr shape memory material films can be used as a sensor in high-temperature measurement applications.

  15. Magnetic glass in shape memory alloy: Ni45Co5Mn38Sn12.

    Science.gov (United States)

    Lakhani, Archana; Banerjee, A; Chaddah, P; Chen, X; Ramanujan, R V

    2012-09-26

    The first order martensitic transition in the ferromagnetic shape memory alloy Ni(45)Co(5)Mn(38)Sn(12) is also a magnetic transition and has a large field induced effect. While cooling in the presence of a field this first order magnetic martensite transition is kinetically arrested. Depending on the cooling field, a fraction of the arrested ferromagnetic austenite phase persists down to the lowest temperature as a magnetic glassy state, similar to the one observed in various intermetallic alloys and in half doped manganites. A detailed investigation of this first order ferromagnetic austenite (FM-A) to low magnetization martensite (LM-M) state transition as a function of temperature and field has been carried out by magnetization measurements. Extensive cooling and heating in unequal field (CHUF) measurements and a novel field cooled protocol for isothermal MH measurements (FC-MH) are utilized to investigate the glass like arrested states and show a reverse martensite transition. Finally, we determine a field-temperature (HT) phase diagram of Ni(45)Co(5)Mn(38)Sn(12) from various magnetization measurements which brings out the regions where thermodynamic and metastable states coexist in the HT space, clearly depicting this system as a 'magnetic glass'.

  16. Phase transition of Ni43Mn41Co5Sn11 Heusler alloy

    Science.gov (United States)

    Elwindari, N.; Kurniawan, C.; Manaf, A.

    2017-07-01

    In the recent years, Heusler alloy has been extensively studied. Among various the Heusler alloys, Ni-Mn-Sn has gained considerable interest due to their multifunctional properties like magnetoresistance, shape memory effect and magnetocaloric effect associated with a first order phase transition martensite to austenite. In this paper, we report the magneto-structural phase transitions under varying temperature of Ni43Mn41Co5Sn11 synthesized through vacuum arc-melting process. The magnetization of the sample was obtained after annealing process at 1173 K for 12 hours. It was evaluated by magnetic measurement using vibrating sample magnetometer (VSM250) up to a field of 21 kOe. The magnetic isotherm (M-H curves) shows the vicinity of the structural phase transition point. Magnetic saturation (Ms) of the NMCS alloy decreased and ferromagnetic transition shift towards higher temperature from 297-372 K. It might occur due to the alignment of the atomic magnetic moments depends on temperature. We discussed also the context of structural disorder and the ferromagnetic correlations in this study. The structural disorder of these alloys will explain the magnetic transition and the entropy change related magnetic properties.

  17. Directional solidification and elastocaloric effect in a Ni45Mn44Sn11 magnetic shape memory alloy

    Science.gov (United States)

    Sun, Wen; Liu, Jian; Zhao, Dewei; Zhang, Mingxiao

    2017-11-01

    In this work, the microstructural evolution, texture development and elastocaloric effect have been investigated in directionally solidified Heusler-type Ni45Mn44Sn11 alloys. A multi-phase structure is found in the as-grown sample, while only L21 phase exists after annealing. By employing the infrared thermography method, a significant average temperature change of  -7.5 K is observed in the annealed Ni45Mn44Sn11 alloy with a highly oriented [2 2 0] texture. Also, the formation of cracks and its influence on the mechanical stability and elastocaloric cooling behavior have been studied.

  18. Synthesis and crystal structure of the novel transition- metal substituted tin hydride H2Sn2[Mn(CO)5]4

    NARCIS (Netherlands)

    Bos, K.D.; Bulten, E.J.; Noltes, J.G.

    1975-01-01

    Dicyclopentadienyltin reacts with manganese pentacarbonyl hydride to give the first transition-metal substituted ditin dihydride, H[Mn(CO)5]2Sn---Sn- [Mn(CO)5]2H, the structure of which has been determined by X-ray analysis. The compound crystallizes in the monoclinic space group with four

  19. Relationship between spin ordering, entropy, and anomalous lattice variation in Mn3Sn(1-ε)Si(ε)C(1-δ) compounds.

    Science.gov (United States)

    Yan, Jun; Sun, Ying; Wen, Yongchun; Chu, Lihua; Wu, Meimei; Huang, Qingzhen; Wang, Cong; Lynn, Jeffrey W; Chen, Yunlin

    2014-02-17

    The crystal and magnetic structures of antiperovskite compounds Mn3SnC, Mn3Sn0.95C0.9, and Mn3Sn0.93Si0.07C0.94 were studied as a function of temperature and magnetic field by neutron powder diffraction. For Mn3SnC, the magnetic field induces a dramatic variation of antiferromagnetic moment and lattice parameter. Because of this spin-lattice coupling, the "square" antiferromagnetic (AFM) structure plays a key role in inducing a negative thermal expansion in the material. Moreover, the thermal expansion parameter is closely related to the rate of change of the AFM moment, which can be controlled by introducing vacancies or by doping. The variations of the AFM moment and lattice parameter in Mn3SnC with magnetic field make it possible to use the tunable properties for technical applications.

  20. Composition Influence on Magnetic Properties in Fe-Cr-Co-Ni-Si-Mn Alloys

    OpenAIRE

    Mariusz, SZPRYNGACZ; Masato, ENOKIZONO; Takashi, TODAKA; Oita University

    2004-01-01

    A new ferromagnetic shape memory alloy consisting of Fe-Cr-Co-Ni-Si-Mn has been developed by means of the melt spinning technique. The alloy has both shape memory effect and comparatively good magnetic properties, however a small modification of its chemical composition can change its properties considerably. This paper discusses such modifications and presents their influence on magnetic material properties.

  1. A note on urinary Cd, Cr, Mn and Pb, in students of the University of ...

    African Journals Online (AJOL)

    A note on urinary Cd, Cr, Mn and Pb, in students of the University of Agriculture Makurdi, Nigeria. GA Odeniran, R Sha'Ato. Abstract. A preliminary investigation of heavy metals exposure of students of the University of Agriculture, Makurdi in Central Nigeria involved AAS analysis of urine from ten (10) of the students (five ...

  2. Kα X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

    Indian Academy of Sciences (India)

    K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental ...

  3. Corrosion Behavior of 35CrMn and Q235 Steel in Simulated Acid Rain Conditions

    Science.gov (United States)

    Zuo, Xiu-li; Xiang, Bin; Li, Xing; Wei, Zi-dong

    2012-04-01

    Effects of pH value, chloride ion concentration and alternation of wetting and drying time in acid rain on the corrosion of 35CrMn and Q235 steel were investigated through the measurement of polarization curves, electrochemical impedance spectroscopy, x-ray diffraction, and quantum mechanical calculations. The corrosion rate of 35CrMn and Q235 steel increased with decreasing pH values of the simulated acid rain, whereas the corrosion potential of 35CrMn and Q235 steel became more negative. The impedance became higher and the corrosion rate decreased with increasing test time. The dissolution rate of samples increased with chloride ion concentration. Results suggested that the corrosion rate of 35CrMn steel was obviously lower than that of Q235 steel for a more compact rust, α-FeOOH. Quantum chemical calculations further revealed that the increase in corrosion rate of the steel resulted from pitting corrosion caused by the corrosive chloride ion.

  4. Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr ...

    Indian Academy of Sciences (India)

    Chemical effect on the K shell fluorescence yield of Fe, Mn, Co, Cr and Cu compounds. U TURGUT. Ataturk University, K.K. Education Faculty, Department of Physics, 25240 Erzurum,. Turkey. E-mail: umitturgut2000@yahoo.com. MS received 5 November 2003; revised 30 March 2004; accepted 15 June 2004. Abstract.

  5. Assessment of the concentration of Cr, Mn and Fe in sediment using ...

    African Journals Online (AJOL)

    In the present study, laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of levels of Cr, Mn and Fe in sediment samples and the results have been compared with that of flame-atomic absorption spectroscopy (F-AAS). Fourteen sediment samples were collected from Tinishu Akaki River ...

  6. Theoretical approach to the magnetic properties of Mn (II), Cr (III ...

    Indian Academy of Sciences (India)

    The magnetic properties of Cu2+, Cr3+, and Mn2+ ions in the newly reported 12- and 15-membered macrocyclic complexes are analysed by a theoretical approach. The calculated magnetic moment and magnetic anisotropy for various situations, especially for Cu(II) ion, suggest that the magnetic properties may lead to a ...

  7. HIGH TEMPERATURE TENSILE PROPERTIES OF NEW FE-CR-MN DEVELOPED STEEL

    Directory of Open Access Journals (Sweden)

    M. Mahmoudiniya

    2017-03-01

    Full Text Available Nowadays, Ni-free austenitic stainless steels are being developed rapidly and high price of nickel is one of the most important motivations for this development. At present research a new FeCrMn steel was designed and produced based on Fe-Cr-Mn-C system. Comparative studies on microstructure and high temperature mechanical properties of  new steel and AISI 316 steel were done. The results showed that new FeCrMn developed steel has single austenite phase microstructure, and its tensile strength and toughness were higher than those of 316 steel at 25, 200,350 and 500°C. In contrast with 316 steel, the new FeCrMn steel did not show strain induced transformation and dynamic strain aging phenomena during tensile tests that represented higher austenite stability of new developed steel. Lower density and higher strength of the new steel caused higher specific strength in comparison with the 316 one that can be considered as an important advantage in structural applications but in less corrosive environment

  8. Photoemission of Mn{sub 6}Cr single-molecule magnets

    Energy Technology Data Exchange (ETDEWEB)

    Heinzmann, U; Merschjohann, F; Helmstedt, A; Gryzia, A; Winter, A; Steppeler, S; Mueller, N; Brechling, A; Sacher, M [Molecular and Surface Physics, 33501 Bielefeld University (Germany); Richthofen, C-G Freiherr v; Glaser, T [Faculty of Chemistry, 33501 Bielefeld University (Germany); Voss, S; Fonin, M; Ruediger, U, E-mail: uheinzm@physik.uni-bielefeld.d [Faculty of Physics, 78457 Konstanz University (Germany)

    2009-11-01

    We present the status of new experimental studies of X-ray absorption spectroscopy, magnetic circular dichroism in photoemission and spin-resolved photoelectron spectroscopy of Mn{sub 6}Cr single-molecule magnet systems by use of circularly-polarized synchrotron radiation of the electron storage rings in Maxlab Lund, Sweden und BESSY, Berlin, Germany.

  9. Effect of Manganese on Microstructures and Solidification Modes of Cast Fe-Mn-Si-Cr-Ni Shape Memory Alloys

    Science.gov (United States)

    Peng, Huabei; Wen, Yuhua; Du, Yangyang; Yu, Qinxu; Yang, Qin

    2013-10-01

    We investigated microstructures and solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys to clarify whether Mn was an austenite former during solidification. Furthermore, we examined whether the Creq/Nieq equations (Delong, Hull, Hammer and WRC-1992 equations) and Thermo-Calc software® together with database TCFE6 were valid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni shape memory alloys. The results have shown that the solidification modes of Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni alloys changed from the F mode to the FA mode with increasing the Mn concentration. Mn is an austenite former during the solidification for the cast Fe-Mn-Si-Cr-Ni shape memory alloys. The Delong, Hull, Hammer, and WRC-1992 equations as well as Thermo-Calc software® together with database TCFE6 are invalid to predict the solidification modes of cast Fe-(13-27)Mn-5.5Si-8.5Cr-5Ni SMAs. To predict the solidification modes of cast Fe-Mn-Si-Cr-Ni alloys, a new Creq/Nieq equation should be developed or the thermodynamic database of Thermo-Calc software® should be corrected.

  10. Room temperature magnetocaloric effect in Ni-Mn-In-Cr ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Akkera, Harish Sharma; Singh, Inderdeep; Kaur, Davinder

    2017-02-01

    The influence of Cr substitution for In on the martensitic phase transformation and magnetocaloric effect (MCE) has been investigated in Ni-Mn-Cr-In ferromagnetic shape memory alloy (FSMA) thin films fabricated by magnetron sputtering. Temperature dependent magnetization (M-T) measurements demonstrated that the martensitic transformation temperatures (TM) monotonously increase with the increase of Cr content due to change in valence electron concentration (e/a) and cell volume. From the study of isothermal magnetization curves (M-H), magnetocaloric effect around the martensitic transformation has been investigated in these FSMA thin films. The magnetic entropy change ∆SM of 7.0 mJ/cm3-K was observed in Ni51.1Mn34.9In9.5Cr4.5 film at 302 K in an applied field of 2 T. Further, the refrigerant capacity (RC) was also calculated for all the films in an applied field of 2 T. These findings indicate that the Cr doped Ni-Mn-In FSMA thin films are potential candidates for room temperature micro-length-scale magnetic refrigeration applications.

  11. Structure, magnetism, and electron-transport properties of Mn2CrGa-based nanomaterials

    Directory of Open Access Journals (Sweden)

    Wenyong Zhang

    2016-05-01

    Full Text Available Mn2CrGa in the disordered cubic structure has been synthesized using rapid quenching and subsequent annealing. The cubic phase transforms to a stable tetragonal phase when a fraction of Cr or Ga is replaced by Pt or Al, respectively. All samples are ferrimagnetic with high Curie temperatures (Tc; Mn2CrGa exhibits the highest Tc of about 813 K. The tetragonal samples have appreciable values of magnetocrystalline anisotropy energy, which leads to an increase in coercivity (Hc that approaches about 10 kOe in the Pt-doped sample. The Hc linearly increases with a decrease of temperature, concomitant with the anisotropy change with temperature. All samples are metallic and show negative magnetoresistance with room-temperature resistivities on the order of 1 mΩcm. The magnetic properties including high Tc and low magnetic moment suggest that these tetragonal materials have potential for spin-transfer-torque-based devices.

  12. Unusual magnetic hysteresis and the weakened transition behavior induced by Sn substitution in Mn3SbN

    Science.gov (United States)

    Sun, Ying; Guo, Yanfeng; Tsujimoto, Yoshihiro; Wang, Cong; Li, Jun; Wang, Xia; Feng, Hai L.; Sathish, Clastin I.; Matsushita, Yoshitaka; Yamaura, Kazunari

    2014-01-01

    Substitution of Sb with Sn was achieved in ferrimagnetic antiperovskite Mn3SbN. The experimental results indicate that with an increase in Sn concentration, the magnetization continuously decreases and the crystal structure of Mn3Sb1-xSnxN changes from tetragonal to cubic phase at around x of 0.8. In the doping series, step-like anomaly in the isothermal magnetization was found and this behavior was highlighted at x = 0.4. The anomaly could be attributed to the magnetic frustration, resulting from competition between the multiple spin configurations in the antiperovskite lattice. Meantime, Hc of 18 kOe was observed at x = 0.3, which is probably the highest among those of manganese antiperovskite materials reported so far. With increasing Sn content, the abrupt change of resistivity and the sharp peak of heat capacity in Mn3SbN were gradually weakened. The crystal structure refinements indicate the weakened change at the magnetic transition is close related to the change of c/a ratio variation from tetragonal to cubic with Sn content. The results derived from this study indicate that the behavior of Mn3Sb1-xSnxN could potentially enhance its scientific and technical applications, such as spin torque transfer and hard magnets.

  13. Reentrant behavior in Cr doped bilayer manganite LaSr2Mn2O7

    Science.gov (United States)

    Bhatia, S. N.; Mohapatra, Niharika

    2017-07-01

    We have studied the effect of replacing Mn3+ by Cr3+ on the structure, transport and magnetism in the bilayered manganite LaSr2Mn2O7. Although no structural transition was observed in LaSr2Mn2-yCryO7 (0.1 ≤ y ≤ 0.6), the electrical transport and the magnetic properties were found to be affected significantly by this substitution. Substitution of Cr3+ reduces the conductivity by restricting the hopping of small polarons. Magnetization increases with increasing Cr3+ concentration suggesting that Cr3+-ions induce ferromagnetic moments. The ferromagnetic and an antiferromagnetic phase observed above ∼60 K merge into an inhomogeneous phase below this temperature. Thermopower yields an essentially concentration independent charge density nearly equal to its value for chromium free composition inspite of its expected decrease with this substitution suggesting that the small charge density of the insulating AFM phase is supplemented by the free carriers in the FM phase. The inhomogeneous phase shows a relaxor type behavior which contrasts with the spin glass behavior seen in La0.46Sr0.54Mn0.98Cr0.02O3 having an identical AFM magnetic state. The difference is attributed to the non-JT character of Cr-ions which reduce the distortion of the Mnsbnd O octahedra located within the FM domains. With a higher lattice strain in the surrounding AFM matrix the carriers remain confined within the FM domains leading to the relaxor type behavior.

  14. Optimized thermoelectric performance of the n-type half-Heusler material TiNiSn by substitution and addition of Mn

    Directory of Open Access Journals (Sweden)

    Enkhtaivan Lkhagvasuren

    2017-04-01

    Full Text Available Alloys based on the half-Heusler compound TiNiSn with the addition of Mn or with a substitution of Ti by Mn are investigated as high-temperature thermoelectric materials. In both materials an intrinsic phase separation is observed, similar to TiNiSn where Ti has been partially substituted by Hf, with increasing Mn concentration the phase separation drastically reduces the lattice thermal conductivity while the power factor is increased. The thermoelectric performance of the n-type conducting alloy can be optimized both by substitution of Ti by Mn as well as the addition of Mn.

  15. Dynamics of nonergodic ferromagnetic/antiferromagnetic ordering and magnetocalorics in antiperovskite Mn3SnC

    Science.gov (United States)

    Ćakır, Ö.; Cugini, F.; Solzi, M.; Priolkar, K.; Acet, M.; Farle, M.

    2017-07-01

    We investigated the time dependence of the magnetic configuration at the mixed magnetic magnetostructural transition in Mn3SnC . The nonergodic nature of the transition involves the stabilization of a final magnetic configuration that involves additional AF ordering which is not present when the transition is initiated and develops only in time. We show the presence of the nonergodicity over a time scale of about 1 hour by field and time-dependent magnetization studies. Two characteristic times related to the transition are observed. We also study the equilibrium thermodynamics under ergodic conditions by heat capacity studies and determine the entropy-change and the adiabatic temperature change around the transition. We find agreement between the indirect and direct methods in determining the adiabatic temperature change and discuss the influence of nonergodic properties on the magnetocaloric effects.

  16. Anomalous Nernst and Righi-Leduc Effects in Mn3Sn : Berry Curvature and Entropy Flow

    Science.gov (United States)

    Li, Xiaokang; Xu, Liangcai; Ding, Linchao; Wang, Jinhua; Shen, Mingsong; Lu, Xiufang; Zhu, Zengwei; Behnia, Kamran

    2017-08-01

    We present a study of electric, thermal and thermoelectric response in noncollinear antiferromagnet Mn3Sn , which hosts a large anomalous Hall effect (AHE). Berry curvature generates off-diagonal thermal (Righi-Leduc) and thermoelectric (Nernst) signals, which are detectable at room temperature and invertible with a small magnetic field. The thermal and electrical Hall conductivities respect the Wiedemann-Franz law, implying that the transverse currents induced by the Berry curvature are carried by Fermi surface quasiparticles. In contrast to conventional ferromagnets, the anomalous Lorenz number remains close to the Sommerfeld number over the whole temperature range of study, excluding any contribution by inelastic scattering and pointing to the Berry curvature as the unique source of AHE. The anomalous off-diagonal thermo-electric and Hall conductivities are strongly temperature dependent and their ratio is close to kB/e .

  17. Heavy Metals (Mg, Mn, Ni and Sn contamination in Soil Samples of Ahvaz II Industrial Estate of Iran in 2013

    Directory of Open Access Journals (Sweden)

    Soheil l Sobhanardakani

    2016-04-01

    Full Text Available Background & Aims of the Study: Due to the rapid industrial development in Khuzestan province of Iran during recent years, this study was performed to analyze the variation of metals concentrations (Mg, Mn, Ni, and Sn in soil samples of Ahvaz II Industrial estate during the spring season of 2013. Materials & Methods: In this experimental study, 27 topsoil samples were collected from nine stations. The intensity of the soil contamination was evaluated, using a contamination factor (Cf and geo-accumulation index (I-geo. Results:  The mean soil concentrations (in mg kg-1 (dry weight were in ranged within 870-1144 (Mg, 188-300 (Mn, 93-199 (Ni and 9-15 (Sn. The data indicated that the I-geo value for all metals falls in class ‘1’. Also the Cf value for Mg and Mn falls in class ‘0’, the Cf value for Sn falls in class ‘1’ and the Cf value for Ni falls in the classes of ‘1’ and ‘2’. The result of the Pearson correlation showed that there were significant positive associations between all metals. Conclusions: According to the results which were achieved by a cluster analysis, there were significant positive associations among all metals based on Pearson correlation coefficient, especially between Ni and Sn; also both of them with Mn. Because the Ni originates from oil sources it can be resulted that Mn and Sn originate from oil sources, too. Therefore, industrial activities and exploitation of oil reservoirs are the main cause of pollution in that area. Also, it can be concluded that, with increasing the distance from the source of pollution, the accumulation of contaminants in the soil samples decreased.

  18. Magnetic properties of the CrMnFeCoNi high-entropy alloy

    Science.gov (United States)

    Schneeweiss, Oldřich; Friák, Martin; Dudová, Marie; Holec, David; Šob, Mojmír; Kriegner, Dominik; Holý, Václav; Beran, Přemysl; George, Easo P.; Neugebauer, Jörg; Dlouhý, Antonín

    2017-07-01

    We present experimental data showing that the equiatomic CrMnFeCoNi high-entropy alloy undergoes two magnetic transformations at temperatures below 100 K while maintaining its fcc structure down to 3 K. The first transition, paramagnetic to spin glass, was detected at 93 K and the second transition of the ferromagnetic type occurred at 38 K. Field-assisted cooling below 38 K resulted in a systematic vertical shift of the hysteresis curves. Strength and direction of the associated magnetization bias was proportional to the strength and direction of the cooling field and shows a linear dependence with a slope of 0.006 ±0.001 emu T . The local magnetic moments of individual atoms in the CrMnFeCoNi quinary fcc random solid solution were investigated by ab initio (electronic density functional theory) calculations. Results of the numerical analysis suggest that, irrespective of the initial configuration of local magnetic moments, the magnetic moments associated with Cr atoms align antiferromagnetically with respect to a cumulative magnetic moment of their first coordination shell. The ab initio calculations further showed that the magnetic moments of Fe and Mn atoms remain strong (between 1.5 and 2 μB ), while the local moments of Ni atoms effectively vanish. These results indicate that interactions of Mn- and/or Fe-located moments with the surrounding magnetic structure account for the observed macroscopic magnetization bias.

  19. Redox Dynamics of Mixed Metal (Mn, Cr, and Fe) Ultrafine Particles

    Energy Technology Data Exchange (ETDEWEB)

    Nico, Peter S.; Kumfer, Benjamin M.; Kennedy, Ian M.; Anastasio, Cort

    2008-08-01

    The impact of particle composition on metal oxidation state, and on changes in oxidation state with simulated atmospheric aging, are investigated experimentally in flame-generated nanoparticles containing Mn, Cr, and Fe. The results demonstrate that the initial fraction of Cr(VI) within the particles decreases with increasing total metal concentration in the flame. In contrast, the initial Mn oxidation state was only partly controlled by metal loading, suggesting the importance of other factors. Two reaction pathways, one reductive and one oxidative, were found to be operating simultaneously during simulated atmospheric aging. The oxidative pathway depended upon the presence of simulated sunlight and O{sub 3}, whereas the reductive pathway occurred in the presence of simulated sunlight alone. The reductive pathway appears to be rapid but transient, allowing the oxidative pathway to dominate with longer aging times, i.e. greater than {approx}8 hours. The presence of Mn within the particles enhanced the importance of the oxidative pathway, leading to more net Cr oxidation during aging implying that Mn can mediate oxidation by removal of electrons from other particulate metals.

  20. Investigations on MnSb and related compounds with b8-type structures

    NARCIS (Netherlands)

    Bouwma, Jakob

    1972-01-01

    This thesis describes investigations on phases with hexagonal B8-type structures in the systems Mn-Sb-Sn, Mn-Sb-Te, Mn-Cr-Sb and Mn-V-Sb. In -chapter 1 some general remarks are made on compounds with B8-type structures. The preparation of the samples, and the X-ray crystallographic investigations

  1. Effect of Aging Treatment on the Sensitization of Fe-Cr-Mn-N Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Young; Park, Yong Soo [Yonsei University, Seoul (Korea, Republic of); Kim, Young Sik [Andong National University, Andong (Korea, Republic of)

    1999-02-15

    In this work, the effects of aging treatment on the precipitation and mechanical properties of Fe-Cr-Mn-N stainless steels were studied. Experimental alloys were designed by the change of Creq/Nieq ratio, and two kinds of alloys having a austenitic phase and a duplex(austenite + ferrite) phase were manufactured. Optical microscope, scanning electron microscope, transmission electron microscope, and XRD were used to identify the precipitates formed by aging treatment. Mechanical properties were measured using techniques of a hardness test, a tensile test, and an impact test. In austenitic Fe-Cr-Mn-N steel, carbide and/or nitride were first precipitated in grain boundary by aging and then the increased aging time made intragranular precipitations which showed lamellar structures and grew from grain boundary into grain. Hardness, yield strength, and tensile strength were slightly increased, and the elongation and impact energy were largely decreased by aging treatment. However, duplex stainless steel showed the ferrite decomposition to sigma phase and austenite Il phase as like in case of Fe-Cr-Ni steels. In case of duplex Fe-Cr-Mn-N steels, the effects of aging treatment on the hardness, yield strength, and tensile strength were relatively small, but its effects were strong on the decrease of elongation and impact energy.

  2. Phase evolution and magnetic characteristics of TiFeNiCr and TiFeNiCrM (M = Mn, Co) high entropy alloys

    Science.gov (United States)

    Mishra, Rajesh K.; Shahi, Rohit R.

    2017-11-01

    The report describes the effect of elemental addition (Mn and Co) on the phase evolution and magnetic properties of equiatomic TiFeNiCr based high entropy alloys (HEAs). HEAs were synthesized through mechanical alloying (MA) of constituent elements for different milling duration. XRD analysis confirms that simple solid solution of face cantered cubic structure is formed for all the three selected HEAs. Double FCC and a sigma phase are evolved for TiFeNiCr and TiFeNiCrMn HEAs. However, for TiFeNiCrCo HEA single FCC phase is formed. Synthesized HEAs show soft magnetic characteristics and the value of saturation magnetization increases as the content of magnetic element increases. Moreover, the investigation also describes the effect of annealing on phase evolution and magnetic properties of synthesized HEAs. The value of saturation magnetization altered for annealed TiFeNiCrM (M = Mn, Co) HEAs.

  3. Metabolismo del Mg, Cu, Zn, Cr, Mn, y Ni en la diabetes melitus

    OpenAIRE

    Saavedra Vallejo, Ma. Pilar

    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...

  4. Microstructure and corrosion properties of CrMnFeCoNi high entropy alloy coating

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Qingfeng [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Lu, Fenggui [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China); Li, Ruifeng [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu, 212003 (China); Huang, Jian; Wu, Yixiong [Shanghai Key laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai, 200240 (China)

    2017-02-28

    Highlights: • Equimolar CrMnFeCoNi high entropy alloy coating are prepared by laser cladding. • The cladding layer forms a simple FCC phase solid solution with identical dendritic structure. • The cladding layer exhibits a noble corrosion resistance in both 3.5 wt.% NaCl and 0.5 M sulfuric acid. • Element segregation makes Cr-depleted interdendrites the starting point of corrosion reaction. - Abstract: Equimolar CrMnFeCoNi high entropy alloy (HEA) is one of the most notable single phase multi-component alloys up-to-date with promising mechanical properties at cryogenic temperatures. However, the study on the corrosion behavior of CrMnFeCoNi HEA coating has still been lacking. In this paper, HEA coating with a nominal composition of CrMnFeCoNi is fabricated by laser surface alloying and studied in detail. Microstructure and chemical composition are determined by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used to investigate the corrosion behavior. The coating forms a simple FCC phase with an identical dendritic structure composed of Fe/Co/Ni-rich dendrites and Mn/Ni-rich interdendrites. Both in 3.5 wt.% NaCl solution and 0.5 M sulfuric acid the coating exhibits nobler corrosion resistance than A36 steel substrate and even lower i{sub corr} than 304 stainless steel (304SS). EIS plots coupled with fitted parameters reveal that a spontaneous protective film is formed and developed during immersion in 0.5 M sulfuric acid. The fitted R{sub t} value reaches its maximum at 24 h during a 48 h’ immersion test, indicating the passive film starts to break down after that. EDS analysis conducted on a corroded surface immersed in 0.5 M H{sub 2}SO{sub 4} reveals that corrosion starts from Cr-depleted interdendrites.

  5. Magnetic and magnetoelastic properties of M-substituted cobalt ferrites (M=Mn, Cr, Ga, Ge)

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sang-Hoon [Iowa State Univ., Ames, IA (United States)

    2007-12-15

    Magnetic and magnetoelastic properties of a series of M-substituted cobalt ferrites, CoMxFe2-xO4 (M=Mn, Cr, Ga; x=0.0 to 0.8) and Ge-substituted cobalt ferrites Co1+xGexFe2-2xO4 (x=0.0 to 0.6) have been investigated.

  6. Preparation and characterization of Mn{sub 6}Cr single-molecule-magnets on surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Sacher, Marc; Helmstedt, Andreas; Gryzia, Aaron; Koop, Peter; Steppeler, Sebastian; Mueller, Norbert; Brechling, Armin; Heinzmann, Ulrich [Fak. f. Physik, Univ. Bielefeld (Germany); Hoeke, Veronika; Glaser, Thorsten [Fak. f. Chemie, Univ. Bielefeld (Germany); Fonin, Mikhail; Ruediger, Ulrich [Fak. f. Physik, Univ. Konstanz (Germany)

    2010-07-01

    The single-molecule-magnet (SMM) Mn{sub 6}Cr consists of two bowl-shaped Mn{sub 3}-salen complexes, bridged by a complex containing a Cr atom. Three counterions are coupled to the SMM to ensure charge neutrality. To study the influence of the molecule-substrate-interaction on the electronic and the magnetic properties a homogeneous preparation of the SMM on the substrate is necessary. The preparation is done by dropping SMM, dissolved in methanol with certain concentration. Depending on the choice of the substrate, the Mn{sub 6}Cr concentration, the substrate inclination and the droplet size the arrangement of the SMM strongly varies. This is visualized in videos of the drying process obtained by optical microscopy with a magnification of up to 1000. The electronic properties of the deposited SMM are investigated by X-ray absorption spectroscopy. These properties change with exposure time due to a low stability of the SMM against X-rays. These changes can be accelerated or slowed down via the choice of the counterions and the SMM concentration on the substrate. Possible reasons are discussed.

  7. Effects of Cr, Mo, W, Mn and Ni on creep properties of 2. 25Cr-Mo-V rotor steel. 2. 25Cr-Mo-V tanko no creep tokusei ni oyobosu Cr, Mo, W, Mn oyobi Ni no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kadoya, Y. (Mitsubishi Heavy Industries Ltd., Tokyo (Japan). Takasago Research and Development Center); Kitai, T.; Matsuo, A.; Tsuji, I. (Mitsubishi Heavy Industries Ltd., Tokyo (Japan)); Azuma, T.; Tanaka, Y. (The Japan Steel Works Ltd., Tokyo (Japan). Muroran Research Lab. ); Ikeda, Y. (The Japan Steel Works Ltd., Tokyo (Japan))

    1993-08-01

    2.2SCr-Mo-V rotor steel is developed and put into practical use as a high and low pressure suitable rotor steel and the gas turbine disk materials. In this study, the creep experiments subjected to stresses of the levels of 220, 250 and 280 MPa at 565[degree]C for 2.25Cr-Mo-V steel were carried out, effect of the alloying elements on creep properties was examined, and effect of the alloying elements on the precipitation of carbides was investigated. Main results obtained were as follows: Cr, Ni and Mn additions decreased the creep rupture strength of 2.25Cr-Mo-V steel, and W addition increased the creep rupture strength. Mo addition did not give a remarkable change on the seep rupture strength. Ni addition up to 1.8% did not exert a significant effect on the creep rupture strength, and its addition more than that value remarkably decreased the creep rupture strength. 20 refs., 12 figs., 2 tabs.

  8. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    Directory of Open Access Journals (Sweden)

    Marafatto F. F.

    2013-04-01

    Full Text Available Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR, in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III and coupled Cr(III ions and a well resolved hyperfine structure due to manganese ions, resulting from Mn(IV and Mn(II. The isotopic and EPR data support the hypothesis of Cr(III being oxidized by Mn oxides which are widespread in the aquifer, possibly related to the oscillation of the phreatic level. The obtained results highlight the usefulness of chromium stable isotopes as environmental tracers and support the observations that naturally occurring Mn oxides in soils may catalize Cr oxidation from the stable Cr(III form to the toxic Cr(VI soluble form, yielding valuable information in planning remediation interventions.

  9. Comparative study of Co, Cr and Al-doped LiMnO2 prepared by ion ...

    Indian Academy of Sciences (India)

    WINTEC

    –xO2 (M = Cr, Co, Al). After. NaMnO2, NaMxMn1–xO2 were added into LiBr n- .... This work was supported by the Scientific Research Fund of Hunan Provincial Education Department (No. 07B060) and the Backbone Young Teacher Fund of ...

  10. The magnetism and electronic transport properties of Mn{sub 3}Sn{sub 1−x}Si{sub x}C

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yongchun [School of Materials Engineering, YanCheng Institute of Technology, YanCheng 224051 (China); Wang, Cong, E-mail: congwang@buaa.edu.cn [Center of Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); Nie, Man [Center of Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); Sun, Ying [Center of Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); School of Materials Engineering, YanCheng Institute of Technology, YanCheng 224051 (China)

    2015-10-01

    The lattice, magnetic and electronic transport properties of the compounds Mn{sub 3}Sn{sub 1−x}Si{sub x}C (0≤x≤0.4) are investigated. The results have shown that Si-doping in the antiperovskite Mn{sub 3}SnC induces the decrease of the nearest neighbouring Mn–Mn bond distance of Mn{sub 3}Sn{sub 1−x}Si{sub x}C, and the magnetic structure transforms from ferrimagnetic to antiferromagnetic when x≥0.2. With the increase of Si, the Neel temperature T{sub N} rises. The T{sub N} of Mn{sub 3}Sn{sub 1−x}Si{sub x}C(x=0.2, 0.3, 0.4) are 217 K, 257 K and 290 K, respectively. However, the magnetovolume effect is quenched. In Mn{sub 3}SnC and Mn{sub 3}Sn{sub 1−x}Si{sub x}C (x=0.2, 0.3, 0.4) compounds, there exists an anomalous increase in resistivity at a certain temperature that coincides well with their Curie temperature T{sub C} or Neel temperature T{sub N}. The temperature dependence of the resistivity of Mn{sub 3}Sn{sub 1−x}Si{sub x}C (x=0, 0.2, 0.3, 0.4) exhibits semiconducting-like behavior at low temperature and metallic-like behavior at high temperature. - Highlights: • The lattice, magnetic and electronic transport properties of Mn3Sn{sub 1−x}Si{sub x}C compounds were investigated for the first time. • Si-doping in Mn{sub 3}SnC antiperovskite induces a decrease of the Mn–Mn distance, and a change of the magnetic interaction from ferromagnetic to antiferromagnetic when x≥0.2. With increasing Si, the magnetovolume effect is quenched. • The temperature dependence of resistivity of Mn{sub 3}Sn{sub 1−x}Si{sub x}C (x= 0, 0.1, 0.2, 0.3, and 0.4) shows semiconducting-like behaviour at low temperatures and metallic-like behaviour at high temperatures.

  11. Electronic structure and magneto-optical Kerr spectra of an epitaxial Ni54.3Mn31.9Sn13.8 Heusler alloy film

    Science.gov (United States)

    Uba, L.; Bonda, A.; Uba, S.; Bekenov, L. V.; Antonov, V. N.

    2017-07-01

    In this joint experimental and ab initio study, we investigated the influence of chemical composition and martensitic phase transition on the electronic, magnetic, optical and magneto-optical properties of ferromagnetic shape-memory Ni-Mn-Sn alloys. Optical properties and polar magneto-optical Kerr effect (MOKE) spectra for Ni-Mn-Sn alloy film of composition Ni54.3Mn31.9Sn13.8 deposited epitaxially on MgO(0 0 1) substrate were measured over the photon energy range 0.8≤slant hν ≤slant 5.8 eV, and the complete set of optical conductivity tensor elements were determined. To explain the microscopic origin of the optical and magneto-optical spectra, extensive first-principles calculations were made, using the spin-polarized fully relativistic linear-muffin-tin-orbital method. The electronic, magnetic and magneto-optical properties of Ni-Mn-Sn Heusler alloys were investigated for the cubic austenitic and 4O orthorhombic martensitic phases, in stoichiometric and off-stoichiometric compositions. The MOKE properties of Ni-Mn-Sn systems are very sensitive to deviation from stoichiometry. It was shown that the ab initio calculations reproduce experimental spectra well, and help to explain the microscopic origin of Ni-Mn-Sn optical and magneto-optical responses. The interband transitions responsible for the prominent structures in the Ni-Mn-Sn MOKE spectra have been identified—they come from relatively narrow energy intervals at several well-defined vicinities of high-symmetry directions of the Brillouin zone. Significant modification of the MOKE spectra can be considered as a fingerprint of martensitic phase transition in Ni-Mn-Sn alloys.

  12. Martensitic transformation and magnetic properties of manganese-rich Ni-Mn-In and Ni-Mn-Sn Heusler alloys; Untersuchung der martensitischen Umwandlung und der magnetischen Eigenschaften Mangan-reicher Ni-Mn-In- und Ni-Mn-Sn-Heusler-Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Krenke, T.

    2007-06-29

    In the present work, the martensitic transition and the magnetic properties of Manganese rich Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} alloys with 5 at%{<=}x(y){<=}25 at% were investigated. Calorimetry, X-ray and neutron diffraction, magnetization, and strain measurements were performed on polycrystalline samples. It was shown that alloys close to the stoichiometric composition Ni{sub 50}Mn{sub 25}Sn{sub 25} and Ni{sub 50}Mn{sub 25}Sn{sub 25} do not exhibit a structural transition on lowering of the temperature, whereas alloys with x{<=}15 at% Tin and y{<=}16 at% Indium transform martensitically. The structural transition temperatures increase linearly with decreasing Tin or Indium content. The crystal structures of the low temperature martensite are modulated as well as unmodulated. Alloys with compositions close to stoichiometry are dominated by ferromagnetic interactions, whereas those close to the binary composition Ni{sub 50}Mn{sub 50} order antiferromagnetically. Ferromagnetic order and structural instability coexist in a narrow composition range between 13 at%{<=}x{<=}15 at% and 15 at%{<=}x{<=}16 at% for Ni{sub 50}Mn{sub 50-x}Sn{sub x} and Ni{sub 50}Mn{sub 50-y}In{sub y} respectively. As a consequence, interesting magnetoelastic effects are observed. The Ni{sub 50}Mn{sub 34}In{sub 16} alloy shows a magnetic field-induced structural transition, whereby application of an external magnetic field in the martensitic state stabilizes the high temperature L2{sub 1} structure. Evidence for this was given by neutron diffraction experiments in external magnetic fields. Moreover, the structural transition temperatures of this alloy show large magnetic field dependencies. By use of calorimetry, M(T), and strain measurements, changes in M{sub s} up to -11 K/Tesla are observed. Such large values have, until now, not been observed in Heusler alloys. Since during transformation the volume changes reversibly, magnetic field-induced strains of about

  13. Optical and magnetic properties of Sn{sub 1−x}Mn{sub x}O{sub 2} dilute magnetic semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Khatoon, Sarvari [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi 110025 (India); Coolahan, Kelsey [Department of Physics and Astronomy, Rowan University, 201 Mullica Hill Road, Glassboro, NJ 08028 (United States)

    2014-12-05

    Highlights: • Monophasic Mn-doped SnO{sub 2} nanoparticles by solvothermal method for first time. • High surface area with smaller particle size. • Increase in band gap with increasing Mn concentration. • Sn{sub 1−x}Mn{sub x}O{sub 2} (x = 0.05 and 0.10) revealed the parasitic ferromagnetism. • Sn{sub 0.85}Mn{sub 0.15}O{sub 2} showed paramagnetic behaviour. - Abstract: Sn{sub 1−x}Mn{sub x}O{sub 2} (x = 0.05, 0.10 and 0.15) nanoparticles with tetragonal structure have been successfully synthesized by solvothermal method using oxalate precursor route. The oxalate precursors and its corresponding oxides were characterized by powder X-ray diffraction (PXRD), thermogravimetric (TG), fourier transform infrared (FTIR) and transmission electron microscopic (TEM) studies. PXRD studies showed the highly crystalline and monophasic nature of the solid solutions. The shifting of X-ray reflections towards higher angle is attributed to the incorporation of Mn{sup 2+} ions in SnO{sub 2} host lattice. The average particle size was found to be in the range of 5–11 nm. Reflectance measurements showed blue shift in energy band gap which increases with increasing Mn{sup 2+} concentration. Surface area of these nanoparticles (59–388 m{sup 2}/g) was found to be high which increases with increasing the dopant ion concentration. Mn-doped SnO{sub 2} showed distinct magnetic behaviour with different manganese concentration. Sn{sub 1−x}Mn{sub x}O{sub 2} (x = 0.05 and 0.10) revealed the parasitic ferromagnetism, however on increasing x = 0.15, sample showed paramagnetic behaviour.

  14. Electronic structure, magnetism and thermoelectricity in layered perovskites: Sr2SnMnO6 and Sr2SnFeO6

    Science.gov (United States)

    Khandy, Shakeel Ahmad; Gupta, Dinesh C.

    2017-11-01

    Layered structures especially perovskites have titanic potential for novel device applications and thanks to the multifunctional properties displayed in these materials. We forecast and justify the robust spin-polarized ferromagnetism in half-metallic Sr2SnFeO6 and semiconducting Sr2SnMnO6 perovskite oxides. Different approximation methods have been argued to put forward their physical properties. The intriguingly intricate electronic band structures favor the application of these materials in spintronics. The transport parameters like Seebeck coefficient, electrical and thermal conductivity, have been put together to establish their thermoelectric response. Finally, the layered oxides are found to switch their application as thermoelectric materials and hence, these concepts design the principles of the technologically desired thermoelectric and spin based devices.

  15. Microplasticity and fracture in a Ti-15V-3Cr-3Al-3Sn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Rabeeh, B.M.; Rokhlin, S.I.; Soboyejo, W.O. [Ohio State Univ., Columbus, OH (United States)

    1996-12-15

    Linear Elasticity is generally considered to occur in most standard textbooks by the strengthening of chemical bonds in the regime below the proportional limit in most materials. In some cases, however, a number of researchers have recognized the possible role of localized microplasticity (microplasticity in this paper refers to localized plasticity on a microstructural level at stresses below the so-called bulk yield stress) in the so-called elastic deformation regime. There is, therefore, a need for careful studies of the micromechanisms of microplasticity in the so-called elastic regime. Micromechanisms of microplasticity will be presented in this paper for a metastable {beta} Ti-15V-3Cr-3Al-3Sn (Ti-15-3) alloy deformed in incremental stages to failure under monotonic loading. Micromechanisms of tensile deformation and fracture will be elucidated for a Ti-15-3 plate with single phase {beta} and Widmanstaetten {alpha}+{beta} microstructures.

  16. A New Set of Creq and Nieq Equations for Predicting Solidification Modes of Cast Austenitic Fe-Mn-Si-Cr-Ni Shape Memory Alloys

    Science.gov (United States)

    Peng, Huabei; Wen, Yuhua; Du, Yangyang; Chen, Jie; Yang, Qin

    2013-12-01

    Solidification microstructures and solidification modes in different austenitic Fe-Mn-Si-Cr-Ni shape memory alloys were investigated. Based on these results, a new set of Creq and Nieq equations (Creq = Cr + 1.5Si; Nieq = Ni + 0.164Mn + 22C) were developed. The above results show that Mn is still an austenite former in austenitic Fe-Mn-Si-Cr-Ni alloys containing above 12 wt pct Mn and 4 wt pct Si, but its effect is weaker than that in austenitic stainless steels with lower Mn content.

  17. Magnetic field dependence of electrical resistivity and thermopower in Ni50Mn37Sn13 ribbons

    Directory of Open Access Journals (Sweden)

    D. V. Maheswar Repaka

    2015-09-01

    Full Text Available We report magnetization, magnetoresistance (MR and magnetothermopower (MTEP of melt spun Ni50Mn37Sn13 ribbons which exhibit an austentite to martensite phase transition at a temperature (TM ≈ 294 K. Upon cooling from 400 K, dc-resistivity and thermopower show abrupt changes at TM, indicating a change in the electronic density of states. The thermopower is negative from 400 K down to 10 K. Application of a magnetic field of μ0H = 5 T decreases TM by 5 K and induces large negative MR (-23% but positive MTEP (9% near TM. While the MR is appreciable from TM down to 10 K, MTEP is significant only below 60 K (MR = -2.5% and MTEP = +300% at 10 K. The magnetic field dependence of resistivity and thermopower show either reversible or irreversible behavior near TM, depending on whether the sample is zero-field cooled or field-cooled, which indicates that the electronic band structure near TM is magnetic history dependent.

  18. Site preference and electronic structure of Mn2RhZ (Z = Al, Ga, In, Si, Ge, Sn, Sb: a theoretical study

    Directory of Open Access Journals (Sweden)

    Ren Zhi

    2016-06-01

    Full Text Available The electronic structure and magnetism of Mn2RhZ (Z = Al, Ga, In, Si, Ge, Sn, Sb Heusler alloys have been studied by using first-principles calculations. Three half-metallic ferromagnets, namely, Mn2RhAl, Mn2RhGe and Mn2RhSb have been considered. The calculated equilibrium lattice constant increases with increasing atomic number of Z atoms lying in same column of periodic table. The calculated total magnetic moments Mtot are 2 µB/f.u. for Mn2RhAl and Mn2RhGa, 3 µB/f.u. for Mn2RhSi, Mn2RhGe and Mn2RhSn, and 4 µB/f.u. for Mn2RhSb, which agrees with the Slater-Pauling curve quite well. In all these compounds, except for Mn2RhSb, the moments of Mn (A and Mn (B are antiparallel to each other. The total magnetic moments of the three considered half-metals assume integral values in a wide range of equilibrium lattice parameters.

  19. Polymorphism and second harmonic generation in a novel diamond-like semiconductor: Li{sub 2}MnSnS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Devlin, Kasey P. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Glaid, Andrew J. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Center for Computational Sciences, Duquesne University, Pittsburgh, PA 15282 (United States); Brant, Jacilynn A.; Zhang, Jian-Han [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Srnec, Matthew N. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Center for Computational Sciences, Duquesne University, Pittsburgh, PA 15282 (United States); Clark, Daniel J. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902 (United States); Soo Kim, Yong [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902 (United States); Department of Physics and Energy Harvest-Storage Research Center, University of Ulsan, 680-749 (Korea, Republic of); Jang, Joon I. [Department of Physics, Applied Physics and Astronomy, Binghamton University, Binghamton, NY 13902 (United States); Daley, Kimberly R.; Moreau, Meghann A. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Madura, Jeffry D. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Center for Computational Sciences, Duquesne University, Pittsburgh, PA 15282 (United States); Aitken, Jennifer A., E-mail: aitkenj@duq.edu [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States)

    2015-11-15

    High-temperature, solid-state synthesis in the Li{sub 2}MnSnS{sub 4} system led to the discovery of two new polymorphic compounds that were analyzed using single crystal X-ray diffraction. The α-polymorph crystallizes in Pna2{sub 1} with the lithium cobalt (II) silicate, Li{sub 2}CoSiO{sub 4}, structure type, where Z=4, R1=0.0349 and wR2=0.0514 for all data. The β-polymorph possesses the wurtz-kesterite structure type, crystallizing in Pn with Z=2, R1=0.0423, and wR2=0.0901 for all data. Rietveld refinement of synchrotron X-ray powder diffraction was utilized to quantify the phase fractions of the polymorphs in the reaction products. The α/β-Li{sub 2}MnSnS{sub 4} mixture exhibits an absorption edge of ∼2.6–3.0 eV, a wide region of optical transparency in the mid- to far-IR, and moderate SHG activity over the fundamental range of 1.1–2.1 μm. Calculations using density functional theory indicate that the ground state energies and electronic structures for α- and β-Li{sub 2}MnSnS{sub 4}, as well as the hypothetical polymorph, γ-Li{sub 2}MnSnS{sub 4} with the wurtz-stannite structure type, are highly similar. - Graphical abstract: Two polymorphs, α- and β-Li{sub 2}MnSnS{sub 4}, have been discovered using single crystal X-ray diffraction. Rietveld refinement of synchrotron X-ray powder diffraction data indicates the presence of both polymorphs in the samples that were analyzed. - Highlights: • Li{sub 2}MnSnS{sub 4} exists as two polymorphs crystallizing in the Pna2{sub 1} and Pn space groups. • The α- and β-Li{sub 2}MnSnS{sub 4} mixture exhibits a moderate SHG response over a broad range. • The α- and β-Li{sub 2}MnSnS{sub 4} mixture exhibits an optical absorption edge of ∼2.6–3.0 eV. • Synchrotron powder diffraction data are necessary to distinguish α- and β-Li{sub 2}MnSnS{sub 4.} • Electronic structure calculations show similar total energies for α- and β-Li{sub 2}MnSnS{sub 4}.

  20. A DFT + U study of V, Cr and Mn doped CeO2(111)

    Science.gov (United States)

    Wang, Jing; Gong, Xue-Qing

    2018-01-01

    Density functional theory calculations corrected by on-site Coulomb interactions have been performed on CeO2(111) surfaces doped with three different transition metals, namely V-CeO2(111), Cr-CeO2(111) and Mn-CeO2(111). The unique physicochemical properties and catalytic reactivities of these doped surfaces were carefully studied, and specifically, the oxygen formation energies and CO reactions with surface O at different sites were systematically calculated. It has been shown that the dopants can help to form surface oxygen vacancies and increase surface reactivities, and in particular, Mn doped surface gives the best performance in surface reactions.

  1. Analysis of Co, Cr and Mn Concentrations in Atmospheric Dry Deposition in Hamadan City

    Directory of Open Access Journals (Sweden)

    P. Shokri Ragheb

    2016-07-01

    Full Text Available Introduction & Objective: Heavy metals are major pollutants that can spread in the atmosphere with particulate matter and dust and because of the toxic and carcinogenic effects, their meas-urement and control is very important. Therefore, this study was conducted to assess Co, Cr and Mn concentration in the atmospheric dry deposition collected from Hamadan city in 2014. Materials & Methods: After collection of 12 dust samples from 3 sampling stations and their laboratory preparation, metals concentrations were determined using ICP–OES. All statistical analyses were performed using the SPSS statistical package. Results: The results showed that the minimum and maximum mean concentrations of Co were 0.19 and 0.29 mg/kg for high and low traffic intensity sampling stations, respectively. The min and max mean concentrations of Cr were 0.65and 1.02 mg/kg for high traffic intensity and suburb sampling stations, respectively and the min and max mean concentrations of Mn were 7.23and 8.82 mg/kg for high and low traffic intensity sampling stations , respectively. Also comparing the mean concentrations of assessed metals with WHO permissible limits showed a significant difference (P< 0.05. The mean concentrations of metals were signifi-cantly lower than the maximum permissible limits. Conclusion: Although the mean concentrations of Co, Cr and Mn are lower than the standard levels, lack of continuous monitoring of heavy metals concentrations in the dust and particu-late matters in the air can lead to the entrance of various types of toxic pollutants such as heavy metals into the air and result in adverse health effects. (Sci J Hamadan Univ Med Sci 2016; 23 (2:149-156

  2. X-ray diffraction study of shock-modified tetragonal phases of SnO[sub 2] and MnO[sub 2

    Energy Technology Data Exchange (ETDEWEB)

    Newcomer, P.; Morosin, B.; Graham, R.A.

    1992-01-01

    X-ray diffraction line-profile analysis on tetragonal forms of Sn02 (cassiterite), Mn02 (pyrolusite), and previously studied Ti02 (rutile), which were subjected to high pressure shock loading, show that residual lattice strain and coherent crystal'' size are a function of shock parameters. An interesting observation on sample of Mn02 concerns the recovery of cubic Mn203 (bixbyite) in the material subjected to 22 GPa, indicating a shock-induced chemical synthesis.

  3. X-ray diffraction study of shock-modified tetragonal phases of SnO{sub 2} and MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Newcomer, P.; Morosin, B.; Graham, R.A.

    1992-11-01

    X-ray diffraction line-profile analysis on tetragonal forms of Sn02 (cassiterite), Mn02 (pyrolusite), and previously studied Ti02 (rutile), which were subjected to high pressure shock loading, show that residual lattice strain and coherent ``crystal`` size are a function of shock parameters. An interesting observation on sample of Mn02 concerns the recovery of cubic Mn203 (bixbyite) in the material subjected to 22 GPa, indicating a shock-induced chemical synthesis.

  4. Spin dynamics evidenced by EPR in Sn{sub 1-x}Mn{sub x}O{sub 2} nanoparticles annealed at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Popa, A.; Toloman, D. [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath 65-103, 400293 Cluj-Napoca (Romania); Raita, O., E-mail: oana.raita@itim-cj.ro [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath 65-103, 400293 Cluj-Napoca (Romania); Stan, M. [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath 65-103, 400293 Cluj-Napoca (Romania); Vasile, B.S. [University ' Politehnica' , Faculty of Applied Chemistry and Material Science, Department of Science and Engineering of Oxide Materials and Nanomaterials, 1-7 Gh. Polizu, 011061 Bucharest (Romania); Leostean, C.; Giurgiu, L.M. [National Institute for Research and Development of Isotopic and Molecular Technologies, Donath 65-103, 400293 Cluj-Napoca (Romania)

    2013-02-25

    Highlights: Black-Right-Pointing-Pointer The mean size of individual nanoparticles was investigated by TEM. Black-Right-Pointing-Pointer The annealed temperature influence on Mn{sup 2+} and Mn{sup 4+} ions content was investigated. Black-Right-Pointing-Pointer A ferromagnetic phase was identified by EPR and his origin was explained. - Abstract: This article reports the effects of the annealing temperature on the structural, morphological and spin dynamic properties of SnO{sub 2} samples doped with 0.005 Mn. The samples were annealed at 400, 600, 700 and 800 Degree-Sign C and analyzed by XRD, TEM, XPS and EPR spectroscopy. The XRD spectra show that the average crystallite size increases with the increase of the annealing temperature. The particles size and morphology were characterized by TEM microscopy. The valence bands of Mn were investigated by measuring the XPS spectra of Mn 2p core-level doublet. Regardless of the annealing temperature, the observed EPR spectra are due to (i) Mn{sup 2+} ions either interstitially situated on the particle surfaces or isolated ones located substitutionally at Sn sites and (ii) Mn{sup 4+} ions which substitute for Sn{sup 4+} in SnO{sub 2} lattice. The effects of the annealing temperature on the relative fractions of Mn{sup 2+} and Mn{sup 4+} ions are presented and discussed. In Sn{sub 1-x}Mn{sub x}O{sub 2} (x = 0.005) sample annealed at 400 Degree-Sign C, a FMR line was identified and attributed to a ferromagnetic phase.

  5. Chemical zoning and diffusion of Ca, Al, Mn, and Cr in olivine of springwater pallasite

    Science.gov (United States)

    Zhou, Y.; Steele, Ian M.

    1993-01-01

    The pallasites, consisting mainly of Fe-Ni metal and olivine, are thought to represent the interior of a planetary body which slowly cooled from high temperature. Although the olivines are nearly homogeneous, ion microprobe studies revealed variations of Ca, Ti, Co, Cr, and Ni near grain edges. These variations were thought to represent diffusion in response to falling temperature of the parent body. Pallasite cooling rates have been estimated based on kamacite taenite textures but results differ by x100. In principle elemental profiles in olivine can allow estimates of cooling rate if diffusion coefficients are known; in addition, given a cooling rate, diffusion coefficients could be derived. Data are presented which show that apparent diffusion profiles can be measured for Al, Ca, Cr, and Mn which qualitatively agree with expected diffusion rates and have the potential of providing independent estimates of pallasite cooling rates.

  6. Exploring the Cr{sup 2+} doping effect on structural, vibrational and dielectric properties of Mn-Zn ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Pankaj; Dar, M. A.; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com, E-mail: ty.ru123@gmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Tyagi, Tarun, E-mail: vdinesh33@rediffmail.com, E-mail: ty.ru123@gmail.com [Amity Institute of Nanotechnology, Amity University, Sector 125, Noida 201303 (India)

    2016-05-23

    A series of Cr doped Mn-Zn ferrites with compositional formula Mn{sub 0.5}Zn{sub 0.5-x}Cr{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.3, 0.5) were prepared by solid-state reaction route. X-ray diffraction (XRD) analysis reveals that the samples prepared are polycrystalline cubic spinel in structure (Fd3m) with some secondary phase of α–Fe{sub 2}O{sub 3}. Slight variation in the lattice parameter of Cr doped Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} has been observed due to difference in ionic radii of cations. Small shift in Raman modes towards higher wave number has been observed. Further the line width decreases with the doping ions. A giant dielectric constant ~10{sup 4} is observed for parent Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} which is found to decrease with increase in Cr{sup 2+} doping. Low dielectric loss is observed for Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and improves with Cr{sup 2+} doping at Zn{sup 2+} site.

  7. Tuning martensitic transformation, large magnetoresistance and strain in Ni50-xFexMn36Sn14 Heusler alloys

    Science.gov (United States)

    Liao, Pan; Jing, Chao; Zheng, Dong; Li, Zhe; Kang, Baojuan; Deng, Dongmei; Cao, Shixun; Lu, Bo; Zhang, Jincang

    2015-09-01

    We have investigated the martensitic transformation, exchange bias, magnetoresistance (MR) and strain in Ni50-xFexMn36Sn14 (x=1, 2, 3, 4) Heusler alloys. With the increase of Fe content, the austenite phase could be stabilized with L21 structure and hence the martensitic transition shifts to a lower temperature and finally disappears. This behavior can be understood by the weakening of Ni-Mn hybridization to suppress AFM interactions and enhancement of Fe-Fe ferromagnetic exchange interactions. The same reason can account for the slight decrease of exchange bias field (HEB) with the increase of the Fe content from x=1 to 2 and the disappearance of HEB for x=3. We observed MR effect for x=3, and a maximum MR value of -52% was achieved, which can be explained by the change in the electronic structure during martensitic transformation induced by the magnetic field. In addition, a large strain of 0.207% in Ni49Fe1Mn36Sn14 was observed due to the changes of lattice parameters during the martensitic transformation induced by temperature.

  8. Slurry Erosion Behavior of Destabilized and Deep Cryogenically Treated Cr-Mn-Cu White Cast Irons

    Directory of Open Access Journals (Sweden)

    S. Gupta

    2016-12-01

    Full Text Available The effects of destabilization treatment and destabilization followed by cryogenic treatment have been evaluated on the microstructural evolution and sand-water slurry erosion behavior of Cr-Mn-Cu white cast irons. The phase transformations after the destabilization and cryotreatment have been characterized by bulk hardness measurement, optical and scanning electron microscopy, x-ray diffraction analysis. The static corrosion rate has been measured in tap water (with pH=7 and the erosion-corrosion behavior has been studied by slurry pot tester using sand-water slurry. The test results indicate that the cryogenic treatment has a significant effect in minimizing the as-cast retained austenite content and transforming into martensitic and bainitic matrix embedded with ultra-fine M7C3 alloy carbides. In contrast, by conventional destabilization treatment retained austenite in the matrix are not fully eliminated. The slurry erosive wear resistance has been compared with reference to destabilized and cryotreated high chromium iron samples which are commonly employed for such applications. The cryotreated Cr-Mn-Cu irons have exhibited a comparable erosive wear performance to those of high chromium irons. Higher hardness combined with improved corrosion resistance result in better slurry erosion resistance.

  9. Thermonuclear 46Cr(p ,γ )47Mn rate in type-I x-ray bursts

    Science.gov (United States)

    He, J. J.; Parikh, A.; Xu, Y.; Zhang, Y. H.; Zhou, X. H.; Xu, H. S.

    2017-10-01

    The thermonuclear rate of the 46Cr(p ,γ )47Mn reaction has been determined using a newly evaluated proton separation energy of Sp(47Mn) =380 ±30 keV and nuclear structure information from the mirror nucleus 47Ti. The astrophysical impact of this new rate and previously available rates has been investigated through one-zone postprocessing type-I x-ray burst calculations. The present 46Cr(p ,γ )47Mn rate leads to a mass fraction at A =46 that is 60 times larger than that obtained using a statistical model rate. The new results constrain the calculated maximum and minimum mass fractions at A =46 and A =48 to be within factors of 12 and 4, respectively. Experimental studies of the level structure of 47Mn near the proton threshold are required to improve these model predictions.

  10. Effect of heat treatment on martensitic transformation of Ni47Mn40Sn13 ferromagnetic shape memory alloy prepared by mechanical alloying

    Science.gov (United States)

    Ghotbi Varzaneh, A.; Kameli, P.; Zahedi, V. R.; Karimzadeh, F.; Salamati, H.

    2015-07-01

    In this paper, an attempt has been made to synthesis of the nanostructured Ni47Mn40Sn13 ferromagnetic shape memory alloy by ball milling of Ni, Mn and Sn powder mixture. The structure and magnetic evaluation of samples were investigated by X-ray diffraction, transmission electron microscopy, differential scanning calorimetry and AC susceptibility measurements. The results showed that after 20 hours of ball milling, the nanostructured L21-Ni47Mn40Sn13 powder was formed with an average particle size of 5 nm. In the as-milled specimen, the martensitic transformation (MT) was not observed. This was basically due to the atomic disordering and large lattice strain in nanoparticles. However, the annealing of milled specimens at temperatures above 1023K for 16 hours led to the occurrence of MT in nanostructured Ni47Mn40Sn13 powders. We also calculated t-he activation energy of MT by using Kissinger method and it was estimated to be about 52 kJ mol-1. The results demonstrate that a combination of MA and subsequent heat treatment has the potential to produce Ni-Mn-Sn magnetic shape memory.

  11. Diamagnetic nuclear 119Sn probes in the copper chromites CuCr2X4 (X = O, S, Se) with a spinel structure

    Science.gov (United States)

    Dmitrieva, T. V.; Lyubutin, I. S.; Stepin, A. S.; Dubinskaya, Yu. L.; Smirnovskaya, E. M.; Berry, F. J.; Thomas, M. F.

    2007-04-01

    The CuCr2X4 (X = O, S, Se) spinel system has been studied by the Mössbauer spectroscopy of the nuclear diamagnetic 119Sn probe at low temperatures in an external magnetic field. The hyperfine magnetic fields H Sn induced by paramagnetic ions at tin nuclei in the CuCr2S4 and CuCr2Se4 chalcogenides have giant values and are somewhat higher than those detected in the CuCr2O4 oxide. This behavior is caused by the strong covalence of the chalcogenides, which is supported by the experimentally found isomer shifts. The H Sn field is found to be mainly contributed by superexchange 90° interactions in the B-sublattice along the Cr[B]-X-Sn[B] bond chain, whose role increases in the series O-S-Se. In the oxygen CuCr2O4 spinel, the partial contributions to the H Sn field induced by the Cu2+ and Cr3+ ions are estimated. The local magnetic structure of the CuCr2O4 spinel is refined, and its total magnetization is shown to be directed along the magnetic moment of copper in the A sublattice.

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

    Science.gov (United States)

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

    2011-08-01

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

  13. Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Pinakidou, Fani; Kaprara, Efthimia [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece); Katsikini, Maria; Paloura, Eleni C.; Simeonidis, Konstantinos [Aristotle University of Thessaloniki, School of Physics, Department of Solid State Physics, 54124 Thessaloniki (Greece); Mitrakas, Manassis, E-mail: manasis@eng.auth.gr [Aristotle University of Thessaloniki, School of Chemical Engineering, Analytical Chemistry Laboratory, 54124 Thessaloniki (Greece)

    2016-05-01

    The feasibility of implementing a Sn(II) oxy-hydroxide (Sn{sub 6}O{sub 4}(OH){sub 4}) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn{sub 6}O{sub 4}(OH){sub 4} for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn{sub 6}O{sub 4}(OH){sub 4} can decrease Cr(VI) concentration below the upcoming regulation limit of 10 μg/L for drinking water. Moreover, an uptake capacity of 7.2 μg/mg at breakthrough concentration of 10 μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH){sub 3} precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO{sub 2}, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ({sup 2}C) and monodentate ({sup 1}V) geometries, at the expense of the present bidentate mononuclear ({sup 2}E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn{sub 6}O{sub 4}(OH){sub 4} in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the {sup 2}C and {sup 1}V configurations, which enhances the safe disposal of spent adsorbents. - Highlights: • Effective Cr(VI) removal from drinking water by Sn{sub 6}O{sub 4}(OH){sub 4} • Sn{sub 6}O{sub 4}(OH){sub 4} transformation to SnO{sub 2} after Cr

  14. Visible light-induced electron transfer from di-mu-oxo-bridged dinuclear Mn complexes to Cr centers in silica nanopores.

    Science.gov (United States)

    Weare, Walter W; Pushkar, Yulia; Yachandra, Vittal K; Frei, Heinz

    2008-08-27

    The compound (bpy) 2Mn (III)(mu-O) 2Mn (IV)(bpy) 2, a structural model relevant for the photosynthetic water oxidation complex, was coupled to single Cr (VI) charge-transfer chromophores in the channels of the nanoporous oxide AlMCM-41. Mn K-edge EXAFS spectroscopy confirmed that the di-mu-oxo dinuclear Mn core of the complex is unaffected when loaded into the nanoscale pores. Observation of the 16-line EPR signal characteristic of Mn (III)(mu-O) 2Mn (IV) demonstrates that the majority of the loaded complexes retained their nascent oxidation state in the presence or absence of Cr (VI) centers. The FT-Raman spectrum upon visible light excitation of the Cr (VI)-O (II) --> Cr (V)-O (I) ligand-to-metal charge transfer reveals electron transfer from Mn (III)(mu-O) 2Mn (IV) (Mn-O stretch at 700 cm (-1)) to Cr (VI), resulting in the formation of Cr (V) and Mn (IV)(mu-O) 2Mn (IV) (Mn-O stretch at 645 cm (-1)). All initial and final states are directly observed by FT-Raman or EPR spectroscopy, and the assignments are corroborated by X-ray absorption spectroscopy measurements. The endoergic charge separation products (Delta E o = -0.6 V) remain after several minutes, which points to spatial separation of Cr (V) and Mn (IV)(mu-O) 2Mn (IV) as a consequence of hole (O (I)) hopping as a major contributing mechanism. This is the first observation of visible light-induced oxidation of a potential water oxidation complex by a metal charge-transfer pump in a nanoporous environment. These findings will allow for the assembly and photochemical characterization of well-defined transition metal molecular units, with the ultimate goal of performing endothermic, multielectron transformations that are coupled to visible light electron pumps in nanostructured scaffolds.

  15. Visible Light-Induced Electron Transfer from Di-mu-oxo Bridged Dinuclear Mn Complexes to Cr Centers in Silica Nanopores

    Energy Technology Data Exchange (ETDEWEB)

    Frei, Heinz; Weare, Walter W.; Pushkar, Yulia; Yachandra, Vittal K.; Frei, Heinz

    2008-06-03

    The compound (bpy)2MnIII(mu-O)2MnIV(bpy)2, a structural model relevant for the photosynthetic water oxidation complex, was coupled to single CrVI charge-transfer chromophores in the channels of the nanoporous oxide AlMCM-41. Mn K-edge EXAFS spectroscopy confirmed that the di-mu-oxo dinuclear Mn core of the complex is unaffected when loaded into the nanoscale pores. Observation of the 16-line EPR signal characteristic of MnIII(mu-O)2MnIV demonstrates that the majority of the loaded complexes retained their nascent oxidation state in the presence or absence of CrVI centers. The FT-Raman spectrum upon visible light excitation of the CrVI-OII --> CrV-OI ligand-to-metal charge-transfer reveals electron transfer from MnIII(mu-O)2MnIV (Mn-O stretch at 700 cm-1) to CrVI, resulting in the formation of CrV and MnIV(mu-O)2MnIV (Mn-O stretch at 645 cm-1). All initial and final states are directly observed by FT-Raman or EPR spectroscopy, and the assignments corroborated by X-ray absorption spectroscopy measurements. The endoergic charge separation products (DELTA Eo = -0.6 V) remain after several minutes, which points to spatial separation of CrV and MnIV(mu-O)2MnIV as a consequence of hole (OI) hopping as a major contributing mechanism. This is the first observation of visible light-induced oxidation of a potential water oxidation complex by a metal charge-transfer pump in a nanoporous environment. These findings will allow for the assembly and photochemical characterization of well defined transition metal molecular units, with the ultimate goal of performing endothermic, multi-electron transformations that are coupled to visible light electron pumps in nanostructured scaffolds.

  16. Enhanced photodegradation activity of methyl orange over Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao; Wu, Jingxia; Liang, Huiping

    2016-05-15

    Highlights: • Novel visible-light-driven Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites are synthesized. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits higher photocatalytic activity than pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}. • Ag{sub 2}CrO{sub 4}/SnS{sub 2} exhibits excellent stability for the photodegradation of MO. • The possible photocatalytic mechanism was discussed in detail. - Abstract: Novel Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites were prepared by a simple chemical precipitation method and characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectroscopy and photoluminescence spectroscopy. The visible light photocatalytic tests showed that the Ag{sub 2}CrO{sub 4}/SnS{sub 2} composites enhanced photocatalytic activities for the photodegradation of methyl orange (MO) under visible light irradiation (λ > 420 nm), and the optimum rate constant of Ag{sub 2}CrO{sub 4}/SnS{sub 2} at a weight content of 1.0% Ag{sub 2}CrO{sub 4} for the degradation of MO was 2.2 and 1.5 times larger than that of pure Ag{sub 2}CrO{sub 4} and SnS{sub 2}, respectively. The improved activity could be attributed to high separation efficiency of photogenerated electrons-hole pairs on the interface of Ag{sub 2}CrO{sub 4} and SnS{sub 2}, which arised from the synergistic effect between Ag{sub 2}CrO{sub 4} and SnS{sub 2}. Moreover, the possible photocatalytic mechanism with superoxide radical anions and holes species as the main reactive species in photocatalysis process was proposed on the basis of experimental results.

  17. Synthesis of LiMn2O4 and LiCr0.2Mn1.8O4 powders by modified Pechini process

    Directory of Open Access Journals (Sweden)

    Alexandre Urbano

    2009-03-01

    Full Text Available LiMn2O4 and LiCr0.2Mn1.8O4 powders were synthesized by Pechini process, modified in order to reduce the number of steps and to work at temperatures below or equal to 400oC. Both phases crystallize in the same spinel structure with lattice constants of 8.21 and 8.22 Å respectively. Although the annealing temperature was low, the cristallinity is good and no residual amounts of organic material were detected.

  18. Sn(II) oxy-hydroxides as potential adsorbents for Cr(VI)-uptake from drinking water: An X-ray absorption study.

    Science.gov (United States)

    Pinakidou, Fani; Kaprara, Efthimia; Katsikini, Maria; Paloura, Eleni C; Simeonidis, Konstantinos; Mitrakas, Manassis

    2016-05-01

    The feasibility of implementing a Sn(II) oxy-hydroxide (Sn6O4(OH)4) for the reduction and adsorption of Cr(VI) in drinking water treatment was investigated using XAFS spectroscopies at the Cr-K-edge. The analysis of the Cr-K-edge XANES and EXAFS spectra verified the effective use of Sn6O4(OH)4 for successful Cr(VI) removal. Adsorption isotherms, as well as dynamic Rapid Small Scale Test (RSSCT) in NSF water matrix showed that Sn6O4(OH)4 can decrease Cr(VI) concentration below the upcoming regulation limit of 10μg/L for drinking water. Moreover, an uptake capacity of 7.2μg/mg at breakthrough concentration of 10μg/L was estimated from the RSSCT, while the residual Cr(VI) concentration ranged at sub-ppb level for a significant period of the experiment. Furthermore, no evidence for the formation of Cr(OH)3 precipitates was found. On the contrary, Cr(III)-oxyanions were chemisorbed onto SnO2, which was formed after Sn(II)-oxidation during Cr(VI)-reduction. Nevertheless, changes in the type of Cr(III)-inner sphere complexes were observed after increasing surface coverage: Cr(III)-oxyanions preferentially sorb in a geometry which combines both bidentate binuclear ((2)C) and monodentate ((1)V) geometries, at the expense of the present bidentate mononuclear ((2)E) contributions. On the other hand, the pH during sorption does not affect the adsorption mechanism of Cr(III)-species. The implementation of Sn6O4(OH)4 in water treatment technology combines the advantage of rapidly reducing a large amount of Cr(VI) due to donation of two electrons by Sn(II) and also the strong chemisorption of Cr(III) in a combination of the (2)C and (1)V configurations, which enhances the safe disposal of spent adsorbents. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Electronic and Optical Properties of Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) Antiperovskite Compounds

    Science.gov (United States)

    Iqbal, Samad; Murtaza, G.; Khenata, R.; Mahmood, Asif; Yar, Abdullah; Muzammil, M.; Khan, Matiullah

    2016-08-01

    The electronic and optical properties of cubic antiperovskites Ca3MN (M = Ge, Sn, Pb, P, As, Sb and Bi) were investigated by applying the full potential linearized augmented plane wave plus local orbitals (FP-LAPW + lo) scheme based on density functional theory. Different exchange correlation potentials were adopted for the calculations. The results of band structure and density of states show that, by changing the central anion of Ca3MN, the nature of the materials change from metallic (Ca3GeN, Ca3SnN, Ca3PbN) to semiconducting with small band gaps (Ca3SbN and Ca3BiN) to insulating (Ca3PN and Ca3AsN). The optical properties such as dielectric function, absorption coefficient, optical conductivity, reflectivity and refractive indices have also been calculated. The results reveal that all the studied compounds are optically active in the visible and ultraviolet energy regions, and therefore can be effectively utilized for optoelectronic devices.

  20. First-principle study of structural, electronic, vibrational and magnetic properties of HCN adsorbed graphene doped with Cr, Mn and Fe

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Li Bin, E-mail: slb0813@sohu.com; Wang, Yong Ping; Dong, Hai Kuan

    2015-02-28

    Graphical abstract: - Highlights: • Cr, Mn and Fe doped graphene is more active to adsorb HCN molecule than pristine graphene. • The conductivity of Fe and Mn doped graphene hardly changes after adsorption HCN molecule. • The conductivity of Cr doped graphene can be affected significantly due to HCN adsorption. • The Cr, Mn and Fe may destroy the long range order in graphene. • Phonon density of states suggests that Cr doped graphene is stable. - Abstract: The adsorption energy, electronic structure, lattice vibration and magnetic properties of Cr, Mn and Fe doped graphene with and without HCN adsorption are investigated by the first principles based on density functional theory. The physisorption and chemisorption have been identified. In the paper, Cr-NG, Mn-NG and Fe-NG denote HCN adsorption on Cr, Mn and Fe doped graphene with N atom toward the adsorption site. It is found that the adsorption energy is −1.36 eV for Fe-NG, −0.60 eV for Mn-NG and −0.86 eV for Cr-NG. The Cr-NG will convert from half-metallic behavior to semiconductor after adsorbing HCN molecule, which indicates that the conductivity changes significantly. Phonon density of states (PDOS) shows that the long range order in graphene can be destroyed by doping Fe, Mn and Cr. The imaginary frequency mode in PDOS suggests that Fe and Mn doped graphene is unstable, while Cr doped graphene is stable. The electronic properties are sensitive toward adsorbing HCN, indicating that Cr doped graphene is a promising sensor for detecting HCN molecule. This study provides a useful basis for understanding of a wide variety of physical properties on graphene.

  1. Magnetic properties of Fe Cr Mn Si based ferromagnetic shape memory ribbons

    Science.gov (United States)

    Todaka, Takashi; Sonoda, Masashi; Enokizono, Masato

    2007-03-01

    This paper presents measured properties of Fe-Cr-Mn-Si-based ferromagnetic shape memory ribbons. The alloys are multi-functional materials, which have both the ferromagnetic and shape memory properties. To improve ferromagnetic function, we investigated to add rare earth elements, and showed that the ferromagnetic functions can be improved by adding up to 1 wt% rare earth elements. The additions worked to shift the Curie point upward and to increase the residual saturation magnetization even after heat treatment. In this paper, to improve ductility of the samples, we made clear the effect of Ni addition. The result shows that addition of Ni over 1.2 wt% improves ductility; however, the Curie temperature is slightly decreased and the region of a ferromagnetic austenitic phase becomes narrower with increasing Ni contents.

  2. Wear Resistance of Steel 20MnCr5 After Surfacing with Micro-jet Cooling

    Directory of Open Access Journals (Sweden)

    Tarasiuk W.

    2016-09-01

    Full Text Available This paper presents results of experimental research concerning the impact of an innovative method of micro-jet cooling on the padding weld performed with MIG welding. Micro-jet cooling is a novel method patented in 2011. It enables to steer the parameters of weld cooling in a precise manner. In addition, various elements which may e.g. enhance hardness or alter tribological properties can be entered into its top surface, depending on the applied cooling gas. The material under study was steel 20MnCr5, which was subject to the welding process with micro-jet cooling and without cooling. Nitrogen was used as a cooling gas. The main parameter of weld assessment was wear intensity. The tests were conducted in a tribological pin-on-disc type position. The following results exhibit growth at approximately 5% in wear resistance of padding welds with micro-jet cooling.

  3. Pressure dependence of resistivity and magnetic properties in a Mn1.9Cr0.1Sb alloy

    Directory of Open Access Journals (Sweden)

    D. V. Maheswar Repaka

    2017-12-01

    Full Text Available We report magnetic-field and hydrostatic pressure dependent electrical resistivity and magnetic properties of a Mn1.9Cr0.1Sb alloy. Upon cooling, the magnetization of Mn1.9Cr0.1Sb exhibits a first-order ferrimagnetic to antiferromagnetic transition at the exchange inversion temperature, TS = 261 K under a 0.1 T magnetic field. Our experimental results show that TS decreases with increasing magnetic field but increase with increasing hydrostatic pressure. The pressure induced transition is accompanied by a large positive baro-resistance of 30.5% for a hydrostatic pressure change of 0.69 GPa. These results show that the lattice parameters as well as the bond distance between Mn-Mn atoms play a crucial role in the magnetic and electronic transport properties of Mn1.9Cr0.1Sb. This sample also exhibits a large inverse magnetocaloric effect with a magnetic entropy change of ΔSm = +6.75 J/kg.K and negative magnetoresistance (44.5% for a field change of 5 T at TS in ambient pressure which may be useful for magnetic cooling and spintronics applications.

  4. Microstructure and Mechanical Properties of High-Alloyed 23Cr-5Mn-2Ni-3Mo Cast Steel / Mikrostruktura I Właściwości Mechaniczne Wysokostopowego Staliwa 23Cr-5Mn-2Ni-3Mo

    Directory of Open Access Journals (Sweden)

    Kalandyk B.

    2015-12-01

    Full Text Available The article presents the microstructure and mechanical properties of cast duplex stainless steel type 23Cr-5Mn-2Ni-3Mo. It has been shown that the structure of the tested cast steel is composed of ferrite enriched in Cr, Mo and Si, and austenite enriched in Mn and Ni. In the initial state, at the interface, precipitates rich in Cr and Mo were present. A high carbon content (0.08%C in this cast steel indicates that probably those were complex carbides of the M23C6 type and/or σ phase. Studies have proved that the solution annealing conducted at 1060°C was not sufficient for their full dissolution, while at the solutioning temperature of 1150°C, the structure of the tested material was composed of ferrite and austenite.

  5. Electronic structure, magnetism and robust half-metallicity of new quaternary Heusler alloy FeCrMnSb

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukhtiyar [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India); Saini, Hardev S. [Department of Physics, National Institute of Technology, Kurukshetra 136 119, Haryana (India); Thakur, Jyoti [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India); Reshak, Ali H. [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Kashyap, Manish K., E-mail: manishdft@gmail.com [Department of Physics, Kurukshetra University, Kurukshetra 136 119, Haryana (India)

    2013-12-15

    Highlights: •A new quaternary Heusler alloy FeCrMnSb is identified with robust half metallicity. •The stability of FeCrMnSb has been examined using elastic constants. •Effect of uniform and tetragonal strains on half metallicity has been studied. -- Abstract: A new quaternary Heusler alloy FeCrMnSb is identified by employing ab initio electronic structure calculations. It is stable in Y-structure which is also verified by various conditions governed by elastic constants c{sub ij}. It is a true half-metallic (HM) ferromagnet with integer magnetic moment of 2.00 μ{sub B} per formula unit. The values of minority band gap and HM gap are found to be 0.65 eV and 0.1 eV, respectively. The HM character of FeCrMnSb sustains for −6% to 9% of uniform strain and −9% to 12% of tetragonal strain. This new quaternary Heusler alloy can be proved as an ideal candidate for spin valves and magnetic tunnel junction applications (MTJs)

  6. Sharp Lines Due to Cr3+ and Mn2+ Impurities in Insulators: Going Beyond the Usual Tanabe−Sugano Approach

    DEFF Research Database (Denmark)

    García Lastra, Juan Maria; García-Fernández, P.; Barriuso, M. T.

    2014-01-01

    This work is aimed at understanding the different behavior of optical sharp lines (corresponding to 10Dq-independent transitions) of Mn(2+) and Cr(3+) in normal and inverted perovskites that cannot be explained within the usual Tanabe-Sugano approach. In particular, we want to clarify why...

  7. Effect of Cr addition on the structural, magnetic and mechanical properties of magnetron sputtered Ni-Mn-In ferromagnetic shape memory alloy thin films

    Science.gov (United States)

    Akkera, Harish Sharma; Kaur, Davinder

    2016-12-01

    The effect of Cr substitution for In on the structural, martensitic phase transformation and mechanical properties of Ni-Mn-In ferromagnetic shape memory alloy (FSMA) thin films was systematically investigated. X-ray diffraction results revealed that the Ni-Mn-In-Cr thin films possessed purely austenitic cubic L21 structure at lower content of Cr, whereas higher Cr content, the Ni-Mn-In-Cr thin films exhibited martensitic structure at room temperature. The temperature-dependent magnetization ( M- T) and resistance ( R- T) results confirmed that the monotonous increase in martensitic transformation temperatures ( T M) with the addition of Cr content. Further, the room temperature nanoindentation studies revealed the mechanical properties such as hardness ( H), elastic modulus ( E), plasticity index ( H/ E) and resistance to plastic deformation ( H 3/ E 2) of all the samples. The addition of Cr content significantly enhanced the hardness (28.2 ± 2.4 GPa) and resistance to plastic deformation H 3/ E 2 (0.261) of Ni50.4Mn34.96In13.56Cr1.08 film as compared with pure Ni-Mn-In film. As a result, the appropriate addition of Cr significantly improved the mechanical properties with a decrease in grain size, which could be further attributed to the grain boundary strengthening mechanism. These findings indicate that the Cr-doped Ni-Mn-In FSMA thin films are potential candidates for microelectromechanical systems applications.

  8. Efficient photocatalytic reduction of aqueous Cr(VI) over flower-like SnIn{sub 4}S{sub 8} microspheres under visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lin [Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Li, Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Teng, Wei; Zhao, Qidong; Shi, Yong [Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Yue, Renliang [State Key Laboratory of Multi-Phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Yunfa, E-mail: yfchen@home.ipe.ac.cn [State Key Laboratory of Multi-Phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2013-01-15

    Highlights: ► SnIn{sub 4}S{sub 8} was used in photocatalytic reduction of aqueous Cr(VI) for the first time. ► Flower-like SnIn{sub 4}S{sub 8} microspheres with numerous uniform pores were fabricated. ► High visible light photocatalytic activity and good photocatalytic stability. -- Abstract: Photocatalytic reduction of aqueous Cr(VI) was successfully achieved on nanostructured SnIn{sub 4}S{sub 8}. The SnIn{sub 4}S{sub 8} particles with flower-like nanostructure were synthesized via a facile solvothermal method. UV–vis diffuse reflectance spectra (DRS) indicated that the SnIn{sub 4}S{sub 8} particles had strong absorption in visible region and the band gap was estimated to be from 2.27 to 2.35 eV. The photocatalytic reduction of aqueous Cr(VI) by flower-like SnIn{sub 4}S{sub 8} was evaluated under visible light (λ > 400 nm) irradiation. The polyvinyl pyrrolidone (PVP) assisted SnIn{sub 4}S{sub 8} sample exhibits excellent removal efficiency of Cr(VI) (∼97%) and good photocatalytic stability. The predominant photocatalytic activity is due to its large surface area, strong absorption in visible-light region and excellent charge separation characteristics.

  9. Study of magnetic compensation behavior in Mn(Cr1-xFex)2O4

    Science.gov (United States)

    Barman, Junmoni; Ravi, S.

    2017-09-01

    We report the preparation of single phase samples of Mn(Cr1-xFex)2O4 for x = 0-0.50 and study of their structural and magnetic properties. These samples are found to crystallize in cubic structure with Fd 3 bar m space group with typical lattice constant varying from a = 8.4396 Å for x = 0 to 8.4588 Å for x = 0.50. The ferrimagnetic transition temperature as per magnetic measurements is found to increase from 46 K for x = 0 to 402 K for x = 0.50 due to the strengthening of the superexchange interaction. The Saturation magnetization value is found to decrease monotonously with increase in Fe concentration beyond x = 0.10 and approaches magnetic compensation at x = 0.40. In addition to composition induced magnetic compensation, we have observed magnetic compensation due to change in temperature for x = 0.40 with a compensation temperature of 267 K. This is explained by considering the substitution of Fe3+ ions in one of the Cr3+ sites and the different temperature dependence of two sublattice moments.

  10. Magnetism and structure of a half-metallic Heusler compound Co-Mn-Cr-Si

    Science.gov (United States)

    Huh, Yung; Joshi, Swarangi; Jain, Sanmati; Pathak, Ojas; Kharel, Parashu

    Half metallic ferromagnetic Heusler compounds have a potential in the development of spintronic devices for its high spin polarization at the Fermi level and lattice structure compatibility. Heusler compounds based on cobalt are considered a good candidate for room temperature half-metals due to their high Curie temperature. Co2CrSi is one of such predicted half-metal, but it is meta-stable and difficult to synthesize in the desired crystal structure. We have successfully synthesized a Heusler compound Co2Mn0.5Cr0.5Si by using arc melting and rapid quenching followed by thermal treatment under high vacuum to control any parasitic contamination. Crystal X-ray diffraction pattern shows the samples crystallize in a cubic Heusler structure with some degrees of structural disorder. Curie temperatures of the prepared samples are observed well beyond room temperature near 900 K. Magnetic anomalies present in as-prepared samples are cleared, and its magnetic properties are improved by thermal treatment. This research is supported by Academic and Scholarly Excellence Funds, and Research/Scholarship Support Fund, South Dakota State University.

  11. Generalized Synthesis of EAs [E = Fe, Co, Mn, Cr] Nanostructures and Investigating Their Morphology Evolution

    Directory of Open Access Journals (Sweden)

    P. Desai

    2015-01-01

    Full Text Available This paper illustrates a novel route for the synthesis of nanostructured transition metal arsenides including those of FeAs, CoAs, MnAs, and CrAs through a generalized protocol. The key feature of the method is the use of one-step hot-injection and the clever use of a combination of precursors which are low-melting and highly reactive such as metal carbonyls and triphenylarsine in a solventless setup. This method also facilitates the formation of one-dimensional nanostructures as we move across the periodic table from CrAs to CoAs. The chemical basis of this reaction is simple redox chemistry between the transition metals, wherein the transition metal is oxidized from elemental state (E0 to E3+in lieu of reduction of As3+ to As3−. While the thermodynamic analysis reveals that all these conversions are spontaneous, it is the kinetics of the process that influences morphology of the product nanostructures, which varies from extremely small nanoparticles to nanorods. Transition metal pnictides show interesting magnetic properties and these nanostructures can serve as model systems for the exploration of their intricate magnetism as well as their applications and can also function as starting materials for the arsenide based nanosuperconductors.

  12. The effect of Pd on martensitic transformation and magnetic properties for Ni50Mn38−xPdxSn12Heusler alloys

    Directory of Open Access Journals (Sweden)

    C. Jing

    2016-05-01

    Full Text Available In the past decade, Mn rich Ni-Mn based alloys have attained considerable attention due to their abundant physics and potential application as multifunctional materials. In this paper, polycrystalline Ni50Mn38−xPdxSn12 (x = 0, 2, 4, 6 Heusler alloys have been prepared, and the martensitic phase transformation (MPT together with the shape memory effect and the magnetocaloric effect has been investigated. The experimental result indicates that the MPT evidently shifts to a lower temperature with increase of Pd substitution for Mn atoms, which can be attributed to the weakness of the hybridization between the Ni atom and excess Mn on the Sn site rather than the electron concentration. The physics properties study focused on the sample of Ni50Mn34Pd4Sn12 shows a good two-way shape memory behavior, and the maximum value of strain Δ L/L reaches about 0.13% during the MPT. The small of both entropy change Δ ST and magnetostrain can be ascribed to the inconspicuous influence of magnetic field induced MPT.

  13. Structural and electromagnetic characterization of Co-Mn doped Ni-Sn ferrites fabricated via micro-emulsion route

    Science.gov (United States)

    Ali, Rajjab; Azhar Khan, Muhammad; Manzoor, Alina; Shahid, Muhammad; FarooqWarsi, Muhammad

    2017-11-01

    Ni0.5Sn0.5CoxMnxFe2-2xO4 ferrites with x = 0.0-0.8 have been prepared by the micro-emulsion method, using CTAB as a surfactant material. X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR) and vibrational sample magnetometer (VSM) were used to investigate the effects of Co and Mn substitutions on cationic distribution, crystallite size, lattice constant, spectral, magnetic and dielectric properties. Lattice constant and crystallite size were found to increase from 7.4 to 9.25 Å and from 11.8 to 19.7 nm respectively with increasing substitution of Co and Mn ions. Saturation magnetization (MS) gradually increased from 20.5 to 47.6 emu/g with increase in the value of x. However, Coercivity increased from 152.7 to 462.4 Oe up to x = 0.4 and then it decreased thereafter. The dielectric constant, complex dielectric constant and tan loss (tanδ) were observed to decrease with increase in frequency, depicting the semiconductor behavior of the ferrites. Dc resistivity was observed to decrease considerably upon addition of Co and Mn content. The outcome for the tunable magnetic properties and achieved modification of the synthesized nanocrystallites may be chosen for tremendous applications; such as miniaturized memory devices that are based on the energy storage principles and capacitive components.

  14. OPTIMIZATION OF STEEL SATURATION PROCESSES USING CARBIDE-FORMING ELEMENTS IN SYSTEMS BASED ON Cr-Ti-V AND Cr-Ti-Mn

    Directory of Open Access Journals (Sweden)

    A. A. Shmatov

    2007-01-01

    Full Text Available Optimization of saturating mixture compositions has been carried out in two three-component systems, namely: Cr-Ti-V and Cr-Ti-Mn in respect of micro-hardness and wear resistance of carbide coatings obtained by thermo-chemical treatment of high carbon steel. «Composition - properties» diagrams have been plotted using mathematical models. Treatment with optimum compositions of powder media permits to increase wear resistance of steel by factor of 30-70 as compared with untreated steel. 

  15. Competition between ferromagnetic and antiferromagnetic interactions by Cr doping at Mn sites in antiperovskite Mn{sub 3−x}Cr{sub x}ZnN (0≤x≤0.5) compounds

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Muhammad Imran; Sun, Ying; Wang, Lei; Deng, Sihao; Shi, Kewen; Hu, Pengwei; Lu, Huiqing; Wang, Cong, E-mail: congwang@buaa.edu.cn

    2016-05-01

    The Cr doping effect on the lattice and magnetic properties in Mn{sub 3−x}Cr{sub x}ZnN was reported in the antiferromagnetic intermetallic host material Mn{sub 3}ZnN. The lattice parameter decreases with the increase of the Cr concentration. Measurements of magnetization from 10 K to 350 K reveal that sharp antiferromagnetic (AFM)-to-paramagnetic (PM) transitions of the host material exist at 185 K (ZFC) and 177 K (FC). The peak is broadened clearly as the Cr doping was increased and when the Cr concentration exceeded 0.3, a significant ferromagnetic (FM) character was found to coexist with an AFM phase. At x=0.4 and 0.5, the M–H curves exhibit small magnetic hysteresis loop, indicating the dominant FM interactions in these samples. Also, a positive value of Weiss Temperature (Θ{sub W}) at x=0.5 in H/M–T plot suggests that the FM interaction is dominant when the Cr doping increases.

  16. A comparative study on the Mn/TiO2-M(M = Sn, Zr or Al) Ox catalysts for NH3-SCR reaction at low temperature.

    Science.gov (United States)

    Zhang, Yaping; Huang, Tianjiao; Xiao, Rui; Xu, Haitao; Shen, Kai; Zhou, Changcheng

    2017-05-29

    A series of TiO2-M(M = Sn, Zr or Al) Ox were prepared and manganese oxide (MnOx) was supported on the carrier by the traditional impregnation method for low-temperature selective catalytic reduction (SCR) of NOx with ammonia as a reductant. The obtained catalysts were characterized by XRD, BET, high-resolution transmission electron microscope (HRTEM), H2-TPR, NH3-TPD, X-ray photoelectron spectroscopy (XPS) and in situ Fourier-transform infrared (FT-IR) and their catalytic activities for NOx reduction with NH3 in the presence of SO2 were investigated comparatively. The results showed that the highest NOx conversion of over 90% could be obtained with the Mn/Ti-Sn catalyst at a wide range of temperature window of 150-270°C. The combination of characterization techniques, such as BET, XRD and HRTEM, revealed that manganese oxides were well dispersed on Ti-Sn. H2-TPR suggested that Ti-Sn and Ti-Zr supports could enhance the reduction ability of catalysts. Accordingly, Mn/Ti-Al exhibited worse activity at low temperature. XPS results were in good agreement with H2-TPR results, and Mn/Ti-Sn had more surface-reducible species of Mn4+ ions and more surface-adsorbed oxygen species, which was conducive to SCR reaction. The in situ FT-IR spectra of NH3 adsorption indicated that all the modified catalysts had more Lewis acid sites and the amide species at 1506 cm-1 had a certain influence on the catalytic reaction at low temperature. Mn/Ti-Zr showed a stronger resistance to SO2 but Mn/Ti-Al was affected more adversely and all the catalysts could not be restored to the initial catalytic activity after stopping feeding SO2. NH3-TPD revealed that the total acid amount of the Mn/Ti-Sn sample was larger than other samples, which indicated that the Ti-Sn solid solution could provide more surface acid sites over the catalyst.

  17. Mössbauer Spectroscopy Studies on Magnetic Properties for 57Fe-substituted Ni-Mn-Sn Metamagnetic Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    Ryosuke Kainuma

    2013-06-01

    Full Text Available In order to investigate the Fe substituted effects on the magnetic properties of the Ni-Mn-Sn metamagnetic shape memory alloys, magnetization and the Mössbauer spectroscopy measurements were carried out with using 57Fe-doped specimens of Ni2Mn1.48−x57FexSn0.52 (x = 0.02, 0.04 and 0.08. Singlet-type Mössbauer spectra were clearly observed for x = 0.02 and 0.04 just below the martensitic transformation temperature, TM, and above the Curie temperature, TC, in the austenite phase. It was clear that the magnetic state in the martensite phase just below TM was paramagnetic for x = 0.02 and 0.04. In further doped 57Fe to Ni2Mn1.48Sn0.52, TC in the austenite phase slightly increased. However, the value of TM significantly decreased. As a result, martensite phase with small spontaneous magnetization directly transformed to the ferromagnetic austenite phase during heating for x = 0.08. These results obtained from the Mössbauer spectra were consistent with the results of the magnetic measurements in this study and the phase diagram reported by Fukushima et al. for normal Fe-doped Ni2Mn1.48−xFexSn0.52 alloys. The breakdown of the general rule, in which the ferromagnetic shape memory alloys with larger value of the valence electrons per atom, e/a, showed higher TM, was also appeared in Ni2Mn1.48−xFexSn0.52 alloys, being similar to Ni2Mn1−xFexGa alloys.

  18. Synthesis and structural stability of Cr-doped Li2MnSiO4/C cathode materials by solid-state method

    Science.gov (United States)

    Cheng, Hong-Mei; Zhao, Shi-Xi; Wu, Xia; Zhao, Jian-Wei; Wei, Lei; Nan, Ce-Wen

    2018-03-01

    The crystal structure of the Li2MnSiO4 cathode material would collapse during the charge and discharge process because of that the Mn-O coordination polyhedron changed from [MnO4] into [MnO6] in the process of Mn+2 to Mn+4, but the Cr element could remain [CrO4] crystal ligand from Cr+2 to Cr+4, so Cr element substitution was used to improve the structural stability of the Li2MnSiO4 cathode material. In this work, Li2Mn1-xCrxSiO4/C nanocomposites were synthesized by solid-state method. XRD, SEM and TEM observations show that the as-prepared Li2Mn1-xCrxSiO4/C materials presents an orthorhombic crystal structure (S.G. Pmn21), the particle size of Li2Mn1-xCrxSiO4/C powder ranges from 50 to 100 nm. The XRD and XPS results indicate that Cr+2 is successfully doped into Li2MnSiO4 lattice and has well compatibility with Li2MnSiO4. The electrochemical results display that Li2Mn92.5%Cr7.5%SiO4/C exhibits significantly enhanced cycle stability and discharge capability. The initial discharge capacity of the Li2Mn92.5%Cr7.5%SiO4/C sample is 255 mAh g-1, and the discharge capacity was still about 60 mAh g-1 after 50 cycles. Furthermore, the XRD patterns, TEM images and Raman analysis reveal that the Cr doping enhances the structural stability of Li2Mn1-xCrxSiO4/C and improves the electrochemical activity of the cathode. Thus, the Li2Mn92.5%Cr7.5%SiO4/C have shown potential applications for lithium ion batteries.

  19. Effect of Si, Mn, Sn on Tensile and Corrosion Properties of Mg-4Zn-0.5Ca Alloys for Biodegradable Implant Materials

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Dae Hyun; Nam, Ji Hoon; Lee, Byeong Woo; Park, Ji Yong; Shin, Hyun Jung; Park, Ik Min [Pusan National University, Busan (Korea, Republic of)

    2015-03-15

    Effect of elements Si, Mn, Sn on tensile and corrosion properties of Mg-4Zn-0.5Ca alloys were investigated. The results of tensile properties show that the yield strength, ultimate tensile strength and elongation of Mg-4Zn-0.5Ca alloy increased significantly with the addition of 0.6 wt% Mn. This is considered the grain refinement effect due to addition of Mn. However addition of 0.6 wt% Si decreased yield strength, ultimate tensile strength and elongation. The bio-corrosion behavior of Mg-4Zn-0.5Ca-X alloys were investigated using immersion tests and potentiodynamic polarization test in Hank's solution. Immersion test showed that corrosion rate of Mg-4Zn-0.5Ca-0.6Mn alloy was the lowest rate and addition of 1.0 wt% Sn accelerated corrosion rate due to micro-galvanic effect in α-Mg/CaMgSn phases interface. And corrosion potential (E{sub c}orr) of Mg-4Zn-0.5Ca-0.6Mn alloy was the most noble among Mg-4Zn-0.5Ca-X alloys.

  20. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, V. P., E-mail: vpfilippov@mephi.ru; Bateev, A. B.; Lauer, Yu. A. [National Research Nuclear University “MEPhI” (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350–360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α–Fe(Cr), α–Fe(Cu), α–Fe {sub 2}O{sub 3} and Fe {sub 3}O{sub 4} compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  1. Mössbauer study of oxide films of Fe-, Sn-, Cr- doped zirconium alloys during corrosion in autoclave

    Science.gov (United States)

    Filippov, V. P.; Bateev, A. B.; Lauer, Yu. A.

    2016-12-01

    Mössbauer investigations were used to compare iron atom states in oxide films of binary Zr-Fe, ternary Zr-Fe-Cu and quaternary Zr-Fe-Cr-Sn alloys. Oxide films are received in an autoclave at a temperature of 350-360 °C and at pressure of 16.8 MPa. The corrosion process decomposes the intermetallic precipitates in alloys and forms metallic iron with inclusions of chromium atoms α-Fe(Cr), α-Fe(Cu), α-Fe 2O3 and Fe 3O4 compounds. Some iron ions are formed in divalent and in trivalent paramagnetic states. The additional doping influences on corrosion kinetics and concentration of iron compounds and phases formed in oxide films. It was shown the correlation between concentration of iron in different chemical states and corrosion resistance of alloys.

  2. The influence of chemical disorder enhancement on the martensitic transformation of the Ni{sub 50}Mn{sub 36}Sn{sub 14} Heusler-type alloy

    Energy Technology Data Exchange (ETDEWEB)

    Passamani, E.C., E-mail: edson@cce.ufes.br [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910 Vitoria, ES (Brazil); Nascimento, V.P.; Larica, C.; Takeuchi, A.Y. [Departamento de Fisica, Universidade Federal do Espirito Santo, 29075-910 Vitoria, ES (Brazil); Alves, A.L.; Proveti, J.R. [Departamento de Ciencias Matematicas e Naturais, Universidade Federal do Espirito Santo, 29932-540, Sao Mateus, ES (Brazil); Pereira, M.C. [Instituto de Ciencia e Tecnologia, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), 39803-371 Teofilo Otoni, Minas Gerais (Brazil); Fabris, J.D. [Departamento de Quimica, UFVJM, 39100-000 Diamantina, Minas Gerais (Brazil)

    2011-07-28

    Highlights: > Chemical disorder affects martensitic transformation in Ni-Mn-Sn Heusler alloys. > Martensitic transition temperature depends on the L21-ferromagnetic fraction. > Grain boundaries induce drastic reduction of magnetization in milled Heusler alloys. > Magnetic properties of the milled Ni50Mn36Sn14 alloy get better after annealing. - Abstract: The effect of chemical disorder over the martensitic phase transformation of the Ni{sub 50}Mn{sub 36}Sn{sub 14} Heusler-type alloy was systematically investigated by performing X-ray diffractometry (DRX), DC magnetization and {sup 57}Fe-doping and {sup 119}Sn-Moessbauer spectroscopy measurements. DRX patterns are characteristics of a L2{sub 1}-type chemically disordered structure, where the presence of this disorder was first evaluated by analyzing the relative intensity of the (1 1 1) DRX reflection, which varies in the case of Fe-doped and practically disappears for the milled samples. In consequence, the magnetic properties of Fe-doped well-milled samples related to the martensitic phase transformation change substantially. 300 K {sup 57}Fe-Moessbauer spectroscopy data suggest that the changes in the magnetic properties related to the martensitic transformation are intrinsically correlated to the ferromagnetic and paramagnetic fractions, which are respectively associated with Fe atoms replacing Mn- and Sn-sites. In the case of milled samples, the drastic reduction of alloy magnetization was explained by the increase of the number of Mn atoms in the shell regions, which have a reduced magnetic moment comparatively to those in the grain cores. The magnetization change and the temperature transition in the martensitic transformation are governed by the grain core. The initial magnetic properties and martensitic transformation can be recovered by a subsequent annealing on the milled sample.

  3. Spin-resolved photoelectron spectroscopy of Mn{sub 6}Cr single-molecule-magnets and of manganese compounds as reference layers

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas; Gryzia, Aaron; Dohmeier, Niklas; Mueller, Norbert; Brechling, Armin; Sacher, Marc; Heinzmann, Ulrich [Faculty of Physics, Bielefeld University (Germany); Hoeke, Veronika; Glaser, Thorsten [Faculty of Chemistry, Bielefeld University (Germany); Fonin, Mikhail; Ruediger, Ulrich [Department of Physics, University of Konstanz (Germany); Neumann, Manfred [Department of Physics, Osnabrueck University (Germany)

    2011-07-01

    The properties of the manganese-based single-molecule-magnet (SMM) Mn{sub 6}Cr are studied. This molecule exhibits a large spin ground state of S{sub T}=21/2. It contains six manganese centres arranged in two bowl-shaped Mn{sub 3}-triplesalen building blocks linked by a hexacyanochromate. The Mn{sub 6}Cr complex can be isolated with different counterions which compensate for its triply positive charge. The spin polarization of photoelectrons emitted from the manganese centres in Mn{sub 6}Cr SMM after resonant excitation with circularly polarized synchrotron radiation has been measured at selected energies corresponding to the prominent Mn L{sub 3}VV and L{sub 3}M{sub 2,3}V Auger peaks. Spin-resolved photoelectron spectra of the reference substances MnO, Mn{sub 2}O{sub 3} and Mn(II)acetate recorded after resonant excitation at the Mn-L{sub 3}-edge around 640eV are presented as well. The spin polarization value obtained from MnO at room temperature in the paramagnetic state is compared to XMCD measurements of Mn(II)-compounds at 5K and a magnetic field of 5T.

  4. Exposure of single-molecule-magnets Mn{sub 6}Cr and Mn{sub 7} to soft X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Merschjohann, Fabian; Helmstedt, Andreas; Gryzia, Aaron; Winter, Andreas; Steppeler, Sebastian; Mueller, Norbert; Brechling, Armin; Sacher, Marc D.; Heinzmann, Ulrich [Fak. f. Physik, Univ. Bielefeld (Germany); Freiherr v. Richthofen, Carl-Georg; Glaser, Thorsten [Fak. f. Chemie, Univ. Bielefeld (Germany); Voss, Soenke; Fonin, Mikhail; Ruediger, Ulrich [Fak. f. Physik, Univ. Konstanz (Germany)

    2009-07-01

    Mn{sub 6}Cr and Mn{sub 7} are two representatives of the new 7-core single-molecule-magnets (SMM) with a large spin moment. Adsorbed on surfaces their electronic configuration may change depending on the substrate material. Possible modifications of the electronic configuration can be studied element-specificly by X-ray absorption spectroscopy and by measuring the spin-polarization of photoelectrons ejected by circularly polarized synchrotron radiation. Drawback of the above mentioned methods is the bad stability of the SMM during X-ray exposure. The SMM degrade due to photoreduction with increasing time of exposure. The trivalent metallic components (here Mn and Cr) become divalent ones. This degradation process was observed by using very small photon fluxes at Maxlab III. Within about one hour of X-ray exposure the degradation saturates. The rate of degradation depends on the substrate material as well as on the SMM-concentration on the substrate. Beneath these results we will present first spin-resolved photo-emission measurements of SMM-crystals.

  5. Reentrant behavior in Cr doped bilayer manganite LaSr{sub 2}Mn{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Bhatia, S.N., E-mail: snbhatia@phy.iitb.ac.in; Mohapatra, Niharika

    2017-07-15

    Highlights: • The FM and the AFM states merge into each other thereby creating an inhomogeneous state. • Cr{sup 3+} creates ferromagnetic moments which behave like FM relaxors. • Electric conduction takes via hopping of small polaron and not by variable range hopping of these polarons. - Abstract: We have studied the effect of replacing Mn{sup 3+} by Cr{sup 3+} on the structure, transport and magnetism in the bilayered manganite LaSr{sub 2}Mn{sub 2}O{sub 7}. Although no structural transition was observed in LaSr{sub 2}Mn{sub 2−y}Cr{sub y}O{sub 7} (0.1 ≤ y ≤ 0.6), the electrical transport and the magnetic properties were found to be affected significantly by this substitution. Substitution of Cr{sup 3+} reduces the conductivity by restricting the hopping of small polarons. Magnetization increases with increasing Cr{sup 3+} concentration suggesting that Cr{sup 3+}-ions induce ferromagnetic moments. The ferromagnetic and an antiferromagnetic phase observed above ∼60 K merge into an inhomogeneous phase below this temperature. Thermopower yields an essentially concentration independent charge density nearly equal to its value for chromium free composition inspite of its expected decrease with this substitution suggesting that the small charge density of the insulating AFM phase is supplemented by the free carriers in the FM phase. The inhomogeneous phase shows a relaxor type behavior which contrasts with the spin glass behavior seen in La{sub 0.46}Sr{sub 0.54}Mn{sub 0.98}Cr{sub 0.02}O{sub 3} having an identical AFM magnetic state. The difference is attributed to the non-JT character of Cr-ions which reduce the distortion of the Mn−O octahedra located within the FM domains. With a higher lattice strain in the surrounding AFM matrix the carriers remain confined within the FM domains leading to the relaxor type behavior.

  6. Evaluation of Surface Mechanical Properties and Grindability of Binary Ti Alloys Containing 5 wt % Al, Cr, Sn, and V

    Directory of Open Access Journals (Sweden)

    Hae-Soon Lim

    2017-11-01

    Full Text Available This study aimed to investigate the relationship between the surface mechanical properties and the grindability of Ti alloys. Binary Ti alloys containing 5 wt % concentrations of Al, Cr, Sn, or V were prepared using a vacuum arc melting furnace, and their surface properties and grindability were compared to those of commercially pure Ti (cp-Ti. Ti alloys containing Al and Sn had microstructures that consisted of only α phase, while Ti alloys containing Cr and V had lamellar microstructures that consisted of α + β phases. The Vickers microhardness of Ti alloys was increased compared to those of cp-Ti by the solid solution strengthening effect. Among Ti alloys, Ti alloy containing Al had the highest Vickers microhardness. At a low SiC wheel speed of 5000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the hardness values of Ti alloys decreased. At a high SiC wheel speed of 10,000 rpm, the grinding rates of Ti alloys showed an increasing tendency as the tensile strength values increased. The Ti alloy containing Al, which showed the lowest tensile strength, had the lowest grinding rate. The grinding ratios of the Ti alloys were higher than those of cp-Ti at both wheel revolution speeds of 5000 and 10,000 rpm. The grinding ratio of the Ti alloy containing Al was significantly increased at 10,000 rpm (p < 0.05.

  7. SYNTHESIS OF SnO₂/Cr PIGMENTS DOPED BY PRASEODYMIUM PREPARED BY DIFFERENT METHODS AND THEIR PIGMENTARY PROPERTIES

    Directory of Open Access Journals (Sweden)

    Jakub Trojan

    2016-07-01

    Full Text Available The violet SnO₂/Cr pigments in which a part of tin ions was substituted by praseodymium ions were examined. The compounds Sn0.99Cr0.005Pr0.005O₂ may represent a potential extension of the range of violet shades, especially in their use in ceramics. Pigments have been prepared by classical ceramic route i.e. solid state reaction method, also by the method of mechanoactivation and finally by a two-step process based on the suspension mixing of the initial reagents. The temperature range for the reaction was from 1350 to 1500 °C. Pigments were characterised in terms of colour, they were also studied with respect to their phase composition as well as the particles size distribution. X-ray analysis confirmed that the synthesis temperature 1350 °C is sufficient to get mono-phase compounds in case of all ways of preparation. Mechanoactivation and two-step process can be suggested as the preferable method for acquirement of pigments with the most interesting colour.

  8. Effect of Microstructure on the Localized Corrosion of Fe-Cr-Mn-N Stainless Steels

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.Y.; Park, Y.S. [Department of Metallurgical Engineering, Yonsei University (Korea); Kim, Y.S. [Department of Materials Science and Engineering, Andong National University (Korea)

    1999-04-01

    This paper dealt with the effect of microstructure on the localized corrosion of Fe-Cr-Mn-N stainless steels. The experimental alloys were made by vacuum induction melting and then hot rolled. The alloys were designed by controlling Creq/Nieq ratio. Two alloys had austenitic phase and one alloy showed (austenite + ferrite) duplex phase. High nitrogen addition in austenitic alloys stabilized the austenitic structure and then suppressed the formations of ferrite and a' martensite, but martensite was formed in the case of large Creq/Nieq ratio and low nitrogen addition. Pitting initiation site was grain boundary in austenitic alloys and was ferrite / austenite phase boundary in duplex alloy in the HCl solution. In sulfuric acids, austenitic alloys showed uniform corrosion, but ferrite phase was preferentially corroded in duplex alloy. The preferential dissolution seems to be related with the distribution of alloying elements between ferrite and austenite. Intergranular corrosion test showed that corrosion rate by immersion Huey test had a linear relation with degree of sensitization by EPR test. 22 refs., 1 tab., 10 figs.

  9. NEW Fe-C-Mn-Si-Cr BEARING ALLOY: TEMPERING CURVES AND TEMPERED MARTENSITE EMBRITTLEMENT

    Directory of Open Access Journals (Sweden)

    José Benedito Marcomini

    2012-12-01

    Full Text Available SAE 52100 steel is not only used as a rolled raw material for bearing manufacturing but for building some rolling devices as well, such as guide rollers and straightener rollers. The purpose of this work is the characterization of a Fe-C-Mn-Si-Cr bearing alloy (SAE 52100 steel, modified with 1.74% Si by plotting the variation of quenched and tempered hardness curve (tempering curve and tempered martensite embrittlement susceptibility. The present application is based on the same idea as 300M steel regarding SAE 4340 steel. The effect of silicon on the kinetics of cementite precipitation leads to a rise in temperature of tempered martensite embrittlement. Quench and temper treatments were carried out and impact tests were performed with modified and commercial steels and the results were compared. Microstructure aspects are studied by scanning electron microscopy and x-ray diffraction analysis. The silicon alloyed steel presents great resistance to softening after tempering and no tempered martensite embrittlement.

  10. Effects of Alloying Elements (Cr, Mn) on Corrosion Properties of Carbon Steel in Synthetic Seawater

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, Youngmin; Kim, Heesan [Hongik University, Sejong (Korea, Republic of)

    2016-02-15

    Effects of alloying elements, manganese and chromium, on corrosion resistance of carbon steel were examined using weight loss test and electrochemical tests (polarization test and electrochemical impedance spectroscopy (EIS)) in synthetic seawater at 60 ℃. The results from the weight loss test showed that chromium effectively improved corrosion resistance of carbon steel during the entire immersion time, but manganese improved corrosion resistance after the lowered corrosion resistance at the beginnings of immersion. Unlike the weight loss test, the electrochemical tests showed that the corrosion resistance did not increase with immersion time, in all the specimens. This disagreement is explained by the presence of rust involved in electrochemical reaction during electrochemical tests. The analysis of rust with transmission electron microscopy (TEM)−energy dispersive spectroscopy (EDS) showed that the amorphous-like rust layer located at the metal/rust interface with enriched alloying element (Cr, Mn) prevents diffusion of corrosive species into a metal/rust interface effectively, which leads to increased corrosion resistance. The initial corrosion behaviour is also affected by the rust types. In other words, manganese accelerated the formation of spinel oxides, negatively affecting corrosion resistance. Meanwhile, chromium accelerated the formation of goethite but impeded the formation of spinel oxides, positively affecting the corrosion resistance. From the above results, the corrosion resistance of steel is closely related with a rust type.

  11. Prediction of half-metallic properties for the Heusler alloys Mn{sub 2}CrZ (Z=Al, Ga, Si, Ge, Sb): A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Luo Hongzhi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)], E-mail: luohz@aphy.iphy.ac.cn; Zhu Zhiyong; Liu Guodong; Xu Shifeng; Wu Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Liu Heyan; Qu Jingping; Li Yangxian [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China)

    2008-02-15

    First-principles FLAPW calculations were performed on the Mn{sub 2}CrZ (Z=Al, Ga, Si, Ge and Sb) alloys. Based on these results we predict two half-metallic ferromagnets (HMFs) namely Mn{sub 2}CrAl and Mn{sub 2}CrSb, and also find an energy gap in Mn{sub 2}CrGa which lies near the Fermi level. The energy gap lies in the majority spin band for Mn{sub 2}CrAl and Mn{sub 2}CrGa, whereas in the minority one for Mn{sub 2}CrSb. The calculated total spin magnetic moments M{sub t}{sup cal} are -1{mu}{sub B} per unit cell for Mn{sub 2}CrAl and Mn{sub 2}CrGa, +1{mu}{sub B} per unit cell for Mn{sub 2}CrSb and zero for Mn{sub 2}CrSi and Mn{sub 2}CrGe, which agree with the Slater-Pauling rule. The calculation indicates a large and localized magnetic moment of Cr at B site. This is meaningful for searching for new half-metallic antiferromagnets in Heusler alloys. The magnetic moment of Cr is found to increase with increasing atomic number of Z and is antiparallel to that of Mn. The change of Mn and Cr spin moments compensates each other and keeps the total spin moment as an integer when the Z atom is changed.

  12. Two-dimensional Ising behavior in c(2×2) antiferromagnetic Mn and Cr monolayers on Ag(001)

    Science.gov (United States)

    Hanf, M. C.; Krembel, C.; Bolmont, D.; Gewinner, G.

    2003-10-01

    The magnetic order MS(T) is determined as a function of temperature for the c(2×2) antiferromagnetic monolayers of Mn and Cr on Ag(001), using the intensity of the coherent superlattice (1/2,1/2) reflections in low-energy electron diffraction to obtain the sublattice magnetization MS. The data fit the Onsager-Yang theoretical result rather well for the spontaneous magnetization of the plane square lattice in the Ising model with critical temperatures TC≈198 and 462 K for Mn and Cr, respectively. Near TC a fit to a universal power law MS(T)˜(1-T/TC)β confirms the two-dimensional Ising class with β close to 1/8 and indicates the importance of second-order magnetic anisotropy in these two-dimensional antiferromagnets.

  13. The Effects of Helium Bubble Microstructure on Ductility in Annealed and HERF 21Cr-6Ni-9Mn Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Tosten, M.H. [Westinghouse Savannah River Company, AIKEN, SC (United States); Morgan, M.J.

    1998-01-01

    This study examined the effects of microstructure on the ambient temperature embrittlement from hydrogen isotopes and decay helium in 21Cr-6Ni-9Mn stainless steel. Hydrogen and tritium-exposed 21Cr-6Ni-9Mn stainless steel tensile samples were pulled to failure and then characterized by transmission electron microscopy (TEM) and optical microscopy. This study determined that ductility differences between annealed and high-energy-rate-forged (HERF) stainless steel containing tritium and its decay product, helium, could be related to differences in the helium bubble microstructures. The HERF microstructures were more resistant to tritium-induced embrittlement than annealed microstructures because the high number density of helium bubbles on dislocations trap tritium within the matrix and away from the grain boundaries.

  14. Effect of Mn on hardenability of 25CrMo axle steel by an improved end-quench test

    Directory of Open Access Journals (Sweden)

    Zhang Yutuo

    2012-11-01

    Full Text Available With the sixth large-scale railway speed-up, the quality of the axles is essential to the safety of the locomotive. According to the high-speed axle technical standard for the control of alloy elements in axle steel, optimization experiments of 25CrMo steel composition were performed by vacuum inductive melting. In order to study the hardenability of high-speed rail axles, an improved end-quench test was put forward. The advantage is that it enables the heat to transfer along the axial direction, thus avoiding edge effects. The hardenability of 25CrMo axle steels with Mn content of 0.60wt.% and 0.80wt.% was investigated mainly by means of optical microscopy and hardness tests. The experimental results indicate that the Mn has a pronounced effect on the hardenability of the steel. With an increase in Mn content from 0.60wt.% and 0.80wt.%, the hardenability of 25CrMo axle steel increases and the hard microstructure is maintained at an increasing distance from the quenched end. From the surface of the water quenched end to the center of the sample, the microstructure is martensite, martensite with bainite, and bainite.

  15. Nano-twin mediated plasticity in carbon-containing FeNiCoCrMn high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Materials Science and Engineering Department, University of Tennessee, Knoxville, TN 37996 (United States); Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Bei, H., E-mail: beih@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2015-10-25

    Equiatomic FeNiCoCrMn alloy has been reported to exhibit promising strength and ductility at cryogenic temperature and deformation mediated by nano-twining appeared to be one of the main reasons. We use the FeNiCoCrMn alloy as a base alloy to seek further improvement of its mechanical properties by alloying additional elements, i.e., interstitial carbon. The effects of carbon on microstructures, mechanical properties and twinning activities were investigated in two different temperatures (77 and 293 K). With addition of 0.5 at% C, the high entropy alloy still remains entirely single phase face-centered cubic (FCC) crystal structure. The materials can be cold rolled and recrystallized to produce a microstructure with equiaxed grains. Both strain hardening rate and strength are enhanced while high uniform elongations to fracture (∼70% at 77 K and ∼40% at 293 K) are still maintained. The increased strain hardening and strength could be caused by the promptness of deformation twinning in C-containing high entropy alloys. - Highlights: • Interstitial atom C was successfully added into FeNiCoCrMn high entropy alloys. • The strain hardening rate and strength are enhanced in the C-containing alloy. • The increased strain-hardening and strength are caused by the nano-twinning.

  16. Hierarchical ZnGa2O4 and Cr doped Zn1 - x Mn x Ga2O4 nanostructures for room temperature light-emitting devices

    Science.gov (United States)

    López, I.; Nogales, E.; Méndez, B.; Piqueras, J.; Castaldini, A.; Cavallini, A.

    2014-04-01

    Branched, hierarchically grown ZnGa2O4 and Zn1 - x Mn x Ga2O4 (0.1 ZnGa2O4 structures emit the characteristic defect-related UV-blue band and Zn1 - x Mn x Ga2O4 nanowires show efficient green emission due to intraionic Mn2+ transitions. Zn1 - x Mn x Ga2O4 structures have been doped with Cr3+ during thermal treatments in presence of Cr. This leads to structures with additional red emission related to Cr3+. The excitation conditions allow selection of the dominant luminescence band. Photocurrent measurements have also been carried out in ZMGO structures, showing the characteristic intraionic Mn2+ transitions.

  17. Magnetic phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Bykov, A.A., E-mail: redi87@bk.ru [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); Chetverikov, Yu.O. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); Moskvin, E.V. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Pirogov, A.N. [Mikheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, Yekaterinburg 620990 (Russian Federation); Ural Federal University, Yekaterinburg 620002 (Russian Federation); Grigoriev, S.V. [Petersburg Nuclear Physics Institute, National Research Centre Kurchatov Institute, Gatchina 188300 (Russian Federation); St. Petersburg State University, St. Petersburg 199034 (Russian Federation)

    2017-02-15

    The Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds (x=0, 0.175, 0.2, 0.225, 0.25) were studied by small angle neutron scattering (SANS) and paramagnetic neutron spin echo. The YMn{sub 6}Sn{sub 6} compound is found to be a helimagnet in the whole temperature range below T{sub N}=310 K. Close to T{sub N} an additional peak of a Lorenz shape was observed at Q=0. The peak is thought to have originated from the ferromagnetic fluctuations of the magnetic Mn moment in the ab-plane of the hexagonal crystal structure. Compounds, in which Y is replaced by Tb, change their magnetic order with the increase of temperature: from easy cone ferromagnetic phase at low T through the helicoidal phase to the ferromagnetic fluctuation close to T{sub N}. Temperature-concentration phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} is built on the basis of the obtained data. - Highlights: • The Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} compounds (x=0, 0.175, 0.2, 0.225, 0.25) were studied by small angle neutron scattering (SANS) and paramagnetic neutron spin echo. • The YMn{sub 6}Sn{sub 6} compound is found to be a helimagnet in the whole temperature range below T{sub N}=310 K. • Close to T{sub N} an additional peak of a Lorenz shape was observed at Q=0. The peak is thought to have originated from the ferromagnetic fluctuations of the magnetic Mn moment in the ab-plane of the hexagonal crystal structure. • Compounds, in which Y is replaced by Tb, change their magnetic order with the increase of temperature: from easy cone ferromagnetic phase at low T through the helicoidal phase to the ferromagnetic fluctuation close to T{sub N}. • Temperature-concentration phase diagram of Y{sub 1−x}Tb{sub x}Mn{sub 6}Sn{sub 6} is built on the basis of the obtained data.

  18. A first principle study of phase stability, electronic structure and magnetic properties for Co{sub 2−x}Cr{sub x}MnAl Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rached, H. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Rached, D., E-mail: rachdj@yahoo.fr [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique de la Matière, (LPQ3M), Université de Mascara, Mascara 29000 (Algeria); Abidri, B.; Rabah, M.; Benkhettou, N. [Laboratoire des Matériaux Magnétiques, Faculté des Sciences exactes, Université Djillali Liabès de Sidi Bel-Abbès, Sidi Bel-Abbès 22000 (Algeria); Omran, S. Bin [Department of Physics and Astronomy, College of Science, King Saud University, P.O.Box 2455, Riyadh 11451 (Saudi Arabia)

    2015-04-01

    The structural stabilities, electronic and magnetic properties of Co{sub 2−x}Cr{sub x}MnAl alloys with (x=0,1 and 2) were investigated using the full-potential linear muffin-tin orbital (FP-LMTO) method, in the framework of the density functional theory (DFT) within the generalized gradient approximation (GGA) for the exchange correlation functional. The ground state properties including lattice parameter, bulk modulus for the two considered crystal structures Hg{sub 2}CuTi-Type (X-Type) and Cu{sub 2}MnAl-Type (L2{sub 1}-Type) are calculated. The half-metallicity within ferromagnetic ground state starts to appear in CoCrMnAl and Cr2MnAl. In the objective for the proposition of the new HM-FM in the Full-Heusler alloys, our results classified CoCrMnAl as new HM-FM material with high spin polarization. - Highlights: • Based on DFT calculations, Co2-xCrxMnAl Heusler alloys have been investigated. • The magnetic phase stability was determined from the total energy calculations. • The LMTO calculations have classified CoCrMnAl as new HM-FM material with high spin polarization.

  19. CuMn1.8O4 protective coatings on metallic interconnects for prevention of Cr-poisoning in solid oxide fuel cells

    Science.gov (United States)

    Sun, Zhihao; Wang, Ruofan; Nikiforov, Alexey Y.; Gopalan, Srikanth; Pal, Uday B.; Basu, Soumendra N.

    2018-02-01

    Cr-poisoning of the cathodes due to the presence of metallic interconnects is detrimental to the performance of intermediate temperature solid oxide fuel cell stacks. Applying a protective coating on the interconnect is an effective solution to preventing Cr-poisoning. In this study, the application of a protective CuMn1.8O4 spinel coating is explored. Dense coatings are deposited on both metallic flat plates and meshes by electrophoretic deposition followed by thermal densification steps. The coating is found to be a mixture of Mn3O4 and cubic spinel phases at room temperature but is a pure cubic spinel phase between 750 °C and 850 °C. A reaction layer between the Cr2O3 scale at the coating/interconnect interface and CuMn1.8O4 coating is found to be a mixture of (Cu,Mn,Cr)3-xO4 cubic spinel phases with Cr-rich precipitates believed to be Cr2O3, indicating that the coating layer acts as a Cr getter. Solubility experiments show that 1 mol of the CuMn1.8O4 phase can getter at least 1.83 mol of Cr2O3 at 800 °C. Electrochemical testing of cells in the presence of coated interconnects show that the CuMn1.8O4 coating getters Cr effectively for 12 days at 800 °C, leading to no performance loss of the cell due to Cr-poisoning.

  20. Effect of Cr addition on the structural, magnetic and mechanical properties of magnetron sputtered Ni-Mn-In ferromagnetic shape memory alloy thin films

    Energy Technology Data Exchange (ETDEWEB)

    Akkera, Harish Sharma [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India); Madanapalle Institute of Technology and Science, Department of Physics, Madanapalle, Chittoor, Andhra Pradesh (India); Kaur, Davinder [Indian Institute of Technology Roorkee, Functional Nanomaterials Research Lab, Department of Physics, Roorkee, Uttarakhand (India)

    2016-12-15

    The effect of Cr substitution for In on the structural, martensitic phase transformation and mechanical properties of Ni-Mn-In ferromagnetic shape memory alloy (FSMA) thin films was systematically investigated. X-ray diffraction results revealed that the Ni-Mn-In-Cr thin films possessed purely austenitic cubic L2{sub 1} structure at lower content of Cr, whereas higher Cr content, the Ni-Mn-In-Cr thin films exhibited martensitic structure at room temperature. The temperature-dependent magnetization (M-T) and resistance (R-T) results confirmed that the monotonous increase in martensitic transformation temperatures (T{sub M}) with the addition of Cr content. Further, the room temperature nanoindentation studies revealed the mechanical properties such as hardness (H), elastic modulus (E), plasticity index (H/E) and resistance to plastic deformation (H{sup 3}/E {sup 2}) of all the samples. The addition of Cr content significantly enhanced the hardness (28.2 ± 2.4 GPa) and resistance to plastic deformation H{sup 3}/E{sup 2} (0.261) of Ni{sub 50.4}Mn{sub 34.96}In{sub 13.56}Cr{sub 1.08} film as compared with pure Ni-Mn-In film. As a result, the appropriate addition of Cr significantly improved the mechanical properties with a decrease in grain size, which could be further attributed to the grain boundary strengthening mechanism. These findings indicate that the Cr-doped Ni-Mn-In FSMA thin films are potential candidates for microelectromechanical systems applications. (orig.)

  1. Low temperature transport anomaly in Cr substituted (La{sub 0.67}Sr{sub 0.33})MnO{sub 3} manganites

    Energy Technology Data Exchange (ETDEWEB)

    Tank, Tejas M., E-mail: tejas.physics2020@gmail.com [Solid State Physics Laboratory, Department of Physics, Barkatullah University, Bhopal-462 026 (India); Shelke, Vilas [Solid State Physics Laboratory, Department of Physics, Barkatullah University, Bhopal-462 026 (India); Das, Sarmistha; Rana, D.S. [Department of Physics, Indian Institute of Scientific Education and Research, Bhopal-462 023 (India); Thaker, C.M. [M.V.M. Science and Home Science College, Rajkot-360 005 (India); Samatham, S.S.; Ganesan, V. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore-452 001 (India); Sanyal, S.P. [Solid State Physics Laboratory, Department of Physics, Barkatullah University, Bhopal-462 026 (India)

    2017-06-15

    Highlights: • The effect of Cr substitution at the Mn-site of La{sub 0.67}Sr{sub 0.33}MnO{sub 3} has been studied. • Electrical and magnetic behaviors correlate with various theoretical models. • First time the low temperature transport anomaly has been explained in terms of e-e scattering phenomenon. • This study shows that FM interaction among Cr{sup 3+} and Mn{sup 3+} is like to the traditional Mn{sup 3+}-O{sup 2−}-Mn{sup 4+} process. - Abstract: The structural, electrical, and magnetic properties of La{sub 0.67}Sr{sub 0.33}Mn{sub 1−x}Cr{sub x}O{sub 3} (0 ≤ x ≤ 0.10) manganites have been studied by substitution of antiferromagnetic trivalent Cr ion at Mn-site. Systematic efforts have been carried out to understand the electrical resistivity behavior in the ferromagnetic metallic and paramagnetic semi-conducting phases of Cr substituted La{sub 0.67}Sr{sub 0.33}Mn{sub 1−x}Cr{sub x}O{sub 3} manganites. Polycrystalline samples show a resistivity minimum at a temperature (T{sub min}) of <40 K in the ferromagnetic metallic phase. T{sub min} shifts to higher temperatures on application of magnetic fields. The appearance of this resistivity minimum was analyzed by fittings the data according to the model that considers e-e scattering caused by enhanced Coulombic interactions. The electrical resistivity data has been best fitted in the metallic and semiconducting regime using various models. Present results suggest that intrinsic magnetic inhomogeneity like Cr{sup 3+} ions in these strongly electron-correlated manganite systems is originating due to the existence of the ferromagnetic interactions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-15

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

  3. Exchange bias effect in martensitic epitaxial Ni-Mn-Sn thin films applied to pin CoFeB/MgO/CoFeB magnetic tunnel junctions

    Science.gov (United States)

    Teichert, N.; Boehnke, A.; Behler, A.; Weise, B.; Waske, A.; Hütten, A.

    2015-05-01

    The exchange bias effect is commonly used to shift the coercive field of a ferromagnet. This technique is crucial for the use of magnetic tunnel junctions as logic or memory devices. Therefore, an independent switching of the two ferromagnetic electrodes is necessary to guarantee a reliable readout. Here, we demonstrate that the intrinsic exchange bias effect of Ni-Mn-Sn can be used to apply a unidirectional anisotropy to magnetic tunnel junctions. For this, we use epitaxial Ni-Mn-Sn films as pinning layers for microfabricated CoFeB/MgO/CoFeB magnetic tunnel junctions. We compare the exchange bias field ( HEB ) measured after field cooling in -10 kOe external field by magnetization measurements with HEB obtained from tunnel magnetoresistance measurements. Consistent for both methods, we find an exchange bias of about HEB=130 Oe at 10 K, which decreases with increasing temperature and vanishes above 70 K.

  4. Surface Hardening of Ti-15V-3Al-3Cr-3Sn Alloy after Cyclic Hydrogenation and Subsequent Solution Treatment

    Directory of Open Access Journals (Sweden)

    Chia-Po Hung

    2014-01-01

    Full Text Available The as-received and preheated (1000°C-30 min. and 500°C-30 min. sheets of Ti-15V-3Al-3Cr-3Sn alloy (Ti-153 were treated according to the predetermined process including a cyclic electrolytic hydrogenation (at 50 mA/cm2 for 1 hr and at 5 mA/cm2 for 10 hrs combining a subsequent solution treatment to see the effects of various operating parameters on the evolution of microstructure and the variations of hardness. The hardening effect deriving from solid-solution strengthening of hydrogen eventually overrode that from precipitation hardening. The maximum hardness elevation was from 236.9 to 491.1 VHN.

  5. EPR spectroscopy of a family of Cr(III) 7M(II) (M = Cd, Zn, Mn, Ni) "wheels": studies of isostructural compounds with different spin ground states

    DEFF Research Database (Denmark)

    Piligkos, Stergios; Weihe, Høgni; Bill, Eckhard

    2009-01-01

    spin states is observed.We present highly resolved multifrequency (X-, K-, Q- and W-band) continous wave EPR spectra of the heterooctametalic "wheels", [(CH(3))(2)NH(2)][Cr(III) (7)M(II)F(8)((CH(3))(3)CCOO)(16)], hereafter Cr(7)M, where M=Cd, Zn, Mn, and Ni. These experimental spectra provide rare...

  6. Facile preparation of magnetic mesoporous MnFe2O4@SiO2-CTAB composites for Cr(VI) adsorption and reduction.

    Science.gov (United States)

    Li, Na; Fu, Fenglian; Lu, Jianwei; Ding, Zecong; Tang, Bing; Pang, Jiabin

    2017-01-01

    Chromium-contaminated water is regarded as one of the biggest threats to human health. In this study, a novel magnetic mesoporous MnFe2O4@SiO2-CTAB composite was prepared by a facile one-step modification method and applied to remove Cr(VI). X-ray diffraction, scanning electron microscopy, transmission electron microscopy, specific surface area, and vibrating sample magnetometer were used to characterize MnFe2O4@SiO2-CTAB composites. The morphology analysis showed that the composites displayed a core-shell structure. The outer shell was mesoporous silica with CTAB and the core was MnFe2O4 nanoparticles, which ensured the easy separation by an external magnetic field. The performance of MnFe2O4@SiO2-CTAB composites in Cr(VI) removal was far better than that of bare MnFe2O4 nanoparticles. There were two reasons for the effective removal of Cr(VI) by MnFe2O4@SiO2-CTAB composites: (1) mesoporous silica shell with abundant CTA(+) significantly enhanced the Cr(VI) adsorption capacity of the composites; (2) a portion of Cr(VI) was reduced to less toxic Cr(III) by MnFe2O4, followed by Cr(III) immobilized on MnFe2O4@SiO2-CTAB composites, which had been demonstrated by X-ray photoelectron spectroscopy results. The adsorption of Cr(VI) onto MnFe2O4@SiO2-CTAB followed the Freundlich isotherm model and pseudo-second-order model. Tests on the regeneration and reuse of the composites were performed. The removal efficiency of Cr(VI) still retained 92.4% in the sixth cycle. MnFe2O4@SiO2-CTAB composites exhibited a great potential for the removal of Cr(VI) from water. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Investigating half-metallicity in PtXSb alloys (X=V, Mn, Cr, Co) at ambient and high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Habbak, Enas L., E-mail: enas_habbak@yahoo.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Shabara, Reham M., E-mail: rehamph@hotmail.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Aly, Samy H., E-mail: samy.ha.aly@gmail.com [Department of Physics, Faculty of Science, Damietta University (Egypt); Yehia, Sherif, E-mail: sherif542002@yahoo.com [Department of Physics, Faculty of Science, Helwan University, Cairo (Egypt)

    2016-08-01

    The structural, electronic, magnetic and elastic properties of half-Heusler alloys PtMnSb, PtVSb, PtCrSb and PtCoSb are investigated using first-principles calculation based on Density Functional Theory DFT. The Full Potential local Orbital (FPLO) method, within the General Gradient Approximation (GGA) and Local Spin Density Approximation (LSDA), have been used. The calculated structural, electronic and magnetic properties are in good agreement with available experimental and theoretical data. Using GGA approximation, only PtVSb shows a half-metallic behavior with a spin-down band gap and total magnetic moment of 0.802 eV and 2 µ{sub B} respectively. Both of PtVSb and PtMnSb alloys are half-metallic with spin-down band gaps of 0.925 eV and 0.832 eV and magnetic moments of 2 µ{sub B} and 4 µ{sub B} respectively using LSDA approximation. The bulk modulus and its first pressure-derivative of these alloys are calculated using the modified Birch–Murnaghan equation of state (EOS). The effect of pressure on the lattice constant, energy gap and bulk modulus is investigated. Under pressure, PtMnSb and PtCrSb turn into half-metallic alloys at nearly 6 GPa and 27 GPa respectively using GGA approximation.

  8. Ultra-robust high-field magnetization plateau and supersolidity in bond-frustrated MnCr2S4

    Science.gov (United States)

    Tsurkan, Vladimir; Zherlitsyn, Sergei; Prodan, Lilian; Felea, Viorel; Cong, Pham Thanh; Skourski, Yurii; Wang, Zhe; Deisenhofer, Joachim; von Nidda, Hans-Albrecht Krug; Wosnitza, Joahim; Loidl, Alois

    2017-01-01

    Frustrated magnets provide a promising avenue for realizing exotic quantum states of matter, such as spin liquids and spin ice or complex spin molecules. Under an external magnetic field, frustrated magnets can exhibit fractional magnetization plateaus related to definite spin patterns stabilized by field-induced lattice distortions. Magnetization and ultrasound experiments in MnCr2S4 up to 60 T reveal two fascinating features: (i) an extremely robust magnetization plateau with an unusual spin structure and (ii) two intermediate phases, indicating possible realizations of supersolid phases. The magnetization plateau characterizes fully polarized chromium moments, without any contributions from manganese spins. At 40 T, the middle of the plateau, a regime evolves, where sound waves propagate almost without dissipation. The external magnetic field exactly compensates the Cr–Mn exchange field and decouples Mn and Cr sublattices. In analogy to predictions of quantum lattice-gas models, the changes of the spin order of the manganese ions at the phase boundaries of the magnetization plateau are interpreted as transitions to supersolid phases. PMID:28345038

  9. Influence of the thermodynamic parameters on the temper embrittlement of SA508 Gr.4N Ni-Cr-Mo low alloy steel with variation of Ni, Cr and Mn contents

    Science.gov (United States)

    Park, Sang-Gyu; Lee, Ki-Hyoung; Min, Ki-Deuk; Kim, Min-Chul; Lee, Bong-Sang

    2012-07-01

    It is well known that SA508 Gr.4N low alloy steel offers improved fracture toughness and strength compared to commercial low alloy steels such as SA508 Gr.3 Mn-Mo-Ni low alloy steel. In this study, the effects of Cr, Mn, and Ni on temper embrittlement in SA508 Gr.4N low alloy steel were evaluated from the viewpoint of thermodynamic parameters such as P diffusivity and C activity. The changes of the ductile-brittle transition temperatures before and after aging were correlated with varying alloying element content, and the diffusivity of P and the activity of C were calculated and correlated with the transition behaviors. The addition of Ni, Cr, and Mn reduce the resistance to temper embrittlement, showing increased Transition-Temperature Shift (TTS) and an increased fraction of intergranular fracture. Although the diffusivity of P is changed by the addition of alloying elements, it does not considerably affect the temper embrittlement. The Mn and Cr content in the matrix significantly reduce the C activity, with showing an inversely proportional relationship to TTS. The change of susceptibility to temper embrittlement caused by Cr and Mn addition could be explained by the variation of C activity. Unlike Cr and Mn, Ni has little effect on the temper embrittlement and C activity.

  10. Influence of the thermodynamic parameters on the temper embrittlement of SA508 Gr.4N Ni-Cr-Mo low alloy steel with variation of Ni, Cr and Mn contents

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang-Gyu; Lee, Ki-Hyoung [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, 150-1 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Min, Ki-Deuk [Division of Material Science and Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Min-Chul, E-mail: mckim@kaeri.re.kr [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, 150-1 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Lee, Bong-Sang [Nuclear Materials Research Division, Korea Atomic Energy Research Institute, 150-1 Deogjin-dong, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2012-07-15

    It is well known that SA508 Gr.4N low alloy steel offers improved fracture toughness and strength compared to commercial low alloy steels such as SA508 Gr.3 Mn-Mo-Ni low alloy steel. In this study, the effects of Cr, Mn, and Ni on temper embrittlement in SA508 Gr.4N low alloy steel were evaluated from the viewpoint of thermodynamic parameters such as P diffusivity and C activity. The changes of the ductile-brittle transition temperatures before and after aging were correlated with varying alloying element content, and the diffusivity of P and the activity of C were calculated and correlated with the transition behaviors. The addition of Ni, Cr, and Mn reduce the resistance to temper embrittlement, showing increased Transition-Temperature Shift (TTS) and an increased fraction of intergranular fracture. Although the diffusivity of P is changed by the addition of alloying elements, it does not considerably affect the temper embrittlement. The Mn and Cr content in the matrix significantly reduce the C activity, with showing an inversely proportional relationship to TTS. The change of susceptibility to temper embrittlement caused by Cr and Mn addition could be explained by the variation of C activity. Unlike Cr and Mn, Ni has little effect on the temper embrittlement and C activity.

  11. FP-LMTO investigation of the structural, electronic and magnetic properties of Heusler compounds Ru2CrZ(Ge, Sn, Si)

    Science.gov (United States)

    Bahlouli, S.; Aarizou, Z.; Elchikh, M.; Vergoten, G.

    2013-01-01

    We report structural and magnetic properties as well as band structures and density of states (DOS) of full Heusler Ru2CrSi, Ru2CrGe and Ru2CrSn. This was performed in the frame work of self-consistent first-principle calculations, using the Full-Potential Linearized Muffin Tin Orbital (FP-LMTO) method based on the Generalized Gradient Approximation (GGA), to investigate the structure and magnetic properties through the calculation of the electronic structure, equilibrium lattice constant and magnetic properties. Our results will show that our three Full-Heusler compounds are antiferromagnets.

  12. Thermal and Structural Analysis of Mn49.3Ni43.7Sn7.0 Heusler Alloy Ribbons

    Directory of Open Access Journals (Sweden)

    Tarek Bachaga

    2015-02-01

    Full Text Available The martensitic transformation and the solidification structures of Mn49.3Ni43.7Sn7.0 alloy ribbons prepared by melt-spinning were investigated by means of scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. In those experiments special attention was given to melt spinning processing parameters such as the linear surface speed of the copper wheel rotating, the injection overpressure and the distance between wheel and injection quartz tube. Transformation entropy was found higher when increasing linear surface speed or the distance from injection point to wheel. The resulting samples showed chemical compositions close to the nominal ones and, at room temperature, crystallized in a monoclinic single-phase martensite with 14M modulation (without a significant variation in the cell parameters. Strong dependence of ribbon thickness on processing parameters was found. The average grain size varied between 1.6 and 6.6 μm, while the start temperature of the martensitic temperature varied from 394 to 430 K.

  13. Effects of the partial substitution of Ni by Cr on the transport, magnetic, and magnetocaloric properties of Ni50Mn37In13

    Directory of Open Access Journals (Sweden)

    Sudip Pandey

    2017-05-01

    Full Text Available The structural, magnetic, and magnetotransport properties of Ni50-xCrxMn37In13 Heusler alloys have been synthesized and investigated by x-ray diffraction (XRD, field and pressure dependent magnetization, and electrical resistivity measurements. The partial substitution of Ni by Cr in Ni50Mn37In13 significantly improves the magnetocaloric effect in the vicinity of the martensitic transition (TM. This system also shows a large negative entropy change at the Curie temperature (TC, making it a candidate material for application in a refrigeration cycle that exploits both positive and negative magnetic entropy changes. The refrigeration capacity (RC values at TM and TC increase significantly by more than 20 % with Cr substitution. The application of hydrostatic pressure increases the temperature stability of the martensitic phase in Ni45Cr5Mn37In13. The influence of Cr substitution on the transport properties of Ni48Cr2Mn37In13 is discussed. An asymmetric magnetoresistance, i.e., a spin-valve-like behavior, has been observed near TM for Ni48Cr2Mn37In13.

  14. Essential trace (Zn, Cu, Mn and toxic (Cd, Pb, Cr elements in the liver of birds from Eastern Poland

    Directory of Open Access Journals (Sweden)

    Komosa A.

    2012-01-01

    Full Text Available We have focused our study on the concentrations of essential heavy metals (Zn, Cu and Mn and non-essential trace metals (Pb, Cd and Cr in the livers of birds from Eastern Poland. The largest mean amount of Zn - as much as 279 mg/kg dry mass (d.m. - was found in mute swans. However, only in one of the analysed buzzard specimens the concentration of Zn, found to be 664 mg/kg d.m., exceeded the level indicative of poisoning for this element. Birds specializing in catching rodents accumulated Mn in their livers in a very narrow range of concentrations, around 5.0 mg/kg d.m. on average. The range of mean Mn concentrations (around 6.5 mg/kg d.m. was also found to be narrow for piscivorous birds. The highest mean levels of Pb were found in mute swans (2.7 mg/kg d.m., and the highest levels of Cd (2.0 mg/kg d.m. for rooks. Concentrations of total Cr above detection level were found in 22 specimens (53.7%, and concentration values were highest for rooks. Analyses showed that the concentrations of biogenic elements did not exceed the levels indicative of poisoning (except in one specimen. The study demonstrated that lead shots remain a hazard to water ecosystems. Pb, Cd and Cr levels in the livers of omnivorous and piscivorous species indicate the permanent presence of these elements in the environment and may confirm the thesis about the growing role of electronic waste, including metallic e-waste, in the emission of the total amount of contamination with these elements.

  15. Synthesis and Structural Studies of Cr(III, Mn(II and Fe(III Complexes of N(2-Benzimidazolylacetylacetohydrazone

    Directory of Open Access Journals (Sweden)

    G. H. Anuradha

    2011-01-01

    Full Text Available The ligand N(2-benzimidazolylacetylacetohydrazone (BAAH have been synthesized and characterized. Coordination complexes of Cr(III, Mn(II and Fe(III have been synthesized with the ligand BAAH. These complexes were characterized on the basis of analytical, conductance, thermal, magnetic data and infrared and electronic spectral data. The ligand BAAH is behaving as a neutral tridentate NNO donar employing two azomethine nitrogens (ring and side chain and carbonyl oxygen. The ligand and it's metal complexes were tested for anti microbial activity on the gram positive S. Aureus, E. coli and Proteus.

  16. Effect of Ti or Sn doping on the catalytic performance of MnOx/CeO2 catalyst for low temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Xiong, Yan; Tang, Changjin; Dong, Lin

    2015-04-01

    The abatement of nitrogen oxides (NOx) emission from exhaust gases of diesel and stationary sources is a significant challenge for economic and social development. Ceria-based solid solutions were synthesized and used as supports to prepare MnOx/Ce0.8Ti0.2O2 and MnOx/Ce0.8Sn0.2O2 catalysts (Mn/CeTi and Mn/CeSn) for low temperature selective catalytic reduction of NO by NH3 (NH3-SCR). The effects of Ti or Sn doping on the catalytic performance of MnOx/CeO2 catalyst were investigated. Experimental results show that doping of Ti or Sn increases the NO removal efficiency of MnOx/CeO2. The NO conversion of Mn/CeTi catalyst is more than 90 % at temperature window of 175 ~ 300 °C under a gas hour space velocity of 60,000 mL•g-1•h-1. Modified catalysts are also found to exhibit greatly improved resistance to sulfur-poisoning. NH3-TPD results suggest that NH3 desorption on the catalysts is observed over a wide temperature range, due to the variability of adsorbed NH3 species with different thermal stabilities. Doping of Ti and Sn into Mn/CeO2 greatly increased the NH3 adsorption ability of the composites which could promote the SCR reaction. Characterization results also indicate that doping of Ti or Sn brings about catalysts with higher BET surface area, enhanced oxygen storage capacity and increased surface acidity. X-ray photoelectron spectroscopy (XPS) analysis of spent catalysts following SCR reaction in the presence of SO2 verify that the loss of surface Mn species was inhibited by doping of Ti, which contributes to extend the catalyst durability.

  17. Stability of Mn{sub 6}Cr single-molecule-magnets adsorbed on surfaces: The influence of X-ray exposure, layer thickness, choice of substrate and counterions

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas; Gryzia, Aaron; Steppeler, Sebastian; Mueller, Norbert; Sacher, Marc D.; Heinzmann, Ulrich [Fak. f. Physik, Univ. Bielefeld (Germany); Hoeke, Veronika; Glaser, Thorsten [Fak. f. Chemie, Univ. Bielefeld (Germany); Fonin, Mikhail; Ruediger, Ulrich [Fak. f. Physik, Univ. Konstanz (Germany)

    2010-07-01

    The single-molecule-magnet (SMM) Mn{sub 6}Cr consists of three main components: Two bowl-shaped Mn{sub 3}-salen complexes are bridged by a complex containing one Cr atom. Three counterions are coupled to the triply charged SMM to ensure charge neutrality. Mn{sub 6}Cr-SMM have a low stability against X-ray exposure, which adversely affects a study of the electronic properties by X-ray absorption- and photoelectron spectroscopy. With increasing exposure time, the spectral features of trivalent Mn representing intact molecules disappear while Mn(II)-typical features increase. This degradation process and its dependence on the photon flux, the substrate and the SMM concentration were observed during beamtimes at BESSY II and MAXLAB III. The rate of degradation shows also a strong dependence on the choice of counterions. The choosen preparation method allows the adsorption of Mn{sub 6}Cr-SMM with varying layer thickness on various substrates. This study reveals an influence of the substrate and the molecule layer thickness on the initial electronic state of the adsorbed molecule layer, i.e. the molecules seem to degrade already during the adsorption process.

  18. Variations of Ni, Cr and Mn Concentration in Soils Formed Along a Toposequence of Ultrabasic Rocks in Western Mashhad

    Directory of Open Access Journals (Sweden)

    S. Akbari

    2016-02-01

    Full Text Available Introduction: Parent materials as one of the main soil formation factors have a great impact on the concentration of heavy metals in the soil. Heavy metals are released to the soil during weathering and pedogenic processes. Ultrabasic rocks are known as the potential natural source of heavy metals, especially Ni, Cr and Mn in the soil. Average concentrations of Ni and Cr in the soils are 84 and 34 mg kg-1, respectively; while, in soil derived from ultrabasic parent material, the concentration of these elements may reach up to 100000 mg kg-1. Binaloud zone in northeastern composed of different geological materials. There is a narrow band of ophiolitic rocks in this zone that located along Mashhad city. The geochemical behavior of ultrabsic rocks and the associated soil have been frequently studied mostly in humid regions. But, there are a few research works done in arid environments. The objective of this study was to investigate the physical and chemical properties and concentrations of Ni, Cr and Mn in soils formed along a toposequence of ultrabasic rocks in western Mashhad. Materials and Methods: The study area is located in the hilly land landscape of Binaloud zone in the Western part of Mashhad. Mean annual precipitation and temperature is 260 mm and 13.7 oC, respectively. Soil temperature and moisture regimes are thermic and aridic boarder on mesic, respectively. Studied soils developed on hornblendite rocks that are ultrabasic rocks with SiO2 less than 45% and contain ferromagnesian minerals. A toposequence was selected and, three soil profiles on shoulder, backslope and footslope geomorphic positions were described acoording to key to soil taxonmy 2014 and the soil horizons were sampled. Air-dried samples were passed through 2 mm sieve and were used for laboratory analysis. Pseudo-total concentrations of Ni, Cr and Mn were extracted by aqua regia digestion procedure. Free iron oxides (Fed and amorphous iron oxides (Feo were extracted by

  19. The End of Amnesia: Measuring the Metallicities of Type Ia SN Progenitors with Manganese Lines in Supernova Remnants

    Science.gov (United States)

    Badenes, Carles; Bravo, Eduardo; Hughes, John P.

    2009-05-01

    The Mn to Cr mass ratio in supernova ejecta has recently been proposed as a tracer of Type Ia SN progenitor metallicity. We review the advantages and problems of this observable quantity, and discuss them in the framework of the Tycho Supernova Remnant. The fluxes of the Mn and Cr Kα lines in the X-ray spectra of Tycho observed by the Suzaku satellite suggests a progenitors of supersolar metallicity.

  20. One-pot synthesis of Mn-doped TiO{sub 2} grown on graphene and the mechanism for removal of Cr(VI) and Cr(III)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Zengping; Li, Yaru; Guo, Meng; Xu, Fengyun; Wang, Peng [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Du, Yu [China Tobacco Yunnan Industrial Co., Ltd., Yunnan 651600 (China); Na, Ping, E-mail: naping@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2016-06-05

    Highlights: • rGO-Mn-TiO{sub 2} is synthesized through one-pot hydrothermal method. • Cr(total) removal effectiveness reaches to 97.32% in 30 min under visible light, as the initial concentration of Cr(VI) is 20 mg/L. • Mn-TiO{sub 2} and rGO synergistically contribute to the adsorption and photocatalytic reduction of Cr. • Cr(III) being adsorbed by rGO helps to the release of abundant photocatalytic sites of Mn-TiO{sub 2}. - Abstract: Mn-doped TiO{sub 2} grown on reduced graphene oxide(rGO) was synthesized by one-pot hydrothermal method and the photocatalytic removal of Cr by the material was investigated under sunlight. The materials were characterized by a combination of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Brunauer-Emmett-Teller method, UV–vis diffuse reflectance spectra, photoluminescence spectra, electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. Cr(total) removal efficiency of the material is 97.32% in 30 min and 99.02% in 60 min under sunlight irradiation, as the initial concentration of Cr(VI) is 20 mg/L. The high photocatalytic activity under visible light is considered mainly due to the Mn-doping, and rGO plays an important role in the synergetic effect of adsorption and photocatalysis to sustain the high efficient removal of Cr(VI) and Cr(III). Cr(VI) adsorbed on the surface of rGO is reduced to Cr(III) by photo electrons which are transported through rGO, and the reaction product Cr(III) continues to be adsorbed. The process contributes to the release of abundant photocatalytic sites of Mn-TiO{sub 2} and improves photocatalytic efficiency. The excellent adsorption and photocatalytic effect with the explanation of the synergetic mechanism are very useful not only for fundamental research but also for the potential practical applications.

  1. Delta-Ferrite Distribution in a Continuous Casting Slab of Fe-Cr-Mn Austenitic Stainless Steel

    Science.gov (United States)

    Chen, Chao; Cheng, Guoguang

    2017-10-01

    The delta-ferrite distribution in a continuous casting slab of Fe-Cr-Mn stainless steel grade (200 series J4) was analyzed. The results showed that the ferrite fraction was less than 3 pct. The "M" type distribution was observed in the thickness direction. For the distribution at the centerline, the maximum ferrite content was found in the triangular zone of the macrostructure. In addition, in this zone, the carbon and sulfur were severely segregated. Furthermore, an equilibrium solidification calculation by Thermo-Calc® software indicates that the solidification mode of the composition in this triangular zone is the same as the solidification mode of the averaged composition, i.e., the FA (ferrite-austenite) mode. None of the nickel-chromium equivalent formulas combined with the Schaeffler-type diagram could predict the ferrite fraction of the Cr-Mn stainless steel grade in a reasonable manner. The authors propose that more attention should be paid to the development of prediction models for the ferrite fraction of stainless steels under continuous casting conditions.

  2. Effect of disorder on the magnetic and electronic structure of a prospective spin-gapless semiconductor MnCrVAl

    Directory of Open Access Journals (Sweden)

    P. Kharel

    2017-05-01

    Full Text Available Recent discovery of a new class of materials, spin-gapless semiconductors (SGS, has attracted considerable attention in the last few years, primarily due to potential applications in the emerging field of spin-based electronics (spintronics. Here, we investigate structural, electronic, and magnetic properties of one potential SGS compound, MnCrVAl, using various experimental and theoretical techniques. Our calculations show that this material exhibits ≈ 0.5 eV band gap for the majority-spin states, while for the minority-spin it is nearly gapless. The calculated magnetic moment for the completely ordered structure is 2.9 μB/f.u., which is different from our experimentally measured value of almost zero. This discrepancy is explained by the structural disorder. In particular, A2 type disorder, where Mn or Cr atoms exchange their positions with Al atoms, results in induced antiferromagnetic exchange coupling, which, at a certain level of disorder, effectively reduces the total magnetic moment to zero. This is consistent with our x-ray diffraction measurements which indicate the presence of A2 disorder in all of our samples. In addition, we also show that B2 disorder does not result in antiferromagnetic exchange coupling and therefore does not significantly reduce the total magnetic moment.

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

    Science.gov (United States)

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

    2017-10-01

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

  4. Magnetic properties of Ni{sub 40+x}Mn{sub 39−x}Sn{sub 21} (x = 0, 2, 4, 6 and 8 at.%) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Lázpita, P., E-mail: patricia.lazpita@ehu.es [BCMaterials and UPV/EHU, Bilbao (Spain); Barandiarán, J.M. [BCMaterials and UPV/EHU, Bilbao (Spain); Chernenko, V.A. [BCMaterials and UPV/EHU, Bilbao (Spain); Ikerbasque, Basque Foundation for Science, Bilbao (Spain); Valle García, B. [UPV/EHU, EUITI Bilbao, Dpto. Ing. Minera, Metalurgia y Ciencia de los Materiales, Bilbao (Spain); Díaz Tajada, E. [UPV/EHU, ETS Náutica y Máquinas Navales, Dpto. Ing. Minera, Metalurgia y Ciencia de los Materiales, Portugalete (Spain); Lograsso, T. [Division of Materials Science and Engineering, Ames Laboratory, Ames, IA (United States); Department of Materials Science and Engineering, Iowa State University, Ames, IA (United States); Schlagel, D.L. [Division of Materials Science and Engineering, Ames Laboratory, Ames, IA (United States)

    2014-05-01

    Highlights: • Curie temperature versus e/a dependence shows broad maximum in NiMnSn alloys. • Magnetic moment versus e/a < 7.75 dependence was determined. • The localized magnetic moment model is compatible with the magnetic moment evolution. • The values of the magnetic moments indicate an almost full atomic order. - Abstract: The low electron concentration region (e/a < 7.75) of the magnetic phase diagram of the off-stoichiometric Ni–Mn–Sn Heusler alloys was investigated in detail by DSC and magnetization measurements of the Ni{sub 40+x}Mn{sub 39−x}Sn{sub 21}(x = 0, 2, 4, 6 and 8 at.%) alloys. The alloys show a stable austenitic phase without any martensitic transformation down to 5 K even after heat treatment. The Curie temperature exhibits a broad maximum over a large composition range. The evolution of the magnetic moment with the electron concentration fits the data of previous studies and confirms the peak-like dependence in the extended range of e/a values predicted by ab initio calculations. The explored part of the moment versus e/a curve can be explained in terms of a localized magnetic moment model and full atomic order in the alloys.

  5. Effect of metal ions doping (M = Ti4+, Sn4+) on the catalytic performance of MnOx/CeO2 catalyst for low temperature selective catalytic reduction of NO with NH3

    Science.gov (United States)

    Xiong, Yan; Tang, Changjin; Dong, Lin

    2015-04-01

    Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China The abatement of nitrogen oxides (NOx) emission from exhaust gases of diesel and stationary sources is a significant challenge for economic and social development. Ceria-based solid solutions were synthesized and used as supports to prepare MnOx/Ce0.8Ti0.2O2 and MnOx/Ce0.8Sn0.2O2 catalysts (Mn/CeTi and Mn/CeSn) for low temperature selective catalytic reduction of NO by NH3 (NH3-SCR). The effects of Ti or Sn doping on the catalytic performance of MnOx/CeO2 catalyst were investigated. Experimental results show that doping of Ti or Sn increases the NO removal efficiency of MnOx/CeO2. The NO conversion of Mn/CeTi catalyst is more than 90 % at temperature window of 175 ~ 300 °C under a gas hour space velocity of 60,000 mL.g-1.h-1. Modified catalysts are also found to exhibit greatly improved resistance to sulfur-poisoning. NH3-TPD results suggest that NH3 desorption on the catalysts is observed over a wide temperature range, due to the variability of adsorbed NH3 species with different thermal stabilities. Doping of Ti and Sn into Mn/CeO2 greatly increased the NH3 adsorption ability of the composites which could promote the SCR reaction. Characterization results also indicate that doping of Ti or Sn brings about catalysts with higher BET surface area, enhanced oxygen storage capacity and increased surface acidity.

  6. A Gel-Polymer Sn-C/LiMn0.5Fe0.5PO4 Battery Using a Fluorine-Free Salt.

    Science.gov (United States)

    Di Lecce, Daniele; Fasciani, Chiara; Scrosati, Bruno; Hassoun, Jusef

    2015-09-30

    Safety and environmental issues, because of the contemporary use of common liquid electrolytes, fluorinated salts, and LiCoO2-based cathodes in commercial Li-ion batteries, might be efficiently mitigated by employing alternative gel-polymer battery configurations and new electrode materials. Herein we study a lithium-ion polymer cell formed by combining a LiMn0.5Fe0.5PO4 olivine cathode, prepared by simple solvothermal pathway, a nanostructured Sn-C anode, and a LiBOB-containing PVdF-based gel electrolyte. The polymer electrolyte, here analyzed in terms of electrochemical stability by impedance spectroscopy (EIS) and voltammetry, reveals full compatibility for cell application. The LiBOB electrolyte salt and the electrochemically delithiaded Mn0.5Fe0.5PO4 have a higher thermal stability compared to conventional LiPF6 and Li0.5CoO2, as confirmed by thermogravimetric analysis (TGA) and by galvanostatic cycling at high temperature. LiMn0.5Fe0.5PO4 and Sn-C, showing in lithium half-cell a capacity of about 120 and 350 mAh g(-1), respectively, within the gelled electrolyte configuration are combined in a full Li-ion polymer battery delivering a stable capacity of about 110 mAh g(-1), with working voltage ranging from 2.8 to 3.6 V.

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

    Directory of Open Access Journals (Sweden)

    Cias A.

    2015-01-01

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

  8. The Effect of Si and Mn on Microstructure and Selected Properties of Cr-Ni Stainless Steels

    Directory of Open Access Journals (Sweden)

    Kalandyk B.

    2017-03-01

    Full Text Available Cast stainless steel of the Cr-Ni duplex type is used, among others, for the cast parts of pumps and valves handling various chemically aggressive media. Therefore, the main problem discussed in this article is the problem of abrasion wear resistance in a mixture of SiC and water and resistance to electrochemical corrosion in a 3% NaCl-H2O solution of selected cast steel grades, i.e. typical duplex cast steel, high silicon and manganese duplex cast steel, and Cr-Ni austenitic cast steel (type AISI 316L. The study shows that the best abrasion wear resistance comparable to Ni-Hart cast iron was obtained in the cast duplex steel, where Ni was partially replaced with Mn and N. This cast steel was also characterized by the highest hardness and matrix microhardness among all the tested cast steel grades. The best resistance to electrochemical corrosion in 3% NaCl-H2O solution showed the cast duplex steel with high content of Cr, Mo and N. The addition of Ni plays rather insignificant role in the improvement of corrosion resistance of the materials tested.

  9. FP-LMTO investigation of the structural, electronic and agneticproperties of Heusler compounds Ru2CrZ (Ge, Sn, Si

    Directory of Open Access Journals (Sweden)

    Elchikh M.

    2013-03-01

    Full Text Available The electronic structure of the antiferomagnetic full Heusler alloys Ru2CrZ (Ge, Sn, Si have been studied by first principal calculations using Full-Potential linearized Muffin Tin Orbital (FP-LMTO method based on the generalized Gradient Approximation (GGA. It was shown that obtained equilibrium lattice parameters agree well with available experimental data. The influence of Z-elements on the electronic structure and magnetic properties of these compounds is analysed.

  10. A note on urinary Cd, Cr, Mn and Pb, in students of the University of ...

    African Journals Online (AJOL)

    Orbuter

    A preliminary investigation of heavy metals exposure of students of the University of. Agriculture, Makurdi in Central Nigeria ... the concentration of these metals was in the order Mn > C r > Pb > Cd, at levels that raise some concern about the health risks .... Nigeria's future prosperity. REFERENCES. 1. Radwan, M. A. and ...

  11. Deposition of La0.8Sr0.2Cr0.97V0.03O3 and MnCr2O4 thin films on ferritic alloy for solid oxide fuel cell application

    DEFF Research Database (Denmark)

    Mikkelsen, Lars; Chen, Ming; Hendriksen, Peter Vang

    2007-01-01

    Single layer dense films of La0.8Sr0.2Cr0.97V0.03O3 (LSC) and MnCr2O4 with a thickness of 500 nm were deposited on a commercially available ferritic alloy (Crofer 22APU) by large-area Pulsed Laser Deposition. The deposited samples were subsequently oxidized at 1173 K for 500 h in humidified air...

  12. DFT study on the adsorption sensitivity of graphane doped with Cr and Mn toward H2CO molecule

    Science.gov (United States)

    Zhou, Qingxiao; Ju, Weiwei; Yong, Yongliang; Su, Xiangying; Li, Xiaohong; Fu, Zhibing; Wang, Chaoyang

    2018-01-01

    In this study, we investigated the interaction between the hydrogenated graphene (graphane) monolayer and the formaldehyde gas molecule using density functional theory calculations. The atomic structures and electronic properties of the adsorption of H2CO molecule on pure, H-vacancy defected and transition-metal doped graphane sheet were performed. The calculated results suggested that the appearance of H-vacancy increased the activity of graphane sheet. However, the small adsorption energies revealed the weak binding of H2CO to the pure and defected graphane. After introducing the dopants (Cr and Mn), the adsorption stability was enhanced and the O atom of H2CO formed chemical bonds with the dopants. To achieve better accuracy for the adsorption energies, we selected Grimme dispersion corrections to calculate the weak binding configurations.

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

    Directory of Open Access Journals (Sweden)

    Cias A.

    2017-03-01

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

  14. Effect of Cr Addition on Wetting Behavior Between Cu and High-Temperature Zn-25Sn-0.15Al-0.1Ga- xCr Pb-Free Solder

    Science.gov (United States)

    Liu, Chin-Wei; Lin, Kwang-Lung

    2014-12-01

    In this study the effect of Cr content (0.02 wt.% to 0.2 wt.%) on the wetting interaction between high-temperature Zn-25Sn-0.15Al-0.1Ga- xCr Pb-free solders and Cu has been investigated using the wetting balance method. Differential scanning calorimetry (DSC) investigation showed that Cr addition reduces the liquidus temperature slightly while raising the solidus temperature. Flux-assisted wetting experiments were carried out at an immersion rate of 15 mm/s at 435°C. The results show that the shortest wetting time of around 0.7 s was achieved when 0.1 wt.% Cr was added, but the wetting force tends to decrease with the Cr content. Cr addition enhances the formation of interfacial Cu5Zn8 intermetallic compound (IMC) during air cooling, but the opposite effect was observed for water cooling. The results suggest that Cr addition depresses the formation of the Cu5Zn8 layer in liquid/solid reaction, but enhances the formation of the Cu5Zn8 layer in solid/solid reaction.

  15. Biosorption of Cd, Cr, Mn, and Pb from aqueous solutions by Bacillus sp strains isolated from industrial waste activate sludge

    Directory of Open Access Journals (Sweden)

    Rocío García

    2016-01-01

    Full Text Available Los microorganismos tienen capacidad de acumular metales pesados como agentes bioadsorbentes ofreciendo una alternativa para la remoción de metales tóxicos en aguas de efluentes industriales. El objetivo del presente trabajo fue aislar e identificar bacterias tolerantes a los metales pesados (Cd, Cr, Mn y Pb de lodos activados provenientes de la planta de tratamiento de agua del Municipio de Santa Rosa Jáuregui, Querétaro. Para seleccionar las bacterias que son tolerantes a los metales se aislaron 37 cepas bacterianas de las cuales se seleccionaron la Cepa-13 y Cepa-16 (C-13 y C-16, que presentaron una máxima capacidad de adsorción para los metales estudiados. En este artículo, el término biosorción describe la remoción de contaminantes y la utilización de biomasas (muerta mediante mecanismos fisicoquímicos como el proceso de adsorción o de intercambio iónico. Para obtener las condiciones de máxima adsorción se aplicó un tratamiento alcalino y uno ácido. La capacidad de adsorción fue menor en medio ácido que el bioadsorbente con tratamiento alcalino. Una segunda etapa del estudio fue la biosorción de metales pesados (Cd, Cr, Mn, y Pb utilizando las biomasas muertas de Bacillus sp (cepa C13 y C16 aisladas de los lodos activados de la primera etapa.

  16. [Measurement and comparison of Zn, Fe, Cu, Mn, Cr, Pb and Cd in rabbit liver of high-adipose group and normal group].

    Science.gov (United States)

    Wu, Yun-Kai; Cao, Hong; Mao, Chang-Jie; Gu, Zhi-Hong; Wang, Yuan

    2012-11-01

    The objective of the present paper is to explore the experimental changes in the content of Zn, Fe, Cu, Mn, Cr, Pb and Cd in white rabbit liver with atherosclerosis disease. The method is to reproduce white rabbit liver with atherosclerosis disease by a high-fat diet, and then measure the Zn, Fe, Cu, Mn, Cr, Pb and Cd content with atomic absorption spectrometry. Results show that the Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in the fodders of the normal group are 137.6, 362.3, 14.39, 9.599 mg x kg(-1) and 159.3, 355.0, 290.0 microg x kg(-1), and 86.09, 277.1, 11.07, 5.366 mg x kg(-1) and 115.2, 286.0, 210.5 microg x kg(-1), in high-adipose group. It was concluded that Zn, Fe, Cu, Mn, Cr, Pb and Cd contents in white rabbit liver decline, which may have something to do with the intake of foods and the abnormalities of lipoprotein metabolism.

  17. Effect of the Austempering Process on the Microstructure and Mechanical Properties of 27MnCrB5-2 Steel

    Directory of Open Access Journals (Sweden)

    Morri A.

    2017-06-01

    Full Text Available The effect of austempering parameters on the microstructure and mechanical properties of 27MnCrB5-2 steel has been investigated by means of: dilatometric, microstructural and fractographic analyses; tensile and Charpy V-notch (CVN impact tests at room temperature and a low temperature.

  18. Balance between thermopower, electric and magnetic interactions in CuCrO2, Bi8Rh7O22 and MnSc2Se4

    NARCIS (Netherlands)

    Ngo, Truong

    2015-01-01

    Transition metal based compounds with Ti, Cr, Mn, Fe, Co, and Ni are essential for many electronic functionalities. These compounds show rich physics with complex structural features that lead to interesting magnetic and electrical properties. Specific transition metal oxides reveal coupling between

  19. Thermal conductivity, electrical resistivity, and thermopower of aerospace alloys from 4 to 300 K. 6: Fe-22Cr-13Ni-5Mn stainless steel

    Science.gov (United States)

    Hust, J. G.; Sparks, L. L.

    1971-01-01

    The equipment and techniques for determining the thermal conductivity, electrical resistivity Lorenz ratio, and thermopower characteristics of Fe-22Cr-13Ni-5Mn stainless steel are discussed. The dimensions of the specimen and its preparation are described. The experimental data are represented by arbitrary functions over the entire range and smooth tables are generated from these functions.

  20. Magnetization reversal and tunable exchange bias in GdCr{sub 1−x}Mn{sub x}O{sub 3} (x=0−0.50)

    Energy Technology Data Exchange (ETDEWEB)

    Dash, Bibhuti B.; Ravi, S., E-mail: sravi@iitg.ernet.in

    2017-05-01

    Single phase samples of GdCr{sub 1-x}Mn{sub x}O{sub 3} (x=0−0.50) were prepared and their magnetic properties were studied by measuring temperature and field variations of magnetization. The Neel temperature, T{sub N} is found to decrease from T{sub N}=174 K for x=0 to 91 K for x=0.50. The magnetization reversal persists upto 5 at% of Mn substitution with a magnetic compensation temperature, T{sub comp} of 136 K and 139 K for x=0 and 0.05 respectively. However, spin reorientation induced magnetization reversal emerges for x=0.40 and 0.50 samples around 30 K. Tunable positive and negative exchange bias fields in the range of −1.0 kOe to +1.6 kOe have been observed. The origin of magnetization reversal and exchange bias field is explained in terms of antiparallel alignment of canted ferromagnetic component of Cr{sup 3+} ions and the paramagnetic moments of Gd{sup 3+} and Mn{sup 3+} ions under the influence of negative internal field due to antiferromagnetically ordered Cr{sup 3+} ions. - Highlights: • Magnetization reversal and bipolar switching in Mn substituted GdCrO{sub 3} • Tunable exchange bias field in the range of −1.0 kOe to +1.6 kOe. • Low temperature spin reorientation transition is observed.

  1. Preparation and characterization of electrically conducting polypyrrole Sn(IV phosphate cation-exchanger and its application as Mn(II ion selective membrane electrode

    Directory of Open Access Journals (Sweden)

    A.A. Khan

    2011-10-01

    Full Text Available Polypyrrole Sn(IV phosphate, an organic–inorganic composite cation-exchanger was synthesized via sol-gel mixing of an organic polymer, polypyrrole, into the matrices of the inorganic precipitate of Sn(IV phosphate. The physico-chemical properties of the material were determined using Atomic Absorption Spectrometry (AAS, CHN elemental analysis (inductively coupled plasma mass spectrometry, ICP-MS, UV–VIS spectrophotometry, FTIR (Fourier Transform Infra-Red, SEM (Scanning Electron Microscopy, TGA–DTA (Thermogravimetric Analysis–Differential Thermal Analysis, and XRD (X-ray diffraction. Ion-exchange behavior was observed to characterize the material. On the basis of distribution studies, the material was found to be highly selective for toxic heavy metal ion Mn2+. Due to its selective nature, the material was used as an electroactive component for the construction of an ion-selective membrane electrode. The proposed electrode shows fairly good discrimination of mercury ion over several other inorganic ions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations for Mn(II in water.

  2. Structural, magnetic and phonon properties of Cr(III)-doped perovskite metal formate framework [(CH3)2NH2][Mn(HCOO)3

    Science.gov (United States)

    Mączka, Mirosław; Gągor, Anna; Hermanowicz, Krzysztof; Sieradzki, Adam; Macalik, Lucyna; Pikul, Adam

    2016-05-01

    We have incorporated Cr(III) into [(CH3)2NH2][Mn(HCOO)3] (DMMn) multiferroic metal organic framework (MOF). The highest concentration of Cr(III) in the synthesized samples reached 15.9 mol%. The obtained samples were characterized by powder and single-crystal X-ray diffraction, DSC, magnetic susceptibility, dielectric, EPR, Raman and IR methods. These methods and the performed chemical analysis revealed that electrical charge neutrality after substitution of Cr(III) for Mn(II) is maintained by partial replacement of dimethylammonium (DMA+) cations by neutral HCOOH molecules. These changes in the chemical composition are responsible for weakening of the hydrogen bonds and decreased flexibility of the framework. This in turn leads to lowering of the ferroelectric phase transition temperature, observed around 185 K for undoped DMMn and around 155 K for the sample containing 3.1 mol% of Cr(III), and lack of macroscopic phase transition for the samples with Cr(III) content of 8.2 and 15.9 mol %. Another interesting effect observed for the studied samples is pronounced strengthening of the weak ferromagnetism of in Cr(III)-doped samples, associated with slight decrease of the ferromagnetic ordering temperature from 8.5 K for DMMn to 7.0 K for the sample with 15.9 mol % Cr(III) content.

  3. Aging precipitation behavior and its influence on mechanical properties of Mn18Cr18N austenitic stainless steel

    Science.gov (United States)

    Qin, Fengming; Li, Yajie; He, Wenwu; Zhao, Xiaodong; Chen, Huiqin

    2017-11-01

    The aging precipitation behavior in Mn18Cr18N austenitic stainless steel was investigated at temperatures from 600 °C to 900 °C. During isothermal aging treatment, the primary precipitate was Cr2N with a = 0.478 nm and c = 0.444 nm, and it preferentially nucleates along initial grain boundaries and gradually grows towards the interior of grains in discontinuous cellular way. Meanwhile, a small amount of granular face-centred cubic M23C6 with a = 1.066 nm also were observed, which mainly form along grain boundaries. The effect of these precipitates on mechanical properties of the alloy was studied. It was found that precipitates result in degeneration of the matrix hardness. Meanwhile, the SEM morphologies of aged tensile sample show that the brittle fracture predominates during deformation, i.e. the fracture mode transforms from intergranular fracture to transgranular fracture with the increasing of aging time. Compared with the solution-treated sample, the strength of the aged tensile samples slightly decreases and plasticity remarkably deteriorates.

  4. Facile synthesis and characterization of a SnO2-modified LiNi0.5Mn1.5O4 high-voltage cathode material with superior electrochemical performance for lithium ion batteries.

    Science.gov (United States)

    Ma, Feng; Geng, Fushan; Yuan, Anbao; Xu, Jiaqiang

    2017-04-12

    A thin-layer-SnO2 modified LiNi0.5Mn1.5O4@SnO2 material is synthesized via a facile synthetic approach. It is physically and electrochemically characterized as a high-voltage lithium ion battery cathode and compared to the pristine LiNi0.5Mn1.5O4 material prepared under similar conditions. The two materials are proved to be crystals of a well-defined disordered spinel phase with the morphology of aggregates of micron/submicron polyhedral particles. The Mn(3+) ions and the inactive NixLiyO phase in the LiNi0.5Mn1.5O4@SnO2 is less than those in the LiNi0.5Mn1.5O4 due to incorporation of a very small amount of Sn(2+) into the spinel structure upon high-temperature calcination of the precursor. Besides, the mean particle size of the LiNi0.5Mn1.5O4@SnO2 is obviously smaller than that of the LiNi0.5Mn1.5O4. The LiNi0.5Mn1.5O4@SnO2 demonstrates much superior electrochemical performance over the LiNi0.5Mn1.5O4 in terms of specific capacity, rate capability and cyclability. For example, the discharge capacities at current rates of 0.2C, 2C and 20C are 145.4, 139.9 and 112.2 mA h g(-1), respectively. A capacity retention rate of ca. 75% is obtained after 500 cycles at 2C rate. The improved electrochemical performance is attributed to the positive effect of the surface protective SnO2 coating layer as well as the structural and morphological modifications of the spinel.

  5. Microstructure and mechanical properties of a novel near-α titanium alloy Ti6.0Al4.5Cr1.5Mn

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong-bin [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China); Wang, Shu-sen; Gao, Peng-yue; Jiang, Tao [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Lu, Xiong-gang; Li, Chong-he [State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advanced Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Shanghai Special Casting Engineering Technology Research Center, Shanghai 201605 (China)

    2016-08-30

    Based on previous Ti-Al-Cr-Mn quaternary system thermodynamic database, a novel near-α titanium alloy Ti-6.0Al-4.5Cr-1.5Mn alloy was designed and successfully prepared by the water-cooled copper crucible. Microscopic observation showed that both as-cast and annealing status consist of α phase, which coincides with the theoretical expectation. The mechanical properties at room temperature were measured and this alloy possesses good mechanical properties, its average yield-strength reaches 1051.5 MPa and tensile-strength is up to 1091.2 MPa while its average elongation is just 8.3%. Compared with the TA15, it has better mechanical strength and worse elongation. In the new alloy Laves phase Cr{sub 2}Ti were detected by XRD pattern and TEM, which may cause the alloy's poor plasticity.

  6. Interface Resistance between FeCr Interconnects and La0.85Sr0.15Mn1.1O3

    DEFF Research Database (Denmark)

    Mikkelsen, Lars; Neufeld, Kai; Hendriksen, Peter Vang

    2009-01-01

    The long term oxidation behaviour and the electrical interface resistance between FeCr interconnects and La0,85Sr0,15Mn1,1O3 plates was studied by a DC four-point method in air at 750{degree sign}C for 10000 h. The tested FeCr alloys were: Crofer 22 APU, Sanergy HT, Plansee IT10, Plansee IT11, an....... Low degradation rates of less than 1 mcm2/1000 h were measured on all interfaces. The microstructure analysis showed that a duplex Cr2O3-(Mn,Co,Cr)3O4 oxide scale with a thickness of 3-5 µm had evolved on the alloys.......The long term oxidation behaviour and the electrical interface resistance between FeCr interconnects and La0,85Sr0,15Mn1,1O3 plates was studied by a DC four-point method in air at 750{degree sign}C for 10000 h. The tested FeCr alloys were: Crofer 22 APU, Sanergy HT, Plansee IT10, Plansee IT11......, and Plansee IT14. The alloys were slurry sprayed with a dual layer coating consisting of an inner Co3O4 layer and an outer layer consisting of La0,85Sr0,15Mn1,1O3 with some Co3O4 added. The microstructure and composition of the oxide scales formed at the interfaces were investigated using SEM/EDX analysis...

  7. Effects of Cr-doping on the electronic transport properties in antiperovskite nitrides Mn{sub 3−x}Cr{sub x}ZnN (0≤x≤0.5)

    Energy Technology Data Exchange (ETDEWEB)

    Malik, Muhammad Imran; Sun, Ying, E-mail: sunying@buaa.edu.cn; Wang, Lei; Deng, Sihao; Shi, Kewen; Hu, Pengwei; Lu, Huiqing; Wang, Cong, E-mail: congwang@buaa.edu.cn

    2016-06-15

    Antiperovskite intermetallic Mn{sub 3−x}Cr{sub x}ZnN (0≤x≤0.5) compounds have been prepared to study the Cr doping effect on the electronic transport properties. The temperature dependent resistivity ρ(T) for x≤0.3 shows notable and broader slope change. Meanwhile, with increasing Cr doping, the slope change shifts to lower temperatures and is gradually suppressed for x>0.3. For x=0.0 and 0.5, the measurements of magnetization from 10 K to 350 K reveal that Mn{sub 3−x}Cr{sub x}ZnN compounds go through a transition from the dominant AFM interactions to one where the FM and AFM interactions coexist. For low-temperature region (15–80 K), the electron–electron scattering is dominant, and the number of phonons abruptly increases with increasing temperature. Small polaron hopping model (SPH) is used to understand the temperature dependence of electrical resistivity in the high-temperature range of 200–300 K and a clear decrease of the polaron activation energy was observed for x≤0.2. The residual resistivity ratio (RRR) decreases while the residual resistivity increases (ρ{sub 0}) with increasing Cr-doping level. The maximum total entropy change (ΔS{sub max}) decreases by increasing the Cr doping from x=0.0 to 0.2.

  8. Contamination assessment of heavy metals in the soils around Khouzestan Steel Company (KSC (Ni, Mn, Pb, Fe, Zn, Cr

    Directory of Open Access Journals (Sweden)

    Fatemeh hormozi Nejad

    2017-02-01

    Full Text Available Introduction Soil plays a vital role in human life as the very survival of mankind is tied to the preservation of soil productivity (Kabata- Pendies and Mukherjee, 2007. The purpose of this study is the assessment of heavy metal contamination (Zn, Mn, Pb, Fe, Ni, Cr of the soil around the Khuzestan Steel Complex. Materials and methods For this purpose, 13 surface soil samples (0-10 cm were taken. Also a control sample was taken from an area away from the steel complex. The coordinates of each point were recorded by Global Positioning System (GPS. The samples were transferred to the laboratory and then were air dried at room temperature for 72 hours. Then they were sieved through a 2mm sieve for determining physical and chemical parameters (soil texture, pH, OC, and a 63-micron sieve for measurement of heavy metal concentration. pH was measured using a calibrated pH meter at a 2: 1 mixture (soil: water, and soil texture was determined using a hydrometer. The amount of organic matter was measured using the Valkey black method (Chopin and Alloway, 2007. After preparation of the samples in the laboratory, the samples were analyzed using the ICP-OES method to assess concentration of heavy metals. Measurement of heavy metals concentration was carried out at the Zar azma laboratory in Tehran. To ensure the accuracy of the analysis of soil samples, replicate samples were also sent to the laboratory. In order to assess the heavy metal pollution in the soil samples, different indices including contamination factor (CF, contamination degree (Cd, anthropogenic enrichment percent (An%, and saturation degree of metals (SDM were calculated. Discussion In addition, the mean concentrations of heavy metals in soil samples were compared to the concentration of these metals in Control Sample and unpolluted soil standard. Measurement of soil pH showed that the soil has a tendency to alkalinity. Also, soil texture is sandy loam (Moyes, 2011. The results showed that

  9. A rare mu-hydroxo-bridged species. synthesis, structure, and properties of mu-hydroxo(tetraphenylporphyrinatomanganese(III))(phthalocyaninato(azido)chromium(III)), [(TPP)Mn-O(H)-CrPc(N3)].

    Science.gov (United States)

    Donzello, Maria Pia; Bartolino, Laura; Ercolani, Claudio; Rizzoli, Corrado

    2006-08-21

    A novel ditetrapyrrolic, heteroleptic, and heterometallic (Mn-Cr) mu-hydroxo-bridged complex has been prepared, and its structural and general properties have been studied. The species mu-hydroxo(tetraphenylporphyrinatomanganese(III))(phthalocyaninato(azido)chromium(III)), [(TPP)Mn-O(H)-CrPc(N3)], isolated as a chloronaphthalene (ClNP) solvate, has been structurally characterized by single-crystal X-ray work. The two (TPP)Mn and CrPc(N3) fragments are held together by the bridging mu-hydroxo ion with long Mn-O [1.993(5) A] and Cr-O [1.976(5) A] bond distances and a Mn-O(H)-Cr angle of 163.7(3) degrees . The five-coordinate Mn center in the (TPP)Mn fragment is displaced from the TPP rigorously planar central N4 core by 0.128 A, and the environment is typical of a Mn(III) high-spin site. The six-coordinate Cr(III) in the CrPc(N3) moiety lies practically in the plane of the phthalocyanine macrocycle (displacement toward the azido group: 0.054 A). The average Mn-N(pyr) and Cr-N(pyr) bond distances are 2.011(6) and 1.982(6) A, respectively, and the Mn-Cr bond distance is 3.929(2) A. The porphyrin and phthalocyanine rings are in an almost eclipsed position [5.16(2) degrees ], and the mean planes of the two macrocycles form a dihedral angle of 5.79(4) degrees. Crystal data for [(TPP)Mn-O(H)-CrPc(N3)].2ClNP, C76H45CrMnN15O.2C10H7Cl: a = 16.645(3) A, b = 17.692(4) A, c = 25.828(5) A, alpha = 90 degrees , beta = 98.79(3) degrees , gamma = 90 degrees , space group P2(1)/c (No. 14), V = 7517(3) A(3), Z = 4, R1 = 0.086, and wR2 = 0.267. IR and UV-vis-near-IR spectral and room temperature magnetic susceptibility data of the [Mn-Cr] species are also presented.

  10. Tempering of Martensite and Subsequent Redistribution of Cr, Mn, Ni, Mo, and Si Between Cementite and Martensite Studied by Magnetic Measurements

    Science.gov (United States)

    Mola, Javad; Luan, Guoqing; Brochnow, David; Volkova, Olena; Wu, Jun

    2017-12-01

    Tempering reactions in ternary Fe-2M-0.7C steels (M=Cr, Ni, Mn, Mo, and Si) were studied by correlative dilatometry and magnetic measurements at room temperature. Magnetic measurements were conducted after tempering at progressively higher temperatures. Based on the magnitude of demagnetization in the temperature range associated with the tempering stage I contraction, Mn- and Si-added steels formed the largest and smallest fractions of transition carbides, respectively. Estimation of the magnetization of paraequilibrium cementite indicated that Cr, Mn, and Mo reduced the magnetization while Ni increased it. In the presence of Si, the decomposition of retained austenite and cementite formation were shifted to higher temperatures. At temperatures above approximately 723 K (450 °C), the enrichment of cementite with Mn and Cr significantly reduced the total magnetization. In the Mo-added steel, on the other hand, the magnetization slightly increased implying the formation of ferromagnetic Mo-rich carbides. For the Ni- and Si-added steels, the magnetization remained almost constant indicating minimal redistribution of Ni and Si subsequent to the formation of cementite. The possibility of analyzing the latter redistribution is one of the main advantages of sequential tempering and magnetic measurements at room temperature compared to in situ thermomagnetic measurements.

  11. High magnetic field phase diagram in electron-doped manganites La(0.4)Ca(0.6)Mn(1-y)Cr(y)O3.

    Science.gov (United States)

    Lu, Chengliang; Hu, Ni; Yang, Ming; Xia, Shuangcheng; Wang, Haowen; Wang, Junfeng; Xia, Zhengcai; Liu, Jun-Ming

    2014-05-09

    We report the charge-order to ferromagnetic phase transition induced by pulsed high magnetic field and impurity doping effects in manganites La(0.4)Ca(0.6)(Mn(1-y)Cr(y))O3 (0 ≤ y ≤ 0.2). Significant charge-order suppression and ferromagnetic tendency upon the Cr(3+)-doping are evidenced, and three different ground states are identified, namely the charge-order state, the phase separated state, and the spin-glass like state. Phase diagram in the H-y plane at 4.2 K is determined by the high magnetic field study, in which the charge-order and ferromagnetic phase boundary is clearly figured out. The critical magnetic field for melting the charge-order phase of La(0.4)Ca(0.6)MnO3 is revealed to reach up to 46 T at 4.2 K. Interestingly, distinct responses of the three states to the high magnetic field are observed, indicating the special physics regarding the charge order melting process in each state. The mechanism of the doping induced charge-order suppression and ferromagnetism promotion can be understood by the competition between the antiferromagnetic interaction of Cr-Mn and local enhancement of electron hopping by Cr(3+).

  12. Large refrigeration capacities near room temperature in Ni{sub 2}Mn{sub 1−x}Cr{sub x}In

    Energy Technology Data Exchange (ETDEWEB)

    Brock, Jeffrey; Khan, Mahmud, E-mail: khanm2@miamioh.edu

    2017-03-01

    We report on the observation of large refrigeration capacities near room temperature in Ni{sub 2}Mn{sub 1−x}Cr{sub x}In Heusler alloys. The alloys exhibit the L2{sub 1} cubic crystal structure and undergo a second order ferromagnetic to paramagnetic phase transition. The respective Curie temperatures vary with Cr concentration from 315 K to 290 K. Net refrigerant capacities of up to 60 J/kg and 168 J/kg are observed in the alloys for applied magnetic fields of 20 kOe and 50 kOe, respectively. Due to the second order phase transition, the materials do not exhibit any hysteresis loss or other problems usually associated with materials exhibiting first order phase transitions. The observed refrigeration capacities in Ni{sub 2}Mn{sub 1−x}Cr{sub x}In are higher than those observed in many Heusler alloys with first order magnetic transitions. - Highlights: • The magnetic and magnetocaloric properties of Ni{sub 2}Mn{sub 1−x}Cr{sub x}In have been investigated. • The materials exhibit ferromagnetic transitions and associated magnetocaloric effects near room temperature. • The materials exhibit refrigeration capacities that are superior to those of Heusler alloys with first order phase transition.

  13. Magnetic properties and temperature-dependent half-metallicity of Co2Mn(Ga(1-x)Z(x)) (Z=Si, Ge, Sn) from first-principles calculation.

    Science.gov (United States)

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

    2013-04-17

    Using the first-principles exact muffin-tin orbitals method in combination with the coherent potential approximation, we investigated the magnetic properties, exchange interactions, and temperature-dependent half-metallicity of the Co2Mn(Ga1-xZx) (Z=Si, Ge, Sn) alloys. The total magnetic moment follows perfectly a previously proposed Slater-Pauling relation, i.e., μ0 = Nt - 24, with Nt being the number of valence electrons. The Co-Mn and Co1-Co2 (inter-sublattice) interactions are dominated by direct exchange, whereas the Co1-Co1 (intra-sublattice) interaction is characterized by superexchange. The Mn-Mn exchange interaction in Co2MnGa is of long-ranged RKKY-type. However, the Mn-Mn exchange interactions in Co2MnZ are relatively localized and can be attributed to superexchange. The Co-Mn, Co1-Co2 and Co1-Co1 total exchange interactions increase with x, whereas the Mn-Mn total exchange interactions show convex behavior. The calculated Curie temperature (TC) increases with x. The ability of Z to enhance TC follows the sequence of Si > Ge > Sn, in agreement with the experimental findings. The temperature dependence of the spin polarization at the Fermi level [P(T)] is investigated based on the disordered local moment model. P(T) drops abruptly at temperatures much lower than TC. At temperatures higher than 200 K, the composition with higher TC generally corresponds to larger P(T).

  14. Competition between ferromagnetic and antiferromagnetic interactions by Cr doping at Mn sites in antiperovskite Mn3-xCrxZnN (0≤x≤0.5) compounds

    Science.gov (United States)

    Malik, Muhammad Imran; Sun, Ying; Wang, Lei; Deng, Sihao; Shi, Kewen; Hu, Pengwei; Lu, Huiqing; Wang, Cong

    2016-05-01

    The Cr doping effect on the lattice and magnetic properties in Mn3-xCrxZnN was reported in the antiferromagnetic intermetallic host material Mn3ZnN. The lattice parameter decreases with the increase of the Cr concentration. Measurements of magnetization from 10 K to 350 K reveal that sharp antiferromagnetic (AFM)-to-paramagnetic (PM) transitions of the host material exist at 185 K (ZFC) and 177 K (FC). The peak is broadened clearly as the Cr doping was increased and when the Cr concentration exceeded 0.3, a significant ferromagnetic (FM) character was found to coexist with an AFM phase. At x=0.4 and 0.5, the M-H curves exhibit small magnetic hysteresis loop, indicating the dominant FM interactions in these samples. Also, a positive value of Weiss Temperature (ΘW) at x=0.5 in H/M-T plot suggests that the FM interaction is dominant when the Cr doping increases.

  15. 139La nuclear magnetic resonance characterisation of La2O3 and La1-xSrxMO3 where M = Cr, Mn or Co.

    Science.gov (United States)

    Bastow, T J

    1994-02-01

    139La Nuclear magnetic resonance (NMR) spectra have been used to obtain nuclear quadrupole coupling parameters for La2O3 and a series of perovskites La1-xSrxMO3 (where M = Cr, Mn or Co). Depending on the doping level of SrO2 these materials are either paramagnetic or ferromagnetic at room temperature. Magnetic transferred hyperfine effects are strongly in evidence in the Mn compounds. A 59Co NMR spectrum was observed in LaCoO3. A precision measurement of the nuclear quadrupole coupling constant in La2O3 was made by nuclear quadrupole resonance (NQR) spectroscopy.

  16. Dry sliding wear of Al-Fe-Cr-Mn quasicrystalline phase former alloy obtained by spray forming; Estudo do comportamento ao desgaste de liga Al-Fe-Cr-Mn obtida por conformacao por spray

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, S.M.T.; Rios, C.T.; Botta Filho, W.J.; Bolfarini, C.; Kiminami, C.S. [Universidade Federal de Sao Carlos (DEMa/UFSCar), SP (Brazil). Dept. de Engenharia de Materiais; Gargarella, P.; Mendes, M.A.B., E-mail: marcio.andreato@gmail.co [Universidade Federal de Sao Carlos (PPG-CEMUFSCar), SP (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2010-07-01

    Samples from different regions of a spray formed billet of Al{sub 92}Fe{sub 3}Cr{sub 2}Mn{sub 3} quasicrystalline phase former alloy were analyzed and their wear behavior has been studied. The microstructures observed depend on the cooling rate imposed to the material. The border of the billet exhibits a very fine structure with presence of quasicrystalline phase and the base showed a fine structure but without presence of quasicrystalline phase. Dry sliding wear tests were made using three loads and samples of these two different regions. The wear surfaces were analyzed by scanning electron microscopy and X-ray diffraction. Similar wear behavior was observed in the border and the base samples at the same load. The wear mechanism verified is the adhesive and the applied load increases the formation of Al{sub 2}O{sub 3}. These particles can take off the surface and act as abrasive, which can explain the large increase in the wear rate for the samples loaded at 30N.(author)

  17. Electrochemical evaluation of adsorption and oxidation of the carbon monoxide towards ordered intermetallic phases Pt-M (M=Mn, Pb, Sb e Sn); Avaliacao eletroquimica da adsorcao e oxidacao do monoxido de carbono sobre fases intermetalicas ordenadas Pt-M (M=Mn, Pb, Sb e Sn)

    Energy Technology Data Exchange (ETDEWEB)

    Nicolai, A.L.; Miguel-Junior, E.; Silva, R.I.V. da; Angelo, A.C.D. [UNESP, Bauru, SP (Brazil). Depto. de Quimica. Lab. de Eletrocatalise

    2004-07-01

    This paper presents the experimental results obtained from the electrochemical evaluation of Pt ordered intermetallic phases (PtMn, PtPb, PtSb, PtSn) as electrode materials towards the CO oxidation reaction. The intermetallics showed a higher performance than pure Pt in the same experimental conditions. PtSn has presented the highest performance among the evaluated materials. There was not observed a clear relationship between the electrocatalytic activity of the materials and their ability in producing oxygen species at lower anodic potentials, suggesting that surface electronic density and structural characteristics of the electrode surfaces must be the properties to be investigated in order to explain the obtained results. (author)

  18. Effect of minor elements and a Ce surface treatment on the oxidation behavior of an Fe-22Cr-0.5Mn (Crofer 22 APU) ferritic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Alman, D.E.; Jablonski, P.D. [National Energy Technology Laboratory, 1450 Queen Ave., S.W. Albany, OR (United States)

    2007-11-15

    This paper details the oxidation behavior of coupons from three different Crofer 22 APU sheets. Oxidation tests were conducted at 800 {sup circle} C in moist air for 2300 h. The major features of the scales were similar in all three coupons, with a continuous Cr-Mn spinel layer forming at the gas-oxide interface and a Cr{sub 2}O{sub 3} layer forming at the oxide-metal interface. Also, at the Cr{sub 2}O{sub 3}-metal interface, large Cr-Mn oxide particles formed in the base metal. Metal extrusions in the oxide scale were observed in the vicinity of these Cr-Mn oxide particles. All three alloys had internal oxide particles forming in the base metal beneath the oxide scale, and the extent of this internal oxidation was related to the Al and Si-content in the coupons (as also reported by Piron-Abellan J, Huczkowski P, Ertl S, Shemet V, Singheiser L, Quadakkers W. In: Fuel cell seminar, 2004. San Antionio, TX, November 1-5, 2004). Of note, discontinuous Ti-oxide and Mn-oxide particles formed above the outer spinel layer on the coupons with relatively high Al and Si contents. The effectiveness of rare-earth surface modification on improving oxidation resistance of this alloy was demonstrated. Pack cementation-like processes were used to treat the surface of the coupons with Ce. A continuous Cr-Mn outer oxide layer and a continuous inner Cr{sub 2}O{sub 3} layer formed on the surface of the treated coupons during oxidation. However, the thickness of the scales and amount of internal oxidation were significantly reduced with the treatment, leading to the decrease in oxidation rate. The amount of internal oxidation was also reduced with the treatment. The treatment appeared to suppress the formation of SiO{sub 2} at the scale-metal interface in high Si containing alloys. ASR measurements indicate that the treatment decreases the electrical resistance, which is a benefit for SOFC interconnect application. (author)

  19. SnO2 nano-rods promoted by In, Cr and Al cations for toluene total oxidation: The impact of oxygen property and surface acidity on the catalytic activity

    Science.gov (United States)

    Liu, Yang; Guo, Yao; Liu, Yaqian; Xu, Xianglan; Peng, Honggen; Fang, Xiuzhong; Wang, Xiang

    2017-10-01

    SnO2 nano-rods doped by In, Cr and Al cations have been fabricated by using hydrothermal method and evaluated for toluene total oxidation. SEM results demonstrate that the initial nano-rods aggregated into three-dimensional microspheres for all the samples. XRD testifies that all the SnO2 nano-rod catalysts are well crystallized with low surface areas and big crystallite sizes. It is revealed by HRTEM images that the pure SnO2 and Sn99Al1 nano-rods preferentially exposed (101) facets, while the Sn99In1 and Sn99Cr1 nano-rods exposed (110) facets, which demonstrated that the doping with a small amount of the secondary cations into the crystal matrix can significantly influence the crystallization process and change the preferentially exposed facets of SnO2 nano-rods. As testified by XPS and O2-TPD, the introduction of Al3+ cations into the crystal matrix of SnO2 nano-rods leads to the formation of more mobile oxygen species. In addition, NH3-TPD results substantiate that the surface acidity of catalysts modified by Al and Cr cations can also be significantly enhanced, which is favorable for the adsorption and activation of the toluene molecules. In conclusion, the oxygen mobility and surface acidity are regarded as the two predominant factors accounting for the improved activity of the doped SnO2 nano-rod catalysts for toluene total oxidation. Due to the optimized concerted action of the two factors, Sn99Al1-rod, a catalyst doped by Al cations shows the highest activity among all the catalysts.

  20. Electronic structure and magnetic properties of Fe{sub 2}YSi (Y = Cr, Mn, Fe, Co, Ni) Heusler alloys: a theoretical and experimental study

    Energy Technology Data Exchange (ETDEWEB)

    Luo Hongzhi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhu Zhiyong [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Ma Li [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Xu Shifeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Liu Heyan [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Qu Jingping [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Li Yangxian [School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Wu Guangheng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-11-21

    A series of Fe{sub 2}YSi (Y = Cr, Mn, Fe, Co, Ni) alloys were synthesized and their electronic and magnetic properties were studied both theoretically and experimentally. In particular, a novel Heusler alloy Fe{sub 2}CrSi single phase was synthesized by means of the melt-spinning method. First principles FLAPW calculations were performed on Fe{sub 2}YSi alloys. Based on the results, Fe{sub 2}CrSi is predicted to be a half-metallic ferromagnet with a spin moment of 2{mu}{sub B}/f.u. and a gap of 0.42 eV. Fe{sub 2}MnSi is also half-metallic in the ferromagnetic state. The saturation magnetic moments at 5 K for this series of alloys fit the theoretical calculations well. Specifically, the saturation magnetic moment of Fe{sub 2}CrSi is 2.05{mu}{sub B}/cell, which agrees with the ideal value of 2{mu}{sub B} derived from the Slater-Pauling rule. The Curie temperatures of Fe{sub 2}YSi alloys are all higher than 500 K except for Fe{sub 2}MnSi, which has a T{sub C} below room temperature. Finally, the effect of lattice distortion on the electronic and magnetic properties of Fe{sub 2}CrSi and Fe{sub 2}CoSi was studied. It is found that Fe{sub 2}CrSi is half-metallic from -3% to +1% uniform lattice distortion, and this character is preferred in systems containing large strain, such as melt-spun ribbons or thin films.

  1. Evaluation of rare earth oxides doping SnO2.(Co1/4,Mn3/4O-based varistor system

    Directory of Open Access Journals (Sweden)

    Alessandro Dibb

    2006-09-01

    Full Text Available The present paper aims to verify the inuence of rare earth oxide such as lanthanum (La2O3 and neodymium (Nd2O3 doping SnO2 + 0.25%CoO + 0.75%MnO2 + 0.05%Ta2O5 system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM at different regions of the samples. From such analysis it was found that La2O3 and Nd2O3 oxides cause heterogeneous segregation and precipitation at grain boundary concerning cobalt and manganese, decreasing the nonohmic electrical properties, as discussed, likely due to the increasing of grain boundary non-active potential barriers.

  2. Magnetic and magnetocaloric properties of martensitic Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Chernenko, Volodymyr A., E-mail: vladimir_chernenko@ehu.es [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Ikerbasque, Basque Foundation for Science, Bilbao 48011 (Spain); Barandiaran, Jose M. [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Rodriguez Fernandez, Jesus; Rojas, Daniel P. [CITIMAC, Fac. Ciencias, Univ. Cantabria, Santander 39005 (Spain); Gutierrez, Jon; Lazpita, Patricia [Universidad del Pais Vasco, Dept. Electricidad y Electronica, PO Box 644, Bilbao 48080 (Spain); Orue, Inaki [SGiker, Vicerrectorado de Inv. UPV/EHU, Sarriena s/n, Leioa 48940 (Spain)

    2012-10-15

    The evolutions of magnetic properties at low temperatures and the influence of magnetic field on the temperature dependence of specific heat in martensitic Ni{sub 2}Mn{sub 1.4}Sn{sub 0.6} Heusler alloy are studied. The frequency-dependent blocking temperature and considerable exchange bias below it are measured in the martensitic phase. From the analysis of the specific heat curves under magnetic field, a large inverse magnetocaloric effect manifested as the magnetic field induced rise of isothermal magnetic entropy and/or magnetic field induced adiabatic temperature decrease in the vicinity of the reverse magnetostructural transformation and a significant value of the conventional magnetocaloric effect at the Curie temperature are obtained. The Debye temperature and electronic coefficient equal to {Theta}{sub D}=310{+-}2 K and {gamma}= 16.6{+-}0.3 mJ/K{sup 2}mol, respectively, do not depend on the magnetic field.

  3. Analysis of the Magnetocaloric Effect in Heusler Alloys: Study of Ni50CoMn36Sn13 by Calorimetric Techniques

    Directory of Open Access Journals (Sweden)

    Elias Palacios

    2015-03-01

    Full Text Available Direct determinations of the isothermal entropy increment, \\(-\\Delta S_T\\, in the Heusler alloy Ni\\(_{50}\\CoMn\\(_{36}\\Sn\\(_{13}\\ on demagnetization gave positive values, corresponding to a normal magnetocaloric effect. These values contradict the results derived from heat-capacity measurements and also previous results obtained from magnetization measurements, which indicated an inverse magnetocaloric effect, but showing different values depending on the technique employed. The puzzle is solved, and the apparent incompatibilities are quantitatively explained considering the hysteresis, the width of the martensitic transition and the detailed protocol followed to obtain each datum. The results show that these factors should be analyzed in detail when dealing with Heusler alloys.

  4. Observation of giant exchange bias in bulk Mn{sub 50}Ni{sub 42}Sn{sub 8} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jyoti; Suresh, K. G., E-mail: suresh@iitb.ac.in [Magnetic Materials Laboratory, Department of Physics, Indian institute of Technology Bombay, Mumbai, Maharashtra 400076 (India)

    2015-02-16

    We report a giant exchange bias (EB) field of 3520 Oe in bulk Mn{sub 50}Ni{sub 42}Sn{sub 8} Heusler alloy. The low temperature magnetic state of the martensite phase has been studied by DC magnetization and AC susceptibility measurements. Frequency dependence of spin freezing temperature (T{sub f}) on critical slowing down relation and observation of memory effect in zero field cooling mode confirms the super spin glass (SSG) phase at low temperatures. Large EB is attributed to the strong exchange coupling between the SSG clusters formed by small regions of ferromagnetic order embedded in an antiferromagnetic (AFM) matrix. The temperature and cooling field dependence of EB have been studied and related to the change in unidirectional anisotropy at SSG/AFM interface. The training effect also corroborates with the presence of frozen (SSG) moments at the interface and their role in EB.

  5. Forced volume magnetostriction in Mn{sub 3.3}Sn{sub 0.7}C compound at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wen Yongchun [Center for Condensed Matter and Materials Physics, Department of Physics, and Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191 (China); Wang Cong, E-mail: congwang@buaa.edu.c [Center for Condensed Matter and Materials Physics, Department of Physics, and Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191 (China); Sun Ying; Nie Man; Chu Lihua [Center for Condensed Matter and Materials Physics, Department of Physics, and Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191 (China)

    2010-10-15

    The negative volume magnetostriction in the external magnetic field for antiperovskite Mn{sub 3.3}Sn{sub 0.7}C compound is discovered. Its magnetic transition temperature from paramagnetism to ferrimagnetism is 348 K. The linear and volume magnetostrictions were investigated by measuring the change in length along the three-dimensional directions of the square samples at room temperature. Volume contraction was observed along all of the three directions throughout the whole magnetization. The value of volume magnetostriction is -44x10{sup -6} at 1.5 T. The magnetization saturates basically at 1.5 T, however the volume magnetostriction should be higher with further increase in magnetic field.

  6. Structural, Magnetic, and Microwave-Absorption Properties of Nanocrystalline Ca(MnSn) x Fe12-2 x O19 Ferrites

    Science.gov (United States)

    Ali-Sharbati; Amiri, G. R.; Mousarezaei, R.

    2015-02-01

    Nanoparticles of Ca(MnSn) x Fe12-2 x O19 with x ranging from 0.00 to 0.6 in steps of 0.2 were prepared by use of the citrate precursor method. The structural, microwave-absorption, and magnetic properties of these ferrites were determined by use of different characterization techniques. The morphology of the ferrite powders was investigated by transmission electron microscopy (TEM). X-ray diffraction (XRD) was used for structural and micro-structural studies, and revealed that the samples had an M-type hexagonal structure. The crystallite size for each sample was calculated by use of the Scherrer formula for the most intense peak (411) and the results were compared with those obtained from TEM images of the samples. The particle size of the powder varied from 60 to 36 nm. Magnetic measurements were performed by vibrating sample magnetometry (VSM) at room temperature. The microwave-absorption properties of ferrite (70 wt.%)-polymer (30 wt.%) composites 2 mm thick were investigated by vector network analysis (VNA) in the frequency range 12-20 GHz. The ferrite for which x = 0.4 had a minimum reflection loss of -29 dB at 17.3 GHz with a -15 dB bandwidth over the extended frequency ranges 12.9-14.5 GHz and 16.7-18 GHz. The minimum loss reached -32 dB at frequency of 17 GHz when the total amount of Mn2+ and Sn4+ ions was 0.6. These results suggest that the synthesized magnetic composites can be used as effective microwave absorbers in military applications (radar cross-section reduction).

  7. Understanding the physical metallurgy of the CoCrFeMnNi high-entropy alloy: an atomistic simulation study

    Science.gov (United States)

    Choi, Won-Mi; Jo, Yong Hee; Sohn, Seok Su; Lee, Sunghak; Lee, Byeong-Joo

    2018-01-01

    Although high-entropy alloys (HEAs) are attracting interest, the physical metallurgical mechanisms related to their properties have mostly not been clarified, and this limits wider industrial applications, in addition to the high alloy costs. We clarify the physical metallurgical reasons for the materials phenomena (sluggish diffusion and micro-twining at cryogenic temperatures) and investigate the effect of individual elements on solid solution hardening for the equiatomic CoCrFeMnNi HEA based on atomistic simulations (Monte Carlo, molecular dynamics and molecular statics). A significant number of stable vacant lattice sites with high migration energy barriers exists and is thought to cause the sluggish diffusion. We predict that the hexagonal close-packed (hcp) structure is more stable than the face-centered cubic (fcc) structure at 0 K, which we propose as the fundamental reason for the micro-twinning at cryogenic temperatures. The alloying effect on the critical resolved shear stress (CRSS) is well predicted by the atomistic simulation, used for a design of non-equiatomic fcc HEAs with improved strength, and is experimentally verified. This study demonstrates the applicability of the proposed atomistic approach combined with a thermodynamic calculation technique to a computational design of advanced HEAs.

  8. Enhancement of spin polarization via Fermi level tuning in Co{sub 2}MnSn{sub 1−x}Sb{sub x} (x = 0, 0.25. 0.5, 0.75, 1) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Mukhtiyar, E-mail: msphysik09@gmail.com; Thakur, Jyoti; Kashyap, Manish K. [Department of Physics, Kurukshetra University, Kurukshetra - 136119, Haryana (India); Saini, Hardev S. [Department of Physics, National Institute of Technology, Kurukshetra - 136119, Haryana (India)

    2014-04-24

    Full potential approach has been employed to tune Fermi level in Co{sub 2}MnSn{sub 1−x}Sb{sub x} (x = 0, 0.25, 0.5, 0.75, 1) Heulser alloys for enhancement of spin polarization and finding signature of half metallicity. Present density functional theory (DFT) based calculation indicates that stoichoimetric Heusler alloy, Co{sub 2}MnSn is not a half-metallic ferromagnet but the doping of Sb in it results in the shifting of E{sup F} in well-defined energy gap which leads the 100% spin polarization in the resultant alloys. The magnetism in present alloys is governed by localized moment on Mn atom mainly. The tuning of half-metallicity using doping can be proved as an ideal technique to search the new materials which can accomplish the need of spintronics.

  9. Antifungal and Spectral Studies of Cr(III and Mn(II Complexes Derived from 3,3′-Thiodipropionic Acid Derivative

    Directory of Open Access Journals (Sweden)

    Amit Kumar Sharma

    2009-01-01

    Full Text Available The Cr(III and Mn(II complexes with a ligand derived from 3,3′-thiodipropionic acid have been synthesized and characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR, UV, and EPR spectral studies. The complexes are found to have [Cr(LX]X2 and [Mn(LX]X, compositions, where L = quinquedentate ligand and X=NO3−, Cl− and OAc−. The complexes possess the six coordinated octahedral geometry with monomeric compositions. The evaluated bonding parameters, Aiso and β, account for the covalent type metal-ligand bonding. The fungicidal activity of the compounds was evaluated in vitro by employing Food Poison Technique.

  10. Microstructural, mechanical and tribological investigation of 30CrMnSiNi2A ultra-high strength steel under various tempering temperatures

    Science.gov (United States)

    Arslan Hafeez, Muhammad; Farooq, Ameeq

    2018-01-01

    The aim of the research was to investigate the variation in microstructural, mechanical and tribological characteristics of 30CrMnSiNi2A ultra-high strength steel as a function of tempering temperatures. Steel was quenched at 880 °C and tempered at five different tempering temperatures ranging from 250 °C to 650 °C. Optical microscopy and pin on disc tribometer was used to evaluate the microstructural and wear properties. Results show that characteristics of 30CrMnSiNi2A are highly sensitive to tempering temperatures. Lathe and plate shaped martensite obtained by quenching transform first into ε-carbide, second cementite, third coarsened and spheroidized cementite and finally into recovered ferrite and austenite. Hardness, tensile and yield strengths decreased while elongation increased with tempering temperatures. On the other hand, wear rate first markedly decreased and then increased. Optimum amalgamation of characteristics was achieved at 350 °C.

  11. Effect of deep cryogenic treatment on the microstructure and wear performance of Cr-Mn-Cu white cast iron grinding media

    Science.gov (United States)

    Vidyarthi, M. K.; Ghose, A. K.; Chakrabarty, I.

    2013-12-01

    The phase transformation and grinding wear behavior of Cr-Mn-Cu white cast irons subjected to destabilization treatment followed by air cooling or deep cryogenic treatment were studied as a part of the development program of substitute alloys for existing costly wear resistant alloys. The microstructural evolution during heat treatment and the consequent improvement in grinding wear performance were evaluated with optical and scanning electron microscopy, X-ray diffraction analysis, bulk hardness, impact toughness and corrosion rate measurements, laboratory ball mill grinding wear test etc. The deep cryogenic treatment has a significant effect in minimizing the retained austenite content and converts it to martensite embedded with fine M7C3 alloy carbides. The cumulative wear losses in cryotreated alloys are lesser than those with conventionally destabilized alloys followed by air cooling both in wet and dry grinding conditions. The cryotreated Cr-Mn-Cu irons exhibit comparable wear performance to high chromium irons.

  12. Local strains, calorimetry, and magnetoresistance in adaptive martensite transition in multiple nanostrips of Ni39+xMn50Sn11−x(x ⩽ 2) alloys

    Science.gov (United States)

    Prasanna, A A; Ram, Shanker

    2013-01-01

    Ni39+xMn50Sn11−x (x = 0.5, 1.0, 1.5 and 2) alloys comprise multiple martensite nanostrips of nanocrystallites when cast in small discs, for example, ∼15 mm diameter and 8 mm width. A single martensite phase with a L10 tetragonal crystal structure at room temperature can be formed at a critical Sn content of 9.0 at.% (x = 2), whereas an austenite cubic L21 phase turns up at smaller x ⩽ 1.5. The decrease in the Sn content from x = 2 to 0.5 also results in a gradual increase in the crystallite size from 11 to 17 nm. Scanning electron microscopy images reveal arrays of regularly displaced multiple martensite strips (x ≽ 1.5) with an average thickness of 20 nm. As forced oscillators, these strips carry over the local strains, magnetic dipoles, and thermions simultaneously in a martensite–austenite (or reverse) phase transition. A net residual enthalpy change ΔHM↔A = −0.12 J g−1 arises in the process that lacks reversibility between the cooling and heating cycles. A large magnetoresistance of (–)26% at 10 T is observed together with a large entropy change of 11.8 mJ g−1 K−1, nearly twice the value ever reported in such alloys, in the isothermal magnetization at 311 K. The ΔHM↔A irreversibility accounts for a thermal hysteresis in the electrical resistivity. Strain induced in the martensite strips leads them to have a higher electrical resistivity than that of the higher-temperature austenite phase. A model considering time-dependent enthalpy relaxation explains the irreversibility features. PMID:27877562

  13. Local strains, calorimetry, and magnetoresistance in adaptive martensite transition in multiple nanostrips of Ni39+xMn50Sn11−x(x ≤ 2 alloys

    Directory of Open Access Journals (Sweden)

    A A Prasanna and Shanker Ram

    2013-01-01

    Full Text Available Ni39+xMn50Sn11−x (x = 0.5, 1.0, 1.5 and 2 alloys comprise multiple martensite nanostrips of nanocrystallites when cast in small discs, for example, ~15 mm diameter and 8 mm width. A single martensite phase with a L10 tetragonal crystal structure at room temperature can be formed at a critical Sn content of 9.0 at.% (x = 2, whereas an austenite cubic L21 phase turns up at smaller x ≤ 1.5. The decrease in the Sn content from x = 2 to 0.5 also results in a gradual increase in the crystallite size from 11 to 17 nm. Scanning electron microscopy images reveal arrays of regularly displaced multiple martensite strips (x ≥ 1.5 with an average thickness of 20 nm. As forced oscillators, these strips carry over the local strains, magnetic dipoles, and thermions simultaneously in a martensite–austenite (or reverse phase transition. A net residual enthalpy change ΔHM↔A = −0.12 J g−1 arises in the process that lacks reversibility between the cooling and heating cycles. A large magnetoresistance of (–26% at 10 T is observed together with a large entropy change of 11.8 mJ g−1 K−1, nearly twice the value ever reported in such alloys, in the isothermal magnetization at 311 K. The ΔHM↔A irreversibility accounts for a thermal hysteresis in the electrical resistivity. Strain induced in the martensite strips leads them to have a higher electrical resistivity than that of the higher-temperature austenite phase. A model considering time-dependent enthalpy relaxation explains the irreversibility features.

  14. Local strains, calorimetry, and magnetoresistance in adaptive martensite transition in multiple nanostrips of Ni39+x Mn50Sn11-x (x ⩽ 2) alloys.

    Science.gov (United States)

    Prasanna, A A; Ram, Shanker

    2013-02-01

    Ni39+x Mn50Sn11-x (x = 0.5, 1.0, 1.5 and 2) alloys comprise multiple martensite nanostrips of nanocrystallites when cast in small discs, for example, ∼15 mm diameter and 8 mm width. A single martensite phase with a L10 tetragonal crystal structure at room temperature can be formed at a critical Sn content of 9.0 at.% (x = 2), whereas an austenite cubic L21 phase turns up at smaller x ⩽ 1.5. The decrease in the Sn content from x = 2 to 0.5 also results in a gradual increase in the crystallite size from 11 to 17 nm. Scanning electron microscopy images reveal arrays of regularly displaced multiple martensite strips (x ≽ 1.5) with an average thickness of 20 nm. As forced oscillators, these strips carry over the local strains, magnetic dipoles, and thermions simultaneously in a martensite-austenite (or reverse) phase transition. A net residual enthalpy change ΔHM↔A = -0.12 J g-1 arises in the process that lacks reversibility between the cooling and heating cycles. A large magnetoresistance of (-)26% at 10 T is observed together with a large entropy change of 11.8 mJ g-1 K-1, nearly twice the value ever reported in such alloys, in the isothermal magnetization at 311 K. The ΔHM↔A irreversibility accounts for a thermal hysteresis in the electrical resistivity. Strain induced in the martensite strips leads them to have a higher electrical resistivity than that of the higher-temperature austenite phase. A model considering time-dependent enthalpy relaxation explains the irreversibility features.

  15. Microstructure, Interface Morphology, and Antioxidant Properties of Sn-8.5Zn-0.1Cr-(Nd,Al,Cu) Solders

    Science.gov (United States)

    Tang, Hongqun; Liu, Moumiao; Ma, Yueyuan; Du, Zaixiang; Zhan, Yongzhong; Yang, Wenchao

    2017-01-01

    The effects of minor alloying element Nd, Al or Cu on the fundamental microstructural properties, interface morphology, and antioxidant properties of Sn-8.5Zn-0.1Cr (SZC) alloy have been investigated. Addition of Nd, Al or Cu element significantly refined the microstructure of SZC alloy, especially promoting disappearance of the stripe Zn-rich phase. Precipitated phases could be found in the β-Sn matrix when the content of each element reached 0.1 wt.%. During soldering, it was found that Nd, Al or Cu element addition did not contribute to intermetallic compound (IMC) formation, as verified by the same IMC phase as at the Sn-8.5Zn/Cu interface and no obvious influence on interface morphology. After 15 days of aging, IMC interface layers increased severely and a wide Zn-poor transition zone formed. The growth rate of IMC was reduced and the transition zone became narrower after microalloying. Meanwhile, addition of Al or Cu element improved the oxidation resistance of the SZC alloy, while Nd-containing alloys oxidized severely. The wettability and microhardness of the SZC- xM alloys were superior to those of SZC alloy.

  16. XMCD at the L/sub 2,3/-edges of Pt in ordered TPt/sub 3/ alloys (T=Cr, Mn, Co)

    CERN Document Server

    Grange, W; Maret, M; Rogalev, A; Goulon, J

    1999-01-01

    We present X-ray magnetic circular dichroism experiments at the L/sub 2,3/ edges of Pt in ordered TPt/sub 3/ alloys (T=Cr, Mn and Co). The derived Pt 5d spin and orbital magnetic moments are found to be in good agreement with band $9 structure calculations. The extraction of 5d magnetic moments from measured X-ray-absorption spectra is discussed in detail. (13 refs).

  17. Distribution of /sup 51/Cr, /sup 54/Mn, /sup 59/Fe, /sup 60/Co, /sup 109/Cd and /sup 124/Sb in organs of lactating cows

    Energy Technology Data Exchange (ETDEWEB)

    Bruwaene, R. van; Kirchmann, R.; Gerber, G.B.; Colard, J.; Vankerkom, J. (Centre d' Etude de l' Energie Nucleaire, Mol (Belgium))

    1983-05-01

    Lactating cows were given /sup 51/Cr, /sup 54/Mn, /sup 59/Fe, /sup 60/Co, /sup 109/Cd and /sup 124/Sb together with maize silage. The animals were slaughtered 97 days later and the distribution of the isotopes in the body was determined. With some notable exceptions, the isotopes accumulated in the large parenchymal organs (liver, kidney and spleen), but substantial amounts, particularly of cadmium and chromium, were also found in the intestine. Manganese concentrated in the pancreas and brain.

  18. Semimicroanalysis of silicate minerals by means of XRF thin layer method. Determination of selected chromatic elements - V, Cr, Mn, Fe, Co

    Energy Technology Data Exchange (ETDEWEB)

    Jurczyk, J.; Buhl, F.; Sitko, R.; Fabis, M.; Czaja, M. [Silesian University, Katowice (Poland)

    1997-12-31

    50 mg of powdered silicate mineral is spread on a substrate, dissolved in a concentrated hydrofluoric acid and dried under the infrared heater; a sample is then protected with a mylar film. Statistical parameters of XRF detection limits for 50 mg samples: V(3-6 ppm), Cr(3-6 ppm), Mn(25 ppm), Fe(4-5 ppm), Co(2-7 ppm). 13 refs, 1 fig., 12 tabs.

  19. Strong pressure dependences of the magnetization and Curie temperature for CrTe and MnAs with NiAs-type structure

    CERN Document Server

    Yamada, H; Kondo, K; Goto, T

    2002-01-01

    To study the strong magneto-volume effects observed in CrTe and MnAs with NiAs-type crystal structure, first-principle band calculations are carried out by a self-consistent linear muffin-tin orbital method within the atomic sphere approximation. The equilibrium volume of the unit cell is obtained as a function of the magnetization M, which gives the volume magnetostriction. The dependence on M of the bulk modulus is also estimated. The coefficients a sub 0 and b sub 0 in the Landau expansion, DELTA E(M) = a sub 0 M sup 2 /2 + b sub 0 M sup 4 /4, are estimated by the fixed-spin-moment method. The calculated results for CrTe and MnAs are compared with those for bcc Fe. It is shown that the values of vertical bar a sub 0 vertical bar and b sub 0 for CrTe and MnAs are so small that the correction term from the magneto-volume coupling constants becomes significant. This fact gives a strong pressure dependence of the spontaneous magnetization. The pressure dependence of the Curie temperature is also discussed by m...

  20. Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

    Science.gov (United States)

    Chandra, Ram; Yadav, Sangeeta

    2011-07-01

    A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater.

  1. STM/STS analysis of molecular chains consisting of Mn{sub 6}Cr single molecule magnets and single molecules on highly ordered pyrolytic graphite (HOPG)

    Energy Technology Data Exchange (ETDEWEB)

    Gryzia, Aaron; Brechling, Armin; Hachmann, Wiebke; Sacher, Marc D.; Heinzmann, Ulrich [Molecular and Surface Physics, Bielefeld University (Germany); Heidemeier, Maik; Glaser, Thorsten [Anorganic Chemistry I, Bielefeld University (Germany)

    2008-07-01

    We report on the preparation and characterization of Mn{sub 6}Cr-Single Molecule Magnets on a HOPG(0001) surface. The Mn{sub 6}Cr-molecules show 1D molecular arrangements with many interesting features, such as the occurrence of discrete kink angles in the molecular chains of 30 deg., only two different molecular orientations, the orientation of the chains along the main crystal axis of HOPG and much larger molecule-molecule distances than expected from the van der Waals radii of the molecules. By STS we characterized Mn{sub 6}Cr, thus gaining information on the electronic levels of the molecule and the shift of the levels whether it is part of a chain or not. One of our goals is to obtain data about the exact orientation of the molecule in respect to the surface; thus we can make a statement for the physical interaction why the molecules are assembling in chains. First results of these measurements are presented.

  2. Cyclic voltammetry of LiCr 0.15Mn 1.85O 4 in an aqueous LiNO 3 solution

    Science.gov (United States)

    Cvjeticanin, Nikola; Stojkovic, Ivana; Mitric, Miodrag; Mentus, Slavko

    Cyclic voltammetry (CV) of LiCr 0.15Mn 1.85O 4, synthesized by rapid glycine-nitrate method (GNM), was performed in a saturated aqueous LiNO 3 (∼9 M) solution. At rather high polarization rate of 10 mV s -1 two well separated characteristic pairs of redox peaks can be clearly observed, which is not entirely the case for LiMn 2O 4 synthesized in the same way. At a reduced scan rate of 1 mV s -1, the shape and position of redox peaks evidence that deintercalation/intercalation of Li + ion is highly reversible and much faster than in the case of organic electrolytes. Faster "CV response" of LiCr 0.15Mn 1.85O 4 is in correlation with higher capacity retention (93%) in comparison to LiMn 2O 4 (88%), registered after 50 charging/discharging cycles in organic electrolyte solution (1 M LiClO 4 in propylene carbonate).

  3. Systematic study of the elastic properties of Mn{sub 3}AC antiperovskite with A = Zn, Al, Ga, In, Tl, Ge and Sn

    Energy Technology Data Exchange (ETDEWEB)

    Medkour, Y.; Roumili, A. [Laboratoire d' Etudes des Surfaces et Interfaces des Materiaux Solides (LESIMS), Universite de Setif (Algeria); Maouche, D., E-mail: djmaouche@yahoo.fr [Laboratory for Developing New Materials and their Characterizations, University of Setif (Algeria); Saoudi, A.; Louail, L. [Laboratory for Developing New Materials and their Characterizations, University of Setif (Algeria)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Single crystal elastic constants C{sub 11}, C{sub 12} and C{sub 44} were calculated. Black-Right-Pointing-Pointer Elastic moduli for polycrystalline aggregate were obtained. Black-Right-Pointing-Pointer Increasing the atomic number of A element reduces B, G Prime , Y and v. Black-Right-Pointing-Pointer Mn{sub 3}AlC has a high melting point and light weight. - Abstract: First principle calculations were made to investigate the elastic properties of Mn{sub 3}AC antiperovskites, A = Zn, Al, Ga, In, Tl, Ge and Sn. The estimated equilibrium lattice parameters are in agreement with the experimental ones. From the single crystal elastic constants we have calculated the polycrystalline elastic moduli: the bulk modulus B, shear modulus G, tetragonal shear modulus G Prime , Young's modulus Y, Cauchy's pressure CP, Poisson's ratio v, elastic anisotropy factor and Pugh's criterion G/B. Using Debye's approximation we have deduced the elastic wave velocities and Debye's temperature.

  4. Core-shell Prussian blue analogue molecular magnet Mn(1.5)[Cr(CN)6]·mH2O@Ni(1.5)[Cr(CN)6]·nH2O for hydrogen storage.

    Science.gov (United States)

    Bhatt, Pramod; Banerjee, Seemita; Anwar, Sharmistha; Mukadam, Mayuresh D; Meena, Sher Singh; Yusuf, Seikh M

    2014-10-22

    Core-shell Prussian blue analogue molecular magnet Mn1.5[Cr(CN)6]·mH2O@Ni1.5[Cr(CN)6]·nH2O has been synthesized using a core of Mn1.5[Cr(CN)6]·7.5H2O, surrounded by a shell of Ni1.5[Cr(CN)6]·7.5H2O compound. A transmission electron microscopy (TEM) study confirms the core-shell nature of the nanoparticles with an average size of ∼25 nm. The core-shell nanoparticles are investigated by using x-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. The Rietveld refinement of the XRD pattern reveals that the core-shell compound has a face-centered cubic crystal structure with space group Fm3m. The observation of characteristic absorption bands in the range of 2000-2300 cm(-1) in IR spectra corresponds to the CN stretching frequency of Mn(II)/Ni(II)-N≡C-Cr(III) sequence, confirming the formation of Prussian blue analogues. Hydrogen absorption isotherm measurements have been used to investigate the kinetics of molecular hydrogen adsorption into core-shell compounds of the Prussian blue analogue at low temperature conditions. Interestingly, the core-shell compound shows an enhancement in the hydrogen capacity (2.0 wt % at 123 K) as compared to bare-core and bare-shell compounds. The hydrogen adsorption capacity has been correlated with the specific surface area and TGA analysis of the core-shell compound. To the best of our knowledge, this is the first report on the hydrogen storage properties of core-shell Prussian blue analogue molecular magnet that could be useful for hydrogen storage applications.

  5. Synthesis, Characterization and Thermal Decomposition Studies of Cr(III), Mn(II) and Fe(III) Complexes of N, N '-Bis[1,3-benzodioxol-5-ylmethylene]butane-1,4-diamine

    National Research Council Canada - National Science Library

    Prasad M. Alex; K. K. Aravindakshan

    2009-01-01

    ... (3,4-dioxymethylenebenzaldehyde) with butane-1,4-diamine. Cr(III), Mn(II), Fe(III) complexes of this chelating ligand were synthesised using acetates, chlorides, bromides, nitrates and perchlorates of these metals...

  6. Co-existence of ferromagnetic and antiferromagnetic interactions in Mn3Ga(1-x)Sn x C

    Science.gov (United States)

    Dias, E. T.; Priolkar, K. R.; Nigam, A. K.

    2014-04-01

    The magnetic properties of the \\text{M}{{\\text{n}}_{3}}\\text{G}{{\\text{a}}_{(1-x)}}\\text{S}{{\\text{n}}_{x}}\\text{C}, 0\\leqslant x\\leqslant 1 antiperovskite compounds have been investigated in detail. Though all compounds of this series crystallize in a cubic structure, the Ga rich (x\\leqslant 0.2) compounds transform, via a first-order transformation, to an antiferromagnetic ground state and the Sn rich (x\\geqslant 0.8) compounds exhibit dominant ferromagnetic interactions at low temperature. In the intermediate range (0.4\\leqslant x\\leqslant 0.7) co-existence of ferromagnetic and antiferromagnetic interactions can be seen. The results have been explained to be due to growth of ferromagnetic sub-lattice at the expense of antiferromagnetic sub-lattice with increasing Sn concentration in \\text{M}{{\\text{n}}_{3}}\\text{G}{{\\text{a}}_{(1-x)}}\\text{S}{{\\text{n}}_{x}}\\text{C}. This growth occurs to a point where the first-order transition is altered from a ferromagnetic-antiferromagnetic type in Ga rich compounds to a paramagnetic-ferrimagnetic type in \\text{M}{{\\text{n}}_{3}}\\text{SnC}.

  7. Studies of electrical resistance in Ni{sub 75}Cr{sub 7}Si{sub 7.5}Mn{sub 10.5} and Ni{sub 80.5}Cr{sub 4.2}Si{sub 6.5}Mn{sub 5}B{sub 3.8}glass-coated wires

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, C. [Dpto. de Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian (Spain); Dpt. Material Science and Engineering, MIT, Cambridge (United States); Zhukova, V.; Blanco, J.M. [Dpto. de Fisica Aplicada, EUPDS, UPV/EHU, San Sebastian (Spain); Val, J.J. del; Zhukov, A. [Dpto. de Fisica de Materiales, Fac. Quimicas, UPV/EHU, San Sebastian (Spain)

    2009-04-15

    In this paper we studied thermal stability of Ni{sub 75}Cr{sub 7}Si{sub 7.5}Mn{sub 10.5} and Ni{sub 80.5}Cr{sub 4.2}Si{sub 6.5}Mn{sub 5}B{sub 3.8} glass coated microwires with metallic nucleus diameters ranging between 10 {mu}m and 20 {mu}m using electrical resistance measurements, X-ray diffraction and DSC methods. Electrical resistance was measured during Joule heating of the sample i.e. flowing the DC current. X-ray diffraction was used to determine the crystalline structure in as-prepared microwires. It was found that electrical resistance per length, {rho}, depends on the sample geometry. Besides this dependence is opposite for Ni{sub 75}Cr{sub 7}Si{sub 7.5}Mn{sub 10.5} and Ni{sub 80.5}Cr{sub 4.2}Si{sub 6.5}Mn{sub 5}B{sub 3.8} glass coated microwires. Such dependences have been related with effect of rapid solidification conditions on the grain sizes and consequently on grain growth process during annealing. Temperature coefficient of resistivity in the case of Ni{sub 75}Cr{sub 7}Si{sub 7.5}Mn{sub 10.5}microwires is much smaller (about 5 times smaller). Considerable dependence of the current density for beginning of phase transition on metallic nucleus diameter has been attributed to the thermal transfer conditions. Efficiently of Joule heating for the case of thinner microwires is smaller and the current density for achieving the phase transition-higher. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Effects of Cr-doping on the electronic transport properties in antiperovskite nitrides Mn3-xCrxZnN (0≤x≤0.5)

    Science.gov (United States)

    Malik, Muhammad Imran; Sun, Ying; Wang, Lei; Deng, Sihao; Shi, Kewen; Hu, Pengwei; Lu, Huiqing; Wang, Cong

    2016-06-01

    Antiperovskite intermetallic Mn3-xCrxZnN (0≤x≤0.5) compounds have been prepared to study the Cr doping effect on the electronic transport properties. The temperature dependent resistivity ρ(T) for x≤0.3 shows notable and broader slope change. Meanwhile, with increasing Cr doping, the slope change shifts to lower temperatures and is gradually suppressed for x>0.3. For x=0.0 and 0.5, the measurements of magnetization from 10 K to 350 K reveal that Mn3-xCrxZnN compounds go through a transition from the dominant AFM interactions to one where the FM and AFM interactions coexist. For low-temperature region (15-80 K), the electron-electron scattering is dominant, and the number of phonons abruptly increases with increasing temperature. Small polaron hopping model (SPH) is used to understand the temperature dependence of electrical resistivity in the high-temperature range of 200-300 K and a clear decrease of the polaron activation energy was observed for x≤0.2. The residual resistivity ratio (RRR) decreases while the residual resistivity increases (ρ0) with increasing Cr-doping level. The maximum total entropy change (ΔSmax) decreases by increasing the Cr doping from x=0.0 to 0.2.

  9. Investigation on the parameter optimization and performance of laser cladding a gradient composite coating by a mixed powder of Co50 and Ni/WC on 20CrMnTi low carbon alloy steel

    Science.gov (United States)

    Shi, Yan; Li, Yunfeng; Liu, Jia; Yuan, Zhenyu

    2018-02-01

    In this study, a gradient composite coating was manufactured on 20CrMnTi alloy steel by laser cladding. The laser power, cladding scan velocity and powder flow rate were selected as influencing factors of the orthogonal cladding experiments. The influencing factors were optimized by the comprehensive analysis of Taguchi OA and TOPSIS method. The high significant parameters and the predicted results were confirmed by the ANOVA method. The macromorphology and microstructures are characterized by using laser microscope, SEM, XRD and microhardness tester. Comparison tests of wear resistance of gradient composite coating, 20CrMnTi cemented quenching sample and the 20CrMnTi sample were conducted on the friction-wear tester. The results show that the phases are γ-Co solid solution, Co3B, M23C6 and etc. The interlayers and wear-resisting layer also contain new hard phases as WC, W2C. The microhardness of the gradient coating was increased to 3 times as compared with that of the 20CrMnTi substrate. The wear resistance of the gradient composite coating and 20CrMnTi cemented quenching sample was enhanced to 36.4 and 15.9 times as compared with that of the 20CrMnTi.

  10. Martensitic transition, inverse magnetocaloric effect and shape memory characteristics in Mn{sub 48−x}Cu{sub x}Ni{sub 42}Sn{sub 10} Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Changqin [Department of Physics, Shanghai University, Shanghai 200444 (China); Li, Zhe [Reasearch center for magnetic materials and devices & Key Laboratory for Advanced Functional and Low Dimensional Materials of Yunnan Higher Education Institute, Qujing Normal University, Qujing 655011 (China); Zhang, Yuanlei [Department of Physics, Shanghai University, Shanghai 200444 (China); Reasearch center for magnetic materials and devices & Key Laboratory for Advanced Functional and Low Dimensional Materials of Yunnan Higher Education Institute, Qujing Normal University, Qujing 655011 (China); Liu, Yang; Sun, Junkun; Huang, Yinsheng; Kang, Baojuan [Department of Physics, Shanghai University, Shanghai 200444 (China); Xu, Kun [Reasearch center for magnetic materials and devices & Key Laboratory for Advanced Functional and Low Dimensional Materials of Yunnan Higher Education Institute, Qujing Normal University, Qujing 655011 (China); Deng, Dongmei [Department of Physics, Shanghai University, Shanghai 200444 (China); Jing, Chao, E-mail: cjing@staff.shu.edu.cn [Department of Physics, Shanghai University, Shanghai 200444 (China)

    2017-03-01

    In this paper, we have systematically prepared a serials of polycrystalline Mn{sub 48−x}Cu{sub x}Ni{sub 42}Sn{sub 10} alloys (x=0, 1, 3, 5, 6, 8, 10 and 12) and investigated the influence of the Cu doping on martensitic transition (MT) as well as magnetic properties. Experimental results indicate that the MT temperature and the martensite Curie temperature (T{sub c}{sup M}) shift to high temperature with increasing the substitution of Cu (from Mn rich alloy to Ni rich alloy), while the austenite Curie temperature (T{sub c}{sup A}) is almost unchanged. It was found that the structures undergo L2{sub 1} and 4O with the increasing of Cu concentration near room temperature. Therefore, the magnetostructural transition can be tuned by appropriate Cu doping in these alloys. Moreover, we mainly studied the multiple functional properties for inverse magnetocaloric effect and shape memory characteristics associated with the martensitic transition. A large positive isothermal entropy change of Mn{sub 48}Ni{sub 42}Sn{sub 10} was obtained, and the maximum transition entropy change achieves about 48 J/kg K as x=8. In addition, a considerable temperature-induced spontaneous strain with the value of 0.16% was obtained for Mn{sub 48}Ni{sub 42}Sn{sub 10} alloys.

  11. Corrosion Resistance of The Bearing Steel 67SiMnCr6-6-4 with Nanobainitic Structure

    Directory of Open Access Journals (Sweden)

    Skołek E.

    2015-04-01

    Full Text Available The paper describes a comparative study of the corrosion resistance of bearing steel 67SiMnCr6-6-4 after two kinds of nanostructuring treatments and two kinds of conventional quenching and tempering treatments. The nanostructuring treatment consisted of austempering with an isothermal quenching at 240°C and 300°C. The conventional heat treatment consisted on quenching and tempering at 350°C for 1 h and quenching and tempering at 550°C for 1 h. Time and temperature of tempering was chosen so that the hardness of both samples (nanostructured as well as quenched and tempered was similar. The microstructure of steel after each heat treatment was described with the use of transmission electron microscopy (TEM. It was shown, that the austempering conducted at 240°C produced homogenous nanobainitic structure consisting of carbide-free bainite plates with nanometric thickness separated by the layers of retained austenite. The austempering at 300°C produced a sub-micrometric carbide-free bainite with retained austenite in form of layers and small blocks. The conventional heat treatments led to a tempered martensite microstructure. The corrosion resistance study was carried out in Na2SO4 acidic and neutral environment using potentiodynamic and electrochemical impedance spectroscopy (EIS methods. The corrosion resistance of nanostructured steel samples were compared to the steel samples with tempered martensite. The obtained results indicate, that the corrosion resistance of bearing steel with nanobainitic structure is similar to steel with tempered martensite in both acidic and neutral environment. This means that the high density of intercrystalline boundaries in nanobinite does not deteriorate the corrosion properties of the bearing steel.

  12. New aspects of magnetocaloric effect in NiMn{sub 0.89}Cr{sub 0.11}Ge

    Energy Technology Data Exchange (ETDEWEB)

    Jaworska-Gołąb, T., E-mail: teresa.jaworska-golab@uj.edu.pl [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Baran, S. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Duraj, R. [Institute of Physics, Cracow University of Technology, Podchorążych 1, 30-084 Kraków (Poland); Marzec, M. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland); Dyakonov, V. [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warszawa (Poland); A.A. Galkin Donetsk Physico-Technical Institute, 83-114 Donetsk (Ukraine); Sivachenko, A. [A.A. Galkin Donetsk Physico-Technical Institute, 83-114 Donetsk (Ukraine); Tyvanchuk, Yu. [Chemistry Department, Ivan Franko National University of Lviv, 79-005 Lviv (Ukraine); Szymczak, H. [Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, 02-668 Warszawa (Poland); Szytuła, A. [Institute of Physics, Jagiellonian University, Łojasiewicza 11, 30-348 Kraków (Poland)

    2015-07-01

    Investigations of structural and magnetic phase transitions in the NiMn{sub 0.89}Cr{sub 0.11}Ge half-Heusler alloy were carried out by DSC, XRD (80–400 K), magnetic susceptibility and magnetization (1.9–400 K, magnetic field up to 9.0 T, pressure up to 5.25 kbar) measurements. At high temperatures the sample is a single phase crystallizing in the hexagonal crystal structure (Ni{sub 2}In-type, space group P6{sub 3}/mmc) while below 260 K, down to 100 K, some amount of the hexagonal phase coexists with the orthorhombic (TiNiSi-type, space group Pnma) one. Strong magnetostructural coupling is observed. Magnetic data indicate that with increasing temperature magnetic properties of the sample change from antiferro- to ferro- and then to paramagnetic ones. The latter magnetic phase transition is associated with the crystal structure change and results in large magnetic entropy change equal to −51 J/kg K at μ{sub 0}H= 9.0 T near 260 K. Application of external pressure shifts T{sub C} towards lower temperatures. - Highlights: • # Pnma below 210 K, # P6{sub 3}/mmc above 260 K, for 210 K

  13. High-Strength Ultra-Fine-Grained Hypereutectic Al-Si-Fe-X (X = Cr, Mn Alloys Prepared by Short-Term Mechanical Alloying and Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Filip Průša

    2016-11-01

    Full Text Available In this work, Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn (wt % alloys were prepared by a combination of short-term mechanical alloying and spark plasma sintering. The microstructure was composed of homogeneously dispersed intermetallic particles forming composite-like structures. X-ray diffraction analysis and TEM + EDS analysis determined that the α-Al along with α-Al15(Fe,Cr3Si2 or α-Al15(Fe,Mn3Si2 phases were present, with dimensions below 130 nm. The highest hardness of 380 ± 7 HV5 was observed for the Al-20Si-10Fe-6Mn alloy, exceeding the hardness of the reference as-cast Al-12Si-1Cu-1 Mg-1Ni alloy (121 ± 2 HV5 by nearly a factor of three. Both of the prepared alloys showed exceptional thermal stability with the hardness remaining almost the same even after 100 h of annealing at 400 °C. Additionally, the compressive strengths of the Al-20Si-10Fe-6Cr and Al-20Si-10Fe-6Mn alloys reached 869 MPa and 887 MPa, respectively, and had virtually the same values of 870 MPa and 865 MPa, respectively, even after 100 h of annealing. More importantly, the alloys showed an increase in ductility at 400 °C, reaching several tens of percent. Thus, both of the investigated alloys showed better mechanical properties, including superior hardness, compressive strength and thermal stability, as compared to the reference Al-10Si-1Cu-1Mg-1Ni alloy, which softened remarkably, reducing its hardness by almost 50% to 63 ± 8 HV5.

  14. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    OpenAIRE

    Marafatto F. F.; Petrini R.; Pinzino C.; Pezzetta E.; Slejko F.; Lutman A.

    2013-01-01

    Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR), in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI) source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III) and coupled Cr(III)...

  15. Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals

    Science.gov (United States)

    Sangeetha, N. S.; Smetana, V.; Mudring, A.-V.; Johnston, D. C.

    2018-01-01

    Crystals of SrMn2Sb2 and BaMn2Sb2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity Cp, and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M (H ) isotherm measurements. SrMn2Sb2 adopts the trigonal CaAl2Si2 -type structure, whereas BaMn2Sb2 crystallizes in the tetragonal ThCr2Si2 -type structure. The ρ (T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn2Sb2 and 0.16 eV for BaMn2Sb2 . The χ (T ) and Cp(T ) data reveal antiferromagnetic (AFM) ordering at TN = 110 K for SrMn2Sb2 and 450 K for BaMn2Sb2 . The anisotropic χ (T ≤TN) data also show that the ordered moments in SrMn2Sb2 are aligned in the hexagonal a b plane, whereas the ordered moments in BaMn2Sb2 are aligned collinearly along the tetragonal c axis. The a b -plane M (H ) data for SrMn2Sb2 exhibit a continuous metamagnetic transition at low fields 0 literature for Mn pnictides with the CaAl2Si2 and ThCr2Si2 crystal structures show that the TN values for the CaAl2Si2 -type compounds are much smaller than those for the ThCr2Si2 -type materials.

  16. Temperature dependence of local structural changes around transition metal centers Cr3+ and Mn2+ in RAl3(BO3)4 crystals studied by EMR

    Science.gov (United States)

    Açıkgöz, Muhammed; Rudowicz, Czesław; Gnutek, Paweł

    2017-11-01

    Theoretical investigations are carried out to determine the temperature dependence of the local structural parameters of Cr3+ and Mn2+ ions doped into RAl3(BO3)4 (RAB, R = Y, Eu, Tm) crystals. The zero-field splitting (ZFS) parameters (ZFSPs) obtained from the spin Hamiltonian (SH) analysis of EMR (EPR) spectra serve for fine-tuning the theoretically predicted ZFSPs obtained using the semi-empirical superposition model (SPM). The SPM analysis enables to determine the local structure changes around Cr3+ and Mn2+ centers in RAB crystals and explain the observed temperature dependence of the ZFSPs. The local monoclinic C2 site symmetry of all Al sites in YAB necessitates consideration of one non-zero monoclinic ZFSP (in the Stevens notation, b21) for Cr3+ ions. However, the experimental second-rank ZFSPs (D =b20 , E = 1 / 3b22) were expressed in a nominal principal axis system. To provide additional insight into low symmetry aspects, the distortions (ligand's distances ΔRi and angular distortions Δθi) have been varied while preserving monoclinic site symmetry, in such way as to obtain the calculated values (D, E) close to the experimental ones, while keeping b21 close to zero. This procedure yields good matching of the calculated ZFSPs and the experimental ones, and enables determination of the corresponding local distortions. The present results may be useful in future studies aimed at technological applications of the Huntite-type borates with the formula RM3(BO3)4. The model parameters determined here may be utilized for ZFSP calculations for Cr3+ and Mn2+ ions at octahedral sites in single-molecule magnets and single-chain magnets.

  17. ⁵³Mn-⁵³Cr and ²⁶Al-²⁶Mg ages of a feldspathic lithology in polymict ureilites

    Energy Technology Data Exchange (ETDEWEB)

    Goodrich, Cyrena Anne [Planetary Science Institute. Tucson, AZ (United States); Hutcheon, Ian D. [Glenn T. Seaborg Institute. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kita, Noriko T. [Dept. of Geoscience. Univ. of Wisconsin, Madison, WI (United States); Huss, Gary R. [NASA Marshall Space Flight Center (MSFC), Huntsville, AL (United States); Cohen, Barbara Anne [Hawaii Institute of Geophysics and Planetology. Univ. of Hawaii, Honolulu, HI (United States); Keil, Klaus

    2010-07-01

    We report 53Mn–53Cr and 26Al–26Mg isotopic data, obtained by in-situ SIMS analysis, for feldspathic clasts in polymict ureilites DaG 319 and DaG 165. The analyzed clasts belong to the “albitic lithology,” the most abundant population of indigenous feldspathic materials in polymict ureilites, and are highly fractionated igneous assemblages of albitic plagioclase, Fe-rich pyroxenes, phosphates, ilmenite, silica, and Fe(Mn, K, P, Ti)-enriched glass. Glass in DaG 165 clast 19 has extremely high and variable 55Mn/52Cr ratios (500–58,000) and shows correlated 53Cr excesses up to ~ 1500‰, clearly indicating the presence of live 53Mn at the time of formation. The slope of the well-correlated isochron defined by glass and pyroxenes from this clast corresponds to (53Mn/55Mn) = (2.84 ± 0.10) × 10-6 (2σ). Data for less 55Mn/52Cr-enriched glasses from DaG 319 clast B1, as well as phosphates from several other clasts, are consistent with this isochron. The 53Mn/55Mn ratio obtained from the isochron implies that these clasts are 0.70 ± 0.18 Ma younger than the D'Orbigny angrite, corresponding to the absolute age of 4563.72 ± 0.22 Ma. Plagioclase in DaG 319 clast B1 has a fairly constant 27Al/24Mg ratio of ~ 900 and shows resolvable 26Mg excesses of ~ 2‰. The slope of the isochron defined by pyroxene and plagioclase in this clast is (3.0 ± 1.1) × 10-7 (2σ), corresponding to a time difference of 5.4 (-0.3/+0.5) Ma after CAI (assuming the canonical initial 26Al/27Al ratio of 5 × 10-5) and an age 0.5 (-0.3/+0.5) Ma younger than D'Orbigny. Its absolute age (relative to D'Orbigny) is 4563.9 (+ 0.4/-0.5) Ma, in agreement with the 53Mn–53Cr age from clast 19. These data provide the first

  18. Structural, electrical and magnetic phase evolution of Cr substituted GdMn{sub 1−x}Cr{sub x}O{sub 3} (0 ⩽ x ⩽ 0.2) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Modi, Anchit, E-mail: anchitmodi87@gmail.com; Gaur, N.K.

    2015-09-25

    Highlights: • GdMn{sub 1−x}Cr{sub x}O{sub 3} (0 ⩽ x ⩽ 0.2) synthesized via a solid state reaction route. • Rietveld refinements of high quality powder XRD show good convergences. • Samples show the semiconducting behavior and fits well with VRH and SPH model. • Magnetization study shows that all samples show weak ferromagnetic nature. - Abstract: A series of GdMn{sub 1−x}Cr{sub x}O{sub 3} (0 ⩽ x ⩽ 0.2) have been synthesized by the conventional solid state reaction method mainly to understand the response of Cr substitution on structural, microstructural, magnetic and electrical transport properties. The X-ray diffraction shows that all samples crystallize with orthorhombic perovskite type symmetry with Pbnm space group. The room temperature Raman spectroscopy shows the reduction of Raman shift as doping concentration increase that related to anti-symmetric Jahn Teller stretching mode and symmetric-stretching mode. The temperature dependence of electrical resistivity show the semiconducting nature of these compounds and support the small polaron hoping model (SPH) and variable range hopping conduction model (VRH). The calculated hopping distance and activation energy increased as rate of Cr content increased whereas density of state at Fermi level decreased. The temperature dependence of magnetization presents that under the zero field cooling (ZFC) mode as doping concentration increases the net magnetization reverses its nature below irreversibility temperature. The magnetization results show that all samples show weak ferromagnetic nature that can further be improved with increasing Cr ions concentration.

  19. Low cost fabrication of sheet structure using a new beta titanium alloy, Ti-15V-3Cr-3Al-3Sn

    Science.gov (United States)

    Kaneko, R. S.; Davis, G. W.; Woods, C. A.; Royster, D. M.

    1982-01-01

    Development efforts have been undertaken to improve the processing and structural efficiencies of advanced cold-formable beta Ti alloys, using the standard, hot-formed and rivetted construction of Ti-6Al-4V sheet structures as a basis for comparison. Ti-15V-3Cr-3Al-3Sn (Ti-15-3) beta alloy is formable, brazable and weldable in the solution-treated condition, and after aging displays mechanical properties suitable for postulated service in the -65 to 600 F temperature range. A novel methodology using cold-formed Ti-15-3 stringers and Ti-6Al-4V face sheets that are joined by means of an out-of-furnace isothermal brazing process, followed by low temperature aging, can reduce production costs by as much as 28 per cent. Structural efficiency has been demonstrated in room and elevated temperature crippling tests of small skin-stringer assemblies.

  20. EPR spectroscopy of a family of Cr(III) 7M(II) (M = Cd, Zn, Mn, Ni) "wheels": studies of isostructural compounds with different spin ground states.

    Science.gov (United States)

    Piligkos, Stergios; Weihe, Høgni; Bill, Eckhard; Neese, Frank; El Mkami, Hassane; Smith, Graham M; Collison, David; Rajaraman, Gopalan; Timco, Grigore A; Winpenny, Richard E P; McInnes, Eric J L

    2009-01-01

    Spinning wheels: The presented highly resolved multifrequency continuous wave EPR spectra (e.g., see figure) of the heterooctametalic "wheels" Cr(7)M provide rare examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excited spin states is observed.We present highly resolved multifrequency (X-, K-, Q- and W-band) continous wave EPR spectra of the heterooctametalic "wheels", [(CH(3))(2)NH(2)][Cr(III) (7)M(II)F(8)((CH(3))(3)CCOO)(16)], hereafter Cr(7)M, where M=Cd, Zn, Mn, and Ni. These experimental spectra provide rare examples of high nuclearity polymetallic systems where detailed information on the spin-Hamiltonian parameters of the ground and excited spin states is observed. We interpret the EPR spectra by use of restricted size effective subspaces obtained by the rigorous solution of spin-Hamiltonians of dimension up to 10(5) by use of the Davidson algorithm. We show that transferability of spin-Hamiltonian parameters across complexes of the Cr(7)M family is possible and that the spin-Hamiltonian parameters of Cr(7)M do not have sharply defined values, but are rather distributed around a mean value.

  1. Possibility of martensite transition in Pt–Y–Ga (Y=Cr, Mn, and Fe) system: An ab-initio calculation of the bulk mechanical, electronic and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Tufan [HBNI, Raja Ramanna Centre for Advanced Technology, Indore - 452013 (India); Chakrabarti, Aparna, E-mail: aparnachakrabarti@gmail.com [HBNI, Raja Ramanna Centre for Advanced Technology, Indore - 452013 (India); ISUD,Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

    2016-03-01

    Using first principles calculations based on density functional theory we have studied the effects of Fe and Cr doping at the Mn site on mechanical, electronic, and magnetic properties of Pt{sub 2}MnGa and Ni{sub 2}MnGa. We predict on the basis of formation energy that all the substituted X{sub 2}Mn{sub 1−x}Y{sub x}Ga alloys (x=0.00, 0.25, 0.75, 1.00; X=Pt, Ni; Y=Fe and Cr) are stable materials. Further, all the substituted materials which we have studied here are likely to undergo martensite transition. In this work, we have reported how the stability of the austenite and martensite phase varies with the extent of substitution by Fe as well as Cr at the Mn site. Further, we study the bulk mechanical properties of the austenite and martensite phases of the stoichiometric systems only. We observe that Pt-based systems are inherently much less brittle in comparison to the Ni-based systems studied here. We also study the magnetic properties. Interestingly, contrary to the unsubstituted case as well as the case when Mn is substituted by Fe, the substitution by Cr at the Mn site leads to lowering of energy in case of an intra-sublattice anti-ferromagnetic configuration compared to the ferromagnetic configuration. - Highlights: • Effect of substitution of Mn by Fe and Cr in Ni{sub 2}MnGa, Pt{sub 2}MnGa has been studied. • We predict stable martensitic phases of Pt{sub 2}FeGa, Pt{sub 2}CrGa and Ni{sub 2}CrGa. • We predict that Pt{sub 2}FeGa is inherently the least brittle one among all the materials. • Trend of martensitic transition temperature as a function of substitution has been studied. • We predict Cr substitution at Mn site leads to intra-sublattice antiferromagnetism.

  2. Air oxidation of a Mn-Cr austenitic steel of potential use for fusion reactor structural applications between 1073 and 1473 K at 10 sup 5 Pa

    Energy Technology Data Exchange (ETDEWEB)

    Nanni, P. (Genoa Univ. (Italy). Ist. di Chimica); Buscaglia, V.; Battilana, G. (Consiglio Nazionale delle Ricerche, Genoa (Italy). ICFAM); Ruedl, E. (Commission of the European Communities, Ispra (Italy). Inst. for Advanced Materials)

    Oxidation tests have been conducted with samples of the Mn-Cr austenitic steel AMCR 0033 to evaluate the behaviour of this material in a fusion reactor in the case of abnormal heating. The tests were carried out in dry air at 1073 and 1273 K up to 20 h and at 1473 K up to 5 h. It was found that the initial experimental conditions strongly influence the oxidation. Slow heating to the test temperature in a moderate vacuum leads to the formation of thin scales which define the oxidation, whereas quick temperature increases in a high vacuum cause preferential Mn evaporation which is probably responsable for the slow kinetics. For longer air exposures the oxidation processes are determined more by thermodynamics than by kinetics. (orig.).

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

    Science.gov (United States)

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

    2014-01-01

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

  4. Synthesize and microstructure characterization of Ni{sub 43}Mn{sub 41}Co{sub 5}Sn{sub 11} Heusler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Elwindari, Nastiti; Manaf, Azwar, E-mail: azwar@ui.ac.id [Physics Department, Faculty of Science, Universitas Indonesia, Depok 16424 (Indonesia)

    2016-06-17

    The ferromagnetic heusler alloys are promising materials in many technical applications due to their multifunctional properties such as shape memory effect, magnetocaloric effect, giant magnetoresistance, etc. In this work, synthesize and characterization of polycrystalline Ni{sub 43}Mn{sub 41}Co{sub 5}Sn{sub 11} (NMCS) alloy are reported. Alloy preparation was conducted by melting the constitute elements under an innert Argon (Ar) atmosphere in a vacuum mini arc-melting furnace. Homogenization of the microstructure of the as-cast ingot was obtained after annealing process at 750°C for 48 hours. It is shown that the dendrites structure has changed to equaixed grains morphology after homogenization. Microstructure characteristics of material by x-ray diffraction revealed that the alloy has a L{sub 21}-type cubic crystal structure as the main phase at room temperature. In order to induce the shape anisotropy, a forging treatment was applied to show the shape orientation of material. Various enhancements of magnetic properties in a longitudinal direction were observed at various degree of anisotropy. The microstructure changes of as-cast NMCS and effects of homogenization treatments as studied by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) are discussed in details.

  5. Magnetic field dependence of electrical resistivity and thermopower in Ni{sub 50}Mn{sub 37}Sn{sub 13} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Maheswar Repaka, D. V.; Chen, X.; Ramanujan, R. V., E-mail: ramanujan@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 639798 (Singapore); Mahendiran, R., E-mail: phyrm@nus.edu.sg [Department of Physics, Faculty of Science, National University of Singapore, 117551 (Singapore)

    2015-09-15

    We report magnetization, magnetoresistance (MR) and magnetothermopower (MTEP) of melt spun Ni{sub 50}Mn{sub 37}Sn{sub 13} ribbons which exhibit an austentite to martensite phase transition at a temperature (T{sub M}) ≈ 294 K. Upon cooling from 400 K, dc-resistivity and thermopower show abrupt changes at T{sub M}, indicating a change in the electronic density of states. The thermopower is negative from 400 K down to 10 K. Application of a magnetic field of μ{sub 0}H = 5 T decreases T{sub M} by 5 K and induces large negative MR (-23%) but positive MTEP (9%) near T{sub M}. While the MR is appreciable from T{sub M} down to 10 K, MTEP is significant only below 60 K (MR = -2.5% and MTEP = +300% at 10 K). The magnetic field dependence of resistivity and thermopower show either reversible or irreversible behavior near T{sub M}, depending on whether the sample is zero-field cooled or field-cooled, which indicates that the electronic band structure near T{sub M} is magnetic history dependent.

  6. Evaluation of the heavy metals Cr, Mn, Fe, Cu, Zn and Pb in water penny wort (Hydrocotyle ranunculoides) from the upper course of the Lerma River, Mexico; Evaluacion de los metales pesados Cr, Mn, Fe, Cu, Zn y Pb en sombrerillo de agua (Hydrocotyle ranunculoides) del curso alto del Rio Lerma, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Zarazua, G.; Avila P, P.; Tejeda, S. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Valdivia B, M.; Macedo M, G. [Instituto Tecnologico de Toluca, Av. Tecnologico s/n, Ex-Rancho La Virgen, 52140 Metepec, Estado de Mexico (Mexico); Zepeda G, C., E-mail: graciela.zarazua@inin.gob.mx [Universidad Autonoma del Estado de Mexico, Cerro de Coatepec s/n, Ciudad Universitaria, 50100 Toluca, Estado de Mexico (Mexico)

    2013-07-01

    The Lerma river is one of the most polluted water bodies in Mexico, it presents low biodiversity and lets grow up aquatic plants resistant to the pollution. The aim of this work was to evaluate the concentration and bioaccumulation factors of Cr, Mn, Fe, Cu, Zn and Pb in aerial and submerged structures of water penny wort (Hydrocotyle ranunculoides) from the upper course of the Lerma river. Inductively coupled plasma-optical emission spectrometry was used to determine the concentration of heavy metals in water and H. ranunculoides. Results show that the bioaccumulation factors of Fe and Zn were higher than those of Cu, Mn, Cr and Pb; with the exception of Zn, bioaccumulation factors were higher in the submerged structures of the plant, which shows low mobility of analyzed metals. As a result of this study H. ranunculoides can be considered as good indicator of metal pollution in water bodies. (Author)

  7. Drinking water interlaboratory ring test. Part IV. Results of some cationic analytes. Al, Zn, Cd, Cr, Pb, Ni, Mn, Fe, Cu and V; Circuito interlaboratorio Unichim sulle acque potabili. Parte IV. Risultati di alcuni cationi metallici. Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V

    Energy Technology Data Exchange (ETDEWEB)

    Cavaterra, E.; Divo, C.; Bottazzini, N. [Unichim, Milan (Italy); Alava, F. [Bergamo Ambiente e Servizi, Bergamo (Italy); Bettinelli, M. [Electric Power Production Company, Piacenza (Italy); Bonfiglioli, F. [Azienda Mediterranea Gas e Acqua SpA, Genoa (Italy)

    2002-01-01

    In this paper results of statistical treatment of experimental data obtained in some cycles of an interlaboratory ring test of content of Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu and V in drinking water are reported. Means, variances and parameters of precision and accuracy of some analytical techniques and methods employed by laboratories participating to the ring test will be reported and discussed. [Italian] Nel presente lavoro vengono riportati i risultati dell'elaborazione statistica dei dati sperimentali ottenuti in alcuni cicli del circuito interlaboratorio e relativi ai seguenti cationi metallici: Al, Zn, Cd, Co, Cr, Pb, Ni, Mn, Fe, Cu e V. Vengono riportati e discussi i valori medi e la varianza ed infine i dati di accuratezza e precisione delle tecniche o metodi d'analisi impiegati dai laboratori partecipanti al circuito.

  8. Effect of variable thermal conductivity and specific heat capacity on the calculation of the critical metal hydride thickness for Ti1.1CrMn

    DEFF Research Database (Denmark)

    Mazzucco, Andrea; Rokni, Masoud

    2014-01-01

    model is applied to the metal hydride system, with Ti 1.1 CrMn as the absorbing alloy, to predict the weight fraction of absorbed hydrogen and solid bed temperat ure . Dependencies of thermal conductivity and specific heat capacity upon pressure and hydrogen content respectively , are accounted for...... with activated powder and embedded heat exchanger makes difficult to set up experimental facilities. Trustable simulation models that can address the system ́s performances to a particular design are then a funda mental step to be taken prior any experimental setup. This study considers a detailed 1D fueling...

  9. Decay Data Evaluation Project (DDEP): Updated decay data evaluations for (24)Na, (46)Sc, (51)Cr, (54)Mn, (57)Co, (59)Fe, (88)Y, (198)Au.

    Science.gov (United States)

    Chechev, Valery P; Kuzmenko, Nikolay K

    2016-03-01

    Updated DDEP evaluations have been presented for the decay characteristics of the radionuclides (24)Na, (46)Sc, (51)Cr, (54)Mn, (57)Co, (59)Fe, (88)Y and (198)Au. Previous DDEP evaluations for these radionuclides were published in the BIPM-5 monographie in 2004. The experimental data published during the intervening period of 2004-2014 were taken into account in the current evaluations as well as other information: new compilations, analyses, and corrections. The updated evaluations are compared to previous results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Monte Carlo and Ab-initio calculation of TM (Ti, V, Cr, Mn, Fe, Co, Ni) doped MgH2 hydride: GGA and SIC approximation

    Science.gov (United States)

    Salmani, E.; Laghrissi, A.; Laamouri, R.; Benchafia, E.; Ez-Zahraouy, H.; Benyoussef, A.

    2017-02-01

    MgH2: TM (TM: V, Cr, Mn, Fe, Co, Ni) based dilute magnetic semiconductors (DMS) are investigated using first principle calculations. Our results show that the ferromagnetic state is stable when TM introduces magnetic moments as well as intrinsic carriers in TM: Co, V, Cr, Ti; Mg0.95TM0.05H2. Some of the DMS Ferro magnets under study exhibit a half-metallic behavior, which make them suitable for spintronic applications. The double exchange is shown to be the underlying mechanism responsible for the magnetism of such materials. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with Curie temperatures within the ambient conditions.

  11. The Effect of a Multiphase Microstructure on the Inverse Magnetocaloric Effect in Ni–Mn–Cr–Sn Metamagnetic Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Paweł Czaja

    2017-07-01

    Full Text Available Two Ni–Mn–Sn alloys substituted with 0.5 and 1 at.% Cr have been studied. The first alloy shows an average composition of Ni49.6Mn37.3Cr0.7Sn12.4 (e/a = 8.107, whereas the second has a multiphase microstructure with the matrix phase of an average Ni52.4Mn32.7Cr1Sn14 composition (e/a = 8.146. Both alloys undergo a reversible martensitic phase transformation. The Ni49.6Mn37.3Cr0.7Sn12.4 alloy transforms to the martensite phase at 239 K and, under the magnetic field change of μ0·ΔH = 1.5 T, gives the magnetic entropy change equal to 7.6 J/kg·K. This amounts to a refrigerant capacity in the order of 48.6 J/kg, reducible by 29.8% due to hysteresis loss. On the other hand, the alloy with a multiphase microstructure undergoes the martensitic phase transformation at 223 K with the magnetic entropy change of 1.7 J/kg·K (1 T. Although the latter spreads over a broader temperature window in the multiphase alloy, it gives much smaller refrigerant capacity of 16.2 J/kg when compared to Ni49.6Mn37.3Cr0.7Sn12.4. The average hysteresis loss for a field change of 1.5 T in the multiphase alloy is 2.7 J/kg, reducing the effective refrigerant capacity by 16.7%. These results illustrate that the key to gaining a large effective refrigerant capacity is the synergy between the magnitude of the magnetic entropy change and its broad temperature dependence.

  12. Structural, magnetic and phonon properties of Cr(III)-doped perovskite metal formate framework [(CH{sub 3}){sub 2}NH{sub 2}][Mn(HCOO){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland); Gągor, Anna; Hermanowicz, Krzysztof [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland); Sieradzki, Adam [Department of Experimental Physics, Wrocław University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław (Poland); Macalik, Lucyna; Pikul, Adam [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Box 1410, 50-950 Wrocław 2 (Poland)

    2016-05-15

    We have incorporated Cr(III) into [(CH{sub 3}){sub 2}NH{sub 2}][Mn(HCOO){sub 3}] (DMMn) multiferroic metal organic framework (MOF). The highest concentration of Cr(III) in the synthesized samples reached 15.9 mol%. The obtained samples were characterized by powder and single-crystal X-ray diffraction, DSC, magnetic susceptibility, dielectric, EPR, Raman and IR methods. These methods and the performed chemical analysis revealed that electrical charge neutrality after substitution of Cr(III) for Mn(II) is maintained by partial replacement of dimethylammonium (DMA{sup +}) cations by neutral HCOOH molecules. These changes in the chemical composition are responsible for weakening of the hydrogen bonds and decreased flexibility of the framework. This in turn leads to lowering of the ferroelectric phase transition temperature, observed around 185 K for undoped DMMn and around 155 K for the sample containing 3.1 mol% of Cr(III), and lack of macroscopic phase transition for the samples with Cr(III) content of 8.2 and 15.9 mol %. Another interesting effect observed for the studied samples is pronounced strengthening of the weak ferromagnetism of in Cr(III)-doped samples, associated with slight decrease of the ferromagnetic ordering temperature from 8.5 K for DMMn to 7.0 K for the sample with 15.9 mol % Cr(III) content. - Graphical abstract: Incorporation of Cr(III) into [(CH3)2NH2[Mn(HCOO)3] framework increases the magnetization. - Highlights: • Chromium(III) substitutes for Mn(II) in the studied MOF. • Charge neutrality is maintained by replacing DMA{sup +} cations by neutral HCOOH molecules. • Compounds with 8.2 and 15.9% of Cr(III) show no phase transition above 100 K. • Doping with Cr(III) increases magnetization.

  13. On-Line pre-concentration of Cr(III) and Mn(II) in FI-FAAS: A critical study involving interference effects and analytical use of an immobilized 8-hydroxyquinoline minicolumn

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, C.G.; Pino, F.E.; Campos, V.H. [Depto. de Analisis Instrumental, Facultad de Farmacia, Universidad de Concepcion, P.O. Box 237, Concepcion (Chile); Nobrega, J.A. [Departamento de Quimica, Universidade Federal de Sao Carlos, Caixa Postal 676, 13565-905, Sao Carlos, SP (Brazil)

    2002-09-01

    A flow injection system with a pre-concentration minicolumn based on a chelating resin was coupled to a flame atomic absorption spectrometer. The focus of this work was the investigation of interference effects and the analytical applicability of the azo-immobilized 8-hydroxyquinoline on controlled-pore glass for the determination of Cr and Mn in mussel and non-fat milk powder. All studied concomitants affected the retention of Cr(III). These effects are probably related to the formation of hydroxo-complexes at the optimum pH range 9.0-10. The positive effect caused by Ca(II) was exploited to increase the retention of Cr(III) species and to improve the slope by 70%. The interferences on Mn(II) retention were less severe. The quantification of Cr and Mn was performed by standard additions. The proposed methodology was validated by analysis of three certified reference materials of mussels (Cr and Mn) and non-fat milk powder (Mn) with a mean relative percent error of <6.5% and mean relative standard deviation of <13%. Chromium and Mn were determined in typical Chilean mussels samples, and Mn was determined in non-fat milk powder samples. Results agreed at the 95% confidence level with those obtained by electrothermal atomic absorption spectrometry (ETAAS) using graphite furnace atomization. The method detection limits for a 30 s pre-concentration time were 0.9 and 1.1 {mu}g L{sup -1} for Mn, and 2.2 and 2.5 {mu}g L{sup -1} for Cr in acid digested solutions of mussel and non-fat milk, respectively. The methodology is simple, fast (sampling frequency 60-72 h{sup -1}), reliable, of low cost, and can be applied to the determination of traces of Cr ({>=}0.18 {mu}g g{sup -1}) and Mn ({>=}0.6 {mu}g g{sup -1}) in mussel samples, and Mn ({>=}0.37 {mu}g g{sup -1}) in non-fat milk powder. (orig.)

  14. High pressure synthesis of a hexagonal close-packed phase of the high-entropy alloy CrMnFeCoNi

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Cameron L.; Park, Sulgiye; Rittman, Dylan R.; Zinkle, Steven J.; Bei, Hongbin; Lang, Maik; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-25

    High-entropy alloys, near-equiatomic solid solutions of five or more elements, represent a new strategy for the design of materials with properties superior to those of conventional alloys. However, their phase space remains constrained, with transition metal high-entropy alloys exhibiting only face- or body-centered cubic structures. Here, we report the high-pressure synthesis of a hexagonal close-packed phase of the prototypical high-entropy alloy CrMnFeCoNi. This martensitic transformation begins at 14 GPa and is attributed to suppression of the local magnetic moments, destabilizing the initial fcc structure. Similar to fcc-to-hcp transformations in Al and the noble gases, the transformation is sluggish, occurring over a range of >40 GPa. However, the behaviour of CrMnFeCoNi is unique in that the hcp phase is retained following decompression to ambient pressure, yielding metastable fcc-hcp mixtures. This demonstrates a means of tuning the structures and properties of high-entropy alloys in a manner not achievable by conventional processing techniques.

  15. Zeolitic tuffs for acid mine drainage (AMD) treatment in Ecuador: breakthrough curves for Mn2+, Cd2+, Cr3+, Zn2+, and Al3.

    Science.gov (United States)

    Buenaño, Xavier; Canoira, Laureano; Martin Sánchez, Domingo; Costafreda, Jorge

    2017-03-01

    Zeolitic tuff constitutes a technical and economical feasible alternative to manage acidic waters in initial phases of generation. A study of cation exchange with two zeolitic tuffs from Ecuador and one from Cuba has been conducted using breakthrough curve methodology. Cations Mn2+, Cd2+, Cr3+, Zn2+, and Al3+ have been chosen owing to their presence in underground water in exploration activities (decline development) in Fruta del Norte (Ecuador). Zeolites characterized by X-ray diffraction and thermal stability after heating overnight as heulandites show a similar exchange behavior for the five cations studied. The clinoptilolite sample Tasajeras shows a relevant cation exchange performance expressed in the important increment of spatial time to reach the breakthrough point in comparison with heulandite samples. The maximum length of unused beds was found for Cr3+ and Zn2+ cations showing, therefore, a lower adsorption performance in relation with Mn2+ and Cd2+. A final disposal method of metal-loaded zeolites with cement is proposed.

  16. AlM2B2 (M  =  Cr, Mn, Fe, Co, Ni): a group of nanolaminated materials

    Science.gov (United States)

    Kádas, K.; Iuşan, D.; Hellsvik, J.; Cedervall, J.; Berastegui, P.; Sahlberg, M.; Jansson, U.; Eriksson, O.

    2017-04-01

    Combining theory with experiments, we study the phase stability, elastic properties, electronic structure and hardness of layered ternary borides AlCr2B2, AlMn2B2, AlFe2B2, AlCo2B2, and AlNi2B2. We find that the first three borides of this series are stable phases, while AlCo2B2 and AlNi2B2 are metastable. We show that the elasticity increases in the boride series, and predict that AlCr2B2, AlMn2B2, and AlFe2B2 are more brittle, while AlCo2B2 and AlNi2B2 are more ductile. We propose that the elasticity of AlFe2B2 can be improved by alloying it with cobalt or nickel, or a combination of them. We present evidence that these ternary borides represent nanolaminated systems. Based on SEM measurements, we demonstrate that they exhibit the delamination phenomena, which leads to a reduced hardness compared to transition metal mono- and diborides. We discuss the background of delamination by analyzing chemical bonding and theoretical work of separation in these borides.

  17. Effect of Cryogenic Treatment on Microstructure and Mechanical Properties of 0Cr12Mn5Ni4Mo3Al Steel

    Science.gov (United States)

    Bai, Xue; Zheng, Linbin; Cui, Jinyan; Wu, Sujun; Song, Ruokang; Xie, Di; Wang, Dawei; Li, Haisheng

    2017-10-01

    This paper systematically investigated the effect of cryogenic temperature and soaking time on the 0Cr12Mn5Ni4Mo3Al steel. Microstructure observation and mechanical tests were performed on the specimens by scanning electron microscopy, x-ray diffraction, Vickers hardness tests and tensile tests. Cryogenic treatments were carried out at different temperatures of -73, -120, -160 and -196 °C for a given soaking time of 4 h and at a specific temperature of -73 °C for different soaking time of 8, 12, 21 and 32 h, followed by the subsequent tempering treatment. The results showed that the volume fraction of martensite in this steel has significantly increased and the size of martensite lath has decreased after cryogenic treatment, which leads to the improvement of the mechanical properties of the steel. The cryogenic treatment affected the microstructure by promoting the transformation of retained austenite to martensite and the formation of reversed austenite in the steel. The optimal hardness and strength of this steel were obtained by cryogenic treatment at -73 °C for 8 h. It has been found that the soaking time is a critical parameter for the mechanical properties of 0Cr12Mn5Ni4Mo3Al steel. When the cryogenic temperature is lower than -73 °C, there is no further improvement of the mechanical properties.

  18. Molecular beam epitaxy growth of [CrGe/MnGe/FeGe] superlattices: Toward artificial B20 skyrmion materials with tunable interactions

    Science.gov (United States)

    Ahmed, Adam S.; Esser, Bryan D.; Rowland, James; McComb, David W.; Kawakami, Roland K.

    2017-06-01

    Skyrmions are localized magnetic spin textures whose stability has been shown theoretically to depend on material parameters including bulk Dresselhaus spin orbit coupling (SOC), interfacial Rashba SOC, and magnetic anisotropy. Here, we establish the growth of a new class of artificial skyrmion materials, namely B20 superlattices, where these parameters could be systematically tuned. Specifically, we report the successful growth of B20 superlattices comprised of single crystal thin films of FeGe, MnGe, and CrGe on Si(1 1 1) substrates. Thin films and superlattices are grown by molecular beam epitaxy and are characterized through a combination of reflection high energy electron diffraction, X-ray diffraction, and cross-sectional scanning transmission electron microscopy (STEM). X-ray energy dispersive spectroscopy (XEDS) distinguishes layers by elemental mapping and indicates good interface quality with relatively low levels of intermixing in the [CrGe/MnGe/FeGe] superlattice. This demonstration of epitaxial, single-crystalline B20 superlattices is a significant advance toward tunable skyrmion systems for fundamental scientific studies and applications in magnetic storage and logic.

  19. Health Risk Assessment of Fe, Mn, Cu, Cr in Drinking Water in some Wells and Springs of Shush and Andimeshk, Khuzestan Province, Southern Iran

    Directory of Open Access Journals (Sweden)

    Mohamad Sakizadeh

    2016-02-01

    Full Text Available Background: In the current study,the hazard quotient, the hazard index (HI and spatial variations of Fe,Mn,Cu and Cr in drinking water sources of Andimesk-Shush, Khuzestan Province, Southern Iranaquifer were assessed. Methods: We compared theconcentrations of aforementioned heavy metals in wells and springs inAndimeshk and Shush regions. The non-carcinogenic risk assessment of heavy metals was implemented usingUnited States Environmental Protection Agency (USEPA index.The spatial maps in the area were developed by geostatistical methods. Results: Mean concentrations of heavy metals in groundwater sources of the study area in decreasing order was as follows: Cu >Mn> Fe> Cr. Except for iron,mean heavy metal concentrations were higher than the standard levels. Manganese concentration in 41.5% of the samples exceeded the permissible limits. Copper was higher than the safety limit in 74% of the samples, and chromium in 54% of the cases. The spatial pattern of heavy metals concentrations indicated higher concentrations in the southern parts of the region. The mean hazard quotients of most samples for the four heavy metals were lower than one, indicating that there was no immediate threat due to the exposure to these heavy metals. The calculated accumulated hazards of these heavy metals produced different results, with hazard indices of higher than one. Conclusion: The accumulated hazard indicesfor the evaluated metals were higher than one, indicating that chronic ingestion of these waters threatens the health of local consumers on the long run.

  20. Study of critical behavior in ferromagnetic LaCr{sub 0.3}Mn{sub 0.7}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bora, Tribedi, E-mail: t.bora@nitm.ac.in [Department of Physics, National Institute of Technology Meghalaya, 793003 (India); Ravi, S. [Department of Physics, Indian Institute of Technology Guwahati, 781039 (India)

    2016-11-15

    The critical exponent behavior of LaCr{sub 0.3}Mn{sub 0.7}O{sub 3} compound in the vicinity of ferromagnetic transition was studied by measuring isothermal dc magnetization and by analyzing them in terms of modified Arrott plot method. The critical exponents β, γ and δ corresponding to the spontaneous magnetization, initial magnetic susceptibility and isothermal magnetization with T{sub C}=186 K were determined to be 0.325±0.006, 1.247±0.066 and 4.823±0.004 respectively and are found to be comparable to the values predicted by 3D Ising model. The obtained result is discussed in terms of presence of strong magnetic anisotropy. - Highlights: • We have reported the critical exponent study of LaCr{sub 0.3}Mn{sub 0.7}O{sub 3} compound. • It was analyzed in terms of modified Arrott plot method. • The estimated values of β, γ and δ are found to be close to 3D Ising model values.

  1. The effect of annealing on the transformation and the microstructure of Mn{sub 1−x}Cr{sub x}CoGe alloys

    Energy Technology Data Exchange (ETDEWEB)

    Torrens-Serra, J., E-mail: j.torrens@uib.es [Departament de Física, Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122 Palma de Mallorca (Spain); Biffi, C.A. [Consiglio Nazionale delle Ricerche CNR—IENI, C.so P.Sposi 29, 23900 Lecco (Italy); Santamarta, R. [Departament de Física, Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122 Palma de Mallorca (Spain); Recarte, V.; Pérez-Landazábal, J.I. [Departamento de Física, Universidad Pública de Navarra, Campus de Arrosadía, E-31006 Pamplona (Spain); Tuissi, A. [Consiglio Nazionale delle Ricerche CNR—IENI, C.so P.Sposi 29, 23900 Lecco (Italy); Cesari, E. [Departament de Física, Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122 Palma de Mallorca (Spain)

    2014-07-01

    In this work the effect of different thermal treatments on the transformation behavior of Mn{sub 1−x}Cr{sub x}CoGe alloys, with x = 0.15 and 0.20 has been analyzed. The changes in the transformation temperatures have been studied by differential scanning calorimetry (DSC). The results show that the structural transition temperature depends on the previous annealing. However, under the same heat treatment no significant change is observed on the transformation temperatures when replacing Mn by Cr. The microstructural evolution has been monitored using in-situ X-ray diffraction and transmission electron microscopy. The effect of an applied magnetic field on the transformation has been explored by SQUID magnetometry. Two different magnetic transitions are found: a first order paramagnetic (PM) to ferromagnetic (FM) corresponding to the transformation observed by calorimetry and a re-entrant spin glass to ferromagnetic transition. - Highlights: • The annealing conditions determine the magnetostructural transition. • A laminar microstructure along preferential planes observed by TEM • A RSG to ferromagnetic transition at low temperatures is detected.

  2. High-efficient treatment of wastewater contained the carcinogen naphthylamine by electrochemical oxidation with γ-Al2O3 supported MnO2 and Sb-doped SnO2 catalyst.

    Science.gov (United States)

    Chen, Fengtao; Yu, Sanchuan; Dong, Xiaoping; Zhang, Shishen

    2012-08-15

    1-Naphthylamine wastewater causes severe environmental pollution because of its acute toxicity and carcinogenicity in humans, which makes it difficult to reuse by conventional technologies. In this study, we report an investigation of the electrochemical catalytic oxidation of 1-naphthylamine in synthetic wastewater in a 150 mL electrolytic batch reactor with Ti/Sb-SnO(2)/PbO(2) as anode and steel plate as cathode, where the reaction was assisted by MnO(2) and Sn(1-x)Sb(x)O(2) composite materials as the catalyst and γ-Al(2)O(3) as the carrier (MnO(2)-Sn(1-x)Sb(x)O(2)/γ-Al(2)O(3)). The catalyst was synthesized by impregnating process and was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of pH and current density on the efficiency of the electrochemical degradation process were also studied. It was found that MnO(2)-Sn(1-x)Sb(x)O(2)/γ-Al(2)O(3) exhibited excellent catalytic activity in the electrochemical degradation of 1-naphthylamine wastewater. The results showed that the refractory organics in wastewater can be effectively removed by this process, and a chemical oxygen demand (COD) removal efficiency of 92.2% was obtained in 20 min at pH 7.0 and current density was equal to 50 mA cm(-2). According to the experimental results, a hypothetical mechanism of electrochemical catalytic degradation was also proposed. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Effect of Cr{sub 2}O{sub 3} on the microstructure and non-ohmic properties of (Co, Sb)-doped SnO{sub 2} varistors

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar M, J. A. [Centro de Investigac ion en Materiales Avanzados, S. C., Alianza Norte No. 202, Parque de Investigacion e Innovacion Tecnologica, Nueva Carretera Aeropuerto Km. 10 Apodaca 66600, Nuevo Leon (Mexico); Pech C, M. I. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Monterrey Km. 13, Saltillo 25900, Coahuila (Mexico); Hernandez, M. B.; Rodriguez, E.; Garcia O, L. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon (Mexico); Glot, A. B., E-mail: josue.aguilar@cimav.edu.mx [Universidad Tecnologica de la Mixteca, Division de Estudios de Posgrado, Carretera Acatlima Km. 2.5, Huajuapan de Leon 69000, Oaxaca (Mexico)

    2013-10-01

    The effect of Cr{sub 2}O{sub 3} addition on the physical characteristics, microstructure, and current-voltage properties of (Co-Sb)-doped SnO{sub 2} varistors was investigated. SnO{sub 2}-Co{sub 3}O{sub 4}-Sb{sub 2}O{sub 5} ceramics with additions of 0.0, 0.03, 0.05 and 0.07 mol % Cr{sub 2}O{sub 3} were sintered at 1350 C under ambient atmosphere and characterized micro structurally and electrically. The characterization by X-ray diffraction and scanning electron microscopy show that the microstructure remains as a single phase material with multimodal size distribution of SnO{sub 2} grains. The greatest effect of Cr{sub 2}O{sub 3} additions is manifested in the electric breakdown field. Additions of high levels (0.07 and 0.05 %) of this oxide promote and increase of approximately 55% in this parameter compared to the Cr{sub 2}O{sub 3}-free sample. Another physical property is affected: the measured density values decreases as the Cr{sub 2}O{sub 3} content increases. A change in the nonlinearity coefficient value is produced only at the highest Cr{sub 2}O{sub 3} content while at intermediate levels there is not change at all. Consequently, when seeking high nonlinearity coefficients, intermediate levels of Cr{sub 2}O{sub 3} are not recommended. (Author)

  4. Reaction of hydrogen with the Laves phase (C14) TiCr{sub 1.78-x}Mn{sub x} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Agresti, F. [Universita di Padova, Dipartimento di Ingegneria Meccanica, Settore Materiali and CNISM, via Marzolo 9, 35131 Padova (Italy); Lo Russo, S. [Universita di Padova, Dipartimento di Fisica and CNISM, via Marzolo 8, 35131 Padova (Italy); Maddalena, A.; Principi, G. [Universita di Padova, Dipartimento di Ingegneria Meccanica, Settore Materiali and CNISM, via Marzolo 9, 35131 Padova (Italy); Mazzolai, G. [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Universita Telematica e-Campus, Via Isimbardi 10, Novedrate (Colombia) (Italy); Coluzzi, B.; Biscarini, A. [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Mazzolai, F.M., E-mail: fabio.mazzolai@fisica.unipg.it [Universita di Perugia, Dipartimento di Fisica, Via A. Pascoli 5, 06100 Perugia (Italy); Tuissi, A. [Istituto per l' Energia e le Interfasi, CNR-IENI, C.so Promessi Sposi, 29, Lecco (Italy)

    2009-09-15

    The lattice constants a and c of the as cast hexagonal (C14) Laves phase TiCr{sub 1.78-x}Mn{sub x} (x = 0, 0.4, 0.6 and 0.8) have been measured by X-ray diffraction at room temperature as a function of the Mn content. It has been found that a decreases with increasing x while c remains almost unchanged. Being this alloy interesting as material for solid state hydrogen storage, pressure-composition isotherms have been traced on desorption mode for the H{sub 2} gas pressure and temperature varying from 10 to 0.01 MPa and from 209 to 307 K, respectively. From the temperature dependence of the plateau pressure the molar quantities {Delta}H-bar{sub H{sub 2}} and {Delta}S-bar{sub H{sub 2}} associated with the hydride decomposition have been determined as a function of the Mn content. With increasing x, both {Delta}H-bar{sub H{sub 2}} and {Delta}S-bar{sub H{sub 2}} progressively decrease, and the desorption pressure initially decreases (for x {<=} 0.4) then slightly increases. At the same time, the pseudo-plateaus become flatter.

  5. Electronic structure and half-metallicity in new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn)

    Science.gov (United States)

    Esteki, S.; Ahmadian, F.

    2017-09-01

    First-principles calculations based on density functional theory (DFT) using the self-consistent full-potential linearized augmented plane wave (FPLAPW) method were applied to study the electronic structures and magnetic properties of new Heusler alloys CoYO2 (Y = Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, and Zn). The calculated formation energies of these compounds were negative, therefore, they can be synthesized experimentally. All compounds were stable in ferromagnetic AlCu2Mn-type structure. In AlCu2Mn-type structure, CoScO2, CoFeO2, and CoNiO2 compounds were HM ferromagnets, CoCuO2 was a nearly half-metal, CoZnO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. In CuHg2Ti-type structure, CoTiO2 compound had a nearly HM characteristic, CoVO2 was a spin gapless semiconductor, and other compounds were conventional ferromagnets. The origin of the half-metallic band gap for CoScO2 alloy Heusler alloy was well understood. The total magnetic moments of the three HM compounds obeyed Slater-Pauling rules (Mtot = 22-Ztot and Mtot = 32-Ztot). CoScO2 had the widest region of half-metallicity between the three half-metals indicating its high robustness of half-metallicity with respect to the variation of lattice constants.

  6. Exposure of [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} single-molecule magnets to soft X-rays: The effect of the counterions on radiation stability

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas, E-mail: andreas.helmstedt@uni-bielefeld.de [Fakultaet fuer Physik, Universitaet Bielefeld, Universitaetsstrasse 25, D-33615 Bielefeld (Germany); Sacher, Marc D.; Gryzia, Aaron; Harder, Alexander; Brechling, Armin; Mueller, Norbert; Heinzmann, Ulrich [Fakultaet fuer Physik, Universitaet Bielefeld, Universitaetsstrasse 25, D-33615 Bielefeld (Germany); Hoeke, Veronika; Krickemeyer, Erich; Glaser, Thorsten [Fakultaet fuer Chemie, Universitaet Bielefeld, Universitaetsstrasse 25, D-33615 Bielefeld (Germany); Bouvron, Samuel; Fonin, Mikhail [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, D-78457 Konstanz (Germany)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} single-molecule magnets adsorbed on gold are investigated. Black-Right-Pointing-Pointer The oxidation state of the Mn{sup III} constituents changes under X-ray exposure. Black-Right-Pointing-Pointer The change is monitored by Mn-L{sub 3}-edge XAS. Black-Right-Pointing-Pointer Choice of anions strongly influences radiation stability of the SMM. Black-Right-Pointing-Pointer No influence of the sample morphology on radiation stability could be observed. - Abstract: X-ray absorption spectroscopy studies of the [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} single-molecule magnet deposited as a microcrystalline layer on gold substrates are presented. The oxidation state of the manganese centers changes from Mn{sup III} to Mn{sup II} due to irradiation with soft X-rays. The influence of the charge-neutralizing anions on the stability of [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} against soft X-ray exposure is investigated for the different anions tetraphenylborate (BPh{sub 4}{sup -}), lactate (C{sub 3}H{sub 5}O{sub 3}{sup -}) and perchlorate (ClO{sub 4}{sup -}). The exposure dependence of the radiation-induced reduction process is compared for [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} with the three different anions.

  7. Investigation of multifunctional properties of Mn{sub 50}Ni{sub 40−x}Co{sub x}Sn{sub 10} (x = 0–6) Heusler alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Jyoti; Suresh, K.G., E-mail: suresh@phy.iitb.ac.in

    2015-01-25

    Highlights: • Mn{sub 50}Ni{sub 40−x}Co{sub x}Sn{sub 10} Heusler alloys exhibit multifunctional properties. • Co doping results decrease in martensitic transition temperature and increase in T{sub C}{sup A}. • Ferromagnetic coupling increases with increase in Co concentration. • Large positive ΔS{sub M} of 10.5 J/kg K and large RCP of 125 J/kg was obtained for x = 1. • Large exchange bias field of 833 Oe was observed for Mn{sub 50}Ni{sub 39}Co{sub 1}Sn{sub 10} alloy. - Abstract: A series of Co doped Mn{sub 50}Ni{sub 40−x}Co{sub x}Sn{sub 10} (x = 0, 1, 2, 2.5, 3, 4 and 6) Heusler alloys has been investigated for their structural, magnetic, magnetocaloric and exchange bias properties. The martensitic transition temperatures are found to decrease with the increase in Co concentration due to the decrease in valence electron concentration (e/a ratio). The Curie temperature of austenite phase increases significantly with increasing Co concentration. A large positive magnetic entropy change (ΔS{sub M}) of 8.6 and 10.5 J/kg K, for a magnetic field change of 50 kOe is observed for x = 0 and 1 alloys, and ΔS{sub M} values decreases for higher Co concentrations. The relative cooling power shows a monotonic increase with the increase in Co concentration. Large exchange bias fields of 920 Oe and 833 Oe have been observed in the alloys with compositions x = 0 and 1, after field cooling in presence of 10 kOe. The unidirectional anisotropy arising at the interface between the frustrated and ferromagnetic phases is responsible for the large exchange bias observed in these alloys. With increase in Co, the magnetically frustrated phase diminishes in strength, giving rise to a decrease in the exchange bias effect for larger Co concentration. The exchange bias fields observed for compositions x = 0 and 1, in the present case are larger than that reported for Co doped Ni–Mn–Z (Z = Sn, Sb, and Ga) alloys. Temperature and cooling field dependence of the exchange bias

  8. High-efficient treatment of wastewater contained the carcinogen naphthylamine by electrochemical oxidation with {gamma}-Al{sub 2}O{sub 3} supported MnO{sub 2} and Sb-doped SnO{sub 2} catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Fengtao, E-mail: cft0923@163.com [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Yu, Sanchuan; Dong, Xiaoping; Zhang, Shishen [Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer A method for the electrochemical catalytic oxidation of 1-naphthylamine in synthetic wastewater is elucidated. Black-Right-Pointing-Pointer The novel catalyst, Mn-Sb-Sn/{gamma}-Al{sub 2}O{sub 3}, was prepared and characterized. Black-Right-Pointing-Pointer A fairly satisfactory result (92.2% COD removal rate) was achieved in 20 min at pH 7 under mild conditions. Black-Right-Pointing-Pointer The hypothetical mechanism of electrochemical catalytic oxidation degradation was also proposed. - Abstract: 1-Naphthylamine wastewater causes severe environmental pollution because of its acute toxicity and carcinogenicity in humans, which makes it difficult to reuse by conventional technologies. In this study, we report an investigation of the electrochemical catalytic oxidation of 1-naphthylamine in synthetic wastewater in a 150 mL electrolytic batch reactor with Ti/Sb-SnO{sub 2}/PbO{sub 2} as anode and steel plate as cathode, where the reaction was assisted by MnO{sub 2} and Sn{sub 1-x}Sb{sub x}O{sub 2} composite materials as the catalyst and {gamma}-Al{sub 2}O{sub 3} as the carrier (MnO{sub 2}-Sn{sub 1-x}Sb{sub x}O{sub 2}/{gamma}-Al{sub 2}O{sub 3}). The catalyst was synthesized by impregnating process and was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of pH and current density on the efficiency of the electrochemical degradation process were also studied. It was found that MnO{sub 2}-Sn{sub 1-x}Sb{sub x}O{sub 2}/{gamma}-Al{sub 2}O{sub 3} exhibited excellent catalytic activity in the electrochemical degradation of 1-naphthylamine wastewater. The results showed that the refractory organics in wastewater can be effectively removed by this process, and a chemical oxygen demand (COD) removal efficiency of 92.2% was obtained in 20 min at pH 7.0 and current density was equal to 50 mA cm{sup -2}. According to the experimental results, a hypothetical mechanism of electrochemical catalytic

  9. Study of the analytic quality in the determinations of Cr, Fe, Mn, Cu, Zn, Pb and Hg through conventional and nuclear analytical techniques in mosses of the MATV; Estudio de la calidad analitica en las determinaciones de Cr, Fe, Mn, Cu, Zn, Pb y Hg a traves de tecnicas analiticas nucleares y convencionales en musgos de la ZMVT

    Energy Technology Data Exchange (ETDEWEB)

    Caballero S, B.

    2013-07-01

    To evaluate the environmental risks of air pollution and to facilitate the decision-making for control, is necessary to have the capacity to generate data with analytical quality. A comparison between nuclear (Neutron activation analysis and total reflection X-ray fluorescence spectrometry) and no nuclear analytical techniques (atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry) for simultaneous determination of metal content (Cr, Cu, Fe, Hg, Mn, Pb and Zn) in mosses from Metropolitan Area of the Toluca Valley (MATV) was performed. Epiphytic mosses (Fabriona ciliaris and Leskea angustata) were sampled in two campaigns, 16 sites (urban, transition and natural) and were prepared for each technique. The biological certified reference materials were used for the quality control and to evaluate accuracy, precision, linearity, detection and quantification limits. Results show that nuclear analytical techniques and no nuclear applied in chemical analysis of Cr, Cu, Fe, Hg, Mn, Pb and Zn in moss from MATV are comparable and therefore all of these can potentially be used for this purpose. However, if its considered both, the performance parameters and economic/operational characteristics is widely recommended inductively coupled plasma optical emission spectrometry, conventional analytical technique, which showed the highest analytical grade quality. Also were observed spatial and temporal variations in the concentrations of Cr, Cu, Fe, Hg, Mn, Pb and Zn in mosses from MATV and was discussed its potential origin. The urban sites had the highest concentration of anthropogenic elements as Cr, Cu, Fe, Hg, Pb and Zn because are strongly impacted by roads with high vehicle traffic. (Author)

  10. Influence of Mn contents in 0Cr18Ni10Ti thin wall stainless steel tube on TIG girth weld quality

    Science.gov (United States)

    Liu, Bo

    2017-03-01

    Three kinds of cold worked 0Cr18Ni10Ti thin wall stainless steel tubes with the manganese contents of 1.27%, 1.35% and 1.44% and the cold worked 0Cr18Ni10Ti stainless steel end plug with manganese content of 1.35% were used for TIG girth welding in the present investigation. The effect of different manganese contents in stainless steel tube on weld quality was studied. The results showed that under the same welding conditions, the metallographic performance of the girth weld for the thin wall stainless steel tube with the manganese element content 1.44% welded with end plug was the best. Under the appropriate welding conditions, the quality of the girth weld increased with the increase of the manganese content till 1.44%. It was found that in the case of the Mn content of 1.44%, and under the proper welding condition the welding defects, such as welding cracks were effectively avoided, and the qualified weld penetration can be obtained.. It is concluded that the appropriate increase of the manganese content can significantly improve the TIG girth weld quality of the cold worked 0Cr18Ni10Ti stainless steel tube.

  11. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-09-21

    The UV photolysis of hexanes solutions containing the complexes M(CO)6 (M=Cr, Mo, W) or CpMn(CO)3 (Cp=η5-C5H5) and excess thiophene (T*) (T*=2,5-dimethylthiophene (2,5-Me2T), benzothiophene (BT), and dibenzothiophene (DBT)) produces the η1(S)-T* complexes (CO)5M(η1(S)-T*) 1-8 or Cp(CO)2Mn1(S)-T*)9-11, respectively. However, when T*=DBT, and M=Mo, a mixture of two products result which includes the η1(S)-DBT complex (CO)5Mo(η1(S)-DBT) 4a and the unexpected π-complex (CO)3Mo(η{sup 6}-DBT) 4b as detected by 1H NMR. The liability of the η1(S)-T* ligands is illustrated by the rapid displacement of DBT in the complex (CO)5W(η1(S)-DBT) (1) by THF, and also in the complexes (CO)5Cr1(S)-DBT) (5) and CpMn(CO)21(S)-DBT) (9) by CO (1 atm) at room temperature. Complexes 1-11 have been characterized spectroscopically (1H NMR, IR) and when possible isolated as analytically pure solids (elemental analysis, EIMS). Single crystal, X-ray structural determinations are reported for (Cη)5W(η1(S)-DBT) and Cp(CO)2Mn1(S)-DBT).

  13. Effect of Aged Microstructure on the Strength and Work Hardening Behavior of Ti-15V-3Cr-3Sn-3Al Alloy

    Science.gov (United States)

    Sarkar, Rajdeep; Mukhopadhyay, A.; Ghosal, P.; Nandy, T. K.; Ray, K. K.

    2015-08-01

    This investigation is aimed at revealing the deformation behavior of a β-Ti alloy, namely Ti-15V-3Cr-3Sn-3Al, under various aged conditions with an emphasis on correlating the work hardening characteristics of the alloy with its corresponding microstructure. The alloy was cast, forged, hot rolled, solution treated, and aged differently to generate microstructures with varying amounts and morphologies of α- and β-phases. While microstructural characterization was carried out using scanning and transmission electron microscopy (TEM), tensile tests were conducted to study the work hardening behavior of the alloy. One may infer from the results that the strength of the alloy deteriorates, while the elongation to failure improves with an increase in the aging temperature. The strength of the alloy depends strongly on the amount of α- and the inter-α-spacing. The work hardening behavior of the alloy aged at temperatures below 808 K (535 °C) is markedly different than those aged at higher temperatures. This characteristic behavior has been explained using the deformation signatures in the α-phase revealed by TEM examinations. A stress gradient-based model and a dislocation evolution-type model are found to satisfactorily describe the strength and the work hardening behavior of the alloy aged under different conditions.

  14. Structural and microstructural comparative analysis on metallic alloys of composition Cu{sub y%}-Ni{sub x%}-Me (Me = Sn, Cr, Al, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Marques, I.M.; Okazaki, A.K.; Silveira, C.R. da; Carvalhal, M.A.; Monteiro, W.A.; Carrio, J.A.G. [Physics Department, CCH, Presbyterian Mackenzie University, Materials Science and Technology Centre, Sao Paulo, SP (Brazil); Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail: jgcarrio@mackenzie.br

    2010-07-01

    This work presents a comparative study of microstructural and electrical properties of polycrystalline material Cu-Ni alloys synthesized by conventional and powder metallurgy. A sample of Cu{sub 99,33%} Ni{sub 0,23%} Pt{sub 0,43%} was produced in electric furnace with voltaic arc and various samples containing Al, Sn and Cr as third element were produced by powder metallurgy. The microstructure of the samples was studied by optical microscopy, Vickers micro hardness and x rays powder diffraction. Their electrical conductivity was measured with a milliohmeter Agilent (HP) 4338B. Refinements of the crystalline structure of the samples were performed by the Rietveld method, using the refinement program GSAS. The refinement results and Fourier differences calculations indicate that the copper matrix structure presents not significant distortions by the used amounts of the other metal atoms. The refinement of non structural parameters allowed the micro-structural characterization. The dependence of the micro-structure with thermal and mechanical treatments is studied. (author)

  15. Reaction of tin(iv) phthalocyanine dichloride with decamethylmetallocenes (M = CrII and CoII). Strong magnetic coupling of spins in (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2.

    Science.gov (United States)

    Konarev, Dmitri V; Troyanov, Sergey I; Shestakov, Alexander F; Yudanova, Evgeniya I; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2018-01-23

    The reaction of tin(iv) phthalocyanine dichloride {SnIVCl2(Pc2-)} with decamethylmetallocenes (Cp*2M, M = Co, Cr) has been studied. Decamethylcobaltocene reduces SnIVCl2(Pc2-) to form the (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2 (1) complex. The negative charge of {SnIVCl2(Pc˙3-)}˙- is delocalized over the Pc macrocycle providing the alternation of the C-N(imine) bonds, the appearance of new bands in the NIR range and a strong blue shift of both the Soret and Q-bands in the spectrum of 1. The magnetic moment of 1 is equal to 1.68μB at 300 K, indicating the contribution of one S = 1/2 spin of the Pc˙3- macrocycles. These macrocycles form closely packed double stacks in 1 with effective π-π interactions providing strong antiferromagnetic coupling of spins at a Weiss temperature of -80 K. Decamethylchromocene initially also reduces SnIVCl2(Pc2-) to form the [(Cp*2Cr+){SnVICl2(Pc˙3-)}˙- complex but further reaction between the ions is observed. This reaction is accompanied by the substitution of one Cp* ligand of Cp*2Cr by chloride anions originating from {SnIVCl2(Pc˙3-)}˙- to form the complex {(Cp*CrCl2)(SnIV(μ-Cl)(Pc2-))}·C6H4Cl2 (2) in which the (Cp*CrCl2) and {SnIV(Pc2-)} species are bonded through the μ-bridged Cl- anion. According to the DFT calculations, this reaction proceeds via an intermediate [(Cp*2CrCl)(SnClPc)] complex.

  16. Powder metallurgy and mechanical alloying effects on the formation of thermally induced martensite in an FeMnSiCrNi SMA

    Directory of Open Access Journals (Sweden)

    Pricop Bogdan

    2015-01-01

    Full Text Available By ingot metallurgy (IM, melting, alloying and casting, powder metallurgy (PM, using as-blended elemental powders and mechanical alloying (MA of 50 % of particle volume, three types of FeMnSiCrNi shape memory alloy (SMA specimens were fabricated, respectively. After specimen thickness reduction by hot rolling, solution treatments were applied, at 973 and 1273 K, to thermally induce martensite. The resulting specimens were analysed by X-ray diffraction (XRD and scanning electron microscopy (SEM, in order to reveal the presence of ε (hexagonal close-packed, hcp and α’ (body centred cubic, bcc thermally induced martensites. The reversion of thermally induced martensites, to γ (face centred cubic, fcc austenite, during heating, was confirmed by dynamic mechanical analysis (DMA, which emphasized marked increases of storage modulus and obvious internal friction maxima on DMA thermograms. The results proved that the increase of porosity degree, after PM processing, increased internal friction, while MA enhanced crystallinity degree.

  17. Structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds

    Science.gov (United States)

    Liu, Yangzhen; Xing, Jiandong; Fu, Hanguang; Li, Yefei; Sun, Liang; Lv, Zheng

    2017-08-01

    The properties of sulfides are important in the design of new iron-steel materials. In this study, first-principles calculations were used to estimate the structural stability, mechanical properties, electronic structures and thermal properties of XS (X = Ti, V, Cr, Mn, Fe, Co, Ni) binary compounds. The results reveal that these XS binary compounds are thermodynamically stable, because their formation enthalpy is negative. The elastic constants, Cij, and moduli (B, G, E) were investigated using stress-strain and Voigt-Reuss-Hill approximation, respectively. The sulfide anisotropy was discussed from an anisotropic index and three-dimensional surface contours. The electronic structures reveal that the bonding characteristics of the XS compounds are a mixture of metallic and covalent bonds. Using a quasi-harmonic Debye approximation, the heat capacity at constant pressure and constant volume was estimated. NiS possesses the largest CP and CV of the sulfides.

  18. Cr(III,Mn(II,Fe(III,Co(II,Ni(II,Cu(II and Zn(II Complexes with Diisobutyldithiocarbamato Ligand

    Directory of Open Access Journals (Sweden)

    Mohammad Tarique

    2011-01-01

    Full Text Available The synthesis of sulphur and nitrogen containing dithiocarbamato ligand derived from diisobutylamine as well as its coordination compounds with 3d series transition metals is presented. These synthesized compounds were characterized on the basis of elemental analysis, conductometric measurements and IR spectral studies. The analytical data showed the stoichiometry 1:2 and 1:3 for the compounds of the types ML2 {M=Mn(II, Co(II, Ni(II, Cu(II and Zn(II} and M'L3{M'=Cr(III and Fe(III} respectively. The conductometric measurements proved the non-electrolytic behaviour of all the compounds. The bidentate nature of dithiocarbamato moiety was confirmed on the basis of IR spectral data.

  19. Effect of cooling conditions on the magnetic properties of bainite transformation in an Fe-2%Mn-0.5%Cr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, S. [Department of Physics, Science and Arts Faculty of Kirikkale University, Yahsihan 71450, Kirikkale (Turkey); Akturk, S. [Department of Physics, Science and Arts Faculty of Mugla University, Koetekli, Mugla (Turkey)], E-mail: akturk_selcuk@yahoo.com; Talas, S. [Technical Education Faculty, A. Kocatepe University, A. Karahisar 03200 (Turkey); Aktas, H. [Department of Physics, Science and Arts Faculty of Kirikkale University, Yahsihan 71450, Kirikkale (Turkey)

    2008-11-30

    The effect of cooling conditions on the magnetic properties of bainitic reaction in Fe-2%Mn-0.5%Cr alloy have been investigated using Moessbauer spectroscopy. Results showed that the bainite phase is magnetically ordered and the amount of magnetic bainite increases by decrease in grain size or increase in cooling rate. It is also shown that the retained austenite has paramagnetic behavior. The morphology of the alloy has been analyzed by using scanning electron microscopy (SEM) in heat-treated specimens at different cooling rates. In addition, the bainite start (B{sub s}) and finish (B{sub f}) temperatures and reverse transformation start (A{sub s}) and finish (A{sub f}) temperatures have been investigated by using differential scanning calorimetry (DSC) system for different heat treatment conditions.

  20. A DFT investigation on geometry and chemical bonding of isoelectronic Si8N6V-, Si8N6Cr, and Si8N6Mn+ clusters

    Science.gov (United States)

    Tam, Nguyen Minh; Pham, Hung Tan; Cuong, Ngo Tuan; Tung, Nguyen Thanh

    2017-10-01

    The geometric feature and chemical bonding of isoelectronic systems Si8N6Mq (M = V, Cr, Mn and q = -1, 0, 1, respectively) are investigated by means of density-functional-theory calculations. The encapsulated form is found for all ground-state structures, where the metal atom locates at the central site of the hollow Si8N6 cage. The Si8N6 cage is established by adding two Si atoms to a distorted Si6N6 prism, which is a combination of Si4N2 and Si2N4 strings. Chemical bonding of Si8N6Mq systems is explored by using the electron localization indicator and theory of atom in molecule, revealing the vital role of metal center in stabilizing the clusters.

  1. Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels.

    Science.gov (United States)

    Ha, Heon-Young; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Sangshik

    2017-03-15

    Stress corrosion cracking (SCC) behavior of Ni-free duplex stainless steels containing N and C (Fe balance -19Cr-8Mn-0.25C-(0.03, 0.21)N, in wt %) was investigated by using a slow strain rate test (SSRT) in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal) and perpendicular (transverse) to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis.

  2. Spin-polarized electron gas in Co2MSi/SrTiO3(M= Ti, V, Cr, Mn, and Fe) heterostructures

    KAUST Repository

    Nazir, S.

    2016-06-08

    Spin-polarized density functional theory is used to study the TiO2 terminated interfaces between the magnetic Heusler alloys Co2Si (M = Ti, V, Cr, Mn, and Fe) and the non-polar band insulator SrTiO3. The structural relaxation at the interface turns out to depend systematically on the lattice mis- match. Charge transfer from the Heusler alloys (mainly the M 3d orbitals) to the Ti dxy orbitals of the TiO2 interface layer is found to gradually grow from M = Ti to Fe, resulting in an electron gas with increasing density of spin-polarized charge carriers. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  3. Effect of cold deformation on pitting corrosion of 00Cr18Mn15Mo2N0.86 stainless steel for coronary stent application.

    Science.gov (United States)

    Ren, Yibin; Zhao, Haochuan; Liu, Wenpeng; Yang, Ke

    2016-03-01

    The high nitrogen nickel-free stainless steel has offered an alternative to further improve the performance of the coronary stents, and simultaneously avoids the potential harms of nickel element. Both cold deformation and pitting corrosion are very important for coronary stents made of stainless steel. In this work, the effect of cold deformation on the pitting corrosion resistance of a high nitrogen nickel-free stainless steel (00Cr18Mn15Mo2N0.86) in 0.9% saline solution was investigated. The results showed that the pitting corrosion of the steel was nearly unchanged with increases of the cold deformation up to 50%, indicating that the higher nitrogen content can reduce the negative effect of cold deformation on the pitting corrosion resistance, which is beneficial for the long term service of coronary stents in blood vessel. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Effects of Nitrogen and Tensile Direction on Stress Corrosion Cracking Susceptibility of Ni-Free FeCrMnC-Based Duplex Stainless Steels

    Directory of Open Access Journals (Sweden)

    Heon-Young Ha

    2017-03-01

    Full Text Available Stress corrosion cracking (SCC behavior of Ni-free duplex stainless steels containing N and C (Febalance-19Cr-8Mn-0.25C-(0.03, 0.21N, in wt % was investigated by using a slow strain rate test (SSRT in air and aqueous NaCl solution with different tensile directions, including parallel (longitudinal and perpendicular (transverse to the rolling direction. It was found that alloying N was effective in increasing the resistance to SCC, while it was higher along the longitudinal direction than the transverse direction. The SCC susceptibility of the two alloys was assessed based on the electrochemical resistance to pitting corrosion, the corrosion morphology, and the fractographic analysis.

  5. Succulent species differ substantially in their tolerance and phytoextraction potential when grown in the presence of Cd, Cr, Cu, Mn, Ni, Pb, and Zn.

    Science.gov (United States)

    Zhang, Chengjun; Sale, Peter W G; Clark, Gary J; Liu, Wuxing; Doronila, Augustine I; Kolev, Spas D; Tang, Caixian

    2015-12-01

    Plants for the phytoextraction of heavy metals should have the ability to accumulate high concentrations of such metals and exhibit multiple tolerance traits to cope with adverse conditions such as coexistence of multiple heavy metals, high salinity, and drought which are the characteristics of many contaminated soils. This study compared 14 succulent species for their phytoextraction potential of Cd, Cr, Cu, Mn, Ni, Pb, and Zn. There were species variations in metal tolerance and accumulation. Among the 14 succulent species, an Australian native halophyte Carpobrotus rossii exhibited the highest relative growth rate (20.6-26.6 mg plant(-1) day(-1)) and highest tolerance index (78-93%), whilst Sedum "Autumn Joy" had the lowest relative growth rate (8.3-13.6 mg plant(-1) day(-1)), and Crassula multicava showed the lowest tolerance indices (wetlands.

  6. Efficient carbon dioxide electrolysis with metal nanoparticles loaded La0·75Sr0·25Cr0·5Mn0·5O3-δ cathodes

    Science.gov (United States)

    Zhu, Changli; Hou, Linxi; Li, Shisong; Gan, Lizhen; Xie, Kui

    2017-09-01

    Solid oxide electrolysis cells with La0·75Sr0·25Cr0·5Mn0·5O3-δ (LSCM) cathode can electrolyze CO2 to generate chemical fuels. Nevertheless, the cathode performance is limited by its electrocatalytic activity. In this work, metal nanoparticles including Ni, Cu and NiCu metals are successfully impregnated in LSCM electrode to improve its activity. XRD, XPS, SEM and TEM together confirm the metal nanocatalysts are homogeneously distributed on LSCM backbone and therefore create active electrochemical interface for CO2 splitting. Electrical properties of LSCM with impregnated metal nanoparticles are investigated and correlated to electrode performances. Electrochemical measurements show that the NiCu-LSCM demonstrates the optimum performance without degradation after operation for ∼100 h and ∼10 redox cycles. It is believed that the enhanced performance of CO2 electrolysis may be attributed to the synergetic effect of metal nanocatalyst and LSCM ceramic electrode.

  7. Measurement of (n,2n) cross-sections for Sc, Mn, Cr and In between 12 and 19 MeV with activation technique

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, S.; Win, Than; Matsuyama, S. [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Odano, N.

    1997-03-01

    Activation cross-sections for scandium, manganese, chromium and indium have been measured in the neutron energies from 12 to 19 MeV. Source neutrons were produced via the T(d,n){sup 4}He reaction by bombarding a 3.2-MeV deuteron beam from the Dynamitron accelerator of Fast Neutron Laboratory at Tohoku University. Ten packages of high or ultra-high purity metal foils for chromium and indium, alloy foils for manganese, and oxide powder for scandium were set around the neutron source at 5 cm from the target in the angular range from 0 to 140 deg covering the incident neutron energies from 19 to 12 MeV at the center position of each package. Activation rates of the samples were obtained by the gamma-ray measurements using a high purity germanium detector. Neutron flux at each sample was determined using the activation rates of two niobium foils locating both sides of that sample; the reference reaction was {sup 93}Nb(n,2n){sup 92m}Nb of which cross-section data was taken from the 1991 NEANDC/INDC standard files. The source neutrons distributions have been measured in detail by the time-of-flight technique. The measured cross-sections are the following important dosimetry or activation reactions: {sup 45}Sc(n,2n){sup 44m}Sc, {sup 55}Mn(n,2n){sup 54}Mn, {sup 52}Cr(n,2n){sup 51}Cr, and {sup 115}In(n,2n){sup 114m}In. These cross-sections are compared with available activation file, dosimetry files and previous experimental data. (author)

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

    Directory of Open Access Journals (Sweden)

    Xinxin Dong

    2017-02-01

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

  9. Composition Dependence of Phase Stability, Deformation Mechanisms, and Mechanical Properties of the CoCrFeMnNi High-Entropy Alloy System

    Science.gov (United States)

    Tasan, C. C.; Deng, Y.; Pradeep, K. G.; Yao, M. J.; Springer, H.; Raabe, D.

    2014-10-01

    The proposal of configurational entropy maximization to produce massive solid-solution (SS)-strengthened, single-phase high-entropy alloy (HEA) systems has gained much scientific interest. Although most of this interest focuses on the basic role of configurational entropy in SS formability, setting future research directions also requires the overall property benefits of massive SS strengthening to be carefully investigated. To this end, taking the most promising CoCrFeMnNi HEA system as the starting point, we investigate SS formability, deformation mechanisms, and the achievable mechanical property ranges of different compositions and microstructural states. A comparative assessment of the results with respect to room temperature behavior of binary Fe-Mn alloys reveals only limited benefits of massive SS formation. Nevertheless, the results also clarify that the compositional requirements in this alloy system to stabilize the face-centered cubic (fcc) SS are sufficiently relaxed to allow considering nonequiatomic compositions and exploring improved strength-ductility combinations at reduced alloying costs.

  10. Tunable magnetocaloric effect around room temperature by Fe doping in Mn0.98Cr (0.02 - x)Fex As compound

    Science.gov (United States)

    Ipus, Jhon J.; Ribeiro, Paula O.; von Ranke, P.; Caraballo Vivas, R. J.; Carvalho, Alexandre M. G.; Coelho, Adelino A.; Franco, Victorino; Rocco, Daniel L.

    2017-08-01

    In this work, we present an investigation of the magnetic and magnetocaloric properties of Mn0.98Cr (0.02 - x)Fex As compounds with x = 0.002, 0.005 and 0.010. Our findings show that as Fe content increases the unit cell volume decreases, which indicates that Fe doping emulates the pressure effect on the crystalline structure. The transition temperature TC decreases as x increases and it can be set at approximate value of room temperature by changing the doping level. In addition, the magnetic entropy change ΔSM was determined using a discontinuous measurement protocol, and realistic values from the magnetocaloric effect presented by MnAs-type compounds under pressure (emulated pressure) could be obtained. The values of Δ SMMAX are very large, around -11 Jkg-1K-1 with ΔH = 15 kOe, which is higher than that observed for most compounds with TC around room temperature. However, ΔSM is confined to a narrow temperature range of 11 K. To overcome this drawback, the composition of a theoretical composite formed by our samples was calculated in order to obtain a table-shaped ΔSM curve. The simulated composite showed a high value of full width at half maximum δTFWHM of 33 K, which is much higher than that of single sample.

  11. Apply Woods model in the predictions of ambient air particles and metallic elements (Mn, Fe, Zn, Cr, and Cu) at industrial, suburban/coastal, and residential sampling sites.

    Science.gov (United States)

    Fang, Guor-Cheng; Huang, Ci-Song

    2012-01-01

    The main purpose for this study was to monitor ambient air particles and metallic elements (Mn, Fe, Zn, Cr, and Cu) in total suspended particulates (TSPs) concentration, dry deposition at three characteristic sampling sites of central Taiwan. Additionally, the calculated/measured dry deposition flux ratios of ambient air particles and metallic elements were calculated with Woods models at these three characteristic sampling sites during years of 2009-2010. As for ambient air particles, the results indicated that the Woods model generated the most accurate dry deposition prediction results when particle size was 18 μm in this study. The results also indicated that the Woods model exhibited better dry deposition prediction performance when the particle size was greater than 10 μm for the ambient air metallic elements in this study. Finally, as for Quan-xing sampling site, the main sources were many industrial factories under process around these regions and were severely polluted areas. In addition, the highest average dry deposition for Mn, Fe, Zn, and Cu species occurred at Bei-shi sampling site, and the main sources were the nearby science park, fossil fuel combustion, and Taichung thermal power plant (TTPP). Additionally, as for He-mei sampling site, the main sources were subjected to traffic mobile emissions.

  12. Magnetic interactions in La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Me{sub x}O{sub 3} (Me=Ga, Fe, Cr) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Troyanchuk, I.O., E-mail: troyan@physics.by [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovki str. 19, 220072 Minsk (Belarus); Bushinsky, M.V.; Karpinsky, D.V.; Tereshko, N.V. [Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovki str. 19, 220072 Minsk (Belarus); Dobryansky, V.M. [Belarussian State Agrarian Technical University, Nezavisimosti av. 99, 220023 Minsk (Belarus); Többens, D.M. [Helmholt-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Sikolenko, V. [Helmholt-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation); Efimov, V. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna (Russian Federation)

    2015-11-15

    Magnetic properties and crystal structure of La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}Me{sub x}O{sub 3} (Me=Ga, Fe, Cr; x≤0.3) have been studied by neutron powder diffraction and magnetization measurements. It is shown that substitution of manganese ions by chromium or gallium ions (x=0.3) leads to phase separation into antiferromagnetic and ferromagnetic phases whereas replacement by Fe ions stabilizes spin glass state (x=0.3). Ferromagnetic interactions in Cr-substituted compounds are much more pronounced than in Fe- and Ga-doped ones. Magnetic properties are discussed in the model assuming a dominance of superexchange interactions. It is considered that ferromagnetism in the Cr-substituted compositions is associated with nearly equal contributions from positive and negative components of the superexchange interaction between Mn{sup 3+} and Cr{sup 3+} ions as well as to mixed valence of chromium ions. The spin glass state observed for the Fe-doped sample (x=0.3) is associated with strong antiferromagnetic superexchange between Fe{sup 3+}–O–Fe{sup 3+} and Fe{sup 3+}–O–(Mn{sup 3+}, Mn{sup 4+}). - Highlights: • Magnetic structure of the compounds has been clarified by NPD. • Magnetic properties of the compounds has been explained using superexchange scenario. • Mn–O–Fe and Fe–O–Fe superexchange interactions are strongly antiferromagnetic.

  13. Mathematical modeling of the hot strip rolling of microalloyed Nb, multiply-alloyed Cr-Mo, and plain C-Mn steels

    Energy Technology Data Exchange (ETDEWEB)

    Siciliano, F. Jr.; Jonas, J.J.

    2000-02-01

    Industrial mill logs from seven different hot strip mills (HSMs) were analyzed in order to calculate the mean flow stresses (MFSs) developed in each stand. The schedules were typical of the processing of microalloyed Nb, multiply-alloyed Cr-Mo, and plain C-Mn steels. The calculations, based on the Sims analysis, take into account work roll flattening, redundant strain, and the forward slip ratio. The measured stresses are then compared to the predictions of a model based on an improved Misaka MFS equation, in which solute effects, strain accumulation, and the kinetics of static recrystallization (SRX) and metadynamic recrystallization (MDRX) are fully accounted for. Good agreement between the measured and predicted MFSs is obtained over the whole range of rolling temperatures. The evolution of grain size and the fractional softening are also predicted by the model during all stages of strip rolling. Special attention was paid to the Nb steels, in which the occurrence of Nb(C, N) precipitation strongly influences the rolling behavior, preventing softening between passes. The present study leads to the conclusion that Mn addition retards the strain-induced precipitation of Nb; by contrast, Si addition has an accelerating effect. The critical strain for the onset of dynamic recrystallization (DRX) in Nb steels is derived, and it is shown that the critical strain/peak strain ratio decreases with increasing Nb content; furthermore, Mn and Si have marginal but opposite effects. It is demonstrated that DRX followed by MDRX occurs under most conditions of hot strip rolling; during the initial passes, it is due to high strains, low strain rates, and high temperatures, and, in the final passes, it is a consequence of strain accumulation.

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

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2016-07-01

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

  15. Spin resolved photoelectron spectroscopy of [Mn{sub 6}{sup III}Cr{sup III}]{sup 3+} single-molecule magnets and of manganese compounds as reference layers

    Energy Technology Data Exchange (ETDEWEB)

    Helmstedt, Andreas; Mueller, Norbert; Gryzia, Aaron; Dohmeier, Niklas; Brechling, Armin; Sacher, Marc D; Heinzmann, Ulrich [Fakultaet fuer Physik, Universitaet Bielefeld, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Hoeke, Veronika; Krickemeyer, Erich; Glaser, Thorsten [Fakultaet fuer Chemie, Universitaet Bielefeld, Universitaetsstrasse 25, 33615 Bielefeld (Germany); Bouvron, Samuel; Fonin, Mikhail [Fachbereich Physik, Universitaet Konstanz, Universitaetsstrasse 10, 78457 Konstanz (Germany); Neumann, Manfred, E-mail: andreas.helmstedt@uni-bielefeld.de [Fachbereich Physik, Universitaet Osnabrueck, Barbarastrasse 7, 49069 Osnabrueck (Germany)

    2011-07-06

    Properties of the manganese-based single-molecule magnet [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} are studied. It contains six Mn{sup III} ions arranged in two bowl-shaped trinuclear triplesalen building blocks linked by a hexacyanochromate and exhibits a large spin ground state of S{sub t} = 21/2. The dominant structures in the electron emission spectra of [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} resonantly excited at the L{sub 3}-edge are the L{sub 3}M{sub 2,3}M{sub 2,3}, L{sub 3}M{sub 2,3}V and L{sub 3}VV Auger emission groups following the decay of the primary p{sub 3/2} core hole state. Significant differences of the Auger spectra from intact and degraded [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} show up. First measurements of the electron spin polarization in the L{sub 3}M{sub 2,3}V and L{sub 3}VV Auger emission peaks from the manganese constituents in [Mn{sup III}{sub 6}Cr{sup III}]{sup 3+} resonantly excited at the L{sub 3}-edge near 640 eV by circularly polarized synchrotron radiation are reported. In addition spin resolved Auger electron spectra of the reference substances MnO, Mn{sub 2}O{sub 3} and Mn{sup II}(acetate){sub 2{center_dot}}4H{sub 2}O are given. The applicability of spin resolved electron spectroscopy for characterizing magnetic states of constituent atoms compared to magnetic circular dichroism (MCD) is verified: the spin polarization obtained from Mn{sup II}(acetate){sub 2{center_dot}}4H{sub 2}O at room temperature in the paramagnetic state compares to the MCD asymmetry revealed for a star-shaped molecule with a Mn{sub 4}{sup II}O{sub 6} core at 5 K in an external magnetic field of 5 T.

  16. Determination of rare earth elements and other trace elements (Y, Mn, Co, Cr) in seawater using Tm addition and Mg(OH)₂ co-precipitation.

    Science.gov (United States)

    Freslon, Nicolas; Bayon, Germain; Birot, Dominique; Bollinger, Claire; Barrat, Jean Alix

    2011-07-15

    This paper reports on a novel procedure for determining trace element abundances (REE and Y, Cr, Mn, Co) in seawater by inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The procedure uses a combination of pre-concentration using co-precipitation onto magnesium hydroxides and addition of thulium spike. The validity of the method was assessed onto 25 ml volumes of certified reference materials (NASS- and CASS-4) and in house seawater standard. Procedural blanks were determined by applying the same procedure to aliquots of seawater previously depleted in trace elements by successive Mg(OH)(2) co-precipitations, yielding estimated contributions to the studied samples better than 1.1% for all elements, with the exception of Cr (<3.3%) and Co (up to 8%). The reproducibility of the method over the six month duration of the study was smaller than 11% RSD for all the studied elements. Results obtained for NASS-5 and CASS-4 agree well with published working values for trace elements. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Small angle neutron scattering study of magnetic clustering in (Pr{sub 0.55}Ca{sub 0.45})(Mn{sub 1-y}Cr{sub y})O{sub 3} manganites

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, C., E-mail: carlo.castellano@unimi.it [Universita degli Studi di Milano, Dipartimento di Chimica, Via Golgi 19, 20133 Milano (Italy); Martinelli, A. [CNR-SPIN, C.so Perrone 24, 16152 Genova (Italy); Ferretti, M. [CNR-SPIN, C.so Perrone 24, 16152 Genova (Italy); Universita degli Studi di Genova, Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146 Genova (Italy); Cimberle, M.R. [CNR-IMEM, Via Dodecaneso 33, 16146 Genova (Italy); Mondelli, C. [CNR-IOM-OGG and TOF at Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Genoble Cedex 9 (France)

    2012-11-25

    Highlights: Black-Right-Pointing-Pointer Magnetic clusters formation in (Pr{sub 0.55}Ca{sub 0.45})(Mn{sub 1-y}Cr{sub y})O{sub 3} manganites is pointed out. Black-Right-Pointing-Pointer We indicate that magnetic clusters formation is favoured by Mn/Cr substitution. Black-Right-Pointing-Pointer The importance of magnetic polarons in manganites phase behaviour is thus emphasized. Black-Right-Pointing-Pointer We tune by chemical substitution the weight of the different phase components. Black-Right-Pointing-Pointer Magnetic clusters formation in Mn/Cr substituted manganites results to be softened. - Abstract: In the present paper we report a small angle neutron scattering (SANS) study of magnetic clusters formation in (Pr{sub 0.55}Ca{sub 0.45})(Mn{sub 1-y}Cr{sub y})O{sub 3} (y = 0.00, 0.03, 0.06) manganites which was performed by analyzing, above and below the magnetic phase transitions, the momentum transfer q dependence of the SANS intensity on temperature and on the applied magnetic field 0 < H < 5 T. Thermal scans between 5 and 300 K in zero field, 1 and 5 T as well as isothermal field-scans at three different temperatures were collected in the suitable q range on each sample. These measurements allowed us to determine the spatial dimensions, density and distribution of the non-overlapping ferromagnetic clusters before, during and after their formation, both in the insulating high temperature and in the percolating low temperature phases. Our results indicate that the magnetic clusters formation is favoured by Mn/Cr partial substitution, thus emphasizing the importance of magnetic polarons in the natural tendency of manganites to phase separation and the possibility to tune by chemical substitution the relative weight of one phase component with respect to the other one.

  18. In situ formation of oxygen vacancy in perovskite Sr0.95Ti0.8Nb0.1M0.1O3 (M = Mn, Cr) toward efficient carbon dioxide electrolysis

    Science.gov (United States)

    Zhang, Jun; Xie, Kui; Wei, Haoshan; Qin, Qingqing; Qi, Wentao; Yang, Liming; Ruan, Cong; Wu, Yucheng

    2014-01-01

    In this work, redox-active Mn or Cr is introduced to the B site of redox stable perovskite Sr0.95Ti0.9Nb0.1O3.00 to create oxygen vacancies in situ after reduction for high-temperature CO2 electrolysis. Combined analysis using X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis confirms the change of the chemical formula from oxidized Sr0.95Ti0.9Nb0.1O3.00 to reduced Sr0.95Ti0.9Nb0.1O2.90 for the bare sample. By contrast, a significant concentration of oxygen vacancy is additionally formed in situ for Mn- or Cr-doped samples by reducing the oxidized Sr0.95Ti0.8Nb0.1M0.1O3.00 (M = Mn, Cr) to Sr0.95Ti0.8Nb0.1M0.1O2.85. The ionic conductivities of the Mn- and Cr-doped titanate improve by approximately 2 times higher than bare titanate in an oxidizing atmosphere and 3–6 times higher in a reducing atmosphere at intermediate temperatures. A remarkable chemical accommodation of CO2 molecules is achieved on the surface of the reduced and doped titanate, and the chemical desorption temperature reaches a common carbonate decomposition temperature. The electrical properties of the cathode materials are investigated and correlated with the electrochemical performance of the composite electrodes. Direct CO2 electrolysis at composite cathodes is investigated in solid-oxide electrolyzers. The electrode polarizations and current efficiencies are observed to be significantly improved with the Mn- or Cr-doped titanate cathodes. PMID:25403738

  19. Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03(Ti0.96Sn0.04O3 lead-free piezoelectric ceramics with high Curie temperature

    Directory of Open Access Journals (Sweden)

    Cheng-Che Tsai

    2016-12-01

    Full Text Available In this work, the process of two-stage modifications for (Ba0.97Ca0.03(Ti0.96Sn0.04-xHfxO3 (BCTS4-100xH100x ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC of about 112 °C, a piezoelectric charge constant (d33 of 313 pC/N, an electromechanical coupling factor (kp of 0.49, a mechanical quality factor (Qm of 122, and a remnant polarization (Pr of 19μC/cm2. In addition, the temperature stability of the resonant frequency (fr, kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ∼ 0.39, d33 ∼ 230 pC/N, Qm ∼ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03(Ti0.96Sn0.04O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.

  20. Experimental studies and nuclear model calculations on proton induced reactions on manganese up to 45 MeV with reference to production of (55)Fe, (54)Mn and (51)Cr.

    Science.gov (United States)

    Al-Abyad, M; Spahn, I; Qaim, S M

    2010-12-01

    Excitation functions of the reactions (55)Mn(p,n)(55)Fe, (55)Mn(p,x)(54)Mn and (55)Mn(p,x)(51)Cr were measured from their respective thresholds up to 18 MeV in the first case and up to 45 MeV in the latter two cases, using the conventional stacked-foil technique. The radioactivity of (55)Fe was determined via high resolution X-ray spectrometry and of other radionuclides via high resolution γ-ray spectrometry. Nuclear model calculations were performed using the codes ALICE-IPPE, EMPIRE and TALYS. In some cases, good agreement was found between the experimental and theoretical data while in others considerable deviations were observed. From the experimental data the expected integral yields of the three investigated radionuclides were calculated. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Tuning magneto-structural properties of Ni{sub 44}Co{sub 6}Mn{sub 39}Sn{sub 11} Heusler alloy ribbons by Fe-doping

    Energy Technology Data Exchange (ETDEWEB)

    Wójcik, Anna, E-mail: a.wojcik@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Street, 30-059 Kraków (Poland); Maziarz, Wojciech; Szczerba, Maciej J. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Street, 30-059 Kraków (Poland); Sikora, Marcin [Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Dutkiewicz, Jan [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Street, 30-059 Kraków (Poland); Cesari, Eduard [Departament de Física, Universitat de les Illes Balears, Ctra. De Valldemossa, km 7.5, E-07122 Palma de Mallorca (Spain)

    2016-07-15

    Graphical abstract: - Highlights: • Fe substitution for Ni in Ni{sub 44}Co{sub 6}Mn{sub 39}Sn{sub 11} causes a drastic decrease of M{sub T} temperature. • The type of structure changes with increasing of iron (12M → 10M + L2{sub 1} → L2{sub 1}). • Content of Fe above 1 at.% has a negative influence on magneto-structural properties. - Abstract: Microstructure, martensitic transformation behavior and magnetic properties of Ni{sub 44−x}Fe{sub x}Co{sub 6}Mn{sub 39}Sn{sub 11} (x = 0, 1, 2 at.%) melt spun ribbons have been investigated. The influence of iron addition has been thoroughly studied by means of electron microscopy, X-ray diffraction and vibrating sample magnetometry. The results show that addition of 1 at.% of iron into quaternary Ni–Co–Mn–Sn Heusler alloy drastically decreases the martensitic transformation temperature by more than 100 K. Higher concentration of iron leads to complete suppression of martensitic transition. The structure of samples change from fully martensite (12 M) through mixed austenite-martensite (L2{sub 1} + 10 M) to fully austenite (L2{sub 1}) with increase of iron content. Addition of 1 at.% of iron leads to enhance magnetization of both austenitic and martensitic phases and also a small increase of Curie temperature occurs. The largest change of magnetic entropy under 15 kOe measured 2.9 and 0.65 J kg{sup −1} K{sup −1} for alloys where x = 0 and 1, respectively.

  2. Struktur und Bindung in Übergangsmetall-Fluoriden MIIMeIVF6. Neutronenbeugungs-Strukturuntersuchungen an CaSnF6, FeZrF6, und CrZrF6

    Science.gov (United States)

    Mayer, H. W.; Reinen, D.; Heger, G.

    1983-11-01

    Compounds MIIMe IVF 6 requently undergo phase transitions from the cubic ordered ReO 3 to the trigonal LiSbF 6 structure when lowering the temperature. In case of a strongly Jahn-Teller unstable cation in the MII position additional phases may occur. Results of powder neutron-diffraction studies on CaSnF 6, FeZrF 6, and CrZrF 6 at different temperatures are reported. The high-temperature phases have the space group Fm3 m; the F - ligands are either statistically displaced from the MIIMe IV directions or undergo a strong thermal motion perpendicular to these directions ( ∢M II FMe IV: 165-180°). The thermal ellipsoids of the CrF bonds are strongly indicative of a dynamical Jahn-Teller effect in addition. In the low-temperature phases of CaSnF 6 and FeZrF 6 (space group R overline3) the ∢M II FMe IV is more distinctly bent (⋍155-160°). CrZrF 6 undergoes two reversible phase transitions, which are determined to occur at 415 ± 5 K (cubic → tetragonal, dynamic to static Jahn-Teller distortion of CrF 6 octahedra and 150 ± 10 K (tetragonal → (pseudo)monoclinic).

  3. Optimization of the Arc Spraying Process Parameters of the Fe–Base Mn-Si-Cr-Mo-Ni Coatings for the Best Wear Performance

    Directory of Open Access Journals (Sweden)

    Justinas GARGASAS

    2016-05-01

    Full Text Available In this paper, the use of Fe–base Mn-Si-Cr-Mo-Ni and Fe–base Mn-Si-Cr wires for thermal arc spraying is presented. For this purpose the mechanical and physical properties of coatings were evaluated. The quality of the coating’s was dependent on the selected equipment, spray materials, technological parameters of the spray and spray technology. The aim was to qualify and optimize the parameters for spray coating to get the best coatings properties with good tribological properties. All coatings were deposited on mild steel S235JR substrates. Two experimental cored wires of unique chemical composition – STEIN-MESYFIL 932 V and STEIN-MESYFIL 954 V – were used for thermal arc spraying. The wires of 1.6 mm diameter were used for the surfacing material. Hardness, porosity and oxide measurements were used to verify the spray parameters and analyze the coatings. Rubber wheel test, which is based on the standard ASTM G65, was used. Dry-sand, rubber-wheel procedure according ASTM G65 was used to investigate low stress abrasion, whereas for high stress abrasion investigations a rubber wheel was used. This experiment was carried out by changing the speed of disc friction, travel distance and measuring the mass loss of surface friction. Miller Test according to ASTM G75-95 Standard was carried out in experiment with friction. The samples were immersed in water with corundum and polished with 22 N load, for 8 hours. Furthermore a correlation was performed between the spraying current and voltage parameter. The coatings’ cross sections were examined using scanning electron microscope (SEM and optical microscopy. The influence of the composite components of the coatings’ microstructure, such as porosity, microhardness, oxide inclusions, on the tribological properties of thermal sprayed coatings is discussed in this paper. DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7339

  4. Properties of the antiferromagnetic selenite MnSeO3 and its non-magnetic analogue ZnSnO3 from first principles calculations

    Science.gov (United States)

    Honer, C. J.; Prosniewski, M. J.; Putatunda, A.; Singh, David J.

    2017-10-01

    We report the properties of the antiferromagnetic selenite MnSeO3 and the non-magnetic analogue ZnSeO3, based on first principles calculations. These compounds are rare examples of ABO3 perovskites with a tetravalent A-site and a divalent B-site. The electronic structure is discussed in the context of the bonding and crystal structure. There is cross-gap hybridization between the O p states that form the valence bands of these compounds and the unoccupied p states of Se, reflecting the lone pair physics that leads to the strong off-centering of Se from the perovskite A-site. The G-type antiferromagnetism of MnSeO3 is a local moment in nature arising from high spin Mn2+ with short range interactions. Additionally, there is an interesting spin-dependent hybridization of Mn d and O p states analogous to that in colossal magnetoresistance manganites.

  5. Effect of Cr substitution on magnetic and magnetic entropy change of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} (0.05≤x≤0.15) rhombohedral nanocrystalline near room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Bellouz, R., E-mail: bellouzridha@yahoo.fr [Laboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir,Université de Monastir, 5019 (Tunisia); Oumezzine, M. [Laboratoire de Physico-chimie des Matériaux, Département de Physique, Faculté des Sciences de Monastir,Université de Monastir, 5019 (Tunisia); Hlil, E.K. [Institut Néel, National Centre for Scientific Research, Université Joseph Fourier, B.P. 166, 38042 Grenoble (France); Dhahri, E. [Laboratoire de Physique appliqué, Département de physique, Faculté des Sciences de Sfax, 3018 (Tunisia)

    2015-02-01

    We have studied the effect of Cr substitution on magnetic and magnetocaloric properties in nanocrystalline La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} (x=0.05, 0.1 and 0.15). The materials were prepared using the Pechini sol–gel method. All the studied samples were crystallized into a single phase rhombohedral structure with R−3C space group. Magnetic measurements indicate that the ferromagnetic double exchange interaction is weakened with increasing Cr concentration, resulting in a shift in T{sub C} from 338 K to 278 K as x varied between 0.05 and 0.15. Detailed analyzes in the vicinity of the ferromagnetic (FM)–paramagnetic (PM) phase-transition temperature prove the samples undergoing a second-order phase transition. The magnetocaloric effect is calculated from the measurement of initial isothermal magnetization versus magnetic field at various temperatures. The maximum magnetic entropy change |ΔS{sub M}{sup max}| is found to decrease with increasing of Cr content from 4.04 J/Kg K for x=0.05–0.78 J/KgK for x=0.15 upon 5 T applied field change. The relative cooling power (RCP) of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} series is nearly 54% of pure Gd, which will be an interesting system for application in room temperature refrigeration. - Highlights: • Nanocrystalline materials La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} were obtained. • The Cr substitution decreases the T{sub C} from 338 K for x=0.05–278 K for x=0.15. • The relative cooling power of La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} is nearly 54% of pure Gd. • Arrott plot analyses was applied to study the order of the magnetic transition. • La{sub 0.65}Eu{sub 0.05}Sr{sub 0.3}Mn{sub 1−x}Cr{sub x}O{sub 3} samples show second order PM–FM transition at T=T{sub C}.

  6. Microstructure of CrMnNi Cast Steel After Explosive-Driven Flyer-Plate Impact at Room Temperature and Below

    Science.gov (United States)

    Eckner, R.; Reichel, B.; Savinykh, A. S.; Krüger, L.; Razorenov, S. V.; Garkushin, G. V.

    2016-01-01

    A low-carbon metastable austenitic CrMnNi cast steel was investigated under shock conditions in a flyer-plate impact test. The samples were impacted by aluminum flyer-plates with impact velocities of 620 ± 30 m/s. Depending on deformation temperature and strain rate, the material exhibited different deformation mechanisms (dislocation glide, martensitic transformation, and mechanical twinning), which determined the microstructural evolution and mechanical behavior. Flyer-plate impact tests were carried out at 213 K and 293 K (-60 °C and +20 °C). A soft recovered sample revealed microstructural changes directly after impact. The subsequent microstructural investigations via light-optical microscopy and scanning electron microscopy revealed that transformation-induced plasticity (TRIP effect) was the primary deformation mechanism. Moreover, it was possible to quantify the martensite volume fraction by different methods and to identify the hcp ɛ-martensite phase as an intermediate transformation stage. A decrease in temperature also increased the driving force for the martensitic transformation.

  7. Properties of Goethite Grown under the Presence of Cr{sup 3+}, Cu{sup 2+} and Mn{sup 2+} Ions

    Energy Technology Data Exchange (ETDEWEB)

    Morales, A. L. [Universidad de Antioquia, Grupo de Estado Solido, Instituto de Fisica (Colombia); Barrero, C. A. [Universidad de Antioquia, Grupo de Estado Solido, Instituto de Fisica, Universidad de Antioquia, A.A. 1226, Medellin, Colombia, Grupo de Corrosion y Proteccion, Facultad de Ingenierias (Colombia); Jaramillo, F.; Arroyave, C. [Universidad de Antioquia, Grupo de Corrosion y Proteccion, Facultad de Ingenierias (Colombia); Greneche, J.-M. [UMR CNRS 6087, Universite du Maine, Laboratoire de Physique de l' Etat Condense (France)

    2003-06-15

    This study is focused on properties of goethite related to the inhibition of the corrosion process in low alloy, weathering steels. These steels are characterized by the presence of small amounts of Cr{sup 3+}, Cu{sup 2+} and Mn{sup 2+} ions, which drive their protecting behavior in mild atmospheres. Several goethite samples with 5 mole % content of the alloying elements in nominal composition are synthesized by a hydrolysis route. Additionally, Cl{sup -}, SO{sub 4}{sup 2-} are used as precursor ions in order to simulate the presence of atmospheric pollutants. All samples are analyzed by X-ray diffraction and {sup 57}Fe transmission Moessbauer spectroscopy (MS). The presence of the alloying elements and pollutant ions reduces the overall magnetic interactions in goethite, which is reflected in the lowering of the hyperfine field of maximum probability at 77 K, in comparison to that of pure goethites. However, the mechanisms of the magnetic interaction reductions are different for each combination of alloying element and pollutant ions. Finally the combined effect of anions and cations produces a wider distribution of particle sizes.

  8. Insights into the deformation behavior of the CrMnFeCoNi high-entropy alloy revealed by elevated temperature nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Maier-Kiener, Verena [Montanuniversitat Leoben, Leoben (Austria); Schuh, Benjamin [Austrian Academy of Sciences, Leoben (Austria); George, Easo P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Clemens, Helmut [Montanuniversitat Leoben, Leoben (Austria); Hohenwarter, Anton [Austrian Academy of Sciences, Leoben (Austria)

    2017-07-27

    A CrMnFeCoNi high-entropy alloy was investigated by nanoindentation from room temperature to 400 °C in the nanocrystalline state and cast plus homogenized coarse-grained state. In the latter case a < 100 >-orientated grain was selected by electron back scatter diffraction for nanoindentation. It was found that hardness decreases more strongly with increasing temperature than Young’s modulus, especially for the coarse-grained state. The modulus of the nanocrystalline state was slightly higher than that of the coarse-grained one. For the coarse-grained sample a strong thermally activated deformation behavior was found up to 100–150 °C, followed by a diminishing thermally activated contribution at higher testing temperatures. For the nanocrystalline state, different temperature dependent deformation mechanisms are proposed. At low temperatures, the governing processes appear to be similar to those in the coarse-grained sample, but with increasing temperature, dislocation-grain boundary interactions likely become more dominant. Finally, at 400 °C, decomposition of the nanocrystalline alloy causes a further reduction in thermal activation. Furthermore, this is rationalized by a reduction of the deformation controlling internal length scale by precipitate formation in conjunction with a diffusional contribution.

  9. Solid-state reactions during mechanical alloying of ternary Fe–Al–X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems: A review

    Energy Technology Data Exchange (ETDEWEB)

    Hadef, Fatma, E-mail: hadef77@yahoo.fr [Laboratoire de Recherche sur la Physico-Chimie des Surfaces et Interfaces, LRPCSI, Université 20 Août 1955, BP 26, Route d’El-Haddaiek, Skikda 21000 (Algeria); Département de Physique, Faculté des Sciences, Université 20 Août 1955, BP 26, Route d’El-Haddaiek, Skikda 21000 (Algeria)

    2016-12-01

    The last decade has witnessed an intensive research in the field of nanocrystalline materials due to their enhanced properties. A lot of processing techniques were developed in order to synthesis these novel materials, among them mechanical alloying or high-energy ball milling. In fact, mechanical alloying is one of the most common operations in the processing of solids. It can be used to quickly and easily synthesize a variety of technologically useful materials which are very difficult to manufacture by other techniques. One advantage of MA over many other techniques is that is a solid state technique and consequently problems associated with melting and solidification are bypassed. Special attention is being paid to the synthesis of alloys through reactions mainly occurring in solid state in many metallic ternary Fe–Al–X systems, in order to improve mainly Fe–Al structural and mechanical properties. The results show that nanocrystallization is the common result occurring in all systems during MA process. The aim of this work is to illustrate the uniqueness of MA process to induce phase transformation in metallic Fe–Al–X (X=Ni, Mn, Cu, Ti, Cr, B, Si) systems. - Highlights: • A review of state of the art on binary Fe–Al alloys was presented. • Structural and microstructural properties of MA ternary Fe–Al–X alloys were summerized. • MA process is a powerful tool for producing metallic alloys at the nanometer scale.

  10. Preparation, structural, optical, electrical, and magnetic characterisation of orthorhombic GdCr{sub 0.3}Mn{sub 0.7}O{sub 3} multiferroic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Deepa; Bamzai, K.K. [Jammu Univ. (India). Crystal Growth and Materials Research Laboratory

    2017-04-01

    In this article, chromium-doped gadolinium manganate (GdCr{sub 0.3}Mn{sub 0.7}O{sub 3}) nanoparticles has been prepared by wet-chemical route in order to investigate their structural, optical, electrical, and room temperature magnetic properties. Microstructural and compositional analyses have been carried out by X-ray diffraction and scanning electron microscopy (SEM). Synthesised material is found to be in orthorhombic crystal structure with Pbnm space group. The spherical morphology of the nanoparticles has been examined from the SEM images. Functional groups have been identified using Fourier transform infrared spectroscopy. Dielectric constant, dielectric loss, AC conductivity (σ{sub ac}), and activation energy in the range of 1 kHz-1 MHz from room temperature to high temperature (400 C) have been investigated. The frequency dependence of AC conductivity obeys the universal power law. The value of activation energy depends on increase in frequency. Room temperature magnetic behaviour suggests the material to be paramagnetic in nature.

  11. Spectroscopic and biological approach in the characterization of Cr(III, Mn(II and Co(II complexes with a novel hexaaza-macrocyclic ligand derived from semicarbazide

    Directory of Open Access Journals (Sweden)

    ARCHANA GAUTAM

    2009-12-01

    Full Text Available Complexes of Cr(III, Mn(II and Co(II with a novel 5,7,12,14-tetraphenyl-1,2,4,8,10,11-hexaazacyclotetradecane-3,9-dione macrocyclic ligand, THTD (L, were synthesized and characterized by elemental analysis, molar conductance and magnetic susceptibility measurements, as well as by mass, 1H-NMR, IR, electronic and EPR spectral studies. Based on the spectral studies, an octahedral geometry was assigned for the Cr(III, Mn(II and Co(II complexes. The ligand and its complexes were screened in vitro against some species of bacteria and plant pathogenic fungi. The metal complexes were found to be more active antimicrobial agents than the free ligand from which they were derived.

  12. Features of electronic properties of band ferromagnets Co2 MeAl and Fe2 MeAl (Me  =  Ti, V, Cr, Mn, Fe, Ni)

    Science.gov (United States)

    Kourov, N. I.; Marchenkov, V. V.; Korolev, A. V.; Lukoyanov, A. V.; Shirokov, A. A.; Perevozchikova, Yu A.

    2017-11-01

    The results of the low-temperature (2  Me  =  Ti, V, Cr, Mn, Fe, Ni) ordered in the L21 crystal structure are presented. A comparative analysis of the behaviour of electronic properties as a function of the number of valence electrons z in the alloys Co2 MeAl and Fe2 MeAl is carried out.

  13. The comparison of micro elements (Mn, Fe and Zn and heavy metals (Co, Cr and Cd in the soil of perennial farms of saffron (Crocus sativus L. in southern Khorasan Province

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Behdani

    2016-05-01

    Full Text Available In order to study concentrations of soil micro and heavy metal elements in some saffron planting regions of Birjand Province, an experiment was performed as factorial layout based on a completely randomized block design with three replications at year 2013. Treatments were three field ages (annual, triennial and quinquennial and five saffron regions including Aryan shahr, Hosseinabad, Khosef, Golferiz and Mahmoei. Soil microelement and hevey methal concentrations such as Fe, Zn, Mn, Co, Cr and Cd of soil were measured. The results showed that the concentrations of Fe, Zn, Mn and Cr in soil were significantly affected by field age (p≤0.05. Effect of planting region was significant on soil Fe, Zn, Mn, Co and Cr concentrations (p≤0.01. Interaction effects between field age and planting region were significant on Fe, Zn and Co concentrations (p≤0.01. By increasing in field age soil Zn concentration was declined and heavy metal concentrations such as Co, Cr and Cd of soil were enhanced. Mn concentration in the quinquennial fields was 29 and 34% higher than annual and triennial first fields, respectively. Co content in the quinquennial fields was 53 and 46% higher than annual and triennial first fields, respectively. The maximum and minimum Fe concentrations were observed with 1.65 and 0.77 ppm for the fields of Khosef and Hosseinabad, respectively. The highest and lowest Fe concentrations were obtained with 2.436 and 0.77 ppm for the annual fields of Khosef and Hosseinabad, respectively. The highest Co concentrations were recorded in Hosseinabad and Khosef fields with 8.7 and 4.31 ppm, respectively. Thus, it is recommended to use ecological managemens such as reducing the application of chemical fertilizers and improving the organic fertilizers to decline the concentrations of these elements in saffron fields.

  14. Measurement and ab initio calculation of the structural parameters and physical properties of 3d transition intermetallics TiMP (M  =  Cr, Mn, Fe, Co, or Ni)

    Science.gov (United States)

    Suzuki, Nobuaki; Asahi, Ryoji; Kishida, Yoshihiro; Masuoka, Yumi; Sugiyama, Jun

    2017-04-01

    In this study, 3d transition metal phosphides TiMP, where M  =  Cr, Mn, Fe, Co, or Ni, were synthesized via solid-state reactions. At 293 K, both TiCrP and TiMnP exhibited hexagonal symmetry with P6-2m space groups, while TiFeP, TiCoP, and TiNiP possessed orthorhombic symmetry with Pnma space groups. The electrical resistivity ρ of each compound was on the order of 10-5 Ω m and was relatively temperature independent above 2 K, except in the case of TiFeP, for which ρ linearly decreased with decreasing temperature. The absolute value of the Seebeck coefficient was small (<30 µV K-1) between 2 K and 300 K and exhibited linear temperature dependence except in the case of TiNiP. The magnetic susceptibilities χ for TiCrP, TiCoP, and TiNiP, which ranged from 1  ×  10-4 emu mol-1 to 3  ×  10-4 emu mol-1, were temperature independent above 2 K, indicating that these species exhibit Pauli paramagnetism. The temperature-independent χ of TiFeP was relatively high, ~2.5  ×  10-3 emu mol-1. The Stoner enhancement factor estimated from the Pauli paramagnetic susceptibility that was determined based on the calculated density of states and the Wilson ratio were 21.2 and 14.1, respectively, for TiFeP, suggesting that the magnetism of TiFeP may be exchange-enhanced Pauli paramagnetism. In contrast, for TiMnP, χ obeyed a Curie-Weiss law, and an effective magnetic moment per TiMnP formula unit of 1.07 μ B and a Weiss temperature of  -8.0 K were obtained. The ab initio calculations for TiMnP yielded a predicted magnetic moment of 1.0 μ B per TiMnP formula unit, which is consistent with the experimental result. On the other hand, the measured electronic specific heat coefficient of TiMnP (48.1 mJ mol-1 · K-2) was about seven times higher than that estimated based on the calculated density of states. These results for TiMnP imply that spin fluctuations may determine its properties.

  15. A new, high energy Sn-C/Li[Li(0.2)Ni(0.4)/3Co(0.4)/3Mn(1.6/3)]O2 lithium-ion battery.

    Science.gov (United States)

    Elia, Giuseppe Antonio; Wang, Jun; Bresser, Dominic; Li, Jie; Scrosati, Bruno; Passerini, Stefano; Hassoun, Jusef

    2014-08-13

    In this paper we report a new, high performance lithium-ion battery comprising a nanostructured Sn-C anode and Li[Li0.2Ni0.4/3Co0.4/3Mn1.6/3]O2 (lithium-rich) cathode. This battery shows highly promising long-term cycling stability for up to 500 cycles, excellent rate capability, and a practical energy density, which is expected to be as high as 220 Wh kg(-1) at the packaged cell level. Considering the overall performance of this new chemistry basically related to the optimized structure, morphology, and composition of the utilized active materials as demonstrated by XRD, TEM, and SEM, respectively, the system studied herein is proposed as a suitable candidate for application in the lithium-ion battery field.

  16. Emerging Trends in Applied Mathematics: Dedicated to the Memory of Sir Asutosh Mookerjee and Contributions of S.N. Bose, M.N. Saha and N.R. Sen

    CERN Document Server

    Basu, Uma; De, Soumen

    2015-01-01

    The book is based on research presentations at the international conference, “Emerging Trends in Applied Mathematics: In the Memory of Sir Asutosh Mookerjee, S.N. Bose, M.N. Saha, and N.R. Sen”, held at the Department of Applied Mathematics, University of Calcutta, during 12–14 February 2014. It focuses on various emerging and challenging topics in the field of applied mathematics and theoretical physics. The book will be a valuable resource for postgraduate students at higher levels and researchers in applied mathematics and theoretical physics. Researchers presented a wide variety of themes in applied mathematics and theoretical physics—such as emergent periodicity in a field of chaos; Ricci flow equation and Poincare conjecture; Bose–Einstein condensation; geometry of local scale invariance and turbulence; statistical mechanics of human resource allocation: mathematical modelling of job-matching in labour markets; contact problem in elasticity; the Saha equation; computational fluid dynamics with...

  17. Preparation of monolayers of [MnIII 6CrIII]3+ single-molecule magnets on HOPG, mica and silicon surfaces and characterization by means of non-contact AFM

    Directory of Open Access Journals (Sweden)

    Hoeke Veronika

    2011-01-01

    Full Text Available Abstract We report on the characterization of various salts of [MnIII 6CrIII]3+ complexes prepared on substrates such as highly oriented pyrolytic graphite (HOPG, mica, SiO2, and Si3N4. [MnIII 6CrIII]3+ is a single-molecule magnet, i.e., a superparamagnetic molecule, with a blocking temperature around 2 K. The three positive charges of [MnIII 6CrIII]3+ were electrically neutralized by use of various anions such as tetraphenylborate (BPh4 -, lactate (C3H5O3 -, or perchlorate (ClO4 -. The molecule was prepared on the substrates out of solution using the droplet technique. The main subject of investigation was how the anions and substrates influence the emerging surface topology during and after the preparation. Regarding HOPG and SiO2, flat island-like and hemispheric-shaped structures were created. We observed a strong correlation between the electronic properties of the substrate and the analyzed structures, especially in the case of mica where we observed a gradient in the analyzed structures across the surface.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-12-01

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

  19. Cyclic voltammetry of LiCr{sub 0.15}Mn{sub 1.85}O{sub 4} in an aqueous LiNO{sub 3} solution

    Energy Technology Data Exchange (ETDEWEB)

    Cvjeticanin, Nikola; Stojkovic, Ivana; Mentus, Slavko [Faculty of Physical Chemistry, Belgrade University, Studentski trg 12-16, P.O. Box 137, 11001 Belgrade (RS); Mitric, Miodrag [The Vinca Institute of Nuclear Sciences, Laboratory for Theoretical and Condensed Matter Physics, P.O. Box 522, 11001 Belgrade (RS)

    2007-12-06

    Cyclic voltammetry (CV) of LiCr{sub 0.15}Mn{sub 1.85}O{sub 4}, synthesized by rapid glycine-nitrate method (GNM), was performed in a saturated aqueous LiNO{sub 3} ({proportional_to}9 M) solution. At rather high polarization rate of 10 mV s{sup -1} two well separated characteristic pairs of redox peaks can be clearly observed, which is not entirely the case for LiMn{sub 2}O{sub 4} synthesized in the same way. At a reduced scan rate of 1 mV s{sup -1}, the shape and position of redox peaks evidence that deintercalation/intercalation of Li{sup +} ion is highly reversible and much faster than in the case of organic electrolytes. Faster ''CV response'' of LiCr{sub 0.15}Mn{sub 1.85}O{sub 4} is in correlation with higher capacity retention (93%) in comparison to LiMn{sub 2}O{sub 4} (88%), registered after 50 charging/discharging cycles in organic electrolyte solution (1 M LiClO{sub 4} in propylene carbonate). (author)

  20. First-principles investigations of electronic, magnetic and thermodynamic properties of Heusler alloy Co{sub 2}Mn{sub 1−x}Ti{sub x}Sn

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lu [Department of Physics, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Zhu, Xingfeng, E-mail: zxf_physics@163.com [Department of Physics, Nanjing Normal University, Nanjing 210023 (China)

    2016-09-15

    Using first-principles density functional theory based method we have investigated the electronic, magnetic and thermodynamic properties of Heusler alloy Co{sub 2}Mn{sub 1−x}Ti{sub x}Sn. From analysis of elastic constants, we find that the cubic L2{sub 1} phase is stable and all the alloys prone to ductility for Co{sub 2}Mn{sub 1−x}Ti{sub x}Sn alloy. The total magnetic moment decreases with increasing x, in agreement with the generalized Slater-Pauling rule. Band structure calculations show that the minority DOS exhibits a gap around Fermi level confirming the half-metallic character of the material for all the concentrations studied and the Fermi level can be shifted within the minority spin gap by changing the Ti concentration. The Curie temperature T{sub C} estimated from the effective exchange constant J{sub 0} decreases with x, and qualitatively accords with the experimental values. Finally, by using a quasi-harmonic Debye model, the temperature dependent bulk modulus, heat capacity and coefficient of thermal expansion have been obtained in the present work. - Highlights: • The cubic L2{sub 1} phase is stable and all the alloys prone to ductility from analysis of elastic constants. • The total magnetic moments are in agreement with the generalized Slater-Pauling line. • The Fermi level can be shifted within the gap by changing the Ti concentration. • The T{sub C} estimated from J{sub 0} qualitatively accords with the experimental values. • The temperature dependent bulk modulus, heat capacity and coefficient of thermal expansion have been obtained.

  1. Synthesis and Electrochemical Properties of LiNi0.5Mn1.5O4 Cathode Materials with Cr(3+) and F(-) Composite Doping for Lithium-Ion Batteries.

    Science.gov (United States)

    Li, Jun; Li, Shaofang; Xu, Shuaijun; Huang, Si; Zhu, Jianxin

    2017-12-01

    A Cr(3+) and F(-) composite-doped LiNi0.5Mn1.5O4 cathode material was synthesized by the solid-state method, and the influence of the doping amount on the material's physical and electrochemical properties was investigated. The structure and morphology of the cathode material were characterized by XRD, SEM, TEM, and HRTEM, and the results revealed that the sample exhibited clear spinel features. No Cr(3+) and F(-) impurity phases were found, and the spinel structure became more stable. The results of the charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) test results suggested that LiCr0.05Ni0.475Mn1.475O3.95F0.05 in which the Cr(3+) and F(-) doping amounts were both 0.05, had the optimal electrochemical properties, with discharge rates of 0.1, 0.5, 2, 5, and 10 C and specific capacities of 134.18, 128.70, 123.62, 119.63, and 97.68 mAh g(-1) , respectively. After 50 cycles at a rate of 2 C, LiCr0.05Ni0.475Mn1.475O3.95F0.05 showed extremely good cycling performance, with a discharge specific capacity of 121.02 mAh g(-1) and a capacity retention rate of 97.9%. EIS test revealed that the doping clearly decreased the charge-transfer resistance.

  2. Synthesis and Electrochemical Properties of LiNi0.5Mn1.5O4 Cathode Materials with Cr3+ and F- Composite Doping for Lithium-Ion Batteries

    Science.gov (United States)

    Li, Jun; Li, Shaofang; Xu, Shuaijun; Huang, Si; Zhu, Jianxin

    2017-06-01

    A Cr3+ and F- composite-doped LiNi0.5Mn1.5O4 cathode material was synthesized by the solid-state method, and the influence of the doping amount on the material's physical and electrochemical properties was investigated. The structure and morphology of the cathode material were characterized by XRD, SEM, TEM, and HRTEM, and the results revealed that the sample exhibited clear spinel features. No Cr3+ and F- impurity phases were found, and the spinel structure became more stable. The results of the charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) test results suggested that LiCr0.05Ni0.475Mn1.475O3.95F0.05 in which the Cr3+ and F- doping amounts were both 0.05, had the optimal electrochemical properties, with discharge rates of 0.1, 0.5, 2, 5, and 10 C and specific capacities of 134.18, 128.70, 123.62, 119.63, and 97.68 mAh g-1 , respectively. After 50 cycles at a rate of 2 C, LiCr0.05Ni0.475Mn1.475O3.95F0.05 showed extremely good cycling performance, with a discharge specific capacity of 121.02 mAh g-1 and a capacity retention rate of 97.9%. EIS test revealed that the doping clearly decreased the charge-transfer resistance.

  3. Studies on magneto-resistance, magnetization and thermoelectric power of Cr substituted La{sub 0.65}Ca{sub 0.35}Mn{sub 1−x}Cr{sub x}O{sub 3} (0≤x≤0.07) manganites

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, S.O. [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Rao, Ashok, E-mail: ashokanu_rao@rediffmail.com [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal 576104 (India); Babu, P.D. [UGC-DAE Consortium for Scientific Research, Mumbai Centre, BARC, Mumbai 400085 (India); Tarachand; Okram, G.S. [UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, MP (India)

    2015-10-15

    A systematic investigation has been carried out on effect of Cr-doping on structural, magneto-resistance, magnetic and thermoelectric power properties of La{sub 0.65}Ca{sub 0.35}Mn{sub 1−x}Cr{sub x}O{sub 3} compounds. Samples were prepared using conventional solid state reaction method. The XRD analysis using Rietveld refinement reveals that the samples are single phased. Temperature dependent electrical resistivity measurements show the existence of the expected metal–insulator transition (T{sub MI}) which is followed by a small hump at temperatures lower than T{sub MI}. With the application of magnetic field, resistivity of all the samples is found to decrease and T{sub MI} is observed to shift towards higher temperature. This is attributed to induced magnetic ordering of the localized t{sub 2g} spins and increased electron transfer integral between Mn{sup 3+}/Mn{sup 4+} via oxygen by the application of magnetic field. MR% is observed to increase with the increasing Cr concentration. Magnetic studies show that the Curie temperature, T{sub C} and magnetic moment decreases with Cr-content which is consistent with the electrical studies. Electrical resistivity and thermoelectric power data have been analyzed using theoretical models and both suggest that the small polaron hopping (SPH) model is operative in the high temperature insulating region for the entire series of samples.

  4. Magneto-structural transformations in Ni{sub 50}Mn{sub 37.5}Sn{sub 12.5−x}In{sub x} Heusler powders

    Energy Technology Data Exchange (ETDEWEB)

    Maziarz, Wojciech; Wójcik, Anna; Czaja, Paweł [Instituite of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str, 30-059 Kraków (Poland); Żywczak, Antoni [AGH University of Science and Technology, Academic Centre for Materials and Nanotechnology, Mickiewicza 30, 30-059 Kraków (Poland); Jan Dutkiewicz [Instituite of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str, 30-059 Kraków (Poland); Hawełek, Łukasz [Institute of Non-Ferrous Metals, ul. Sowinskiego 5, 44-100 Gliwice (Poland); Cesari, Eduard [Department de Física, Universitat de les Illes Balears, Ctra. de Valldemossa, km 7.5, Palma de Mallorca E-07122 (Spain)

    2016-08-15

    The effect of ball milling and subsequently annealing of melt spun ribbons on magneto-structural transformations in Ni{sub 50}Mn{sub 37.5}Sn{sub 12.5−x}In{sub x} (x=0, 2, 4, 6) ribbons is presented. Short time vibration milling allows to obtain chemically homogenous powders of angular particle shapes and size within 10–50 μm. Milling does not change the characteristic temperatures of martensitic transformation in comparison to the melt spun ribbons. The effect of In substitution for Sn on martensitic transformation has a complex mechanism, associated with electron density change. Substitution of Sn by In in both milled and annealed powders leads to decrease of Curie temperature of austenite and increase of martensitic transformation temperature, stabilizing martensitic phase. The coexistence of magnetic transformation of austenite and martensitic transformation at low magnetic field was observed. The intermartensitic transformation of 4O martensite to L1{sub 0} martensite was observed during cooling at low magnetic field and this was confirmed by TEM microstructure observations. The annealing process of as-milled powders leads to the change of their martensitic structure due to relaxation of internal stresses associated with anisotropic columnar grain microstructure formed during melt spinning process. The level of stresses introduced during milling of ribbons has no significant influence on martensitic transformation. The annealing process of as milled powders leads to enhancement of their magnetic properties, decrease of Curie temperature of austenite, and marginal change of temperature of martenisitic transformation. - Highlights: • Vibration milling of ribbons allows to obtain angular powders of size 10–50 μm. • Vibration milling improves chemical homogeneity of alloys. • Indium addition changes the magneto-structural transformations in Ni–Mn–Sn–In alloys. • Complex character of magneto-structural transformations is visible. • Multistep

  5. Structural and Electrochemical Investigation of Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4 - x Fx (x=0, 0.08 Synthesized by Solid-State Method

    Directory of Open Access Journals (Sweden)

    Hai-Lang Zhang

    2013-01-01

    Full Text Available To improve the cycle performance of spinel LiMn2O4 as the cathode of 4-V-class lithium secondary batteries, spinel phases Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4 - xFx (x=0, 0.08 have been successfully prepared by a conventional solid-state method. The structure and physicochemical properties of this as-prepared powder were investigated by powder X-ray diffraction (XRD, electrochemical impedance spectroscopy (EIS, and galvanostatic charge-discharge test in detail. The results reveal that the multiple doping spinel Li1.02Mn1.92Al0.02Fe0.02Cr0.02O4F0.08 have better electrochemical performance than the undoped or only metal-element doped material, which may be contributed to the multiple cation and anion doping to lead to a more stable spinel framework with good capacity retention rate.

  6. Spectroscopy and tunable mid-infrared lasing of a novel gain medium: Cr sup 2 sup + doped Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te

    CERN Document Server

    Seo, J T; Trivedi, S B; Kutcher, S W; Chen, R J; Wang, C C; Zong, H; Boyd, P R; Tardiff, W

    1999-01-01

    A novel mid-infrared transition-metal laser has been developed based on chromium (II)-doped Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te. The characteristic spectroscopy features of Cr sup 2 sup + : Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te are large absorption and emission cross sections (approx 10 sup - sup 1 sup 8 cm sup 2), a predicted absence of excited state absorption (ESA), and a broad emission band extending from 2.1 approx 3.5 mu m. The broad emission band makes Cr sup 2 sup + : Cd sub 0 sub . sub 8 sub 5 Mn sub 0 sub . sub 1 sub 5 Te very attractive for the development of a widely tunable mid-infrared laser. In initial studies, a laser tunability from 2.3 to 2.75 mu m has been demonstrated with a full width at half maximum of 2.3 nm. A larger tuning range seems possible with the appropriate optics. The highest slope efficiency achieved for a pulsed (2 Hz) free-running laser was 44.2%.

  7. Electrochemical behaviour of LiMyMn2–yO4 (M= Cu, Cr; 0≤ y≤ 0⋅ 4)

    Indian Academy of Sciences (India)

    In this paper, we report on the effect of partial substitution of manganese in the LiMn2O4 phase with copper (II) and chromium (III) ions. It has been shown that the higher octahedral stabilization energy of trivalent chromium imparts greater structural stability to chromium-doped LiMn2O4 spinels. Both copper and chromium ...

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

    Science.gov (United States)

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

    2014-04-01

    Specific heat (Cp) thermal expansion (α) and Bulk modulus (BT) of lightly doped Rare Earth manganites (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B3+ = Fe3+,Cr3+,Ga3+,Al3+,Ru4+); (0.3specific heat (Cp)lat of (La0.3Pr0.7)0.65Ca0.35Mn0.97Fe0.03O3 as a function of temperature (10K≤T≤ 200K) is found to be in agreement with the published data. The trend of variation of Debye temperature with B-site cationic radius is predicted probably for the first time for the B-site doped rare earth manganites.

  9. Luminescence quenching of [Os(bpy){sub 3}]{sup 2+} by Mn{sup 7+}, Cr{sup 6+} and Ce{sup 4+} ions in acidic aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Abdel-Shafi, Ayman A., E-mail: aabdelshafi@kfu.edu.sa [Department of Chemistry, College of Science, King Faisal University, PO Box 400, Hufof 31982 (Saudi Arabia); Department of Chemistry, Faculty of Science, Ain Shams University, Abbassia, Cairo 11566 (Egypt)

    2014-11-15

    Luminescence quenching of [Os(bpy){sub 3}]{sup 2+} by Mn{sup 7+}, Cr{sup 6+} and Ce{sup 4+} ions in acidic aqueous media are studied. Ground state interactions between [Os(bpy){sub 3}]{sup 2+} and these ions show ground state association with stoichiometric ratios in accordance with the electron transfer process. Positive deviation is observed from the linear Stern–Volmer relationship which with the ground state association is in support of static quenching mechanism. Benesi-HildEbrand equation was used to evaluate the association constant which were found to be 5×10{sup 3} M{sup −1}, 6.6×10{sup 4} M{sup −1} and be 1.1×10{sup 5} M{sup −1} for association of [Os(bpy){sub 3}]{sup 2+} with Ce{sup 4+}, Cr{sup 6+} and Mn{sup 7+}, respectively, based on luminescence intensity measurements. Different models for static luminescence quenching were employed to discuss the results. - Highlights: • Pure luminescence static quenching of [Os(bpy){sub 3}]{sup 2+} by strong oxidizing agents are reported. • Ground state association is observed between [Os(bpy){sub 3}]{sup 2+} and Ce{sup 4+}, Cr{sup 6+} and Mn{sup 7+} ions. • Interaction of [Os(bpy){sub 3}]{sup 2+} with these ions was found to depend on their stoichiometric ratios. • Emission intensity of [Os(bpy){sub 3}]{sup 2+} was found to depend on its uncomplexed concentration.

  10. Investigations of the spin Hamiltonian parameters and local structures for Fe{sup 3+}, Cr{sup 3+} and Mn{sup 4+} in rutile TiO{sub 2} single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui-Ning [College of Physics and Engineering, Chengdu Normal University, Chengdu 611130 (China); College of Science, Chongqing University of Posts and Telecommunications, Chongqing (China); Liu, Xu-Sheng, E-mail: xsliu999@126.com [College of Physics and Engineering, Chengdu Normal University, Chengdu 611130 (China); College of Science, Chongqing University of Posts and Telecommunications, Chongqing (China); Zhou, Hong-Fei [College of Science, Chongqing University of Posts and Telecommunications, Chongqing (China)

    2015-11-15

    The spin Hamiltonian parameters (g factors, hyperfine structure constants and zero-field splittings (ZFSs)) and local structures for the rhombic substitutional Fe{sup 3+}, Cr{sup 3+} and Mn{sup 4+} in rutile (TiO{sub 2}) single crystal are theoretically investigated from the high order perturbation calculations based on the cluster approach including both the crystal-field (CF) and charge-transfer (CT) contributions to the g factors and hyperfine structure constants. The impurity centers are found to undergo the local axial distortions ΔZ (≈0.22, 0.14 and –0.18 Ǻ) and the planar bond angle variations Δφ (≈4.3, 5.9 and 0.2°) for Fe{sup 3+}, Cr{sup 3+} and Mn{sup 4+}, respectively. The signs for ZFSs D and E are analyzed in the light of those for ΔZ and rhombic distortion angle δφ (=φ′–π/4) related to an ideal octahedron. The magnitudes of ΔZ and Δφ are conveniently illustrated by the axial and perpendicular ZFS relative variations ΔF and ΔG for the deviations of D and E based on the local distortion parameters from those (D{sub H} and E{sub H}) based on the host structural data of Ti{sup 4+} site. The validity of the above local structures is discussed in view of size and charge mismatch of the various impurity centers. The CT contributions to g-shift are opposite in sign and about 13–56% in magnitude compared with the CF ones, indicating the increasing importance (Cr{sup 3+}Mn{sup 4+}). The CT contributions to hyperfine structure constants are the same in sign and about 19–22% in magnitude with respect to the corresponding CF contributions.

  11. Resistência à erosão por cavitação de aços inoxidáveis austeníticos CrMnSiN depositados por PTA Cavitation erosion resistance of CrMnSiN austenitic stainless steels deposited by PTA

    Directory of Open Access Journals (Sweden)

    Hélio Ormeu Ribeiro

    2010-06-01

    Full Text Available A erosão por cavitação deteriora componentes em serviço, tais como partes metálicas de bombas de água, válvulas e, em especial, pás de turbinas hidráulicas, sendo nesse último caso responsável por elevados prejuízos ligados tanto aos custos da manutenção direta, como sobretudo às perdas por interrupção na geração de energia elétrica. Dentre os materiais aplicados no reparo por soldagem de danos por cavitação incluem-se aços inoxidáveis tradicionais tipo AISI 308 e 309, aços inoxidáveis ao Co e ligas à base de Co (stellites, caracterizando-se essas últimas pela maior sensibilidade a trincas, dificuldade de esmerilhamento e pelo mais alto custo. Nesse contexto este trabalho buscou formular, depositar e analisar o desempenho de aços inoxidáveis austeníticos CrMnSiN, soldados pelo processo PTA. A resistência à erosão por cavitação foi avaliada segundo a norma ASTM G 32-92. A microestrutura foi caracterizada por microscopia ótica e microscopia eletrônica de varredura e a formação de martensitas α' e ε, induzida pela cavitação, foi avaliada por difração de raios-X. A integridade da superfície dos depósitos foi controlada por END, além disso a dureza e a facilidade de acabamaneto por esmerilhamento serviram como critérios para avaliar os revestimentos soldados. Verificou-se que os revestimentos aplicados por PTA eram livres de trincas de solidificação, com baixa porosidade, boa molhabilidade e adequado acabamento superficial. A melhor liga inoxidável austenítica elaborada (0,03%C; 0,35% N; 13,2%Cr; 11,8% Mn; 2,8%Si; bal %Fe mostrou uma resistência à erosão por cavitação próxima aquela das principais ligas comerciais.Cavitation erosion deteriorates components like metallic parts of water pumps, valves and blades of hydraulic turbines, in this last case being responsible for high economical losses, associated to direct maintenance costs, but above all due to the interruption of the electric

  12. Determinación de Cr, Mn, Fe, Co, Ni, Cu, Zn y As en aguas del río Rímac por fluorescencia de rayos-X en reflexión total.

    OpenAIRE

    Tiznado, William; Olivera, Paula

    2002-01-01

    Se han analizado muestras tomadas en trece estaciones a lo largo de la cuenca del río Rímac. Los muestreos se realizaron durante un período de un año (septiembre 1998 – agosto 1999), con una frecuencia de un muestreo por mes. Se ha utilizado la técnica de Análisis por Fluorescencia de Rayos-X en Reflexión Total para determinar los elementos Cr, Mn, Fe, Co, Ni, Cu, Zn y As en su fase disuelta. De los resultados obtenidos se observa: que la relación de la presencia de estaciones mineras con e...

  13. Investigation of pitting resistance in ultra clean IQ-Steel vs commonly used conventional steel; 158Q vs 16MnCr5 : Back-to-back pitting tests

    OpenAIRE

    Bergseth, Ellen; Sosa, Mario; Andersson, Martin; Olofsson, Ulf

    2015-01-01

    KTH Machine Design has conducted pitting tests on gears made out of two different types of steel in a standard back-to-back pitting test rig (FZG). The tested gears were produced from Ovako’s IQ-Steel in grade 158Q and compared to the behaviour of a reference steel, commonly used conventional steel in grade 16MnCr5 (reference steel, RS). The test method is a mechanical test procedure generally used to determine the pitting load capacity of gear transmission lubricants, but in this study the p...

  14. Influence of Mn site doping on electrical resistivity of polycrystalline La1-yAyMn1-xBxO3 (A=Ba, Sr; B=Cu, Cr, Co Manganites

    Directory of Open Access Journals (Sweden)

    Paunović N.

    2008-01-01

    Full Text Available We have the measured electrical resistivity of La1-yBayMn1-xCuxO3 (0.17≤y≤0.30; 0.04≤x≤0.10, La1-ySryMn1-xCrxO3 and La1-ySryMn1-xCoxO3 (0.270≤y≤0.294; 0.02≤x≤0.10 polycrystalline samples in the 25-325 K temperature range. The increase of Mn site doping concentration leads to an increase of the electrical resistivity of the samples and the appearance of a “double-peak” structure in the electrical resistivity versus temperature graphs. The first peak represents the insulator-metal transition in vicinity of the paramagnetic-ferromagnetic transition (TC. We have found that the intensity of the second peak increases with an increase of concentration of Mn substituents, due to the hole scattering by the random potential of the Mn site impurities.

  15. Critical behavior of resistivity in the pressure-induced first to second order transition in Pr0.6Ca0.4Mn0.96B0.04O3 (B=Co and Cr) polycrystals

    Science.gov (United States)

    Thiyagarajan, R.; Mahendiran, R.; Arumugam, S.

    2015-06-01

    We have investigated the hydrostatic pressure (P) dependence of the resistivity on Pr0.6Ca0.4Mn0.96B0.04O3 (B = Co and Cr) polycrystals. At ambient pressure, the temperature dependence of resistivity [ρ(T)] of both the samples show a first order paramagnetic insulator-ferromagnetic metallic transition at T=TIM. The application of P on both the samples increases the TIM, reduces the resistivity, and suppresses the hysteresis width, indicating a crossover from first to second order transition. The critical pressure, where the first-second order crossover takes place, are 2.02 and 2.40 GPa for Co and Cr doped samples respectively. The critical property of both systems around second order transition is investigated using Fisher-Langer relation and Suezaki-Mori method. The estimated critical exponents are close to the three-dimensional Heisenberg model for the Co doped sample suggesting short range interaction, and the exponents for the Cr doped sample follow the mean field theory suggesting long range ferromagnetic order. Further, the application of P suppresses the high temperature resistivity by reducing high temperature polarons in the case of the Cr doped sample, but it does not happen for the Co doped sample. The application of P helps to examine the stability of polarons in the high temperature regime.

  16. Effect of ball milling and thermal treatment on exchange bias and magnetocaloric properties of Ni{sub 48}Mn{sub 39.5}Sn{sub 10.5}Al{sub 2} ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Czaja, P., E-mail: p.czaja@imim.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland); Przewoźnik, J. [AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, Department of Solid State Physics, Al. Mickiewicza 30, 30-059 Krakow (Poland); Fitta, M.; Bałanda, M. [The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 152 Radzikowskiego Str., 31-342 Krakow (Poland); Chrobak, A. [A. Chelkowski Institute of Physics, University of Silesia, 4 Uniwersytecka Str., Katowice 40-007 (Poland); Kania, B. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland); Zackiewicz, P. [Institute of Non Ferrous Metals, 5 Sowinskiego Str., Gliwice 44-100 (Poland); Wójcik, A.; Szlezynger, M.; Maziarz, W. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Kraków (Poland)

    2016-03-01

    The combined effect of ball milling and subsequent heat treatment on microstructure, magnetic, magnetocaloric and exchange bias properties of Ni{sub 48}Mn{sub 39.5}Sn{sub 10.5}Al{sub 2} ribbons is reported. The annealing treatment results in the increase of the critical martensitic transformation temperature. The magnetic entropy change ΔS{sub M} of the order of 7.9 and −2.3 J kg K{sup −1} for the annealed 50–32 µm powder fraction is determined. This is less than in the as melt spun ribbon but appears at a considerably higher temperature. At the same time EB is decreased due to annealing treatment. This decrease is attributed to the strengthened ferromagnetic exchange coupling due heat induced stress and structural relaxation. - Highlights: • Milling and annealing of Ni–Mn–Sn–Al ribbons increases the MT temperature. • ΔS{sub M} equal to 7.9 and −2.3 J kg K{sup −1} for the annealed 50–32 µm powder fraction. • Exchange Bias decreases due to annealing treatment. • Milling and annealing are useful for tuning of properties of Ni–Mn–Sn–Al alloys.

  17. Synthesis and characterization of metal oxides (CeO2, CuO, NiO, Mn3O4, SnO2 and ZnO) nanoparticles as photo catalysts for degradation of textile dyes.

    Science.gov (United States)

    Gnanasekaran, Lalitha; Hemamalini, R; Saravanan, R; Ravichandran, K; Gracia, F; Agarwal, Shilpi; Gupta, Vinod Kumar

    2017-08-01

    The progress of the enriched photocatalytic degradation predominantly depends on materials fabrication. In the recent times, the outcomes of nanomaterials show extraordinary efficiency due to its shape and size. In this connection, the present work concentrates on the fabrication of single digit metal oxides (CeO2, CuO, NiO, Mn3O4, SnO2 and ZnO) through precipitation method. The structural information of different metal oxides (MOs) and their crystallite size were estimated via XRD analysis and their consistent results revealed that the crystalline sizes of the prepared metal oxide were exhibited in nano size. The morphology and dimension of the synthesized MOs were identified through FE-SEM and TEM techniques. The FE-SEM images were apparently defined that the actual morphology of each metal oxide expresses different dimension due to nucleation and growth process. The result of UV-vis absorption spectra was helped to identify the band gap of MOs and a suitable light for photocatalytic irradiation. Additionally, the synthesized single digit MOs nanoparticles were magnificently applied for the degradation of methyl orange and methylene blue under UV light irradiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Study on the behavior of the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs in an estuarine ecosystem using Mytilus galloprovincialis as a bioindicator species: the case of Thermaikos gulf, Greece

    Energy Technology Data Exchange (ETDEWEB)

    Catsiki, Vassiliki-Angelique [Hellenic Centre for Marine Research, Mavro Lithari, 46.7 Km Athens-Sounio, Anavyssos Attikis 19013 (Greece)]. E-mail: cats@ath.hcmr.gr; Florou, H. [National Centre for Scientific Research ' Demokritos' , Ag. Paraskevi 153 10, Athens (Greece)

    2006-07-01

    Mussels are worldwide recognized as pollution bioindicators and used in Mussel Watch programs, because they accumulate pollutants in their tissues at elevated levels in relation to pollutant biological availability in the marine environment. The present study deals with the use of Mytilus galloprovincialis as a local bioindicator of heavy metal and {sup 137}Cs contamination in an estuarine ecosystem (Thermaikos gulf, Greece in Eastern Mediterranean). M. galloprovincialis samples were collected monthly from two aquaculture farms during the period April to October 2000. Analyses for the heavy metals Cu, Cr, Ni, Zn, Fe, Mn and {sup 137}Cs showed that the concentrations measured were low and similar to those from other non-polluted Mediterranean areas. In terms of the two sampling stations, there were no statistically significant differences between them. On the contrary, the seasonal evolution of either heavy metals or {sup 137}Cs levels presented high variation. The levels were found to increase during the cold period of the year, especially for Cu, Zn, Mn and Cr which are essential for life. Stable metals were positively inter-related and moreover, metals more involved in biochemical activities seem to present more correlations than others with less significant role in the metabolism of the organisms.

  19. The effect of particle size of iron powder on {alpha} to {gamma} transformation in the nanostructured high nitrogen Fe-Cr-Mn-Mo stainless steel produced by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Tehrani, F.; Abbasi, M.H. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Golozar, M.A., E-mail: golozar@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Panjepour, M. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-05-15

    Research highlights: {yields} High nitrogen austenitic Fe18Cr10Mn4Mo stainless steel can be produced by MA and without annealing. {yields} The initial powder particle size plays an important role on the rate of nitrogen absorption and consequently on phase transformation kinetics. {yields} Nitrogen content in the steel is the most effective parameter for {alpha} to {gamma} kinetic enhancement. - Abstract: In this study, the effect of particle size of iron powder on {alpha} to {gamma} transformation in the nanostructured high nitrogen Fe-18Cr-10Mn-4Mo stainless steel, produced by mechanical alloying (MA) was investigated. For this purpose iron powders with two different particle sizes were used. MA was performed under nitrogen atmosphere, using a high-energy planetary ball mill. X-ray diffraction (XRD) patterns and nitrogen analysis revealed that by decreasing the iron mean particle size, a higher transformation rate is obtained due to increase in the rate of nitrogen absorption. Moreover, nitrogen solubility in both milled samples was increased noticeably by increasing the milling time. This is believed to be due to the increase of lattice defects and development of nanostructure through MA. Variations of grain size and internal lattice strain versus milling time, for both iron particle sizes, showed that the critical ferrite grain size for austenite nucleation is less than 10 nm.

  20. Effect of microstructure on the corrosion and deformation behavior of a newly developed 6Mn-5Cr-1.5Cu corrosion-resistant white iron

    Science.gov (United States)

    Rao, P. N. V. R. S. S. V. Prasada; Patwardhan, A. K.; Jain, N. C.

    1993-02-01

    An experimental study has been made of the effect of heat treatment on the transformation behavior of a 4.8 pct Cr white iron, alloyed with 6 pct Mn and 1.5 pct Cu, by employing optical metallography, X-ray diffractometry, and differential thermal analysis (DTA) techniques, with a view to assess the suitability of the different microstructures in resisting aqueous corrosion. The matrix microstructure in the as-cast condition, comprising pearlite + bainite/martensite, transformed to austenite on heat-treating at all the temperatures between 900 °C and 1050 °C. Increasing the soaking period at each of the heat-treating temperatures led to an increase in the volume fraction and stability of austenite. M3C was the dominant carbide present in the as-cast condition. On heat-treating, different carbides formed: M23C6 carbide was present on heat-treating at 900 °C and 950 °C; on heat-treating at 1000 °C, M7C3 formed and persisted even on heattreating at 1050 °C. The possible formation of M5C2 carbide in the as-cast and heat-treated conditions (900 °C and 950 °C) is also indicated. Dispersed carbides (DC), present in austenite up to 950 °C, mostly comprised M3C and M5C2. On stress relieving of the heat-treated samples, M7C3-type DC also formed. The hardness changes were found to be consistent with the micro-structural changes occurring on heat-treating. The as-cast state was characterized by a reasonable resistance to corrosion in 5 pct NaCl solution. On heat-treating, the corrosion resistance improved over that in the as-cast state. After 4 hours soaking, increasing the temperature from 900 °C to 1050 °C led to an improvement in corrosion resistance. However, after 10 hours soaking, corrosion resistance decreased on increasing the temperature from 900 °C to 950 °C and improved thereafter on increasing the heat-treating temperature. Deformation behavior responded to the microstructure on similar lines as the corrosion behavior. Although in an early stage of

  1. Estudo de metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn na Bacia do Tarumã-Açu Manaus (AM Heavy metal (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn study in the Tarumã-Açu Basin Manaus (AM

    Directory of Open Access Journals (Sweden)

    Genilson Pereira Santana

    2007-01-01

    Full Text Available Os resíduos gerados em domicílios incluem diversos produtos, como pesticidas, produtos farmacêuticos, detergentes, óleos de cozinha, metais pesados contidos em baterias e outros utensílios. Esses resíduos são lançados continuamente em aterro sanitário ou lixões em cidades como Manaus. O chorume produzido nesses aterros, quando não tratados, contamina recursos hídricos superficiais e subterrâneos. Neste estudo foi feita uma avaliação das conseqüências da liberação do chorume no sistema hídrico da bacia do Tarumã-Açu. Amostras de água e sedimento foram coletadas nos igarapés Matrinxã, Acará, Bolívia, bacia do Tarumã-Açu e dentro do aterro sanitário (Manaus - Amazonas - Brasil em março 2001. As amostras de água foram filtradas em filtro Milipore (0,45 mm de poro e, em seguida, tratadas com HNO3 concentrado. As amostras de sedimento foram peneiradas em malha de 0,053 mm e digeridas com HCl:HNO3 (1:3 a 150ºC. As concentrações de alguns metais pesados (Co, Cu, Fe, Cr, Ni, Mn, Pb e Zn foram determinadas nas amostras de água e sedimento por espectrometria de absorção atômica de chama. Os resultados revelaram que a concentração dos metais pesados é muito acima dos permitidos pela resolução 357/2005 do CONAMA em praticamente todos os locais amostrados, mostrando que o Aterro Sanitário é um dos principais responsáveis pelo impacto ambiental observado nos corpos hídricos estudados. As análises dos componentes principais (PCA e hierárquica de cluster (HCA, revelam que os pontos de coleta localizados dentro do aterro sanitário apresentam características diferentes dos outros locais amostrados. Além disso, o HCA e PCA mostraram que existe uma similaridade entre os pontos de coleta localizados fora do aterro o que permite afirmar que o chorume do aterro se dissolve por todo corpo hídrico estudado.Domestic sewage involves several products, such as pesticides, pharmaceutics products, detergents, soybean oil

  2. Thermodynamic modeling of La2O3-SrO-Mn2O3-Cr2O3 for solid oxide fuel cell applications

    DEFF Research Database (Denmark)

    Povoden-Karadeniz, E.; Chen, Ming; Ivas, Toni

    2012-01-01

    The thermodynamic La–Sr–Mn–Cr–O oxide database is obtained as an extension of thermodynamic descriptions of oxide subsystems using the calculation of phase diagrams approach. Concepts of the thermodynamic modeling of solid oxide phases are discussed. Gibbs energy functions of SrCrO4, Sr2.67Cr2O8,...... thermodynamics of traditional lanthanum manganite cathode with Cr-impurities. It represents the fundament for extensions to higher orders, aiming on thermodynamic calculations in noble symmetric solid oxide fuel cells...

  3. First-principles investigations into the thermodynamics of cation disorder and its impact on electronic structure and magnetic properties of spinel Co(Cr1-x Mn x )2O4

    Science.gov (United States)

    Das, Debashish; Ghosh, Subhradip

    2017-02-01

    Cation disorder over different crystallographic sites in spinel oxides is known to affect their properties. Recent experiments on Mn doped multiferroic \\text{CoC}{{\\text{r}}2}{{\\text{O}}4} indicate that a possible distribution of Mn atoms among tetrahedrally and octahedrally coordinated sites in the spinel lattice give rise to different variations in the structural parameters and saturation magnetisations in different concentration regimes of Mn atoms substituting the Cr. A composition dependent magnetic compensation behaviour points to the role conversions of the magnetic constituents. In this work, we have investigated the thermodynamics of cation disorder in \\text{Co}{{≤ft(\\text{C}{{\\text{r}}1-x}\\text{M}{{\\text{n}}x}\\right)}2}{{\\text{O}}4} system and its consequences on the structural, electronic and magnetic properties, using results from first-principles electronic structure calculations. We have computed the variations in the cation-disorder as a function of Mn concentration and the temperature and found that at the annealing temperature of the experiment many of the systems exhibit cation disorder. Our results support the interpretations of the experimental results regarding the qualitative variations in the sub-lattice occupancies and the associated magnetisation behaviour, with composition. We have analysed the variations in structural, magnetic and electronic properties of this system with variations in the compositions and the degree of cation disorder from the variations in their electronic structures and by using the ideas from crystal field theory. Our study provides a complete microscopic picture of the effects that are responsible for composition dependent behavioural differences of the properties of this system. This work lays down a general framework, based upon results from first-principles calculations, to understand and analyse the substitutional magnetic spinel oxides A{{≤ft({{B}1-x}{{C}x}\\right)}2}{{\\text{O}}4} in presence of

  4. Evolution of secondary phases in 0.17C-16Cr-11Mn-0.43N austenitic stainless steel at 800 and 850°C: Thermodynamic modeling of phase equilibria and experimental kinetic studies

    Directory of Open Access Journals (Sweden)

    Čička R.

    2012-01-01

    Full Text Available The precipitation of secondary phases was investigated in the 0.17C-16Cr-11Mn-0.43N austenitic stainless steel during annealing at 800 and 850°C for times between 5 min and 100 h. Light microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, and differential thermal analysis were used in experiments. Thermodynamic calculations were done by the ThermoCalc database software package. Cr2N and M23C6 were considered to be stable phases at the annealing temperatures. Cells consisting of alternating Cr2N and austenite lamellae were observed in the steel microstructure after sufficiently long annealing. The metastable chi phase was also found in all the annealed samples. After 100 h of annealing the equilibrium sigma started to precipitate. The thermodynamically predicted M6C was not confirmed experimentally in any of the annealed samples. DTA analysis showed the initial precipitation stage was followed by the phase dissolution. For the investigated steel the computational thermodynamics can be used only for qualitative interpretation of the experimental results as the measured endothermal peaks were found to be shifted of about 50 ÷ 70°C related to the computed results.

  5. Tris(pyridinealdoximato)metal complexes as ligands for the synthesis of asymmetric heterodinuclear Cr(III)M species [M = Zn(II), Cu(II), Ni(II), Fe(II), Mn(II), Cr(II), Co(III)]: a magneto-structural study.

    Science.gov (United States)

    Ross, S; Weyhermüller, T; Bill, E; Wieghardt, K; Chaudhuri, P

    2001-12-17

    Reactions of the LCr(III) unit with an in situ prepared M(PyA)(3)(n-) ion, where L represents 1,4,7-trimethyl-1,4,7-triazacyclononane and PyA(-) is the monoanion of pyridine-2-aldoxime, yield heterodinuclear complexes of general formula [LCr(III)(PyA)(3)M](2+/3+) as perchlorate salts, where M = Cr(II) (1), Mn(II) (2), low-spin Fe(II) (3), Ni(II) (4), Cu(II) (5), Zn(II) (6), and low-spin Co(III) (7). These compounds contain three oximato anions as bridging ligands. The hexadentate ligand with the identical donor atoms, tris(2-aldoximato-6-pyridyl)phosphine, P(PyA)(3), has been employed to prepare a second Cr(III)Ni(II) species 8, whose magnetic properties differ significantly from those of 4. Complexes 1-8 have been characterized on the basis of elemental analysis, mass spectrometry, IR, UV-vis, Mössbauer, and EPR spectroscopies, and variable-temperature (2-295 K) magnetic susceptibility measurements. They are isostructural in the sense that they all contain a terminal Cr(III) ion in a distorted octahedral environment, CrN(3)O(3), and a second six-coordinated metal ion M in a mostly trigonal prismatic MN(6) geometry. The crystal structures of the perchlorate salts of 2-5, 7, and 8 have been determined by X-ray crystallography at 100 K. The structures consist of mixed-metal Cr(III)M(II) and Cr(III)Co(III) complexes with a geometry in which two pseudooctahedral polyhedra are joined by three oximato (=N-O(-)) groups, with an intramolecular Cr.M(Co) distance in the range of 3.4-3.7 A. The cyclic voltammograms of the complexes reveal ligand oxidation and reduction processes, and in addition, metal-centered oxidation processes have been observed. X-band EPR spectroscopy has been used to establish the electronic ground state of the heterodinuclear complexes. Analysis of the susceptibility data indicates the presence of weak exchange interactions, both ferro- and antiferromagnetic, between the paramagnetic centers. A qualitative rationale on the basis of the Goodenough

  6. Electrochemical behaviour of LiMyMn2–yO4 (M = Cu, Cr; 0 ≤ y ≤ 0 ...

    Indian Academy of Sciences (India)

    Unknown

    Abstract. Spinel lithium manganese oxide, LiMn2O4, is beset with problems of capacity fade upon repeated cycling. The loss in capacity upon cycling is attributable to Jahn–Teller distortion and manganese dissolution in the electrolyte in the charged state. One way to circumvent this capacity fade is to introduce other 3d ...

  7. Reactions of M(+)(H2O)n, n < 40, M = V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, with D2O reveal water activation in Mn(+)(H2O)n.

    Science.gov (United States)

    van der Linde, Christian; Beyer, Martin K

    2012-11-08

    Reactions of M(+)(H(2)O)(n), n hydrogen occurs. For manganese, HDO formation occurs in the size regime n ≈ 8-20. Additional experiments show that, in this size regime, Mn(+)(H(2)O)(n) is slowly converted into HMnOH(+)(H(2)O)(n-1) under the influence of room temperature blackbody radiation. The reaction is mildly exothermic; ΔH ≈ -21 ± 10 kJ mol(-1).

  8. Magnetotransport in La0.7Sr0.3MnO3/CuCr2O4/Fe3O4 magnetic junctions

    Science.gov (United States)

    Iwata-Harms, Jodi M.; Chopdekar, Rajesh V.; Wong, Franklin J.; Nelson-Cheeseman, Brittany B.; Jenkins, Catherine A.; Arenholz, Elke; Suzuki, Yuri

    2015-01-01

    We demonstrate distinct magnetic and resistive switching with junction magnetoresistance up to -6% in magnetic tunnel junctions with a CuCr2O4 barrier. Junction magnetoresistance is inversely related to barrier thickness and reveals a maximum at a finite applied bias that converges to zero bias at low temperatures for all barrier thicknesses. The non-monotonic bias dependence is attributed to a charge gap from the Fe3O4 electrode and possible spin filtering from the spin-split conduction band of the ferrimagnetic CuCr2O4 barrier.

  9. Current-voltage characteristics of SnO{sub 2}-Co{sub 3}O{sub 4}-Cr{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Martinez, J A [Centro de Investigacion en Materiales Avanzados, S.C. (CIMAV), Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica (PIIT), Nueva Carretera Aeropuerto km. 10, Apodaca, Nuevo Leon, CP 66600 (Mexico); Glot, A B [Posgrado, Universidad Tecnologica de la Mixteca, Carretera Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca, CP 69000 (Mexico); Gaponov, A V [Department of Radioelectronics, Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Hernandez, M B [Instituto de Mineria, Universidad Tecnologica de la Mixteca, Carretera Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca, CP 69000 (Mexico); Guerrero-Paz, J, E-mail: josue.aguilar@cimav.edu.m [Particulate Materials Lab, Universidad Autonoma del Estado de Hidalgo, Pachuca, CP 42184 (Mexico)

    2009-10-21

    The effect of mechanical treatment in a planetary mill on the microstructure and electrical properties of tin dioxide based varistor ceramics in the system SnO{sub 2}-Co{sub 3}O{sub 4}-Cr{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} sintered in the range 1150-1450 {sup 0}C was studied. The mechanical treatment leads to an increase in shrinkage, decrease in porosity, decrease in sample diameter, change in colour of the sintered samples from grey to black and enhancement of nonlinearity. For the sample sintered at 1350 {sup 0}C the mechanical treatment enhances the nonlinearity coefficient from 11 to 31 and decreases the electric field E{sub 1} (at 10{sup -3} A cm{sup -2}) from 3500 to 2800 V cm{sup -1}. The observed changes in physical properties are explained in terms of an additional size reduction of oxide particles and a better mixing of oxide powder followed by the formation of potential barriers at the grain boundaries throughout the whole sample. In spite of the low porosity, the low-field electrical conductivity of mechanically treated ceramics is significantly increased with the growth of relative humidity. A higher humidity sensitivity is found for mechanically treated ceramics with higher barrier height and higher nonlinearity coefficient.

  10. La5Zn2Sn

    Directory of Open Access Journals (Sweden)

    Igor Oshchapovsky

    2011-11-01

    Full Text Available A single crystal of pentalanthanum dizinc stannide, La5Zn2Sn, was obtained from the elements in a resistance furnace. It belongs to the Mo5SiB2 structure type, which is a ternary ordered variant of the Cr5B3 structure type. The space is filled by bicapped tetragonal antiprisms from lanthanum atoms around tin atoms sharing their vertices. Zinc atoms fill voids between these bicapped tetragonal antiprisms. All four atoms in the asymmetric unit reside on special positions with the following site symmetries: La1 (..m; La2 (4/m..; Zn (m.2m; Sn (422.

  11. Experimental and first-principles study of ferromagnetism in Mn-doped zinc stannate nanowires

    KAUST Repository

    Deng, Rui

    2013-07-17

    Room temperature ferromagnetism was observed in Mn-doped zinc stannate (ZTO:Mn) nanowires, which were prepared by chemical vapor transport. Structural and magnetic properties and Mn chemical states of ZTO:Mn nanowires were investigated by X-ray diffraction, superconducting quantum interference device (SQUID) magnetometry and X-ray photoelectron spectroscopy. Manganese predominantly existed as Mn2+ and substituted for Zn (Mn Zn) in ZTO:Mn. This conclusion was supported by first-principles calculations. MnZn in ZTO:Mn had a lower formation energy than that of Mn substituted for Sn (MnSn). The nearest neighbor MnZn in ZTO stabilized ferromagnetic coupling. This observation supported the experimental results. © 2013 AIP Publishing LLC.

  12. The electronic, structural and magnetic properties of Heusler compounds ZrCrCoZ(Z=B, Al, Ga, In): A first-principles study

    Science.gov (United States)

    Guo, R. K.; Liu, G. D.; Lin, T. T.; Wang, W.; Wang, L. Y.; Dai, X. F.

    2018-02-01

    It is predicted that the ZrCrCoZ(Z=B, Al, Ga, In) compounds with LiMnPbSn-type structure are half-metallic ferrimagnets with a large half-metallic gap by the first-principles calculations. The half-metallicity of the ZrCrCoZ(Z=B, Al, Ga, In) compounds are quite robust to the axial and uniaxial strain. The total magnetic moments in per unit cell are 4 μB for the ZrCrCoZ(Z=B, Al, Ga, In) compounds and follow the Slater-Pauling rule, which can be attributed to the great spin-splitting. The calculated formation energies are negative for all the ZrCrCoZ(Z=B, Al, Ga, In) compounds, which indicates that those compounds are in the thermodynamic stability and the possibility of synthesis in experiment.

  13. Influence of different combined severe shot peening and laser surface melting treatments on the fatigue performance of 20CrMnTi steel gear

    Energy Technology Data Exchange (ETDEWEB)

    Lv, You, E-mail: llvvyou@163.com.cn; Lei, Liqun; Sun, Lina

    2016-03-21

    In this paper, the effect of severe shot peening combined with laser melting (LSMSSP for short) on the fatigue resistance of 20CrMiTi steel gears is investigated in comparison with the effect of traditional shot peening on the fatigue resistance of the laser surface melted (LSMTSP for short) 20CrMiTi steel gear. The surface characteristics of the gear have been analyzed by a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). The Forschungsstelle für Zahnräder und Getriebebau (FZG) back-to-back spur gear test rig was used for fatigue experiments. Experimental results showed that the residual stresses, full width at half maximum (FWHM), microhardness and retained austenite of the LSMSSP gears and LSMTSP gear were entirely different. Although the LSMSSP gears had higher surface roughness than the LSMTSP gear, the LSMSSP gears still had better fatigue resistance than the LSMTSP gear and laser surface melted gear. The nanocrystallized surface layer on the gear tooth flank created by severe shot peening might be a very important factor for improving the fatigue property of the LSMSSP gears.

  14. The effect of solid solution treatment on the hardness and microstructure of 0.6%wt C-10.8%wt Mn-1.44%wt Cr austenitic manganese steel

    Science.gov (United States)

    Nurjaman, F.; Bahfie, F.; Astuti, W.; Shofi, A.

    2017-04-01

    Austenitic manganese steel is steel alloy that has high manganese content (10-14%wt Mn). The characteristics of austenitic manganese steel are good in toughness, ductility, and wear resistance. Effect of solid solution treatment on the hardness and microstructure of austenitic manganese steel was studied in this experiment. The solid solution treatment process of austenitic manganese steel, 0.6%wt C-10.8%wt Mn-1.44%wt Cr, was conducted by heating the material at varied temperatures (950°C, 1000°C, 1050°C) for an hour and then quenching it in two different quenching media, i.e. oil and water. Further, the samples were tempered at three different temperatures (300°C, 400°C, and 500°C) for 2 hours. The treated materials were analyzed by Rockwell Hardness Tester to obtain the information of materials hardness and by an optical microscope and XRD to investigate the microstructure phase of the treated materials. Heating the austenitic manganese steel at 950°C for an hour followed by water quenching dissolved all carbide in as-cast condition and resulted the fully austenitic on its microstructure. Carbide precipitation occurred due to the prolongation of soaking time in solid solution treatment and tempering process. The optimum hardness of sample was 53.3 HRC, which was resulted by heating this material until 1000°C for an hour, followed by water quenching and tempering at 400°C for 2 hours.

  15. Spark plasma sintering of MgAl{sub 2}O{sub 4}–LaCr{sub 0.5}Mn{sub 0.5}O{sub 3} composite thermistor ceramics and a comparison investigation with conventional sintering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Bo; Zhao, Qing [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Chang, Aimin, E-mail: changam@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Wu, Yiquan, E-mail: wuy@alfred.edu [Kazuo Inamori School of Engineering, New York State College of Ceramics at Alfred University, Alfred, NY 14802 (United States); Li, Hongyi [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Product Quality Supervision and Inspection Institute of Xinjiang Uygur Autonomous Region, Urumqi 830013 (China)

    2016-08-05

    The microstructure and negative temperature coefficient (NTC) electrical properties of the MgAl{sub 2}O{sub 4}–LaCr{sub 0.5}Mn{sub 0.5}O{sub 3} composite ceramics prepared by spark plasma sintering (SPS) were investigated. The effects of SPS and conventional sintering (CS) on electrical properties and high temperature aging characteristics of 0.6MgAl{sub 2}O{sub 4}–0.4LaCr{sub 0.5}Mn{sub 0.5}O{sub 3} ceramics were comparatively studied. X-ray diffraction (XRD) results showed both SPS- and CS-sintered ceramics were indexed to be cubic spinel MgAl{sub 2}O{sub 4} phase and orthorhombic perovskite LaCr{sub 0.5}Mn{sub 0.5}O{sub 3} phase isomorphic to LaCrO{sub 3}. Microstructural study reveled that SPS-sintered specimens had a higher relative density more than 96%. The electrical properties of the SPS-sintered NTC thermistors could be adjusted by changing MgAl{sub 2}O{sub 4} content and sintering temperature. The SPS-sintered samples possessed a higher resistivity than that from conventionally sintered ceramics. The reasons for the increase of resistivity in the SPS-sintered samples, and the aging mechanism of the thermistor ceramics were investigated through applying the defect chemistry theory. - Highlights: • MgAl{sub 2}O{sub 4}–LaCr{sub 0.5}Mn{sub 0.5}O{sub 3} composite ceramics have been successfully fabricated by SPS. • Comparison investigation has been performed on the SPS- and CS-sintered ceramics. • The NTC electrical properties of these composite ceramics have been investigated. • The aging mechanism of the thermistor ceramics has been investigated.

  16. DNA interaction, antimicrobial, anticancer activities and molecular docking study of some new VO(II), Cr(III), Mn(II) and Ni(II) mononuclear chelates encompassing quaridentate imine ligand.

    Science.gov (United States)

    Abdel-Rahman, Laila H; Abu-Dief, Ahmed M; Aboelez, Moustafa O; Hassan Abdel-Mawgoud, Azza A

    2017-05-01

    The present study was conducted to synthesis of some new imine Cr(III), VO(II), Mn(II) and Ni(II) complexes derived from the condensation of 2-amino phenol with 2-hydroxynapthaldehyde were synthesized. The prepared HNPN imine ligand was analyzed by its melting point, IR, (1)H NMR and (13)C NMR spectroscopies. The investigated HNPN imine complexes were characterized by elemental analysis, FT IR, UV-vis and thermal analysis (TGA) under nitrogen atmosphere from ambient temperature to 750°C. The experimental results revealed that the investigated complexes contain hydrated water molecules. The molar conductance values of complexes are relatively low, indicating the non-electrolytic nature of these complexes. Magnetic susceptibility measurements show that the investigated complexes are paramagnetic. Moreover, the stability constants of the preparing complexes were determined spectrophotometrically. All the complexes were found to be monomeric 1:1 (M:L) stoichiometry in nature with octahedral geometry for Cr(III), tetrahedral for Mn(II), square planner for Ni(II) and square pyramidal for VO(II). Moreover, the prepared HNPN imine ligand and its complexes were evaluated for antimicrobial effect against some types of bacteria such as Bacillus subtilis (+ve), Escherichia coli(-ve) and Staphylococcus aureus (+ve) and some types of fungi such as Aspergillusniger, Candida glabrata and Trichophyton rubrum. The results of these studies indicate that the metal complexes exhibit a stronger antibacterial and antifungal efficiency compared to their corresponding imine ligand. Moreover, the interaction of the investigated complexes with CT-DNA was checked using spectral studies, viscosity measurements and gel electrophoreses. The absorption titration studies revealed that each of these complexes is an avid binder to calf thymus-DNA. Also, there was appreciable changes in the relative viscosity of DNA, which is consistent with enhanced hydrophobic interaction of the aromatic rings and

  17. SN Refsdal

    DEFF Research Database (Denmark)

    Kelly, P. L.; Brammer, G.; Selsing, J.

    2016-01-01

    (SNe), and we find strong evidence for a broad H-alpha P-Cygni profile in the HST grism spectrum at the redshift (z = 1.49) of the spiral host galaxy. SNe IIn, powered by circumstellar interaction, could provide a good match to the light curve of SN Refsdal, but the spectrum of a SN IIn would not show...... 1987A, we estimate it would have an ejecta mass of 20+-5 solar masses. The evolution of the light curve at late times will provide additional evidence about the potential existence of any substantial circumstellar material (CSM). Using MOSFIRE and X-shooter spectra, we estimate a subsolar host-galaxy...

  18. Varistor and humidity-sensitive properties of SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramics with V{sub 2}O{sub 5} addition

    Energy Technology Data Exchange (ETDEWEB)

    Gaponov, A.V. [Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Glot, A.B. [Universidad Tehnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000 (Mexico)], E-mail: alexglot@mixteco.utm.mx; Ivon, A.I. [Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Chack, A.M. [Solid State Institute, Technion, Haifa 32000 (Israel); Jimenez-Santana, G. [Universidad Tehnologica de la Mixteca, Huajuapan de Leon, Oaxaca 69000 (Mexico)

    2007-12-20

    It is shown that tin dioxide based SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramic material exhibits not only varistor properties discussed in the literature but also humidity-sensitive properties. At low electric fields conductivity of SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramics is increased with relative humidity of air, however, highly nonlinear current-voltage characteristic is observed even at relative humidity 93%. Conduction mechanism in this material is grain-boundary controlled and decrease of the barrier height on voltage and on relative humidity is responsible, respectively, for varistor and sensor effects. Slow decrease of the low-field conductivity with time during several months after the sintering or high-temperature heat treatment is observed. Such ageing effect is accompanied by the decrease of the lowest value of the current density at highly nonlinear part of current-voltage characteristic. Addition of V{sub 2}O{sub 5} to SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} causes strong decrease of the nonlinearity coefficient, increase of the low-field conductivity, decrease of the activation energy of electrical conduction and decrease of the humidity sensitivity. At quite small V{sub 2}O{sub 5} addition (about 1 mol.%) the transition to a percolation along the V{sub 2}O{sub 5} phase is assumed. Secondary conductive V{sub 2}O{sub 5} phase acts as a shunt to the grain boundaries.

  19. Statistical theory of diffusion in concentrated bcc and fcc alloys and concentration dependencies of diffusion coefficients in bcc alloys FeCu, FeMn, FeNi, and FeCr

    Energy Technology Data Exchange (ETDEWEB)

    Vaks, V. G.; Khromov, K. Yu., E-mail: khromov-ky@nrcki.ru; Pankratov, I. R. [National Research Center “Kurchatov Institute,” (Russian Federation); Popov, V. V. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-07-15

    The statistical theory of diffusion in concentrated bcc and fcc alloys with arbitrary pairwise interatomic interactions based on the master equation approach is developed. Vacancy–atom correlations are described using both the second-shell-jump and the nearest-neighbor-jump approximations which are shown to be usually sufficiently accurate. General expressions for Onsager coefficients in terms of microscopic interatomic interactions and some statistical averages are given. Both the analytical kinetic mean-field and the Monte Carlo methods for finding these averages are described. The theory developed is used to describe sharp concentration dependencies of diffusion coefficients in several iron-based alloy systems. For the bcc alloys FeCu, FeMn, and FeNi, we predict the notable increase of the iron self-diffusion coefficient with solute concentration c, up to several times, even though values of c possible for these alloys do not exceed some percent. For the bcc alloys FeCr at high temperatures T ≳ 1400 K, we show that the very strong and peculiar concentration dependencies of both tracer and chemical diffusion coefficients observed in these alloys can be naturally explained by the theory, without invoking exotic models discussed earlier.

  20. Study of the properties of flux cored wire of Fe-C-Si-Mn-Cr-Mo-Ni-V-Co system for the strengthening of nodes and parts of equipment used in the mineral mining

    Science.gov (United States)

    Gusev, A. I.; Kozyrev, N. A.; Usoltsev, A. A.; Kryukov, R. E.; Osetkovsky, I. V.

    2017-09-01

    The effect of the introduction of vanadium and cobalt into the charge of the powder surfacing wire of Fe-C-Si-Mn-Cr-Mo-Ni system is studied. In the laboratory conditions, the samples of flux cored wires were produced. The surfacing made by the prepared wire was produced under the flux AN-26C, on the plates of steel St3 in 6 layers with the help of ASAW-1250 welding tractor. Reduction of carbon content in the deposited layer to 0.19-0.2% with simultaneous change in the content of chromium, nickel, molybdenum and other elements present in it contributes to the enlargement of the martensite needles and the increase in the size of the former austenite grain. The obtained dependences of hardness of the deposited layer and its wear resistance on the mass fraction of elements, included in the composition of powder wires of the proposed system, can be used to predict the hardness of the welded layer and its wear resistance under different operating conditions for mining equipment and coal mining equipment.

  1. Effects of Ag addition on electrical transport and magnetic properties of La{sub 0.67}Ba{sub 0.33}Mn{sub 0.88}Cr{sub 0.12}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Xiaobo [State Key Laboratory of Crystal Materials, Department of Physics, Shandong University, Jinan, Shandong 250100 (China); Liu Yihua [State Key Laboratory of Crystal Materials, Department of Physics, Shandong University, Jinan, Shandong 250100 (China)]. E-mail: yhliu@sdu.edu.cn; Yin Na [State Key Laboratory of Crystal Materials, Department of Physics, Shandong University, Jinan, Shandong 250100 (China); Wang Chengjian [State Key Laboratory of Crystal Materials, Department of Physics, Shandong University, Jinan, Shandong 250100 (China); Mei Liangmo [State Key Laboratory of Crystal Materials, Department of Physics, Shandong University, Jinan, Shandong 250100 (China)

    2006-11-15

    We have prepared a series of polycrystalline manganites with the nominal compositions, La{sub 0.67}Ba{sub 0.33}Mn{sub 0.88}Cr{sub 0.12}O{sub 3}/Ag{sub x} (LBMCO/Ag{sub x}) (x is the mole fraction) with x=0, 0.05, 0.1, 0.15, 0.2, 0.23, 0.27, 0.3, 0.35. The X-ray diffraction patterns show that the samples with x>0.05 are two-phase composites. The Ag addition in LBMCO improves the properties of grain surfaces/boundaries and reduces the resistivity of the composites. For x=0.30 sample, a minimum resistivity is obtained and a maximum room temperature magnetoresistance up to -54.5% was observed at 288K, 1T field. The room temperature T{sub C} and the reduced resistivity are responsible for the enhancement of room temperature MR.

  2. SCC investigation of low alloy ultra-high strength steel 30CrMnSiNi2A in 3.5wt% NaCl solution by slow strain rate technique

    Directory of Open Access Journals (Sweden)

    Liu Jianhua

    2014-10-01

    Full Text Available To evaluate stress corrosion cracking (SCC mechanism of low alloy ultra-high strength steel 30CrMnSiNi2A in environment containing NaCl, SCC behavior of the steel in 3.5wt% NaCl solution is investigated by slow strain rate technique (SSRT with various strain rates and applied potentials, surface analysis technique, and electrochemical measurements. SCC susceptibility of the steel increases rapidly with strain rate decreasing from 1 × 10−5 s−1 to 5 × 10−7 s−1, and becomes stable when strain rate is lower than 5 × 10−7 s−1. SCC propagation of the steel in the solution at open circuit potential (OCP needs sufficient hydrogen which is supplied at a certain strain rate. Fracture surface at OCP has similar characteristics with that at cathodic polarization −1000 mVSCE, which presents characteristic fractography of hydrogen induced cracking (HIC. All of these indicate that SCC behavior of the steel in the solution at OCP is mainly controlled by HIC rather than anodic dissolution (AD.

  3. Characterization of La1-xSrxMnO3±d (x = 0.15, d 0) and La1-xSrxCrO3±d (x = 0.2, d 0) Powders by X-ray Powder Diffraction

    DEFF Research Database (Denmark)

    Berg, Rolf; Andersen, Mette M.; Bjerrum, Niels

    1996-01-01

    C, resulting in homogeneous single phased ceramic powders. X-ray diffraction diagrams were taken using copper Ka radiation with a Bragg-Brentano diffractometer. The obtained X-ray diagrams of the synthesised La0.85Sr0.15MnO3±d and La0.8Sr0.2CrO3±d (d 0) powders were compared to data in the literature which...

  4. Influence of annealing temperature on the electrochemical and surface properties of the 5-V spinel cathode material LiCr0.2Ni0.4Mn1.4O4 synthesized by a sol–gel technique

    DEFF Research Database (Denmark)

    Younesi, Reza; Malmgren, Sara; Edström, Kristina

    2014-01-01

    LiCr0.2Ni0.4Mn1.4O4 was synthesized by a sol–gel technique in which tartaric acid was used as oxide precursor. The synthesized powder was annealed at five different temperatures from 600 to 1,000 °C and tested as a 5-V cathode material in Li-ion batteries. The study shows that annealing at higher...

  5. Effect of A-site cation size on the structural, magnetic, and electrical properties of La{sub 1−x}Nd{sub x}Mn{sub 0.5}Cr{sub 0.5}O{sub 3} perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Devinder, E-mail: drdssambyal@rediffmail.com; Mahajan, Arun

    2015-09-25

    Highlights: • Rare earth chromium manganites have been synthesized by sol–gel method. • Upon Nd doping on La site, unit cell volume and the B–O–B bond angle are reduced. • The magnetic interactions are predominantly ferromagnetic. • The Curie temperature decreases with increasing Nd content. • Electric transport behavior can be described by the small polaron hoping model. - Abstract: A systematic investigation of rare earth chromium manganites with general formula La{sub 1−x}Nd{sub x}Mn{sub 0.5}Cr{sub 0.5}O{sub 3} (x = 0.0, 0.3, 0.6 and 0.9) has been undertaken mainly to understand their structural, magnetic as well as electrical behavior. Upon Nd doping on La site, unit cell volume and the B–O–B bond angle are reduced. The magnetic interactions in the materials are predominantly ferromagnetic and we believe that double exchange interactions between Mn{sup 3+} and Mn{sup 4+}, and Mn{sup 3+} and Cr{sup 3+} should be the origin of ferromagnetism. The Curie temperature decreases with increasing Nd content. All the samples are semiconducting throughout the temperature range studied. The electric transport behavior can be described by the adiabatic small polaron hoping model, with an apparent increase of polaron activation energy with Nd content.

  6. Optimizing the superconducting transition temperature and upper critical field of Sn <mn>1mn>-x In x Te

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, R. D.; Schneeloch, J. A.; Shi, X. Y.; Xu, Z. J.; Zhang, C.; Tranquada, J. M.; Li, Q.; Gu, G. D.

    2013-07-01

    Sn 1 - x In x Te is a possible candidate for topological superconductivity. Previous work has shown that substitution of In for Sn in the topological crystalline insulator SnTe results in superconductivity, with the transition temperature, T c , growing with In concentration. We have performed a systematic investigation of Sn 1 - x In x Te for a broad range of x , synthesizing single crystals (by a modified floating-zone method) as well as polycrystalline samples. The samples have been characterized by x-ray diffraction, resistivity, and magnetization. For the single crystals, the maximum T c is obtained at x = 0.45 with a value of 4.5 K, as determined by the onset of diamagnetism.

  7. Behaviour of DFT-based approaches to the spin-orbit term of zero-field splitting tensors: a case study of metallocomplexes, MIII(acac)3(M = V, Cr, Mn, Fe and Mo).

    Science.gov (United States)

    Sugisaki, Kenji; Toyota, Kazuo; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji

    2017-11-15

    Spin-orbit contributions to the zero-field splitting (ZFS) tensor (D SO tensor) of M III (acac) 3 complexes (M = V, Cr, Mn, Fe and Mo; acac = acetylacetonate anion) are evaluated by means of ab initio (a hybrid CASSCF/MRMP2) and DFT (Pederson-Khanna (PK) and natural orbital-based Pederson-Khanna (NOB-PK)) methods, focusing on the behaviour of DFT-based approaches to the D SO tensors against the valence d-electron configurations of the transition metal ions in octahedral coordination. Both the DFT-based approaches reproduce trends in the D tensors. Significantly, the differences between the theoretical and experimental D (D = D ZZ - (D XX + D YY )/2) values are smaller in NOB-PK than in PK, emphasising the usefulness of the natural orbital-based approach to the D tensor calculations of transition metal ion complexes. In the case of d 2 and d 4 electronic configurations, the D SO (NOB-PK) values are considerably underestimated in the absolute magnitude, compared with the experimental ones. The D SO tensor analysis based on the orbital region partitioning technique (ORPT) revealed that the D SO contributions attributed to excitations from the singly occupied region (SOR) to the unoccupied region (UOR) are significantly underestimated in the DFT-based approaches to all the complexes under study. In the case of d 3 and d 5 configurations, the (SOR → UOR) excitations contribute in a nearly isotropic manner, which causes fortuitous error cancellations in the DFT-based D SO values. These results indicate that more efforts to develop DFT frameworks should be directed towards the reproduction of quantitative D SO tensors of transition metal complexes with various electronic configurations and local symmetries around metal ions.

  8. Gaseous Phase and Electrochemical Hydrogen Storage Properties of Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu for Nickel Metal Hydride Battery Applications

    Directory of Open Access Journals (Sweden)

    Jean Nei

    2016-07-01

    Full Text Available Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu metal hydride alloys were studied. X-ray diffraction (XRD and scanning electron microscopy (SEM revealed the multi-phase nature of all alloys, which were composed of a stoichiometric TiNi matrix, a hyperstoichiometric TiNi minor phase, and a Ti2Ni secondary phase. Improvement in synergetic effects between the main TiNi and secondary Ti2Ni phases, determined by the amount of distorted lattice region in TiNi near Ti2Ni, was accomplished by the substitution of an element with a higher work function, which consequently causes a dramatic increase in gaseous phase hydrogen storage capacity compared to the Ti50Zr1Ni49 base alloy. Capacity performance is further enhanced in the electrochemical environment, especially in the cases of the Ti50Zr1Ni49 base alloy and Ti50Zr1Ni44Co5 alloy. Although the TiNi-based alloys in the current study show poorer high-rate performances compared to the commonly used AB5, AB2, and A2B7 alloys, they have adequate capacity performances and also excel in terms of cost and cycle stability. Among the alloys investigated, the Ti50Zr1Ni44Fe5 alloy demonstrated the best balance among capacity (394 mAh·g−1, high-rate performance, activation, and cycle stability and is recommended for follow-up full-cell testing and as the base composition for future formula optimization. A review of previous research works regarding the TiNi metal hydride alloys is also included.

  9. The effect of interstitial carbon on the mechanical properties and dislocation substructure evolution in Fe 40.4 Ni 11.3 Mn 34.8 Al 7.5 Cr 6 high entropy alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhangwei; Baker, Ian; Cai, Zhonghou; Chen, Si; Poplawsky, Jonathan D.; Guo, Wei

    2016-11-01

    A systematic study of the effects of up to 1.1 at. % carbon on the mechanical properties and evolution of the dislocation substructure in a series of a high entropy alloys (HEA) based on Fe40.4Ni11.3Mn34.8Al7.5Cr6 is presented. Transmission electron microscopy (TEM), synchrotron X-ray diffraction (XRD) and atom probe tomography (APT) were used to show that all the alloys are single-phase f.c.c. random solid solutions. The lattice constant, determined from synchrotron XRD measurements, increases linearly with increasing carbon concentration, which leads to a linear relationship between the yield strength and the carbon concentration. The dislocation substructures, as determined by a TEM, show a transition from wavy slip to planar slip and, at higher strains, and from cell-forming structure (dislocations cells, cell blocks and dense dislocation walls) to non-cell forming structure (Taylor lattice, microbands and domain boundaries) with the addition of carbon, features related to the increase in lattice friction stress. The stacking fault energy (measured via weak-beam imaging of the separation of dislocation partials) decreases with increasing carbon content, which also contributes to the transition from wavy slip to planar slip. The formation of non-cell forming structure induced by carbon leads to a high degree of strain hardening and a substantial increase in the ultimate tensile strength. The consequent postponement of necking due to the high strain hardening, along with the plasticity accommodation arising from the formation of microbands and domain boundaries, result in an increase of ductility due to the carbon addition. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Electrical and magnetic properties of La{sub 0.67}Ba{sub 0.33}Mn{sub 1-x}(Me){sub x}O{sub 3} perovskite manganites: case of manganese substituted by trivalent (Me = Cr) and tetravalent (Me = Ti) elements

    Energy Technology Data Exchange (ETDEWEB)

    Oumezzine, Marwene [Universite de Monastir, Laboratoire de Physico-Chimie des Materiaux, Departement de Physique, Faculte des Sciences de Monastir, Monastir (Tunisia); Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes Cedex (France); Pena, Octavio; Guizouarn, Thierry [Universite de Rennes 1, Institut des Sciences Chimiques de Rennes, UMR 6226, Rennes Cedex (France); Kallel, Sami; Kallel, Nabil; Oumezzine, Mohamed [Universite de Monastir, Laboratoire de Physico-Chimie des Materiaux, Departement de Physique, Faculte des Sciences de Monastir, Monastir (Tunisia); Gouttefangeas, Francis [Universite de Rennes 1, C.M.E.B.A. (Centre de Microscopie Electronique a Balayage et Microanalyse), Rennes Cedex (France)

    2014-03-15

    The effects of non-magnetic Ti{sup 4+} substitution on the structural, electrical and magnetic properties of La{sub 0.67}Ba{sub 0.33}Mn{sub 1-x}Ti{sub x}O{sub 3} (0 ≤x ≤0.1) are investigated and compared to those existing in La{sub 0.67}Ba{sub 0.33}Mn{sub 1-x}Cr{sub x}O{sub 3} (magnetic Cr{sup 3+}). The structural refinement by the Rietveld method revealed that Ti-doped samples crystallize in the cubic lattice with space group Pm anti 3m, while samples with Cr crystallize in the hexagonal setting of the rhombohedral R anti 3C space group for identical contents of dopant. The most relevant structural features are an increase of the lattice parameters, of the cell volume and of the inter-ionic distances with increasing Ti doping level. Both series of samples show a decrease of the paramagnetic-ferromagnetic transition temperature when the amount of chromium or titanium increases. Transport measurements show that when increasing the metal doping, the resistivity increases whereas the metallic behavior of the parent compound La{sub 0.67}Ba{sub 0.33}MnO{sub 3} is destroyed. For a substitution higher than 5 at.% of Ti and 10 at.% of Cr, the samples exhibit a semiconducting behavior in the whole range of temperature, for which the electronic transport can be explained by variable range hopping and/or small polaron hopping models. (orig.)

  11. Influência da refusão por plasma na microestrutura de um revestimento Fe-Mn-Cr-Si depositado por aspersão térmica arco elétrico sobre aço inoxidável ASTM A743-CA6NM Influence of plasma remelting on the microstructure of Fe-Mn-Cr-Si arc thermal spray coating deposited on ASTM A743-CA6NM stainless steel

    Directory of Open Access Journals (Sweden)

    Anderson Geraldo Marenda Pukasiewicz

    2012-03-01

    Full Text Available ASTM A743-CA6NM é um aço inoxidável martensítico muito utilizado na fabricação de turbinas hidráulicas devido a sua elevada tenacidade, entretanto apresenta restrições com relação à regiões recuperadas por soldagem. Diferentes técnicas de deposição tem sido aplicadas com o intuito de reduzir ou eliminar a tensão residual. A deposição de revestimentos resistentes a cavitação é outra forma importante de aumentar a vida útil destes componentes. O objetivo deste trabalho é avaliar a influência do tipo e intensidade de corrente de refusão por plasma na microestrutura, composição química e microdureza de um revestimento Fe-Mn-Cr-Si resistente a cavitação depositado por aspersão térmica arco elétrico sobre aço ASTMA743-CA6NM. Observou-se que a adoção de menores valores de corrente média, assim como a utilização de corrente pulsada reduziram a formação de ferrita δ e a espessura final da ZTA, possibilitando a formação do revestimento com menores alterações na microestrutura do metal base. Verificou-se que a microestrutura e microdureza dos revestimentos refundidos não se mostraram muito sensível a variações na diluição do metal base. A utilização de corrente contínua promoveu um alinhamento da estrutura dendrítica no sentido da movimentação da tocha, entretanto este comportamento não foi observado em revestimentos refundidos com corrente pulsada.ASTM A743-CA6NM martensitic stainless steel have been used in hydraulic turbines manufacturing, but show some restrictions in welded recovered areas. Different techniques have been applied in order to reduce or eliminate residual stress, with life increase. The deposition of cavitation resistant coatings is another important way to increase the service life of these components. The objective of this study is evaluate the influence of type and intensity of plasma remelting current on the microstructure, chemical composition and microhardness of the Fe-Cr-Mn

  12. The half-metallicity of LiMgPdSn-type quaternary Heusler alloys FeMnScZ (Z=Al, Ga, In: A first-principle study

    Directory of Open Access Journals (Sweden)

    Y. C. Gao

    2015-05-01

    Full Text Available Based on the first-principles calculations, quaternary Heusler alloys FeMnScZ (Z=Al, Ga, In including its phase stability, band gap, the electronic structures and magnetic properties has been studied systematically. We have found that, in terms of the equilibrium lattice constants, FeMnScZ (Z=Al, Ga, In are half-metallic ferrimagnets, which can sustain the high spin polarization under a very large amount of lattice distortions. The half-metallic band gap in FeMnScZ (Z=Al, Ga, In alloys originates from the t1u-t2g splitting instead of the eu-t1u splitting. The total magnetic moments are 3μB per unit cell for FeMnScZ (Z=Al, Ga, In alloys following the Slater–Pauling rule with the total number of valence electrons minus 18 rather than 24. According to the study, the conclusion can be drawn that all of these compounds which have a negative formation energy are possible to be synthesized experimentally.

  13. Emission of SN 1006 produced by accelerated cosmic rays

    OpenAIRE

    Berezhko, E. G.; Ksenofontov, L. T.; Voelk, H. J.

    2002-01-01

    The nonlinear kinetic model of cosmic ray (CR) acceleration in supernova remnants (SNRs) is used to describe the properties of the remnant of SN 1006. It is shown, that the theory fits the existing data in a satisfactory way within a set of parameters which is consistent with the idea that SN 1006 is a typical source of Galactic CR nucleons, although not necessarily of CR electrons. The adjusted parameters are those that are not very well determined by present theory or not directly amenable ...

  14. [Changing the contents of Fe and Mn in the tonsils of children exposed to passive smoking and their local imission example Chorzow].

    Science.gov (United States)

    Nogaj, Ewa; Kwapuliński, Jerzy; Bazowska, Maria; Krawczyk, Łukasz; Ahnert, Bozena; Rzepka, Jerzy; Nogaj, Piotr; Olender, Jacek; Paprotny, Łukasz

    2010-01-01

    The subject of the research were samples of overgrown adenoids removed by adenoidectomy 56 children, including 30 boys and 26 girls, exposure and unexposure from passive smoking, living in the administrative area of Chorzów. The statistic characteristic of Fe and Mn occurrence is presented in the thesis. The studies were carried out on the changes of Fe and Mn and other elements, (B, Al, La, Cd, Co, Cr, Cu, Ni, Pb, Zn, As, Se, Hg, V, Be, Mo, Sn, V, Ti, Sb, Bi, TI, Zr, Ca, Mg, Na, Ba, Sr, Li) respectively. The elemental composition of adenoids was determined with ICP-AES method (Inductively Coupled Plasma - Atomic Emission Spectroscopy). The studies on Fe and Mn occurrence in adenoids showed the presence of its higher concentrations in exposure boys (Fe - 116.13 microg/g; Mn - 0.70 microg/g), in comparison with exposure girls from passive smoking (93.06 microg/g; Mn - 0.57 microg/g).

  15. Effect of small quantity of chromium on the electrical, magnetic and magnetocaloric properties of Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.98}Cr{sub 0.02}O{sub 3} manganite

    Energy Technology Data Exchange (ETDEWEB)

    Bettaibi, A.; Rahmouni, H. [Universite de Gabes, Laboratoire de Physique des Materiaux et des Nanomateriaux appliquee a l' Environnement, Faculte des Sciences de Gabes cite Erriadh, Gabes (Tunisia); M' nassri, R. [Kairouan University, Higher Institute of Applied Sciences and Technology of Kasserine, Kasserine (Tunisia); Universite de Monastir, Laboratoire de Physico-Chimie des Materiaux, Departement de Physique, Faculte des Sciences de Monastir, Monastir (Tunisia); Selmi, A.; Cheikhrouhou, A. [Sfax University, Laboratory of Physics of Materials, Faculty of Sciences of Sfax, Sfax (Tunisia); Khirouni, K. [Kairouan University, Higher Institute of Applied Sciences and Technology of Kasserine, Kasserine (Tunisia); Chniba Boudjada, N. [Institut NEEL, Grenoble Cedex 09 (France)

    2016-03-15

    Structural, electrical and thermomagnetic properties of Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.98}Cr{sub 0.02}O{sub 3} were investigated. Sample was prepared by solid-state reaction method. X-ray diffraction revealed that the sample crystallizes in the orthorhombic system with Pnma space group. Electrical conductivity and complex impedance studies of Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.98}Cr{sub 0.02}O{sub 3} system are analyzed. The investigated compound exhibits a semiconductor behavior in the whole explored temperature range. From 100 to 206 K, the increase in DC conductance is more than two decade. At higher temperatures, the conductance varies slowly and a saturation region appears. The conduction mechanism is found to be governed by small polaron hopping process which is explained by the short range thermally activated energy. Conductance spectrum is well described by Jonsher law, and the temperature dependence of the frequency exponent confirms that conduction mechanism is governed by hopping process of the localized carriers. Using complex impedance analysis, the compound is modeled by an electrical equivalent circuit. Also, such analysis confirms the contribution of grain boundary to the transport properties. The substitution of Mn by 2 % Cr destroyed the charge order state observed in the parent compound and induced a ferromagnetic phase at low temperatures. For a magnetic field change of 5 T, the material shows a maximum magnetic entropy change ∇S {sup max} = 2.69 J kg{sup -1} K{sup -1} with a full width at half maximum δ {sub TFWHM} = 145 K, and a relative cooling power RCP = 389 J kg{sup -1}. Pr{sub 0.7}Ca{sub 0.3}Mn{sub 0.98}Cr{sub 0.02}O{sub 3} material demonstrates potential proprieties to be used in electronic and thermal devices and as magnetic refrigerant. (orig.)

  16. Effects of metal doping on photoinduced hydrophilicity of SnO2 thin ...

    Indian Academy of Sciences (India)

    to the formation of associated oxygen vacancy states between valence and conduction bands in the SnO2 lattice. Therefore, with doping, higher concentration of oxygen vacancy is crea- ted by replacing of Sn4+ by a lower valency Mn2+, which is beneficial for enhancing hydrophilicity. The formation of oxygen ion vacancies ...

  17. Analytical and sampling methodology used for determining the impact of a MHD test facility. [Al, As, Ca, Cd, Fe, K, Mn, Pb, Zn, B, Be, Bi, Co, Cr, Hg, Mg, Mo, Ni, Sb, Se, Sn, V

    Energy Technology Data Exchange (ETDEWEB)

    Jenke, D.R.

    1984-01-01

    The suitability of various analytical and sampling methodologies for the determination of the environmental impact of a test scale MHD (magnetohydrodynamic) power generation facility is evaluated. Media which were sampled included airbourne particulates, soils, vegetation and natural waters. Analytical techniques examined include plasma emission and atomic absorption spectrometry and ion chromatography. Except in the case of the sampling of particulates with moss ball samplers, the analytical and sampling methodologies can be integrated in such a manner so as to maximize precision and thereby facilitate the statistical evaluation of impact effects. 12 references, 1 figure, 7 tables.

  18. Critical behavior of resistivity in the pressure-induced first to second order transition in Pr{sub 0.6}Ca{sub 0.4}Mn{sub 0.96}B{sub 0.04}O{sub 3} (B = Co and Cr)

    Energy Technology Data Exchange (ETDEWEB)

    Thiyagarajan, R.; Esakki Muthu, S.; Kalai Selvan, G. [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Mahendiran, R. [Department of Physics, 2 Science Drive 3, Faculty of Science, National University of Singapore, Singapore 117551 (Singapore); Arumugam, S., E-mail: sarumugam1963@yahoo.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India)

    2015-01-05

    Highlights: • 1st order PMI–FMM transition at T{sub IM} Pr{sub 0.6}Ca{sub 0.4}Mn{sub 0.96}B{sub 0.04}O{sub 3} (B = Co and Cr) samples. • Crossover from 1st to 2nd order is observed by the application of P on both the samples. • Critical exponents’ are close to the 3D Heisenberg model for the Co doped sample. • Critical exponents’ are close to the Mean field model for the Cr doped sample. - Abstract: We have investigated the hydrostatic pressure (P) dependence of the resistivity on Pr{sub 0.6}Ca{sub 0.4}Mn{sub 0.96}B{sub 0.04}O{sub 3} (B = Co and Cr) polycrystals. At ambient pressure, the temperature dependence of resistivity [ρ(T)] of both the samples show a first order paramagnetic insulator–ferromagnetic metallic transition at T = T{sub IM}. The application of P on both the samples increases the T{sub IM}, reduces the resistivity, and suppresses the hysteresis width, indicating a crossover from first to second order transition. The critical pressure, where the first–second order crossover takes place, are 2.02 and 2.40 GPa for Co and Cr doped samples respectively. The critical property of both systems around second order transition is investigated using Fisher–Langer relation and Suezaki–Mori method. The estimated critical exponents are close to the three-dimensional Heisenberg model for the Co doped sample suggesting short range interaction, and the exponents for the Cr doped sample follow the mean field theory suggesting long range ferromagnetic order. Further, the application of P suppresses the high temperature resistivity by reducing high temperature polarons in the case of the Cr doped sample, but it does not happen for the Co doped sample. The application of P helps to examine the stability of polarons in the high temperature regime.

  19. Electrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 90oCElectrochemical Studies of Passive Film Stability on Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4 Amorphous Metal in Seawater at 9

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J C; Haslam, J; Day, S D; Lian, T; Saw, C K; Hailey, P D; Choi, J S; Rebak, R B; Yang, N; Payer, J H; Perepezko, J H; Hildal, K; Lavernia, E J; Ajdelsztajn, L; Branagan, D J; Buffa, E J; Aprigliano, L F

    2007-04-25

    An iron-based amorphous metal, Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4} (SAM2X5), with very good corrosion resistance was developed. This material was prepared as a melt-spun ribbon, as well as gas atomized powder and a thermal-spray coating. During electrochemical testing in several environments, including seawater at 90 C, the passive film stability was found to be comparable to that of high-performance nickel-based alloys, and superior to that of stainless steels, based on electrochemical measurements of the passive film breakdown potential and general corrosion rates. This material also performed very well in standard salt fog tests. Chromium (Cr), molybdenum (Mo) and tungsten (W) provided corrosion resistance, and boron (B) enabled glass formation. The high boron content of this particular amorphous metal made it an effective neutron absorber, and suitable for criticality control applications. This material and its parent alloy maintained corrosion resistance up to the glass transition temperature, and remained in the amorphous state during exposure to relatively high neutron doses.

  20. Nanowire-templated formation of SnO2/carbon nanotubes with enhanced lithium storage properties.

    Science.gov (United States)

    Zhou, Xiaosi; Yu, Le; Lou, Xiong Wen David

    2016-04-21

    In this work, we have designed and synthesized SnO2 nanotubes wrapped by a porous carbon layer via a multistep method. Single-crystalline MnO(x) nanowires are employed as the template. SnO2 is grown on MnO(x) nanowires by a simple hydrothermal method to generate MnO(x)/SnO2 core-shell nanocables, followed by further coating with a layer of polydopamine. After carbonization of polydopamine and selective removal of MnO(x) nanowires, carbon coated SnO2 nanotubes are obtained. This structure combines several advantages. First, the internal empty space of the tubular structure can buffer the huge volume variation during lithium insertion-extraction processes properly, leading to improved cycling performance. Second, the nanosized SnO2 subunits and porous carbon coating not only shorten the distance for lithium ion diffusion but also offer large electrode-electrolyte contact area for fast Li(+) crossing the interface, thus enabling improved rate capability. Third, the flexible carbon coating is closely covered onto the SnO2 nanocrystals, which could facilitate the electronic transport and also significantly mitigate the pulverization. As a result, the as-synthesized SnO2/C-NT nanocomposites exhibit a high reversible capacity of 596 mA h g(-1) after 200 cycles, as well as an outstanding rate capability.

  1. Magnetic properties and magnetocaloric effect in Ni–Mn–Sn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dan, N.H., E-mail: dannh@ims.vast.ac.vn [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Duc, N.H.; Yen, N.H.; Thanh, P.T. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Bau, L.V.; An, N.M. [Hong Duc University, 565 Quang Trung, Dong Ve, Thanh Hoa (Viet Nam); Anh, D.T.K.; Bang, N.A.; Mai, N.T. [Faculty of Physics, VNU University of Science, 334 Nguyen Trai, Hanoi (Viet Nam); Anh, P.K. [Vietnam Academy of Military Science, 322 Le Trong Tan, Thanh Xuan, Hanoi (Viet Nam); Thanh, T.D. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi (Viet Nam); Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Phan, T.L. [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Yu, S.C., E-mail: scyu@chungbuk.ac.kr [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of)

    2015-01-15

    Magnetic and magnetocaloric properties in Ni{sub 50}Mn{sub 50−x}Sn{sub x} alloys with wide range of the Sn-concentration (x=0–40) were investigated. The alloys were prepared by arc-melting and subsequently annealing at 850 °C for 4 h. The X-ray diffraction analyses manifest the formation of the crystalline phases (Ni{sub 2}MnSn, NiMn, Ni{sub 3}Sn{sub 2}, Mn{sub 3}Sn, and MnSn{sub 2}) in the alloys with various compositions and fabrication conditions. With increasing x, the saturation magnetization first increases from near zero (at x=10) to above 40 emu/g (at x=20) and then decreases to below 10 emu/g (at x=40) for both the as-melted and annealed cases. The martensitic–austenitic transition was observed in the alloys with a narrow range of x (13–15). The magnetic transitions in the alloy can be controlled by changing Sn-concentration. The alloy reveals both the positive and negative entropy changes with quite large magnitude (∆S{sub m}>1 J/kg K with ∆H=12 kOe) with appropriate compositions and annealing conditions. - Highlights: • Crystalline phases and magnetic properties in Ni{sub 50}Mn{sub 50−x}Sn{sub x} alloys (x=0–40). • Simultaneous transitions of structural and magnetic phases. • Coexistence of positive and negative giant magnetocaloric effect in Heusler alloys. • Tuning giant magnetocaloric effect in room temperature region.

  2. Magnetic field in supernova remnant SN 1987A

    OpenAIRE

    Berezhko, E. G.; Ksenofontov, L. T.

    2006-01-01

    A nonlinear kinetic theory of cosmic ray (CR) acceleration in supernova remnants is employed to investigate the properties of the remnant SN 1987A. It is shown that a large downstream magnetic field ~10 mG is required to fit the existing observational data. Such a strong field together with the strong shock modification due to CR backreaction provides the steep and concave radioemission spectrum and considerable synchrotron cooling of high energy electrons which diminish their X-ray synchrotr...

  3. The improvement of the Li-ion insertion behaviour of Li{sub 1.05}Cr{sub 0.10}Mn{sub 1.85}O{sub 4} in an aqueous medium upon addition of vinylene carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Stojkovic, Ivana B.; Cvjeticanin, Nikola D.; Mentus, Slavko V. [University of Belgrade, Faculty of Physical Chemistry, Studentski Trg 12-16, Belgrade 11158 (RS)

    2010-03-15

    The influence of vinylene carbonate addition to aqueous LiNO{sub 3} solution on the Li-ion insertion performance of a Li{sub 1.05}Cr{sub 0.10}Mn{sub 1.85}O{sub 4} was studied by galvanostatic charging/discharging. Without additive, the coulombic capacity amounted initially to 80 mA h g{sup -1} and, during 50 galvanostatic charging/discharging cycles, decreased to 44.1% of the initial value. Upon VC addition in an amount of 1 wt.%, the initial discharge capacity of 112 mA h g{sup -1} was registered which after 100th charging/discharging cycles retained even 82% of the initial value. This is the first report of a successful use of an additive to improve the behaviour of a Li-intercalation material in an aqueous solution. (author)

  4. CASSCF/CI calculations for first row transition metal hydrides - The TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), FeH(4,6-delta) and NiH(2-delta) states

    Science.gov (United States)

    Walch, S. P.; Bauschlicher, C. W., Jr.

    1983-01-01

    Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.

  5. Stabilization of mercury over Mn-based oxides: Speciation and reactivity by temperature programmed desorption analysis

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Haomiao [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Ma, Yongpeng [Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, Zhengzhou University of Light Industry, No. 136, Science Avenue, Zhengzhou 450001 (China); Huang, Wenjun; Mei, Jian; Zhao, Songjian; Qu, Zan [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yan, Naiqiang, E-mail: nqyan@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2017-01-05

    Highlights: • Hg-TPD method was used for speciation of mercury species. • Different elements modified MnO{sub x} have different mercury binding state. • Understanding mercury existed state was beneficial for designing novel materials. - Abstract: Mercury temperature-programmed desorption (Hg-TPD) method was employed to clarify mercury species over Mn-based oxides. The elemental mercury (Hg{sup 0}) removal mechanism over MnO{sub x} was ascribed to chemical-adsorption. HgO was the primary mercury chemical compound adsorbed on the surface of MnO{sub x}. Rare earth element (Ce), main group element (Sn) and transition metal elements (Zr and Fe) were chosen for the modification of MnO{sub x}. Hg-TPD results indicated that the binding strength of mercury on these binary oxides followed the order of Sn-MnO{sub x} < Ce-MnO{sub x} ∼ MnO{sub x} < Fe-MnO{sub x} < Zr-MnO{sub x}. The activation energies for desorption were calculated and they were 64.34, 101.85, 46.32, 117.14, and 106.92 eV corresponding to MnO{sub x}, Ce-MnO{sub x}, Sn-MnO{sub x}, Zr-MnO{sub x} and Fe-MnO{sub x}, respectively. Sn-MnO{sub x} had a weak bond of mercury (Hg-O), while Zr-MnO{sub x} had a strong bond (Hg≡O). Ce-MnO{sub x} and Fe-MnO{sub x} had similar bonds compared with pure MnO{sub x}. Moreover, the effects of SO{sub 2} and NO were investigated based on Hg-TPD analysis. SO{sub 2} had a poison effect on Hg{sup 0} removal, and the weak bond of mercury can be easily destroyed by SO{sub 2}. NO was favorable for Hg{sup 0} removal, and the bond strength of mercury was enhanced.

  6. Structural transformations in intermetallic electrodes for lithium batteries : an in situ XRD study of lithiated MnSb and Mn{sub 2}Sb.

    Energy Technology Data Exchange (ETDEWEB)

    Fransson, L. M. L.; Vaughey, J. T.; Edstrom, K.; Thackeray, M. M.; Chemical Engineering; Uppsala Univ.

    2003-01-01

    The electrochemical reactions of lithium with MnSb (NiAs-type structure) and Mn{sub 2}Sb (Cu{sub 2}Sb-type structure) have been investigated by in situ X-ray diffraction. Lithiation of MnSb proceeds via an intermediate LiMnSb structure before transforming, with Mn extrusion, to Li{sub 3}Sb. The reaction is reversible. On delithiation, the X-ray data show solid-solution behavior between Li{sub 3}Sb and LiMnSb, which is facilitated by the strong structural relationship between these two compounds. MnSb electrodes deliver a rechargeable capacity of 330 mAh/g when cycled between 1.5 and 0 V vs. metallic lithium. By contrast, the initial reaction of Mn{sub 2}Sb with lithium proceeds almost directly to Li{sub 3}Sb with little LiMnSb formation. Thereafter, Mn{sub 2}Sb electrodes behave in an almost identical manner to MnSb electrodes, but deliver a rechargeable capacity of less than 300 mAh/g because of the surplus Mn in the electrode. The electrochemical and structural properties of MnSb and Mn{sub 2}Sb are compared with the structurally related compounds Cu{sub 6}Sn{sub 5} (NiAs-type structure) and Cu{sub 2}Sb, respectively.

  7. Red luminescence from ZnO : Cr nanophosphors under visible ...

    Indian Academy of Sciences (India)

    Administrator

    3+ nanophosphors under visible excitation. N PUSHPA1, M K KOKILA1,*, B M NAGABHUSHANA2, H NAGABHUSHANA3 and. A JAGANNATHA REDDY. 4 ... method at the temperature of 400°C. Powder X-ray diffraction results confirmed that Cr3+-doped and un- ... different transition metal dopants such as (Ni, Cr, Mn,.

  8. SnO{sub 2} foam grain-shaped nanoparticles: Synthesis, characterization and UVA light induced photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Abdelkader, Elaziouti, E-mail: elaziouti_a@yahoo.com [Laboratory of Electronic Microscope and Materials Science, University of Science and Technology of Oran (USTO M. B), BP 1505 El M' naouar, 31000 Oran (Algeria); Nadjia, Laouedj, E-mail: nlaouedj@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, University of Science and Technology of Oran (USTO M. B), BP 1505 El M' naouar, 31000 Oran (Algeria); Naceur, Benhadria, E-mail: nacer1974@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, University of Science and Technology of Oran (USTO M. B), BP 1505 El M' naouar, 31000 Oran (Algeria); Noureddine, Bettahar, E-mail: nbettahar2001@yahoo.fr [Laboratory of Inorganic Materials Chemistry and Application, University of Science and Technology of Oran (USTO M. B), BP 1505 El M' naouar, 31000 Oran (Algeria)

    2016-09-15

    Cassiterite (tin oxide; SnO{sub 2}) nanoparticles (NPs), has been successfully synthesized via a sol-gel method. The obtained compounds are subsequently calcined at 80, 450 and 650 °C for 4 h and are assigned as SnO{sub 2}-80, SnO{sub 2}-450 NPs and SnO{sub 2}-650 NPs, respectively. All prepared samples were characterized using thermogravimetric analysis coupled with mass spectroscopy (TG-SM), X-ray diffraction (XRD), scanning electron microscope (SEM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The XRD results confirmed the aggregated cassiterite SnO{sub 2} nanoparticles (NPs) with a size ranging from 13 to 23 nm. The absorption edge of the SnO{sub 2} NPs samples calcined at higher temperatures showed 25 nm (SnO{sub 2}-450 NPs) and 10 nm (SnO{sub 2}-650 NPs) red shifted compared with that of commercial SnO{sub 2}-com NPs sample. The photodegradation efficiency of SnO{sub 2} NPs was investigated using Congo red (CR) dye, as model organic pollutant. The effect of environmental factors (e.g., reaction time and calcination temperature) on the photocatalysis process of CR on SnO{sub 2} NPs was investigated in photocatalysis process under UVA light irradiation. We found that the SnO{sub 2}-650 NPs with 23 nm particle size and about 3.49 eV band gap was higher than that of the SnO{sub 2}-450 as well as the commercial SnO{sub 2}-com NPs. Pseudo-first-order kinetic model gave the best fit, with highest correlation coefficients (R{sup 2} ≥ 0.95). On the basis of the energy band diagram positions, the enhanced photodegradation efficiency SnO{sub 2} NPs catalyst could be proceeded via direct reactions with (O{sub 2}·{sup -} and ·OH), as active oxidative species involved in the photocatalysis process of CR dye under UVA-light irradiation. - Highlights: • SnO{sub 2} NPs photocatalysts were synthesized using a facile sol–gel route. • As-prepared SnO{sub 2} NPs were characterized by XRD, SEM and UV–vis-DRS techniques. • Noticeably UVA

  9. Bioaccumulation of Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn in trophosome and vestimentum of the tube worm Riftia pachyptila from Guaymas basin, Gulf of California

    Science.gov (United States)

    Ruelas-Inzunza, J.; Páez-Osuna, F.; Soto, Luis A.

    2005-07-01

    Twenty two specimens of vestimentiferan tube worms Riftia pachyptila were collected from Guaymas Basin. The distribution of ten trace metals in trophosome and vestimentum was investigated. Highest mean concentrations of Co, Cu and Fe were detected in the trophosome; while higher mean levels of Cd, Hg, Mn, Ni, Pb and Zn were measured in the vestimentum. However, the t-student test resulted in significant differences (p<0.05) only in the case of Co. Cd and Fe concentrations in vestimentum increased accordingly with the size of specimens. With respect to vent fluids, extreme uptake seems to be a characteristic of R. pachyptila in the case of Cu and Zn but not for the rest of the analyzed metals. Studies concerning accumulation mechanisms of trace metals in R. pachyptila are needed, particularly on the capacity of this organism to tolerate elevated levels of elements considered as non-essential.

  10. Structural, elastic and magnetic properties of Mn and Sb doped chromium nitride – An ab initio study

    Energy Technology Data Exchange (ETDEWEB)

    Ikram Un Nabi Lone; Sheik Sirajuddeen M Mohamed, E-mail: msheiksiraj@bsauniv.ac.in; Shameem Banu, I.B.; Sathik Basha, S.

    2017-05-01

    Structural, magnetic and elastic properties of Mn and Sb doped CrN were investigated by the electronic band structure calculations using Full Potential Linear Augmented Plane Wave (FP-LAPW) method. The host compound CrN was doped with Mn and Sb separately, in the doping concentration of 12.5% to replace Cr atoms. The introduction of Mn and Sb atoms replacing the Cr atoms does not change the structural stability of the compound. The changes in magnetic and elastic properties were investigated and compared in GGA and GGA+U methods. The doped CrN undergoes a relative increase in the magnetic order with the substitution of Mn and Sb atoms. In GGA method, the magnetic moments are found to be greater in Mn doped CrN than that found in Sb doped Cr{sub 0.875}NSb{sub 0.125}. When doped with Sb, the elastic moduli such as Young’s modulus, bulk modulus and rigidity modulus show a relative increase in comparison with that in Mn doped CrN. Using Hubbard model in GGA+U method, both the magnetic and elastic properties increase in Mn and Sb doped compounds. - Highlights: • Mn and Sb doped Chromium Nitride. • Structural properties. • Magnetic properties. • Elastic properties.

  11. Improving cycle stability of SnS anode for sodium-ion batteries by limiting Sn agglomeration

    Science.gov (United States)

    Wang, Wenhui; Shi, Liang; Lan, Danni; Li, Quan

    2018-02-01

    Flower-like SnS nanostructures are obtained by a simple solvothermal method for anode applications in Na-ion batteries. We show experimental evidence of progressive Sn agglomeration and crystalline Na2S enrichment at the end of de-sodiation process of the SnS electrode, both of which contribute to the capacity decay of the electrode upon repeated cycles. By replacing the commonly adopted acetylene black conductive additive with multi-wall carbon nanotubes (MWCNT), the cycle stability of the SnS electrode is largely improved, which correlates well with the observed suppression of both Sn agglomeration and Na2S enrichment at the end of de-sodiation cycle. A full cell is assembled with the SnS/MWCNT anode and the P2-Na2/3Ni1/3Mn1/2Ti1/6O2 cathode. An initial energy density of 262 Wh/kg (normalized to the total mass of cathode and anode) is demonstrated for the full cell, which retains 71% of the first discharge capacity after 40 cycles.

  12. Enhancing the Ductility of Sn-Ag-Cu Lead-Free Solder Joints by Addition of Compliant Intermetallics

    Science.gov (United States)

    Xie, H. X.; Chawla, N.

    2013-03-01

    Tin (Sn)-rich lead (Pb)-free solders containing rare-earth (RE) elements have been shown to exhibit desirable attributes of microstructural refinement and enhanced ductility relative to conventional Sn-3.9Ag-0.7Cu lead-free solder, due to the unique mechanical properties of RE-Sn intermetallics. However, the roles of soft intermetallic phase in the enhanced ductility of Pb-free solder still need to be further investigated. In this paper, Ca and Mn were selected as doping elements for Sn-Ag-Cu solder. The mechanical properties of Ca-Sn and Mn-Sn intermetallics as a function of indentation depth were measured by nanoindentation using the continuous stiffness method (CSM). The microstructure and mechanical properties of as-reflowed Ca- and Mn-containing Sn-Ag-Cu solder joints were studied and compared with those of conventional Sn-Ag-Cu and RE-containing solder joints. It is shown that soft intermetallics result in higher ductility in Pb-free solders.

  13. Thin film nano-photocatalyts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B  =  Fe, Mn, and Co)

    Science.gov (United States)

    Loc Luu, Cam; Thuy Van Nguyen, Thi; Nguyen, Tri; Nguyen, Phung Anh; Hoang, Tien Cuong; Ha, Cam Anh

    2018-03-01

    By dip-coating technique the thin films of nano-photocatalysts TiO2, Cr-doped TiO2, LaBO3 perovskites (B  =  Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, TGA, Raman and UV–vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ  =  365 nm) and LED lamps (λ  =  400–510 nm). The obtained results showed that TiO2 and TiO2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10–100 nm. Doping TiO2 with 0.1%mol Cr2O3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (λ  =  622 nm). LaBO3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8–40 nm, a BET surface area of 17.6–32.7 m2 g‑1 and band gap energy of 1.87–2.20 eV. UiO66-NH2 was obtained in the ball shape of 100–200 nm, a BET surface area of 576 m2 g‑1 and a band gap energy of 2.83 eV. The low band gap energy nano-photocatalysts based on Cr-doped TiO2 and LaBO3 perovskites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV–vis light. Perovskite LaFeO3 and Cr–TiO2 thin films were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene/g cat.

  14. Influencia de la distribución de precipitados de Al (Mn, Fe, Cr en la reproducibilidad de la respuesta electroquímica de la aleación AA5083 en disolución de NaCl

    Directory of Open Access Journals (Sweden)

    Aballe, A.

    2002-04-01

    Full Text Available The corrosion behavior of alloy AA5083 in solutions of NaCl at 3.5% is controlled by the cathodic precipitates of Al(Mn, Fe, Cr present in the alloy. These precipitates are not distributed homogeneously on the surface of the alloy. Further, their presence influence the electrochemical response of the alloy. For these reasons, in order to guarantee the reproducibility of electrochemical tests on this alloy, it is necessary to determine the minimum surface area exposed to the medium, which represents the average behavior of the system. In the present study, a systematic analysis has been conducted of the degree of reproducibility of OCP and LP tests as a function of the area of surface exposed for the alloy AA5083 in solutions of NaCl at 3.5%. The results obtained from three sizes of area studied indicate that the minimum area available for exposure required to provide results of good reproducibility is 25.5 cm2.

    El comportamiento frente a la corrosión de la aleación AA5083 en disoluciones de NaCl al 3,5 % está controlado por los precipitados de Al(Mn, Fe, Cr presentes en la misma. Estos precipitados no se encuentran homogéneamente distribuidos en la superficie de la aleación, debido al tipo de proceso de conformado de la misma. Por otra parte, su presencia condiciona la respuesta electroquímica de la aleación. Por estas razones, para garantizar la reproducibilidad de los ensayos electroquímicos sobre esta aleación, es necesario que el área de la superficie expuesta al medio represente el comportamiento medio del sistema. En el presente trabajo se ha llevado a cabo un estudio sistemático del grado de reproducibilidad de ensayos OCP y LP en función del área de superficie expuesta para la aleación AA5083 en disolución de NaCl al 3,5 %. De acuerdo con los resultados obtenidos, se requiere disponer de un mínimo de 25,5 cm2 de exposición para garantizar la reproducibilidad de los resultados.

  15. Atom transfer as a preparative tool in coordination chemistry. Synthesis and characterization of Cr(V) nitrido complexes of bidentate ligands

    DEFF Research Database (Denmark)

    Birk, Torben; Bendix, Jesper

    2003-01-01

    The transfer of a terminal nitrido ligand from MnV(N)(salen) to Cr(III) complexes is explored as a new preparative route to CrV nitrido complexes. Reaction of MnV(N)(salen) with labile CrCl3(THF)3 in acetonitrile solution precipitate [Mn(Cl)(salen)]·(CH3CN) and yields a solution containing a mixt...

  16. Temperature dependent electrical characteristics of an organic-inorganic heterojunction obtained from a novel organometal Mn complex

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, Y.S., E-mail: yusufselim@gmail.co [Department of Science, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Ebeoglu, M.A. [Department of Electrical and Electronics Engineering, Faculty of Engineering, University of Dumlupinar, Kutahya (Turkey); Topal, G. [Department of Chemistry, Faculty of Education, University of Dicle, Diyarbakir (Turkey); Kilicoglu, T., E-mail: tahsin@dicle.edu.t [Department of Physics, Faculty of Art and Science, University of Dicle, Diyarbakir (Turkey); Department of Physics, Faculty of Art and Science, University of Batman, Batman (Turkey)

    2010-05-01

    This study includes synthesizing a Mn hexaamide (MnHA) organometal compound (C{sub 27}H{sub 21}N{sub 9}O{sub 6}MnCl{sub 2}).(1/2H{sub 2}O), fabrication of MnHA/n-Si organic-inorganic heterojunction and analysis of conduction mechanism of the device over the room temperature. After synthesizing the molecule, the structure of the compound was determined using spectroscopic methods. The Sn/MnHA/n-Si structure was constructed by forming a thin MnHA layer on n-Si inorganic semiconductor and evaporating Sn metal on organic complex. The structure has shown good rectifying behavior and obeys the thermionic emission theory. The current-voltage (I-V) characteristics of the diode have been measured at temperatures ranging from 300 to 380 K at 10 K intervals to determine the temperature dependent electrical characteristics of the device.

  17. Synthesis, photocatalytic and antimicrobial properties of SnO2, SnS2 and SnO2/SnS2 nanostructure.

    Science.gov (United States)

    Fakhri, Ali; Behrouz, Sajjad; Pourmand, Melika

    2015-08-01

    Nanoscale SnO2, SnS2 and SnO2/SnS2 were synthesized by hydrothermal treatment method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH) and UV-vis spectra. The photocatalytic activity of SnO2, SnS2 and SnO2/SnS2 were tested with Enrofloxacin antibiotic. The tetragonal and hexagonal SnO2 and SnS2 phase was confirmed through XRD, respectively. The photocatalytic results indicated that the SnO2/SnS2 enhanced the photocatalytic activity and could be effectively used as photocatalyst for degradation of Enrofloxacin antibiotic pollutant. The results of antibacterial experiment under visible light irradiation demonstrate that the SnO2/SnS2 nanocomposite exhibit enhanced antibacterial efficiency compared with pure SnO2 and SnS2. The antifungal activity of the nanoscale SnO2, SnS2 and SnO2/SnS2 against Candida albicans was assessed using the disc-diffusion susceptibility tests. It was seen that the antifungal activity of SnO2/SnS2 nanocomposite is higher than the pure SnO2 and SnS2 toward pathogenic C. albicans. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Structures of Mn clusters

    Indian Academy of Sciences (India)

    Abstract. The geometries of several Mn clusters in the size range Mn13–Mn23 are studied via the generalized gradient approximation to density functional theory. For the 13- and 19-atom clusters, the icosahedral structures are found to be most stable, while for the 15-atom cluster, the bcc structure is more favoured.

  19. Structures of Mn clusters

    Indian Academy of Sciences (India)

    Unknown

    Abstract. The geometries of several Mn clusters in the size range Mn13–Mn23 are studied via the generalized gradient approximation to density functional theory. For the 13- and 19-atom clusters, the icosahedral struc- tures are found to be most stable, while for the 15-atom cluster, the bcc structure is more favoured.

  20. Characteristics of radiation porosity and structural phase state of reactor austenitic 07C-16Cr-19Ni-2Mo-2Mn-Ti-Si-V-P-B Steel after neutron irradiation at a temperature of 440-600°C to damaging doses of 36-94 dpa

    Science.gov (United States)

    Portnykh, I. A.; Panchenko, V. L.

    2016-06-01

    The phase composition and the characteristics of vacancy voids in cold-worked steel 07C-16Cr-19Ni-2Mo-2Mn-Ti-Si-V-P-B (CW EK164-ID) after neutron irradiation at damaging doses of 36-94 dpa and temperatures of 440-600°C are investigated. In the entire range of damaging doses and temperatures, voids with different sizes are observed in the material. The maximum void size increases with irradiation temperature up to ~550°C, whereas their concentration decreases. At higher irradiation temperatures, almost no coarse voids are observed. The concentration of fine voids (to 10 nm in size) sharply increases with temperature from 440 to 480°C. Further increases in the temperature do not result in the noticeable concentration growth. In the irradiation temperature range of 440-515°C, second phases precipitate ( G phase, γ' phase, and complex fcc carbides). At higher irradiation temperatures, there are Laves-phase particles, fine second carbides of the MC type, and needle shape precipitates identified as phosphides in the material.

  1. Comparison of structural and magnetic properties of Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} spinel oxides

    Energy Technology Data Exchange (ETDEWEB)

    Thummer, K. P., E-mail: kpthummer@yahoo.co.in [Department of Electronics, Saurashtra University, Rajkot-360005 (India); Tanna, A. R., E-mail: ashish.tanna@rku.ac.in [School of Science, RK University, Rajkot (India); Joshi, H. H. [Department of Physics, Saurashtra University, Rajkot-360005 (India)

    2016-05-23

    The spinel oxides Zn{sub x}Mg{sub 1.5-x}Mn{sub 0.5}FeO{sub 4} (x = 0.0 to 0.6) and MgAl{sub x}Cr{sub x}Fe{sub 2-2x}O{sub 4} (x = 0.0 to 0.6) abbreviated as ZMMFO and MACFO respectively, were synthesized by standard ceramic processing. The compositional purity of all the specimens was checked by EDAX technique. The X-ray diffractometry was employed to determine the lattice constants and distribution of cations in the interstitial voids. The initial decrease of cell edge parameter (a) for ZMMFO up to x = 0.2 and thereafter expected rise in the ‘a’ and the initial slower rate of reduction in the lattice constant for MACFO are explained as basic of cation occupancy. The magnetic ordering in both systems is explained by invoking statistical canting models. The compositional variation of magneton number (n{sub B}) for ZMMFO could be very well explained by Localized canting of spin (LCS) model while Random canting of spin (RCS) model was used for MACFO system.

  2. Magnetic and magnetocaloric properties of Fe5-xMnxSn3

    Science.gov (United States)

    Dianoux, Alexy; Malaman, Bernard; Mazet, Thomas

    2017-07-01

    We investigate the crystal, magnetic and magnetocaloric properties of the Fe5-xMnxSn3 series (0 ≤ x ≤ 5) from X-ray diffraction and DC magnetization experiments. The alloys crystallize with the lacunar Ni2In type of structure (P 63 / mmc). The diffraction patterns of the richer Fe alloys (x ≤ 2) contain tiny superstructure lines due to ordering of T atoms and vacancies within the partially filed 2d position. The Curie temperatures decrease in a non-monotonous manner with the Mn content from 544 K in Fe5Sn3 down to 190 K in Fe1Mn4Sn5, before increasing again up to 219 K in Mn5Sn3. While most of the alloys behave as simple ferromagnets, low-field thermomagnetization data show that the Fe5-xMnxSn3 alloys with intermediate compositions (x=2.5 and 3) undergo two close ferromagnetic-like transitions. The magnetocaloric effect is of moderate magnitude ( 1 J kg-1 K-1 for μ0 ΔH = 2 T). The results are compared with previously published data and briefly discussed in view of potential high-temperature magnetocaloric applications.

  3. Magnetic interactions in martensitic Ni-Mn based Heusler systems

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, Seda

    2010-04-22

    In this work, magnetic, magnetocaloric and structural properties are investigated in Ni-Mn-based martensitic Heusler alloys with the aim to tailor these properties as well as to understand in detail the magnetic interactions in the various crystallographic states of these alloys. We choose Ni{sub 50}Mn{sub 34}In{sub 16} as a prototype which undergoes a martensitic transformation and exhibits field-induced strain and the inverse magnetocaloric effect. Using the structural phase diagram of martensitic Ni-Mn-based Heusler alloys, we substitute gallium and tin for indium to carry these effects systematically closer to room temperature by shifting the martensitic transformation. A magneto-calorimeter is designed and built to measure adiabatically the magnetocaloric effect in these alloys. The temperature dependence of strain under an external magnetic field is studied in Ni{sub 50}Mn{sub 50-x}Z{sub x} (Z: Ga, Sn, In and Sb) and Ni{sub 50}Mn{sub 34}In{sub 16-x}Z{sub x} (Z: Ga and Sn). An argument based on the effect of the applied magnetic field on martensite nucleation is adopted to extract information on the direction of the magnetization easy axis in the martensitic unit cell in Heusler alloys. Parallel to these studies, the structure in the presence of an external field is also studied by powder neutron diffraction. It is demonstrated that martensite nucleation is influenced by cooling the sample under a magnetic field such that the austenite phase is arrested within the martensitic state. The magnetic interactions in Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 40}Sb{sub 10} are characterized by using neutron polarization analysis. Below the martensitic transformation temperature, M{sub s}, an antiferromagnetically correlated state is found. Ferromagnetic resonance experiments are carried out on Ni{sub 50}Mn{sub 37}Sn{sub 13} and Ni{sub 50}Mn{sub 34}In{sub 16} to gain more detailed information on the nature of the magnetic interactions. The experimental

  4. Limits of Nb3Sn Accelerator Magnets

    CERN Document Server

    Caspi, Shlomo

    2005-01-01

    Pushing accelerator magnets beyond 10T holds a promise of future upgrades to machines like the Tevatron at FermiLab and the LHC at CERN. Exhausting the current density limits of NbTi, superconductor, Nb3Sn is at the present time the only practical superconductor capable of generating fields beyond 10T. Several Nb3Sn pilot magnets, with fields as high as 16T, have been built and tested, paving the way for future attempts at fields approaching 20T. The combination of high current density and the required high magnetic fields has resulted in reduced conductor volume and significantly increased the accumulated Lorentz forces. Future coil and structure designs will be required to deal with stresses of several 100’s of MPa and forces of 10’s of MN/m. The combined engineering requirements on size and cost of accelerator magnets will require a magnet technology that diverges from the one currently used with NbTi conductor. How far can the engineering of high field magnets be pushed, what are the i...

  5. Reactive-template fabrication of porous SnO2 nanotubes and their remarkable gas-sensing performance.

    Science.gov (United States)

    Zhang, Jun; Guo, Jing; Xu, Hongyan; Cao, Bingqiang

    2013-08-28

    A facile reactive-template strategy has been developed to fabricate porous SnO2 nanotubes using MnO2 nanorods as the sacrificial template. The formation of nanotubes is based on the redox reaction mechanism, which requires no post-treatment of the MnO2 templates. The morphological and structural characteristics of the samples have been systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal-gravimetric (TG), and N2 adsorption-desorption techniques. A gas-sensor device was constructed using as-prepared SnO2 nanotubes and was tested for its ability to detect ethanol and some other compounds. Because of the porous structure and relative large specific surface area, the SnO2 nanotube sensor manifests remarkably improved sensing performance, including fast response recovery, high sensitivity, and excellent repeatability, suggesting the promising application of the SnO2 nanotube materials.

  6. High-Performance Corrosion-Resistant Iron-Based Amorphous Metals - The Effects of Composition, Structure and Environment: Fe49.7Cr17.7Mn1.9Mo7.4W1.6B15.2C3.8Si2.4

    Energy Technology Data Exchange (ETDEWEB)

    Farmer, J; Haslam, J; Day, S; Lian, T; Saw, C; Hailey, P; Choi, J; Yang, N; Bayles, R; Aprigliano, L; Payer, J; Perepezko, J; Hildal, K; Lavernia, E; Ajdelsztajn, L; Branagan, D J; Beardsely, M B

    2006-10-20

    Several Fe-based amorphous metal formulations have been identified that appear to have corrosion resistance comparable to (or better than) that of Ni-based Alloy C-22 (UNS No. N06022), based on measurements of breakdown potential and corrosion rate in seawater. Both chromium (Cr) and molybdenum (Mo) provide corrosion resistance, boron (B) enables glass formation, and rare earths such as yttrium (Y) lower critical cooling rate (CCR). SAM2X5 (Fe{sub 49.7}Cr{sub 17.7}Mn{sub 1.9}Mo{sub 7.4}W{sub 1.6}B{sub 15.2}C{sub 3.8}Si{sub 2.4}) has no yttrium, and is characterized by relatively high critical cooling rates of approximately 600 Kelvin per second. Data for the SAM2X5 formulation is reported here. In contrast to yttrium-containing iron-based amorphous metals, SAM2X5 can be readily gas atomized to produce spherical powders which enable more facile thermal spray deposition. The reference material, nickel-based Alloy C-22, is an outstanding corrosion-resistant engineering material. Even so, crevice corrosion has been observed with C-22 in hot sodium chloride environments without buffer or inhibitor. SAM2X5 also experiences crevice corrosion under sufficiently harsh conditions. Both Alloy C-22 and Type 316L stainless lose their resistance to corrosion during thermal spraying, due to the formation of deleterious intermetallic phases which depletes the matrix of key alloy elements, whereas SAM2X5 can be applied as coatings with the same corrosion resistance as a fully-dense completely amorphous melt-spun ribbon, provided that its amorphous nature is preserved during thermal spraying. The hardness of Type 316L Stainless Steel is approximately 150 VHN, that of Alloy C-22 is approximately 250 VHN, and that of HVOF SAM2X5 ranges from 1100-1300 VHN [MRS12-13]. Such hardness makes these materials particularly attractive for applications where corrosion-erosion and wear are also issues. Since SAM2X5 has high boron content, it can absorb neutrons efficiently, and may therefore find

  7. Phase relations in the pseudobinary systems RAO3-R2Ti2O7 (R: rare earth element and Y, A: Fe, Ga, Al, Cr and Mn) and syntheses of new compounds R(A1-xTix)O3+x/2 (2/3≤x≤3/4) at elevated temperatures in air

    Science.gov (United States)

    Brown, Francisco; Jacobo-Herrera, Ivan; Alvarez-Montaño, Victor; Kimizuka, Noboru; Kurashina, Keiji; Michiue, Yuichi; Matsuo, Yoji; Mori, Shigeo; Ikeda, Naoshi; Medrano, Felipe

    2017-07-01

    Phase relations in the pseudo-binary systems RFeO3-R2Ti2O7 (R: Lu, Ho and Dy), RGaO3-R2Ti2O7 (R: Lu and Er), LuAlO3-Lu2Ti2O7 and RAO3-R2Ti2O7 (R: Lu and Yb. A: Cr and Mn) at elevated temperatures in air were determined by means of a classic quenching method. There exist Lu(Fe1-xTix)O3+x/2, R(Ga1-xTix)O3+x/2 (R: Lu and Er) and Lu(Al1-xTix)O3+x/2 (2/3≤ x≤3/4) having the Yb(Fe1-xTix)O3+x/2-type of crystal structure (x=0.72, space group: R3m, a(Å)=17.9773 and c(Å)=16.978 as a hexagonal setting) in these pseudo binary systems. Eighteen compounds R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) were newly synthesized and their lattice constants as a hexagonal setting were measured by means of the X-ray powder diffraction method. The R occupies the octahedral site and both A and Ti does the trigonalbipyramidal one in these compounds. Relation between lattice constants for the rhombic R(A1-xTix)O3+x/2 and the monoclinic In(A1-xTix)O3+x/2 are as follows, ah≈5 x bm, ch≈3 x cm x sin β and am=31/2 x bm, where ah and ch are the lattice constants as a hexagonal setting for R(A1-xTix)O3+x/2 and am, bm, cm and β are those of the monoclinic In(A1-xTix)O3+x/2. Crystal structural relationships among α-InGaO3 (hexagonal, high pressure form, space group: P63/mmc), InGaO3 (rhombic, hypothetical), (RAO3)n(BO)m and RAO3(ZnO)m (R: Lu-Ho, Y and In, A: Fe, Ga, and Al, B: divalent cation element, m, n: natural number), the orthorhombic-and monoclinic In(A1-xTix)O3+x/2 (A: Fe, Ga, Al, Cr and Mn) and the hexagonal-and rhombic R(A1-xTix)O3+x/2 (R: Lu-Sm and Y, A: Fe, Ga and Al) are schematically presented. We concluded that the crystal structures of both the α-InGaO3 (high pressure form, hexagonal, space group: P63/mmc) and the hypothetical InGaO3 (rhombic) are the key structures for constructing the crystal structures of these compounds having the cations with CN=5.

  8. Speciation of Cr, Fe, Cu, Pb in the surface and under water sediment ...

    African Journals Online (AJOL)

    ... and carbonate bound fractions (2.01 µg/g and 4.02 µg/g) respectively. The result also indicated an increase in Cr concentrations at Fe-Mn oxide fraction of the bottom sediment (14.04 µg/g) compared to the surface sediment where Cr was not detected at the Fe-Mn oxide phase. Copper and Pb were generally not detected ...

  9. The role of particle size on the electrochemical properties at 25 and at 55 deg. C of the LiCr{sub 0.2}Ni{sub 0.4}Mn{sub 1.4}O{sub 4} spinel as 5 V-cathode materials for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Aklalouch, Mohamed [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain); ECME, Faculte des Sciences et Techniques Marrakech, Universite Cadi Ayyad, Av. A. El Khattabi, B.P.549 Marrakech (Morocco); Rojas, Rosa M.; Rojo, Jose Maria [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain); Saadoune, Ismael [ECME, Faculte des Sciences et Techniques Marrakech, Universite Cadi Ayyad, Av. A. El Khattabi, B.P.549 Marrakech (Morocco); Amarilla, Jose Manuel, E-mail: amarilla@icmm.csic.e [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC) c/Sor Juana Ines de la Cruz, 3 28049-Madrid (Spain)

    2009-12-01

    The role of the particle size on the electrochemical properties at 25 and at 55 deg. C of the LiCr{sub 0.2}Ni{sub 0.4}Mn{sub 1.4}O{sub 4} spinel synthesized by combustion method has been determined. Samples with different particle size were obtained by heating the raw spinel from 700 to 1100 deg. C, for 1 h in air. X-ray diffraction patterns revealed that all the prepared materials are single-phase spinels. The main effect of the thermal treatment is the remarkable increase of the particles size from approx60 to approx3000 nm as determined by transmission electron microscopy. The electrochemical properties were determined at high discharge currents (1C rate) in two-electrode Li-cells. At 25 and at 55 deg. C, in spite of the great differences in particle size, the discharge capacity drained by all samples is similar (Q{sub dch} approx 135 mAh g{sup -1}). Instead, the cycling performances strongly change with the particle size. The spinels with PHI > 500 nm show better cycling stability at 25 and at 55 deg. C than those with PHI < 500 nm. The samples heated at 1000 and 1100 deg. C, with high potential (E approx 4.7 V), elevate capacity (Q approx 135 mAh g{sup -1}), and remarkable cycling performances (capacity retention after 250 cycles >96%) are very attractive materials as 5V-cathodes for high-energy Li-ion batteries.

  10. Good thermoelectric performance in strongly correlated system SnCCo3 with antiperovskite structure.

    Science.gov (United States)

    Lin, Shuai; Tong, Peng; Wang, Bosen; Lin, Jianchao; Huang, Yanan; Sun, Yuping

    2014-04-07

    We report the magnetic, electrical, and thermoelectric properties of SnCCo3, where good thermoelectric performance [figure of merit ZT ∼ 0.035(2), 258 K] and strong electron correlation (Kadowaki-Woods ratio RKW ∼ 4a0) are observed. The thermoelectric properties of ACCo3 (A = Al, Ga, Ge) and SnCM3 (M = Mn, Fe) were also investigated for comparison. As a result, the ZT value of SnCCo3 is the largest among all of those samples, which is mainly attributed to the large Seebeck coefficient caused by the strong electron correlation and low carrier density. Moreover, the ZT value can be effectively enhanced by proper chemical doping in SnCCo3.

  11. Epitaxial Growth of Hard Ferrimagnetic Mn3Ge Film on Rhodium Buffer Layer

    Directory of Open Access Journals (Sweden)

    Atsushi Sugihara

    2015-06-01

    Full Text Available Mn\\(_3\\Ge has a tetragonal Heusler-like D0\\(_{22}\\ crystal structure, exhibiting a large uniaxial magnetic anisotropy and small saturation magnetization due to its ferrimagnetic spin structure; thus, it is a hard ferrimagnet. In this report, epitaxial growth of a Mn\\(_3\\Ge film on a Rh buffer layer was investigated for comparison with that of a film on a Cr buffer layer in terms of the lattice mismatch between Mn\\(_3\\Ge and the buffer layer. The film grown on Rh had much better crystalline quality than that grown on Cr, which can be attributed to the small lattice mismatch. Epitaxial films of Mn\\(_3\\Ge on Rh show somewhat small coercivity (\\(H_{\\rm c}\\ = 12.6 kOe and a large perpendicular magnetic anisotropy (\\(K_{\\rm u}\\ = 11.6 Merg/cm\\(^3\\, comparable to that of the film grown on Cr.

  12. Linear M[triple bond]E-Me versus bent M-E-Me: bonding analysis in heavier metal-ylidyne complexes [(Cp)(CO)2M[triple bond]EMe] and metallo-ylidenes [(Cp)(CO)3M-EMe] (M = Cr, Mo, W; E = Si, Ge, Sn, Pb).

    Science.gov (United States)

    Pandey, Krishna K; Lledós, Agustí

    2009-04-06

    The electronic and molecular structures of the complexes [(eta(5)-C(5)H(5))(CO)(2)M[triple bond]EMe] and [(eta(5)-C(5)H(5))(CO)(3)M-EMe] (M = Cr, Mo, W; E = Si, Sn, Pb) are calculated at the density-functional theory (DFT) level using the exchange correlation functionals B3LYP and BP86. The theoretically predicted bond lengths and angles of the model compounds are in excellent agreement with experimental values. The calculations reveal the presence of a strong M[triple bond]E triple (sigma + 2pi) bond in [(eta(5)-C(5)H(5))(CO)(2)M[triple bond]EMe]. The M-E bond lengths in [(eta(5)-C(5)H(5))(CO)(3)M-EMe] are longer than those expected for a single bond. The nature of the M[triple bond]EMe and M-EMe interactions was analyzed with charge and energy decomposition methods. In the M[triple bond]EMe bond, the M-E sigma-bonding orbitals are always polarized toward the silicon, tin, and lead atoms, and the polarization increases from chromium to tungsten. In contrast, in the M-EMe bond, the M-E sigma-bonding orbitals are significantly polarized toward the metal atom. The hybridization at the metal atoms in the M[triple bond]E bonds has d character in the range 60.6-68.8%, while in the M-E bonds has large d character which is always >86% of the total atomic orbital contribution. In the complexes [(eta(5)-C(5)H(5))(CO)(2)M[triple bond]EMe], the contributions of the electrostatic interactions, DeltaE(elstat), and the covalent bonding, DeltaE(orb), have nearly the same values for silylidyne and germylidyne complexes, while for the stannylidyne and plumbylidyne complexes, the electrostatic interactions, DeltaE(elstat), are greater than the orbital interaction, DeltaE(orb). The covalent bonding has a high degree of pi-character. The total interaction energy DeltaE(int) in the compound [(eta(5)-C(5)H(5))(CO)(3)M-EMe] is less attractive than those in the complexes [(eta(5)-C(5)H(5))(CO)(2)M[triple bond]EMe]. The M-ER bonds have a slightly lower degree of covalent bonding (34

  13. Texture-Etched SnO2 Glasses Applied to Silicon Thin-Film Solar Cells

    Directory of Open Access Journals (Sweden)

    Bing-Rui Wu

    2014-01-01

    Full Text Available Transparent electrodes of tin dioxide (SnO2 on glasses were further wet-etched in the diluted HCl:Cr solution to obtain larger surface roughness and better light-scattering characteristic for thin-film solar cell applications. The process parameters in terms of HCl/Cr mixture ratio, etching temperature, and etching time have been investigated. After etching process, the surface roughness, transmission haze, and sheet resistance of SnO2 glasses were measured. It was found that the etching rate was increased with the additions in etchant concentration of Cr and etching temperature. The optimum texture-etching parameters were 0.15 wt.% Cr in 49% HCl, temperature of 90°C, and time of 30 sec. Moreover, silicon thin-film solar cells with the p-i-n structure were fabricated on the textured SnO2 glasses using hot-wire chemical vapor deposition. By optimizing the texture-etching process, the cell efficiency was increased from 4.04% to 4.39%, resulting from the increment of short-circuit current density from 14.14 to 15.58 mA/cm2. This improvement in cell performances can be ascribed to the light-scattering effect induced by surface texturization of SnO2.

  14. Cation/Anion Substitution in Cu2ZnSnS4 for Improved Photovoltaic Performance

    Science.gov (United States)

    Ananthoju, Balakrishna; Mohapatra, Jeotikanta; Jangid, Manoj K.; Bahadur, D.; Medhekar, N. V.; Aslam, M.

    2016-01-01

    Cations and anions are replaced with Fe, Mn, and Se in CZTS in order to control the formations of the secondary phase, the band gap, and the micro structure of Cu2ZnSnS4. We demonstrate a simplified synthesis strategy for a range of quaternary chalcogenide nanoparticles such as Cu2ZnSnS4 (CZTS), Cu2FeSnS4 (CFTS), Cu2MnSnS4 (CMTS), Cu2ZnSnSe4 (CZTSe), and Cu2ZnSn(S0.5Se0.5)4 (CZTSSe) by thermolysis of metal chloride precursors using long chain amine molecules. It is observed that the crystal structure, band gap and micro structure of the CZTS thin films are affected by the substitution of anion/cations. Moreover, secondary phases are not observed and grain sizes are enhanced significantly with selenium doping (grain size ~1 μm). The earth-abundant Cu2MSnS4/Se4 (M = Zn, Mn and Fe) nanoparticles have band gaps in the range of 1.04–1.51 eV with high optical-absorption coefficients (~104 cm−1) in the visible region. The power conversion efficiency of a CZTS solar cell is enhanced significantly, from 0.4% to 7.4% with selenium doping, within an active area of 1.1 ± 0.1 cm2. The observed changes in the device performance parameters might be ascribed to the variation of optical band gap and microstructure of the thin films. The performance of the device is at par with sputtered fabricated films, at similar scales. PMID:27748406

  15. ASSESSMENT OF THE CONCENTRATION OF Cr, Mn AND Fe IN ...

    African Journals Online (AJOL)

    Preferred Customer

    , Ethiopia. 2Department of ... Quantification of these metals was conducted against certified reference materials of sediments and soils. The .... stain textile and fixtures that can cause permanent damage on industrial boilers, equipment and.

  16. Atomic resolution imaging of precipitate transformation from cubic TaN to tetragonal CrTaN

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John; Somers, Marcel A. J.

    2012-01-01

    In 9–12% Cr creep-resistant steels Cr(V,Nb,Ta)N Z-phase is known to replace metastable (V,Nb,Ta)N MN precipitates at high temperatures. The precipitation process of Z-phase does not follow the classical nucleation theory, where dissolving MN particles provide constituents for Z-phase nucleation...... in the matrix. Using atomic resolution transmission electron microscopy, the current work demonstrates that metastable cubic TaN precipitates in a complex steel gradually transform compositionally and crystallographically into stable tetragonal CrTaN precipitates under the influence of Cr indiffusion from...... the steel matrix....

  17. Rates of Cr(VI) Generation from CrxFe1-x(OH)3Solids upon Reaction with Manganese Oxide.

    Science.gov (United States)

    Pan, Chao; Liu, Huan; Catalano, Jeffrey G; Qian, Ao; Wang, Zimeng; Giammar, Daniel E

    2017-11-07

    The reaction of manganese oxides with Cr(III)-bearing solids in soils and sediments can lead to the natural production of Cr(VI) in groundwater. Building on previous knowledge of MnO 2 as an oxidant for Cr(III)-containing solids, this study systematically evaluated the rates and mechanisms of the oxidation of Cr(III) in iron oxides by δ-MnO 2 . The Fe/Cr ratio (x = 0.055-0.23 in Cr x Fe 1-x (OH) 3 ) and pH (5-9) greatly influenced the Cr(VI) production rates by controlling the solubility of Cr(III) in iron oxides. We established a quantitative relationship between Cr(VI) production rates and Cr(III) solubility of Cr x Fe 1-x (OH) 3 , which can help predict Cr(VI) production rates at different conditions. The adsorption of Cr(VI) and Mn(II) on solids shows a typical pH dependence for anions and cations. A multichamber reactor was used to assess the role of solid-solid contact in Cr x Fe 1-x (OH) 3 -MnO 2 interactions, which eliminates the contact of the two solids while still allowing aqueous species transport across a permeable membrane. Cr(VI) production rates were much lower in multichamber than in completely mixed batch experiments, indicating that the redox interaction is accelerated by mixing of the solids. Our results suggest that soluble Cr(III) released from Cr x Fe 1-x (OH) 3 solids to aqueous solution can migrate to MnO 2 surfaces where it is oxidized.

  18. Observation of magnetization reversal and magnetocaloric effect in manganese modified EuCrO3 orthochromites

    Science.gov (United States)

    Kumar, Surendra; Coondoo, Indrani; Vasundhara, M.; Puli, Venkata S.; Panwar, Neeraj

    2017-08-01

    We report here an investigation on the structural, magnetic and magnetocaloric properties of Mn doped EuCr0.85Mn0.15O3 (ECMO) chromites synthesized via ceramic route. The compound crystallized into distorted orthorhombic structure with Pnma space group similar to that of its parent EuCrO3 compound, as revealed from the refined of x-ray powder diffraction pattern, but with an increase in the lattice volume. Neel temperature, noticed at 162 K from the temperature variation of magnetization, smaller than that reported for pristine EuCrO3; indicated the influence of Mn3+ substitution in decreasing the antiferromagnetic ordering. Magnetization reversal evolved in the studied compound under lower field while such feature was absent in the undoped EuCrO3. Magnetocaloric effect was measured through the magnetic entropy change and relative cooling power. Near the spin reorientation transition temperature 40 K, the magnetic entropy change was equal to 3.788 J kg-1 K-1 under 90 kOe field with 215.22 J kg-1relative cooling power. The results have been understood in terms of the competition between Cr-rich clusters, Mn-rich clusters and local Mn-Cr ordered clusters and their different temperature dependency.

  19. From single- to double-first-order magnetic phase transition in magnetocaloric Mn1?xCrxCoGe compounds

    NARCIS (Netherlands)

    Trung, N.T.; Biharie, V.; Zhang, L.; Caron, L.; Buschow, K.H.J.; Brück, E.H.

    2010-01-01

    Substitution of some Cr for Mn atoms in MnCoGe was employed to control the magnetic and structural transitions in this alloy to coincide, leading to a single first-order magnetostructural transition from the ferromagnetic to the paramagnetic state with a giant magnetocaloric effect observed near

  20. Structures of tin cluster cations Sn3(+) to Sn15(+).

    Science.gov (United States)

    Drebov, Nedko; Oger, Esther; Rapps, Thomas; Kelting, Rebecca; Schooss, Detlef; Weis, Patrick; Kappes, Manfred M; Ahlrichs, Reinhart

    2010-12-14

    We employ a combination of ion mobility measurements and an unbiased systematic structure search with density functional theory methods to study structure and energetics of gas phase tin cluster cations, Sn(n)(+), in the range of n = 3-15. For Sn(13)(+) we also carry out trapped ion electron diffraction measurements to ascertain the results obtained by the other procedures. The structures for the smaller systems are most easily described by idealized point group symmetries, although they are all Jahn-Teller distorted: D(3h) (trigonal bipyramid), D(4h) (octahedron), D(5h) (pentagonal bipyramid) for n = 5, 6, and 7. For the larger systems we find capped D(5h) for Sn(8)(+) and Sn(9)(+), D(3h) (tricapped trigonal prism) and D(4d) (bicapped squared antiprism) plus adatoms for n = 10, 11, 14, and 15. A centered icosahedron with a peripheral atom removed is the dominant motif in Sn(12)(+). For Sn(13)(+) the calculations predict a family of virtually isoenergetic isomers, an icosahedron and slightly distorted icosahedra, which are about 0.25 eV below two C(1) structures. The experiments indicate the presence of two structures, one from the I(h) family and a prolate C(1) isomer based on fused deltahedral moieties.

  1. Chromium and iron contained half-Heusler MnNiGe-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Budzynski, M. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Valkov, V.I.; Golovchan, A.V.; Kamenev, V.I. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Mitsiuk, V.I., E-mail: vmitsiuk@gmail.com [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus); Sivachenko, A.P. [Donetsk Institute for Physics and Engineering, 72, R.Luxemburg str., 83114 Donetsk (Ukraine); Surowiec, Z. [UMCS, Institute of Physics, 1 sq.M.Curie-Skłodowska, 20-031 Lublin (Poland); Tkachenka, T.M. [Scientific-Practical Materials Research Center of National Academy of Sciences of Belarus, 19 P.Brovky Str., 220072 Minsk (Belarus)

    2015-12-15

    The magnetic characteristics of chromium and iron containing MnNiGe-based alloys with several types of quenching and annealing were investigated. It was found that the quenched Mn{sub 0.89}Cr{sub 0.11}NiGe has a spontaneous and magnetic field induced magnetostructural first-order transitions at room temperature. These transitions might be accompanied by a large magnetocaloric effect. In general, Mn{sub 0.89}Cr{sub 0.11}NiGe can be classified as promising material for use in the magnetocaloric application at room temperatures. The first order magnetostructural phase transition from the ferromagnetic to paramagnetic state is not realized in MnNi0.90Fe0.10Ge. In contrast to Mn{sub 0.89}Cr{sub 0.11}NiGe, however, the FM state in quenched-on-wheel MnNi0.90Fe0.10Ge is preserved to the lowest temperatures. Based on the set of the magnetic properties, it has been concluded that the iron containing MnNiGe-based alloys are less promising for practical use.

  2. Defect energetics and magnetic properties of 3 d-transition-metal-doped topological crystalline insulator SnTe

    Science.gov (United States)

    Wang, Na; Wang, JianFeng; Si, Chen; Gu, Bing-Lin; Duan, WenHui

    2016-08-01

    The introduction of magnetism in SnTe-class topological crystalline insulators is a challenging subject with great importance in the quantum device applications. Based on the first-principles calculations, we have studied the defect energetics and magnetic properties of 3 d transition-metal (TM)-doped SnTe. We find that the doped TM atoms prefer to stay in the neutral states and have comparatively high formation energies, suggesting that the uniform TMdoping in SnTe with a higher concentration will be difficult unless clustering. In the dilute doping regime, all the magnetic TMatoms are in the high-spin states, indicating that the spin splitting energy of 3 d TM is stronger than the crystal splitting energy of the SnTe ligand. Importantly, Mn-doped SnTe has relatively low defect formation energy, largest local magnetic moment, and no defect levels in the bulk gap, suggesting that Mn is a promising magnetic dopant to realize the magnetic order for the theoretically-proposed large-Chern-number quantum anomalous Hall effect (QAHE) in SnTe.

  3. Studies on Transient-Stage-Scale Growth on Fe-22wt.% Cr Alloys Containing 120 PPM La + 270 PPM Ce

    Science.gov (United States)

    2009-02-01

    diffuse towards the surface where a scale rich in spinel starts to form. This spinel evolves becoming richer in Cr and Mn and nodules made out of chromium ... chromium content iron alloys Abstract Reactive elements (RE), such as Ce, La or Y, are known to improve oxidation resistance of Fe based alloys that...but when the oxidation time is long enough, Cr and Mn oxides will bury it under an oxides layer. This indicates the formation of chromium and

  4. A yield-optimized access to double-helical SnIP via a Sn/SnI2 approach

    Science.gov (United States)

    Utrap, André; Xiang, Ng Yan; Nilges, Tom

    2017-10-01

    Herein we report on the optimized synthesis process of SnIP, the first inorganic double helix compound which shows high mechanical flexibility, a strong tendency for cleavage or delamination and intriguing electronic properties. In this work we analyzed the influence of SnI2 as a reaction promotor or mineralizer compound for the synthesis of SnIP. In previous studies Sn/SnI4 was used as a precursor and chemical transport agent for the SnIP synthesis but significant amounts of non-reacted tin halide (SnI2 and SnI4) remained after the formation of the target compound reducing its quality and yield. Significantly less tin halide residue can be observed which suggests a reduction of side-reactions. While the Sn/SnI4 couple works perfectly for the synthesis of the two-dimensional material phosphorene precursor black phosphorus the Sn/SnI2 couple is beneficial for the one-dimensional ternary polyphosphide SnIP. These results strongly encourage the theory of SnI2 as the important reaction intermediate in the synthesis of covalently-bonded polyphosphide substructures and element allotropes at elevated temperatures.

  5. Sucrose-aided combustion synthesis of nanosized LiMn{sub 1.99-y}Li{sub y}M{sub 0.01}O{sub 4} (M = Al{sup 3+}, Ni{sup 2+}, Cr{sup 3+}, Co{sup 3+}, y = 0.01 and 0.06) spinels. Characterization and electrochemical behavior at 25 and at 55 C in rechargeable lithium cells

    Energy Technology Data Exchange (ETDEWEB)

    Amarilla, J.M.; Pico, F.; Rojo, J.M.; Rojas, R.M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC), Sor Juana Ines de la Cruz no. 3, Cantoblanco, 28049 Madrid (Spain); Petrov, K.; Avdeev, G. [Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2009-06-15

    Doubly doped LiMn{sub 1.99-y}Li{sub y}M{sub 0.01}O{sub 4} (M = Al{sup 3+}, Ni{sup 2+}, Cr{sup 3+}, Co{sup 3+}; y = 0.01 and 0.06) spinels have been synthesized by the sucrose-aided combustion method. Combined TG/DTA and XRD studies have shown that stoichiometric single-phase spinels are formed after annealing of the samples at 700 C for 1 h. The samples obtained are nanocrystalline materials having a narrow size-distribution and a coherent domain size between 40 and 60 nm, depending on the amount of fuel (sucrose) used in the synthesis. The influence of the Li-excess, the type of M{sup n+}-dopant cation and the amount of fuel used in the synthesis on the electrochemical behavior of the spinels in a Li-cell at room and at elevated temperature (55 C) has been studied. At 25 C all the spinels synthesized have a good capacity retention after 100 cycles, QRt-100 > 92%. At 55 C the increase of the Li-excess improves the cycling performances. Rate capability studies show that the spinels retain >90% of their capacity even at 5C rate. The synergic effect of the Li-excess and the particle size on the electrochemical properties of the spinels as cathode material has been settled. The LiMn{sub 1.93}Li{sub 0.06}M{sub 0.01}O{sub 4}, (M = Al{sup 3+}, Ni{sup 2+}) spinels, with cyclabilities >99.9% by cycle at both 25 and 55 C, and high rate capabilities, are the ones that show the best electrochemical properties. (author)

  6. High Mn austenitic stainless steel

    Science.gov (United States)

    Yamamoto, Yukinori [Oak Ridge, TN; Santella, Michael L [Knoxville, TN; Brady, Michael P [Oak Ridge, TN; Maziasz, Philip J [Oak Ridge, TN; Liu, Chain-tsuan [Knoxville, TN

    2010-07-13

    An austenitic stainless steel alloy includes, in weight percent: >4 to 15 Mn; 8 to 15 Ni; 14 to 16 Cr; 2.4 to 3 Al; 0.4 to 1 total of at least one of Nb and Ta; 0.05 to 0.2 C; 0.01 to 0.02 B; no more than 0.3 of combined Ti+V; up to 3 Mo; up to 3 Co; up to 1W; up to 3 Cu; up to 1 Si; up to 0.05 P; up to 1 total of at least one of Y, La, Ce, Hf, and Zr; less than 0.05 N; and base Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein the alloy forms an external continuous scale including alumina, nanometer scale sized particles distributed throughout the microstructure, the particles including at least one of NbC and TaC, and a stable essentially single phase FCC austenitic matrix microstructure that is essentially delta-ferrite-free and essentially BCC-phase-free.

  7. Electronic structure and band alignments of ZnTe/CrTe(0 0 1), CdSe ...

    Indian Academy of Sciences (India)

    2011-08-02

    Heusler NiMnSb and PtMnSb alloys, several half-metallic ferro- magnets such as rutile CrO2 [2], double perovskite Sr2FeMoO6 [3], spinel Fe3O4 [4], pyrite-type CoS2 [5,6] and Heusler alloys [7] have been theoretically predicted ...

  8. Electrical properties of SnO{sub 2} ceramics for low voltage varistors

    Energy Technology Data Exchange (ETDEWEB)

    Glot, A.B., E-mail: alexglot@mixteco.utm.mx [Universidad Tecnologica de la Mixteca, Huajuapan de Leon 69000, Oaxaca (Mexico); Bulpett, R. [Brunel University, Uxbridge, UB8 3PH (United Kingdom); Ivon, A.I. [Dnepropetrovsk National University, Dnepropetrovsk 49010 (Ukraine); Gallegos-Acevedo, P.M. [Universidad Tecnologica de la Mixteca, Huajuapan de Leon 69000, Oaxaca (Mexico)

    2015-01-15

    It is shown that an addition of bismuth oxide Bi{sub 2}O{sub 3} (0.5 mol%) to the system SnO{sub 2}–CoO–Nb{sub 2}O{sub 5}–Cr{sub 2}O{sub 3} with small amounts of Nb{sub 2}O{sub 5} and Cr{sub 2}O{sub 3} (0.05 mol%) leads to a significant decrease in the electric field where a strong nonlinearity of the current–voltage characteristic takes place. This effect facilitates manufacture of ceramic materials for low voltage varistors with a relatively high nonlinearity coefficient of 15–20 and an electric field of 430−580Vcm{sup −1} (at a sintering temperature of 1300 °C) and, respectively, 11 and 287Vcm{sup −1} (at 1400 °C). The obtained experimental data indicate that ceramic materials in the system SnO{sub 2}–CoO–Nb{sub 2}O{sub 5}–Cr{sub 2}O{sub 3}–Bi{sub 2}O{sub 3} exhibit the typical structure of varistor ceramics with conductive grains of tin dioxide (SnO{sub 2}) and highly resistive grain boundaries. In particular, the capacitance at 10 Hz and high dc bias becomes negative as in other SnO{sub 2} and ZnO varistors.

  9. The microstructure and properties of as-cast Sn-Zn-Bi solder alloys

    Directory of Open Access Journals (Sweden)

    Mladenović Srba A.

    2012-01-01

    Full Text Available Research on the lead-free solders has attracted wide attention, mostly as the result of the implementation of the Directive on the Restriction of the Use of Hazardous Substances in Electrical and Electronic Equipment. The Sn-Zn solder alloys have been considered to be one of the most attractive lead-free solders due to its ability to easily replace Sn-Pb eutectic alloy without increasing the soldering temperature. Furthermore, the mechanical properties are comparable or even superior to those of Sn-Pb solder. However, other problems still persist. The solution to overcoming these drawbacks is to add a small amount of alloying elements (Bi, Ag, Cr, Cu, and Sb to the Sn-Zn alloys. Microstructure, tensile strength, and hardness of the selected Sn-Zn-Bi ternary alloys have been investigated in this study. The SEM-EDS was used for the identification of co-existing phases in the samples. The specimens’ microstructures are composed of three phases: Sn-rich solid solution as the matrix, Bi-phase and Zn-rich phase. The Bi precipitates are formed around the Sn-dendrit grains as well as around the Zn-rich phase. The amount of Bi segregation increases with the increase of Bi content. The Sn-Zn-Bi alloys exhibit the high tensile strength and hardness, but the values of these mechanical properties decrease with the increase of Bi content, as well as the reduction of Zn content. The results presented in this paper may offer further knowledge of the effects various parameters have on the properties of lead-free Sn-Zn-Bi solders.

  10. Chromium doping effects on structural and dielectric properties of Mn-Zn cobaltites

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, A. [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Department of Physics, MEDICAPS Institute of Science and Technology, Pithampur 45331 (India); Dar, Mashkoor A., E-mail: darmashkoor.phst@gmail.com; Choudhary, P.; Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Shah, P. [Amity Institute of Nanotechnology, Amity University, Sector 125, Noida 201303 (India)

    2016-05-06

    The effect of transition metal Cr{sup 2+} ion as a dopant of Zn{sup 2+} in Mn{sub 0.5}Zn{sub 0.5}Co{sub 2}O{sub 4} is investigated. Co-doped Mn{sub 0.5}Zn{sub 0.5-x}Cr{sub x}Co{sub 2}O{sub 4} (x = 0, 0.3 and 0.5) cobaltites were prepared by solid-state reaction route. X-ray powder diffraction (XRD) analysis reveals that the samples prepared are polycrystalline single-phase cubic spinel in structure having a space group Fd3m. An increase in average particle size observed with Cr{sup 2+} doping. However other structural parameters such as X-ray density, micro strain and dislocation density shows almost a similar decreasing trend with increase in Cr{sup 2+}. High value of permittivity ∼10{sup 5} is observed for the parent Mn{sub 0.5}Zn{sub 0.5}Co{sub 2}O{sub 4} and shows a substantial decrease with increase in the Cr{sup 2+} doping. Higher doping of Cr{sup 2+} also increases the dielectric loss and hence limits its technological importance. At lower frequencies ac conductivity has been found to increase with increase in Cr{sup 2+} content.

  11. PROTEUS-SN User Manual

    Energy Technology Data Exchange (ETDEWEB)

    Shemon, Emily R. [Argonne National Lab. (ANL), Argonne, IL (United States); Smith, Micheal A. [Argonne National Lab. (ANL), Argonne, IL (United States); Lee, Changho [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-02-16

    PROTEUS-SN is a three-dimensional, highly scalable, high-fidelity neutron transport code developed at Argonne National Laboratory. The code is applicable to all spectrum reactor transport calculations, particularly those in which a high degree of fidelity is needed either to represent spatial detail or to resolve solution gradients. PROTEUS-SN solves the second order formulation of the transport equation using the continuous Galerkin finite element method in space, the discrete ordinates approximation in angle, and the multigroup approximation in energy. PROTEUS-SN’s parallel methodology permits the efficient decomposition of the problem by both space and angle, permitting large problems to run efficiently on hundreds of thousands of cores. PROTEUS-SN can also be used in serial or on smaller compute clusters (10’s to 100’s of cores) for smaller homogenized problems, although it is generally more computationally expensive than traditional homogenized methodology codes. PROTEUS-SN has been used to model partially homogenized systems, where regions of interest are represented explicitly and other regions are homogenized to reduce the problem size and required computational resources. PROTEUS-SN solves forward and adjoint eigenvalue problems and permits both neutron upscattering and downscattering. An adiabatic kinetics option has recently been included for performing simple time-dependent calculations in addition to standard steady state calculations. PROTEUS-SN handles void and reflective boundary conditions. Multigroup cross sections can be generated externally using the MC2-3 fast reactor multigroup cross section generation code or internally using the cross section application programming interface (API) which can treat the subgroup or resonance table libraries. PROTEUS-SN is written in Fortran 90 and also includes C preprocessor definitions. The code links against the PETSc, METIS, HDF5, and MPICH libraries. It optionally links against the MOAB library and

  12. Laser processing issues of nanosized intermetallic Fe-Sn and metallic Sn particles

    Energy Technology Data Exchange (ETDEWEB)

    Alexandrescu, R., E-mail: ralexandrescu2001@yahoo.co.uk [National Institute for Lasers, Plasma and Radiation Physics Bucharest, POB MG-36, 077125 (Romania); Morjan, I.; Dumitrache, F.; Birjega, R.; Fleaca, C.; Morjan, Iuliana; Scarisoreanu, M.; Luculescu, C.R.; Dutu, E. [National Institute for Lasers, Plasma and Radiation Physics Bucharest, POB MG-36, 077125 (Romania); Kuncser, V.; Filoti, G. [National Institute of Materials Physics, POB MG-7, 077125 Bucharest-Magurele (Romania); Vasile, E. [Metav R and D, Rosetti 31, Bucharest (Romania); Ciupina, V. [Ovidius University of Constanta, Bd. Mamaia 124, Constanta (Romania)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Intermetallic Fe-Sn and metallic Sn nanoparticles synthesized by laser pyrolysis. Black-Right-Pointing-Pointer Fe(CO){sub 5} and Sn(CH{sub 3}){sub 4} were used as precursors. Black-Right-Pointing-Pointer FeSn{sub 2}, Sn and Fe{sub 3}SnC phases were identified by XRD. Black-Right-Pointing-Pointer Complex core-shell structural characteristics were found by HRTEM analysis. Black-Right-Pointing-Pointer Higher magnetization was found in samples with increased Fe/Sn atomic ratio. - Abstract: Intermetallic Fe-Sn and nanocrystalline metallic Sn nanoparticles have been successfully synthesized from organic precursors using the laser pyrolysis technique with ethylene as sensitizer. Nano-structured Sn (single phase) was prepared by the pyrolysis of Sn(CH{sub 3}){sub 4} (TMT) vapors. Controlled Fe/Sn atomic ratios, ranging from 0.69 to 1.64 were obtained for the prepared Fe-Sn nanopowders by the control of Fe(CO){sub 5} and TMT flows, respectively. XRD studies evidence three main phases: the tetragonal metallic Sn phase and the intermetallic FeSn{sub 2} phase and, to a much lesser extent, the cubic ternary carbide Fe{sub 3}SnC. Complex core-shell structural characteristics were found by HRTEM analysis. More complete information about the Fe phase distributions in the new intermetallic Fe-Sn nanomaterial is provided by temperature dependent {sup 57}Fe Moessbauer spectroscopy.

  13. Effect of iron addition on the crystal structure of the α-AlFeMnSi phase formed in the quaternary Al-Fe-Mn-Si system

    Directory of Open Access Journals (Sweden)

    Luna-Álvarez, S.

    2011-12-01

    Full Text Available Cubic and hexagonal α-phases, formed during thermal analysis experiments and specific isothermal treatments, have been analyzed for a series of Al-Mn-Si alloys with different iron contents. In these alloys, the Fe/Mn weight ratio was varied from 0.1 to 8.4. This study shows that in Al-Fe-Mn-Si alloys with Fe/Mn weight ratios up to 4, the a-phase has a cubic crystal structure, while in alloys with a Fe/Mn weight ratio of 5.3 or more, the a-phase has a hexagonal crystal structure. Hence, the critical Fe/Mn weight ratio for the cubic to hexagonal crystal structure transition falls between 4 and 5.3 for the studied alloys.Las fases α de estructura cristalina cúbica y hexagonal, formadas durante los ensayos de análisis térmico y tratamientos isotérmicos específicos, han sido analizadas para una serie de aleaciones Al-Mn-Si con diferente contenido de hierro. En estas aleaciones, la relación en peso Fe/Mn se varió de 0,1 a 8,4. Este estudio muestra que las aleaciones Al-13,4Si-1,1 Mn-Fe con relación en peso Fe/Mn menor o igual a 4, la fase a presenta estructura cristalina cúbica, mientras que en aleaciones con una relación Fe/Mn igual o mayor a 5,3, la fase a presenta estructura cristalina hexagonal. Por lo tanto, la relación crítica Fe/Mn para la transición de estructura cristalina de cúbica a hexagonal se encuentra entre 4 y 5,3 para las aleaciones estudiadas.

  14. Energy levels of 56Mn

    DEFF Research Database (Denmark)

    Van Assche, P. H. M.; Baader, H. A.; Koch, H. R.

    1971-01-01

    The low-energy spectrum of the 55Mn(n,γ)56 Mn reaction has been studied with a γ-diffraction spectrometer. These data allowed the construction of a level scheme for 56Mn with two previously unobserved doublets. High-energy γ-transitions to the low-energy states have been measured for different...

  15. Mn-based antiperovskite functional materials: Review of research

    Science.gov (United States)

    Tong, Peng; Wang, Bo-Sen; Sun, Yu-Ping

    2013-06-01

    Our recent research on the Mn-based antiperovskite functional materials AXMn3 (A: metal or semiconducting elements; X: C or N) is outlined. Antiperovskite carbides (e.g., AlCMn3) show large magnetocaloric effect comparable to those of typical magnetic refrigerant materials. Enhanced giant magnetoresistance up to 70% at 50 kOe (1 Oe = 79.5775 Am-1) over a wide temperature span was obtained in Ga1-xZnxCMn3 and GaCMn3-xNix. In Cu0.3Sn0.5NMn3.2, negative thermal expansion (NTE) was achieved in a wide temperature region covering room temperature (α = -6.8 ppm/K, 150 K-400 K). Neutron pair distribution function analysis suggests the Cu/Sn-Mn bond fluctuation is the driving force for the NTE in Cu1-xSnxNMn3. In CuN1-xCxMn3 and CuNMn3-yCoy, the temperature coefficient of resistivity (TCR) decreases monotonically from positive to negative as Co or C content increases. TCR is extremely low when the composition approaches the critical points. For example, TCR is ~ 1.29 ppm/K between 240 K and 320 K in CuN0.95C0.05Mn3, which is one twentieth of that in the typical low-TCR materials (~ 25 ppm/K). By studying the critical scaling behavior and X deficiency effect, some clues of localized-electron magnetism have been found against the background of electronic itinerant magnetism.

  16. Atomic resolution investigations of phase transformation from TaN to CrTaN in a steel matrix

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson; Hald, John

    2012-01-01

    atoms diffuse from the steel matrix into TaN precipitates and physically transform them into CrTaN. The crystal structure of the precipitates changes from that of a typical MN NaCl type crystal structure to a Z-phase crystal structure with alternating double layers of Cr and TaN. Since there is a large...

  17. Study of the magnetic structure and the cation distributions in MnCo spinel ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Lang, L.L. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Xu, J. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); School of Science, Hebei University of Engineering, Handan City 050038 (China); Li, Z.Z.; Qi, W.H. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Tang, G.D., E-mail: tanggd@mail.hebtu.edu.cn [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China); Shang, Z.F.; Zhang, X.Y.; Wu, L.Q.; Xue, L.C. [Hebei Advanced Thin Film Laboratory, Department of Physics, Hebei Normal University, Shijiazhuang City 050024 (China)

    2015-04-01

    Single-phase powder samples of the spinel ferrites Mn{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4} (0.0≤x≤0.3) were prepared using a conventional co-precipitation method. Comparing with the samples Cr{sub x}Ni{sub 1−x}Fe{sub 2}O{sub 4} (0.0≤x≤0.3) reported recently by our group, we found that there are two different trends in the magnetic moments (μ{sub exp}) per formula of samples measured at 10 K: the value of μ{sub exp} increased when Mn (Mn{sup 2+} with 3d{sup 5} electron configuration) substituted for Co (Co{sup 2+} with 3d{sup 7} electron configuration), while μ{sub exp} decreased when Cr (Cr{sup 2+} with 3d{sup 4}) substituted for Ni (Ni{sup 2+} with 3d{sup 8}). The dependences of μ{sub exp} on the doping level x for the two series of samples were fitted successfully, using the quantum-mechanical potential barrier model earlier proposed by our group. In the fitting process, the magnetic moment directions of the Cr{sup 3+}, Cr{sup 2+} and Mn{sup 3+} cations were assumed to be antiparallel to those of the other cations in the same sublattices due to constraints arising from Hund's rules.

  18. SN 2009E: a faint clone of SN 1987A

    DEFF Research Database (Denmark)

    Pastorello, A.; Pumo, M. L.; Navasardyan, H.

    2012-01-01

    Context.1987A-like events form a rare sub-group of hydrogen-rich core-collapse supernovae that are thought to originate from the explosion of blue supergiant stars. Although SN 1987A is the best known supernova, very few objects of this group have been discovered and, hence, studied. Aims. In thi...

  19. Synthesis of magnetically separable MnFe2O4 nanocrystals via salt-assisted solution combustion method and their utilization as dye adsorbent

    National Research Council Canada - National Science Library

    ZHONG, Xiaochao; YANG, Jun; CHEN, Yuanyuan; QIU, Xiaoyan; ZHANG, Yuanming

    2015-01-01

      MnFe2O4 nanocrystals with spinel structure were prepared by conventional solution combustion synthesis and salt-assisted solution combustion synthesis, respectively, and their adsorption capacities for Congo red (CR...

  20. Synthesis of magnetically separable MnFe2O4 nanocrystals via salt-assisted solution combustion method and their utilization as dye adsorbent

    National Research Council Canada - National Science Library

    ZHONG, Xiaochao; YANG, Jun; CHEN, Yuanyuan; QIU, Xiaoyan; ZHANG, Yuanming

    2015-01-01

    MnFe2O4 nanocrystals with spinel structure were prepared by conventional solution combustion synthesis and salt-assisted solution combustion synthesis, respectively, and their adsorption capacities for Congo red (CR...

  1. Structure and mechanical properties of as-cast Ti–5Sn–xCr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Hsueh-Chuan; Wu, Shih-Ching; Hsu, Shih-Kuang [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Institute of Biomedical Engineering and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); Chen, Chien-Yu [Advanced Materials and BioMaterials Laboratory, Department of Materials Science and Engineering, Da-Yeh University, 168 University Road, Dacun, Changhua 51591, Taiwan, ROC (China); Ho, Wen-Fu, E-mail: fujii@mail.dyu.edu.tw [Advanced Materials and BioMaterials Laboratory, Department of Materials Science and Engineering, Da-Yeh University, 168 University Road, Dacun, Changhua 51591, Taiwan, ROC (China)

    2014-06-01

    In this study, the effects of chromium (Cr) on the structure and mechanical properties of a Ti–5Sn-based system were examined, with an emphasis on improving the strength/modulus ratio. Commercially pure titanium (c.p. Ti) was used as a control. As-cast Ti–5Sn and a series of Ti–5Sn–xCr (x=1, 3, 5, 7, 9, 11 and 13 wt%) alloys prepared by using a commercial arc-melting vacuum-pressure casting system were investigated. X-ray diffraction (XRD) for phase analysis was conducted using a diffractometer. Three-point bending tests were performed on all specimens to evaluate their mechanical properties. The experimental results indicate that the structure and mechanical properties of these alloys changed with the addition of various amounts of Cr. The as-cast Ti–5Sn has a hexagonal α' phase. When 1 wt% Cr was introduced into the Ti–5Sn alloy, the structure essentially stayed the same. When the Cr content was at 3 wt%, retention of the metastable β phase began. When the Cr content was increased to 5 wt% or greater, the β phase was entirely retained. The ω phase was detected in Ti–5Sn–3Cr and Ti–5Sn–5Cr. Ti–5Sn–5Cr, which had the largest quantity of the ω phase, exhibited the highest microhardness value due to the hardening effect of the ω phase. Among all Ti–5Sn-based alloys, the β-phase Ti–5Sn–7Cr alloy had the lowest elastic modulus. It also exhibited higher bending strength/modulus ratios, which at 26.8 were higher than that of c.p. Ti (8.5) and that of Ti–6Al–4V (17.4). Furthermore, the elastically recoverable angle of this alloy (31.0°) was much greater than that of c.p. Ti (2.7°). In the search for better implant materials, the low modulus, ductile property, excellent elastic recovery capability and high strength/modulus ratio of β-phase Ti–5Sn–7Cr make this alloy a promising candidate.

  2. Laser processing issues of nanosized intermetallic Fe-Sn and metallic Sn particles

    Science.gov (United States)

    Alexandrescu, R.; Morjan, I.; Dumitrache, F.; Birjega, R.; Fleaca, C.; Morjan, Iuliana; Scarisoreanu, M.; Luculescu, C. R.; Dutu, E.; Kuncser, V.; Filoti, G.; Vasile, E.; Ciupina, V.

    2012-09-01

    Intermetallic Fe-Sn and nanocrystalline metallic Sn nanoparticles have been successfully synthesized from organic precursors using the laser pyrolysis technique with ethylene as sensitizer. Nano-structured Sn (single phase) was prepared by the pyrolysis of Sn(CH3)4 (TMT) vapors. Controlled Fe/Sn atomic ratios, ranging from 0.69 to 1.64 were obtained for the prepared Fe-Sn nanopowders by the control of Fe(CO)5 and TMT flows, respectively. XRD studies evidence three main phases: the tetragonal metallic Sn phase and the intermetallic FeSn2 phase and, to a much lesser extent, the cubic ternary carbide Fe3SnC. Complex core-shell structural characteristics were found by HRTEM analysis. More complete information about the Fe phase distributions in the new intermetallic Fe-Sn nanomaterial is provided by temperature dependent 57Fe Mössbauer spectroscopy.

  3. First principles study of the structural properties of Ni1.75Co0.25Mn1.5-xCrxIn0.5 Heusler alloy

    Directory of Open Access Journals (Sweden)

    Pavlukhina Oksana

    2015-01-01

    Full Text Available In this work, the structural and magnetic properties of Cr – doped Ni1.75Co0.25MnCr0.5In0.5 Heusler alloys are investigated by using the density functional theory calculations. The chemical disorder is treated by the 16-atom supercell approach. Three compositions with substitution of 6.25%, 12.5 %, 18.75%, and 25% Cr for Mn are taken into consideration. The formation energy, magnetic moments and lattice parameters depending on the Cr content are found. It is shown that compositions with 6.25% and 12.5% of Cr are energetically stable in austenite.

  4. Effect of genotype, Cr(III and Cr(VI on plant growth and micronutrient status in Silene vulgaris (Moench

    Directory of Open Access Journals (Sweden)

    A. E. Pradas-del-Real

    2013-06-01

    Full Text Available Chromium released into the environment from industrial activities has become an important environmental concern. Silene vulgaris has been proven to be tolerant to many heavy metals, so it is considered an interesting species in the revegetation and restoration of polluted soils, but no information is available about its response to Cr. The objective of this work was to study uptake and influence on plant growth of Cr(III and Cr(VI in six genotypes (four hermaphrodites and two females of S. vulgaris from different sites of Madrid (Spain. Plants were treated for 12 days with 60 µM of Cr(III or Cr(VI in semihydroponics. Dry weights, soil-plant analysis development values (SPAD reading with chlorophylls and micronutrient and total Cr concentrations were determined. Metal uptake was higher in presence of Cr(VI than of Cr(III and poorly translocated to the shoots. In both cases S. vulgaris did not show visual toxicity symptoms, biomass reduction, or differences among SPAD values as consequence of Cr additions. However genotypes SV36 and SV38 showed Fe and Mn imbalance. This is the first report on the relatively good performance of hermaphrodite and female S. vulgaris genotypes in Cr uptake and physiological traits, but further studies will be necessary to elucidate the mechanisms by which the gender may influence these variables. S. vulgaris presented high diversity at genotypic level; the treatment with hexavalent Cr increased the differences among genotypes so the use of cuttings from an homogeneous genotype seems to be an adequate method for the study of this species.

  5. Manganese-mediated ferromagnetism in La2 Mn2x O6 perovskite ...

    Indian Academy of Sciences (India)

    Administrator

    nent in figure 4) which are not accountable in the refinement, indicating the presence of minor impu- rity phase (also perovskite-like). The orthorhombic structure of the La2Fe1–xMn2x. Cr1–xO6 samples for x ≤ 0⋅5 is similar to the parent. La2FeCrO6, having c/a > √2; a < b (O-orthorhombic structure). We do however find ...

  6. Magnetic properties of mixed valence La 2/3 Sr Mn T O 3 (T= Fe ...

    Indian Academy of Sciences (India)

    Polycrystalline manganites of composition La2/3Sr1/3Mn1−TO3 (T = Cr3+ or Fe3+, x = 0.0-0.10) were obtained by the Pechini method. Their magnetic properties exhibited a marked dependence on Fe/Cr content, with significant reduction of the magnetic moment per formula unit and their Curie temperatures. In addition ...

  7. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    Science.gov (United States)

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  8. crRNA biogenesis

    NARCIS (Netherlands)

    Charpentier, E.; Oost, van der J.; White, M.

    2013-01-01

    Mature crRNAs are key elements in CRISPR-Cas defense against genome invaders. These short RNAs are composed of unique repeat/spacer sequences that guide the Cas protein(s) to the cognate invading nucleic acids for their destruction. The biogenesis of mature crRNAs involves highly precise processing

  9. Thermoelectric transport properties of Mn4 Si7 thin films

    Science.gov (United States)

    Shin, Yooleemi; Duong, Anh Tuan; Choi, Jeongyong; Cho, Sunglae

    2014-03-01

    The deposition of transition metal layers on silicon and their reaction with substrate are important issues in semiconductor device technology. The interface between metal and semiconductor determines the device performance. The 3d transition metal monosilicides such as FeSi, CoSi, MnSi and CrSi have attracted much attention because they are easily formed in the interface between transition metal and Si. On the other hand, the Mn4Si7 compound is well known a pseudo-direct band gap semiconductor (0.42 ~ 0.98 eV) with a fundamental gap increasing linearly with the compression along c- or a-axis. We have grown Mn thin films on Si (111) substrates at 600 °C using MBE, resulting in the formation of Mn4Si7. In order to investigate the correlation between magnetization and charge carrier transport, we performed magnetoresistance and Hall resistance measurements by using a physical property measurement system. Interestingly, we observed the Seebeck coefficient of -565 μV/K and electrical resistivity of 2.26 m Ω cm in Mn4Si7 films grown on Si substrate, resulting in the power factor of 14 mW/K2m.

  10. Surface activation of MnNb{sub 2}O{sub 6} nanosheets by oxalic acid for enhanced photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Junshu; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Li, Hongyi; Li, Yongli; Du, Yucheng; Yang, Yilong; Jia, Xinjian

    2017-05-01

    Graphical abstract: Visible light driven photoreduction of Cr(VI) over MnNb{sub 2}O{sub 6} nanosheets is enhanced via oxalic acid surface complex to generate activation layer. - Highlights: • MnNb{sub 2}O{sub 6} nanosheets are crystallized by a surface capping route of sulfonate groups. • Oxalic acid on MnNb{sub 2}O{sub 6} nanosheets forms an excited surface complex hybrid layer. • Surface activation enhances visible-light induced reduction of Cr(VI) into Cr(III). - Abstract: MnNb{sub 2}O{sub 6} nanosheets (P-MNOs) is selectively crystallized by using surface capping ligand with functional sulfonate group (sodium dodecyl benzene sulphonate), which binds to the (131) surface of MnNb{sub 2}O{sub 6} inducing the morphology-controlled crystallization of MnNb{sub 2}O{sub 6} materials. Surface modification of photoactive P-MNOs with electron-rich oxalic acid ligands establishes an excited surface complex layer on phase-pure P-MNO as evidenced by spectroscopic analyses (FT-IR, UV–vis, Raman, PL, etc.), and thus more efficiently photocatalyzes the reduction of Cr(VI) into Cr(III) than solely P-MNOs or oxalic acid under visible light (λ > 420 nm) via a ligand-to-metal interfacial electron transfer pathway. However, the interaction between oxalic acid and MnNb{sub 2}O{sub 6} is highly dependent upon the morphology of solid MnNb{sub 2}O{sub 6} substrate due to the higher surface-area-to-volume ratio and higher surface activity of (131) planes in the sheet-like morphology. This study could assist the construction of stable niobate material systems to allow a versatile solid surface activation for establishing more energy efficient and robust catalysis process under visible light.

  11. Natural attenuation of Cr(VI) contaminated groundwater at two industrial sites in the eastern U.S.A.: A Cr isotope study

    Science.gov (United States)

    Novak, Martin; Hellerich, Lucas A.; Sebek, Ondrej; Andronikov, Alexandre; Chrastny, Vladislav; Curik, Jan; Stepanova, Marketa; Pacherova, Petra; Martinkova, Eva; Prechova, Eva; Veselovsky, Frantisek

    2017-04-01

    Hexavalent chromium [Cr(VI)], found in various compartments of the environment, has generated much interest due to its extreme toxicity and mobility. We studied natural attenuation of Cr(VI)-contaminated groundwater at one site in Connecticut (site A), and one site in New Jersey (site B), U.S.A. Shallow groundwater was contaminated by electroplating solutions at site A, and by water-soluble chromite ore-processing residues at site B. Site A had lower Cr(VI) concentrations of less than 1 mg L-1 in comparison to site B (200 mg L-1). Site A also had lower mean del53Cr values (1.4 per mil) than site B (2.9 per mil). Chromium isotope composition of the pollution sources (plating bath, ore) was known (del53Cr of 0.0 to 0.2 per mil). The positive Cr isotope shift from the pollution source Cr(VI) to groundwater Cr(VI) at both sites indicated that spontaneous Cr(VI) reduction to insoluble Cr(III) is under way. This process is removing toxicity from the groundwater. Del53Cr values of groundwater were strongly positively correlated with the concentration of dissolved organic carbon (DOC), but not with divalent Fe and Mn, indicating that DOC may be the main Cr-reducing agent. A Rayleigh model indicated that 30 and 57 % of the original contaminant may have been removed from the groundwater by natural attenuation at site A and B, respectively. Interestingly, del53Cr values of the residual Cr(VI) in the groundwater at site A decreased significantly over the past 15 years, during which the water is being extracted for chemical treatment. At present, older, less fractionated Cr(VI) may be extracted at site A.

  12. Supernova 2004cr in UGC 11603

    Science.gov (United States)

    Armstrong, M.

    2004-06-01

    Further to IAUC 8357, M. Armstrong, reports his discovery of an apparent supernova (mag 17.8) on unfiltered CCD images taken on June 17.035 and 18.965 UT with a 0.35-m reflector. SN 2004cr is located at R.A. = 20h36m06s.84, Decl. = +63o44'12".4 (equinox 2000.0), which is approximately 45".9 west and 10".6 south of the center of UGC 11603. Nothing was visible at this position on his images taken on 2001 Aug. 5, 31, and 2003 July 13 (limiting mag about 19.5) or on Palomar Sky Survey red and blue plates.

  13. Cosmic ray acceleration parameters from multi-wavelength observations. The case of SN 1006

    Science.gov (United States)

    Berezhko, E. G.; Ksenofontov, L. T.; Völk, H. J.

    2009-10-01

    Aims: The properties of the Galactic supernova remnant (SNR) SN 1006 are theoretically reanalysed. Methods: Nonlinear kinetic theory is used to determine the acceleration efficiency of cosmic rays (CRs) in the supernova remnant SN 1006. The known range of astronomical parameters and the existing measurements of nonthermal emission are examined in order to define the values of the relevant physical parameters that determine the CR acceleration efficiency. Results: It is shown that the parameter values - proton injection rate, electron to proton ratio and downstream magnetic field strength -are determined with the appropriate accuracy. In particular the observed azimuthal variations in the γ-ray morphology also agree with the theoretical expectation. These parameter values, together with the reduction of the γ-ray flux relative to a spherically symmetric acceleration geometry, allow a good fit to the existing data, including the recently detected TeV emission by H.E.S.S. Conclusions: SN 1006 represents the first example where a high efficiency of nuclear CR production, required for the Galactic CR sources, is consistently established.

  14. A Mn-54 Radiotracer Study of Mn Isotope Solid-Liquid Exchange during Reductive Transformation of Vernadite (δ-MnO₂) by Aqueous Mn(II)

    Energy Technology Data Exchange (ETDEWEB)

    Elzinga, Evert J.; Kustka, Adam B. [Rutgers

    2015-04-09

    We employed Mn-54 radiotracers to characterize the extent and dynamics of Mn atom exchange between aqueous Mn(II) and vernadite (δ-Mn(IV)O2) at pH 7.5 under anoxic conditions. Exchange of Mn atoms between the solid and liquid phase is rapid, reaching dynamic equilibrium in 2–4 days. We propose that during the initial stages of reaction, Mn atom exchange occurs through consecutive comproportionation-disproportionation reactions where interfacial electron transfer from adsorbed Mn(II) to lattice Mn(IV) generates labile Mn(III) cations that rapidly disproportionate to reform aqueous Mn(II) and solid-phase Mn(IV). Following nucleation of Mn(III)OOH phases, additional exchange likely occurs through electron transfer from aqueous Mn(II) to solid-phase Mn(III). Our results provide evidence for the fast and extensive production of transient Mn(III) species at the vernadite surface upon contact of this substrate with dissolved Mn(II). We further show that HEPES buffer is a reductant of lattice Mn(IV) in the vernadite structure in our experiments. The methods and results presented here introduce application of Mn-54 tracers as a facile tool to further investigate the formation kinetics of labile Mn(III) surface species and their impacts on Mn-oxide structure and reactivity over a range of environmentally relevant geochemical conditions.

  15. Catalytic growth of vertically aligned SnS/SnS2 p-n heterojunctions

    Science.gov (United States)

    Degrauw, Aaron; Armstrong, Rebekka; Rahman, Ajara A.; Ogle, Jonathan; Whittaker-Brooks, Luisa

    2017-09-01

    Nanowire arrays of SnS/SnS2 p-n heterojunctions are grown on transparent indium tin oxide (ITO) coated-glass and Si/SiO2 substrates via chemical vapor transport (CVT). The nanowire arrays are comprised of individual SnS/SnS2 heterostructures that are highly oriented with their lengths and morphologies controlled by the CVT conditions (i.e. reaction temperature, flow rate, and reaction time). The growth and optoelectronic characterization of these well-defined SnS/SnS2 p-n heterostructures pave the way for the fabrication of highly efficient solar cell devices.

  16. Magnetic interactions and electronic structure of Pt2Mn1− xYxGa (Y ...

    Indian Academy of Sciences (India)

    2017-06-19

    Jun 19, 2017 ... We study the magnetic exchange interaction between the atoms for the materials with ferromagnetic and antiferromagnetic configurations to show the effects of Fe and Cr substitution at Mn site on the magnetic interactions of these systems. Detailed analysis of electronic structure in terms of density of states ...

  17. Novel Preparation Methods of 52Mn for ImmunoPET Imaging

    DEFF Research Database (Denmark)

    Graves, Stephen A.; Hernandez, Reinier; Fonslet, Jesper

    2015-01-01

    52Mn (t1/2 =5.59 d, ß+ = 29.6%, Eßave = 0.24 MeV) shows promise in positron emission tomography (PET) and in dual-modality manganese-enhanced magnetic resonance imaging (MEMRI) applications including neural tractography, stem cell tracking, and biological toxicity studies. The extension to biocon......52Mn (t1/2 =5.59 d, ß+ = 29.6%, Eßave = 0.24 MeV) shows promise in positron emission tomography (PET) and in dual-modality manganese-enhanced magnetic resonance imaging (MEMRI) applications including neural tractography, stem cell tracking, and biological toxicity studies. The extension...... to bioconjugate application requires high specific activity 52Mn in a state suitable for macromolecule labeling. To that end a 52Mn production, purification, and labeling system is presented, and its applicability in preclinical, macromolecule PET is shown using the conjugate 52Mn-DOTA-TRC105. 52Mn is produced......% efficient (n=7) in 52Mn recovery, leading to a separation factor from Cr of (1.6 ± 1.0) x106 (n = 4), and an average effective specific activity of 0.8 GBq/µmol (n = 4) in titration against DOTA. 52Mn-DOTA-TRC105 conjugation and labeling demonstrate the potential for chelation applications. In vivo images...

  18. Controlling the antibacterial activity of CuSn thin films by varying the contents of Sn

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Yujin; Park, Juyun; Kim, Dong-Woo; Kim, Hakjun; Kang, Yong-Cheol, E-mail: yckang@pknu.ac.kr

    2016-12-15

    Highlights: • We deposit CuSn thin films on a Si substrate with various Cu/Sn ratio. • Antibacterial activities of CuSn thin films increased as the ratio of Cu and the contact time increased. • XPS was utilized to assign the chemical environment of CuSn thin films before and after antibacterial test. - Abstract: We investigated antibacterial activity of CuSn thin films against Gram positive Staphylococcus aureus (S. aureus). CuSn thin films with different Cu to Sn ratios were deposited on Si(100) by radio frequency (RF) magnetron sputtering method using Cu and Sn metal anodes. The film thickness was fixed at 200 nm by varying the sputtering time and RF power on the metal targets. The antibacterial test was conducted in various conditions such as different contact times and Cu to Sn ratios in the CuSn films. The antibacterial activities of CuSn thin films inc