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Sample records for base fe 2605sa1

  1. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    International Nuclear Information System (INIS)

    Cabral P, A.; Garcia S, I.; Contreras V, J. A.; Garcia S, F.; Nava, N.

    2010-01-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  2. Spectroscopic and mechanical studies on the Fe-based amorphous alloy 2605SA1

    Energy Technology Data Exchange (ETDEWEB)

    Cabral P, A.; Garcia S, I. [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Contreras V, J. A.; Garcia S, F. [Universidad Autonoma del Estado de Mexico, Facultad de Ciencias, El Cerrillo Piedras Blancas, Toluca, Estado de Mexico (Mexico); Nava, N., E-mail: agustin.cabral@inin.gob.m [Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, 07730 Mexico D. F. (Mexico)

    2010-07-01

    The Vickers micro-hardness of this alloy was unusually dependent on the heat treatment from 300 to 634 K, inferring important micro-structural changes and the presence of amorphous grains before its phase transition. Once the alloy is crystallized, the micro-hardness is characteristic of a brittle alloy, the main problem of these alloys. Within the amorphous state, other properties like free-volume, magnetic states and Fe-Fe distances were followed by Positron annihilation lifetime spectroscopy and Moessbauer spectroscopy, respectively, to analyze those micro-structural changes, thermally induced, which are of paramount interest to understand their brittleness problem. (Author)

  3. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness; Tratamiento termico de la aleacion amorfa base Fe 2605SA1, analisis de sus defectos y microdureza

    Energy Technology Data Exchange (ETDEWEB)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J. [Facultad de Ciencias, Universidad Autonoma del Estado de Mexico. El Cerillo Piedras Blancas, 50000 Toluca, Estado de Mexico (Mexico)

    2007-07-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  4. Thermal treatment of the amorphous base alloy Fe 2605SA1, analysis of its defects and microhardness

    International Nuclear Information System (INIS)

    Contreras V, J.A.; Cabral P, A.; Garcia Santibanez S, F.; Ramirez, J.; Lopez M, J.; Villaverde L, A.; Montoya E, A.; Merino, F.J.

    2007-01-01

    By means of the use of the positron lifetime technique those characteristics of the present crystalline defects in an amorphous base alloy Fe (SA1) are determined, when this is subjected to thermal treatments from 293 K until 808 K. Also, some results about the microhardness and electric resistivity are presented. (Author)

  5. Frequency dependence of the magnetostrictive phenomenon in Metglas® 2605SA1 ribbon: A minor-loop case

    Directory of Open Access Journals (Sweden)

    S. U. Jen

    2014-12-01

    Full Text Available Frequency dependence of magnetostrictive phenomenon of as-cast 2605SA1 ribbon was studied. We applied a sinusoidal sweeping field (H, with a fixed frequency (f, along length (L of the ribbon, and simultaneously recorded the longitudinal magnetostriction (λ∥ and the transverse magnetostriction (λ⊥ as a function of time (t, respectively. f was varied from 0.07 to 122 Hz. In the low-f case (f =0.07 Hz, we observed the frequency-doubling (FD feature in λ∥(t and λ⊥(t curves; i.e., only even harmonic magnetostrictive signals showed up. In the high-f case (f = 122 Hz, we observed the no-frequency-doubling (NFD feature; i.e., both odd and even harmonic magnetostrictive signals showed up. A theory, based on the balance among various torques acting on magnetization, is developed to explain the f dependence of the magnetostriction phenomenon observed. From this theory, we conclude that only when the reflection symmetry of the system is reserved, i.e., when the equivalent easy axis (EEA is perpendicular to L, will λ∥(t and λ⊥(t have the true-frequency-doubling (TFD feature. However, for the as-cast 2605SA1 ribbon, EEA is not perpendicular to L. Thus, strictly speaking, we should observe the NFD feature only. Nevertheless, in the low-f limit, we can show that the FD feature is somewhat allowed under the condition, b/α being close to 1, where b and α are the two parameters used in the theory. From experimental data, this condition is met for as-cast 2605SA1. To make a distinction from TFD, this low-f feature is called close-frequency-doubling (CFD in this paper. In general, the theory explains all the experimental results fairly well.

  6. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    Abstract. Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the dominant ...

  7. Electronic structure of Fe-based superconductors

    Indian Academy of Sciences (India)

    2015-05-29

    May 29, 2015 ... Fe-based superconductors have drawn much attention during the last decade due to the presence of superconductivity in materials containing the magnetic element, Fe, and the coexistence of superconductivity and magnetism. Extensive study of the electronic structure of these systems suggested the ...

  8. Biomimetic peptide-based models of [FeFe]-hydrogenases: utilization of phosphine-containing peptides

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Souvik [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Nguyen, Thuy-Ai D. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Gan, Lu [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA; Jones, Anne K. [Department of Chemistry and Biochemistry; Arizona State University; Tempe, USA

    2015-01-01

    Peptide based models for [FeFe]-hydrogenase were synthesized utilizing unnatural phosphine-amino acids and their electrocatalytic properties were investigated in mixed aqueous-organic solvents.

  9. Research Progress on Fe-based Amorphous Coatings

    Directory of Open Access Journals (Sweden)

    LIANG Xiu-bing

    2017-09-01

    Full Text Available The latest research progresses on Fe-based amorphous coatings were reviewed. The typical alloy system and the classification of Fe-based amorphous coatings were clarified. The status, progress and development of the Fe-based amorphous coatings prepared by thermal spray processing and laser cladding process were discussed. The main mechanical properties and potential applications of the Fe-based amorphous coatings were also described. Furthermore, based on the main problems mentioned above, the future development of the Fe-based amorphous coatings was discussed, including the exploitation preparation technologies of high amorphous content of the Fe-based coatings, the development of the low cost and high performance Fe-based coating alloys system, the broadening application of Fe-based amorphous coatings, and so on.

  10. The new Fe-based superconductors

    International Nuclear Information System (INIS)

    Mao, Zhiqiang

    2011-01-01

    The discovery of unconventional superconductivity in doped iron pnictides has ushered in a new era of high temperature superconductivity. The superconductivity of these materials occurs in close proximity to magnetic instability; superconductivity is achieved by suppressing a long-range antiferromagnetic (AFM) order through charge carrier doping or pressure. In this talk, I will first give a brief overview of the phase diagrams of iron-based superconductors, and then talk about our recent research on iron chalcogenide Fe 1+y (Te 1-x Se x ) superconductors, which is structurally the simplest of the Fe-based superconductors. Although the Fermi surface of iron chalcogenides is similar to iron pnictides, the parent compound Fe 1+y Te exhibits AFM order with in-plane magnetic wave-vector (π, 0). This contrasts the pnictide parent compounds where the magnetic order has an in-plane magnetic wave-vector (π, π) that connects hole and electron parts of the Fermi surface. Despite these differences, both the pnictide and chalcogenide Fe-superconductors exhibit superconducting spin resonances around (π, π), suggesting a common symmetry for their superconducting order parameter. A central question in this burgeoning field is therefore how (π, π) superconductivity can emerge from a (π, 0) magnetic instability. I will address this issue in my talk. I will show the phase diagram of electronic and magnetic properties we recently established for this system and discuss the relationship between magnetic coupling and electronic properties. Our results reveal that the magnetic soft mode evolving from the (π, 0)-type magnetic long-range order is associated with weak charge carrier localization. Bulk superconductivity occurs only as magnetic correlations near (π, 0) are strongly suppressed and the magnetic mode at (π, π) becomes dominant; this suggests a common magnetic origin for superconductivity in iron chalcogenide and pnictide superconductors. (author)

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

    Science.gov (United States)

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

    2018-06-01

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

  12. A new rhodamine-based fluorescent probe for the discrimination of Fe"3"+ from Fe"2"+

    International Nuclear Information System (INIS)

    You, Qi Hua; Huang, Hua Bin; Zhuang, Zhi Xia; Wang, Xiao Ru; Chan, Wing Hong

    2016-01-01

    A new rhodamine-based fluorescent probe for the discrimination of Fe"3"+ from Fe"2"+ has been designed and investigated. The probe shows an immediate visual color change in response to Fe"3"+ and Cu"2"+, while only Fe"3"+ triggers the fluorescent change of the probe. The existence of large amount of other metal ions shows negligible interference in the detection of Fe"3"+. The association constant K_a_s_s of 4.64 × 10"8 M"-"2 (R"2 = 0.994) and 5.38 × 10"8 M"-"2 (R"2 = 0.991) of the complex was derived from UV/Vis and fluorescence titration assuming 1:2 stoichiometry of probe–Fe"3"+ complex, respectively

  13. Poor glass-forming ability of Fe-based alloys

    DEFF Research Database (Denmark)

    Zheng, H.J.; Hu, L.N.; Zhao, X.

    2017-01-01

    processes. By using the concept of fluid cluster and supercooled liquid fragility in metallic liquids, it has been found that this dynamic transition makes the Fe-based supercooled liquids become more unstable, which leads to the poor GFA of Fe-based alloys. Further, it has been found that the degree...

  14. The activation mechanism of Fe-based olefin metathesis catalysts

    KAUST Repository

    Poater, Albert

    2014-08-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts. © 2014 Elsevier B.V.

  15. The activation mechanism of Fe-based olefin metathesis catalysts

    KAUST Repository

    Poater, Albert; Pump, Eva; Vummaleti, Sai V. C.; Cavallo, Luigi

    2014-01-01

    Density functional theory calculations have been used to describe the first turnover for olefin metathesis reaction of a homogenous Fe-based catalyst bearing a N-heterocyclic carbene ligand with methoxyethene as a substrate. Equal to conventional Ru-based catalysts, the activation of its Fe congener occurs through a dissociative mechanism, however with a more exothermic reaction energy profile. Predicted upper energy barriers were calculated to be on average ∼2 kcal/mol more beneficial for Fe catalyzed metathesis. Overall, this present computational study emphasises on advantages of Fe-based metathesis and gives a potential recipe for the design of an efficient Fe-based olefin metathesis catalysts. © 2014 Elsevier B.V.

  16. Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Hsu, T.Y.

    2000-01-01

    Characteristics of martensitic transformation fcc(γ)→hcp(ε) in Fe-Mn-Si based alloys are briefly reviewed. By analyzing the influences of constituents and treatments on shape memory effect (SME) in Fe-Mn-Si, the main factors controlling SME are summarized as austenite strengthening, stacking fault energy (probability) and antiferromagnetic temperature. Contribution of thermomechanical training to SME is introduced. The Fe-Mn-Si-RE (rare earth elements) and Fe-Mn-Si-Cr-N alloys are recommended as two novel shape memory alloys with superior SME. (orig.)

  17. Microstructure and wear behaviour of FeAl-based composites ...

    Indian Academy of Sciences (India)

    FeAl-based composites; precipitation; mechanical properties; wear. 1. Introduction. Fe–Al alloys ... ground to 1500 grit and polished with alumina powder. (0.5 μm). ... Alloy-2 (figure 2) consists of cuboid-shaped ZrC (region C), an FeAl matrix ...

  18. Nematicity and Magnetism in FeSe and Other Families of Fe-Based Superconductors

    Directory of Open Access Journals (Sweden)

    Youichi Yamakawa

    2016-06-01

    Full Text Available Nematicity and magnetism are two key features in Fe-based superconductors, and their interplay is one of the most important unsolved problems. In FeSe, the magnetic order is absent below the structural transition temperature T_{str}=90  K, in stark contrast to the fact that the magnetism emerges slightly below T_{str} in other families. To understand such amazing material dependence, we investigate the spin-fluctuation-mediated orbital order (n_{xz}≠n_{yz} by focusing on the orbital-spin interplay driven by the strong-coupling effect, called the vertex correction. This orbital-spin interplay is very strong in FeSe because of the small ratio between the Hund’s and Coulomb interactions (J[over ¯]/U[over ¯] and large d_{xz}, d_{yz}-orbital weight at the Fermi level. For this reason, in the FeSe model, the orbital order is established irrespective of the fact that the spin fluctuations are very weak, so the magnetism is absent below T_{str}. In contrast, in the LaFeAsO model, the magnetic order appears just below T_{str} both experimentally and theoretically. Thus, the orbital-spin interplay due to the vertex correction is the key ingredient in understanding the rich phase diagram with nematicity and magnetism in Fe-based superconductors in a unified way.

  19. New developments in NdFeB-based permanent magnets

    International Nuclear Information System (INIS)

    Liu, Z.W.

    2011-01-01

    NdFeB based alloys have been used as permanent magnets for almost thirty years. The recent researches aim at optimizing the composition, microstructure and properties, reducing cost, and developing new processes. The demand for sintered magnet is increasing. Efforts are directed towards improving properties by controlling grain boundary diffusion, minimizing the rare earth (RE) content and also improving production yield. As for bonded magnets, to enhance remanence and energy product, nanocrystalline powders are employed. High thermal stability has been realized by mixing NdFeB with hard ferrite powders. For nanocrystalline and nano composite NdFeB based alloys, both compositional modification and microstructural optimization have been carried out. New approaches have also been proposed to prepare NdFeB magnets with idea structure. Surfactant assisted ball milling is a good top-down method to obtain nano sized hard magnetic particles and anisotropic nano flakes. Synthesis of NdFeB nanoparticles and NdFeB/Fe (Co) nano composite powders by bottom-up techniques, such as chemical reduction process and co-precipitation, has been successful very recently. To assemble nanocrystalline NdFeB powders or nanoparticles into bulk magnets, various novel consolidation processes including spark plasma sintering and high velocity press have been employed. Hot deformation can be selected as the process to achieve anisotropy in nanocrystalline magnets. (author)

  20. Corrosion resistance of Fe-based amorphous alloys

    International Nuclear Information System (INIS)

    Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

    2014-01-01

    Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

  1. Adsorption of As(V) from water using Mg-Fe-based hydrotalcite (FeHT)

    Energy Technology Data Exchange (ETDEWEB)

    Tuerk, T. [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey); Alp, I., E-mail: ialp@ktu.edu.tr [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey); Deveci, H. [Mineral Processing Division, Department of Mining Engineering, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2009-11-15

    This paper describes a study of the sorptive removal of arsenate (As(V)) from aqueous solutions by synthetically prepared Mg-Fe-based hydrotalcites (FeHT) as layered double hydroxide (LDH) adsorbents. The synthesis of Fe{sup 3+}-substituted hydrotalcites (FeHT) with the chemical formula [Mg(II){sub 6}Fe(III){sub 2}(OH){sub 16}]{sup 2+}[CO{sub 3} x yH{sub 2}O]{sup 2-} was achieved by a co-precipitation method. The reaction products were characterized by powder X-ray diffraction analysis. The influences of solution pH, initial arsenate (As(V)) concentration, and sorbent concentration were investigated in multiple kinetic runs. The adsorption rates and isotherms were investigated in batch experiments. The pseudo-first-order and second-order kinetic models were tested and the latter was found to fit better to the experimental data. Langmuir and Freundlich isotherms were used to describe the adsorption data from equilibrium experiments. The results have shown that FeHT has a high arsenate removal efficiency, with the ability to reduce the concentration of arsenate in the aqueous solution from an initial value of 330 {mu}g/l to <10 {mu}g/l (i.e. below the limit value specified by WHO).

  2. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Fuel performance codes approximate this complex behavior using an axisymmetric, axially-stacked, one-dimensional radial representation to save computation cost. However, the need for improved modeling of PCMI and, particularly, the importance of multidimensional capability for accurate fuel performance simulation has been identified as safety margin decreases. Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed

  3. Campbell penetration depth in Fe-based superconductors

    International Nuclear Information System (INIS)

    Prommapan, Plegchart

    2011-01-01

    A 'true' critical current density, j c , as opposite to commonly measured relaxed persistent (Bean) current, j B , was extracted from the Campbell penetration depth, λ c (T,H) measured in single crystals of LiFeAs, and optimally electron-doped Ba(Fe 0.954 Ni 0.046 ) 2 As 2 (FeNi122). In LiFeAs, the effective pinning potential is nonparabolic, which follows from the magnetic field - dependent Labusch parameter α. At the equilibrium (upon field - cooling), α(H) is non-monotonic, but it is monotonic at a finite gradient of the vortex density. This behavior leads to a faster magnetic relaxation at the lower fields and provides a natural dynamic explanation for the fishtail (second peak) effect. We also find the evidence for strong pinning at the lower fields.The inferred field dependence of the pinning potential is consistent with the evolution from strong pinning, through collective pinning, and eventually to a disordered vortex lattice. The value of j c (2 K) ≅ 1.22 x 10 6 A/cm 2 provide an upper estimate of the current carrying capability of LiFeAs. Overall, vortex behavior of almost isotropic, fully-gapped LiFeAs is very similar to highly anisotropic d-wave cuprate superconductors, the similarity that requires further studies in order to understand unconventional superconductivity in cuprates and pnictides. In addition to LiFeAs, we also report the magnetic penetration depth in BaFe 2 As 2 based superconductors including irradiation of FeNi122. In unirradiated FeNi122, the maximum critical current value is, j c (2K) ≅ 3.3 x 10 6 A/cm 2 . The magnetic-dependent feature was observed near the transition temperature in FeTe 0.53 Se 0.47 and irradiated FeNi122. Because of this feature, further studies are required in order to properly calibrate the Campbell penetration depth. Finally, we detected the crossing between the magnetic penetration depth and London penetration depth in optimally hold-doped Ba 0.6 K 0.4 Fe 2 As 2 (BaK122) and isovalent doped BaFe 2 (As 0

  4. Fe-based composite materials with improved mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Werniewicz, Katarzyna [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland); Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering, Warsaw (Poland)

    2008-07-01

    Following a previous study by the authors two new compositions (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 91}C{sub 9} and (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} have been developed with the aim of improving the ductility of Fe{sub 65.5}Cr{sub 4}Mo{sub 4}Ga{sub 4}P{sub 12}C{sub 5}B{sub 5.5} bulk metallic glass (BMG). In contrast to the alloys in that study, the recently prepared Fe-based materials are Ga-free. It was expected that the variations in the composition will lead to the changes in the phase formation and, hence, in the mechanical response of the investigated alloys. It was recognized that in-situ formed Fe-based composites show superior plasticity ({epsilon}{sub pl}{approx}37%) for the alloy with lower C content and ({epsilon}{sub pl}{approx}4%) for the alloy with higher C content compared to monolithic glass ({epsilon}{sub pl}{approx}0.2%). Furthermore, on the basis of present as well as previous investigations it has been shown that the Ga addition is beneficial for the plasticity of these Fe-based alloys. It was observed that the (Fe{sub 89.0}Cr{sub 5.5}Mo{sub 5.5}){sub 83}C{sub 17} alloy exhibits a significantly smaller fracture strain ({epsilon}{sub f}{approx}5%) compared to its Ga-containing counterpart ({epsilon}{sub f}{approx}16%). Therefore, it can be concluded that appropriate alloying additions are crucial in enhancing the mechanical properties of the complex Fe-based materials developed here.

  5. Aluminium base amorphous and crystalline alloys with Fe impurity

    International Nuclear Information System (INIS)

    Sitek, J.; Degmova, J.

    2006-01-01

    Aluminium base alloys show remarkable mechanical properties, however their low thermal stability still limits the technological applications. Further improvement of mechanical properties can be reached by partial crystallization of amorphous alloys, which gives rise to nanostructured composites. Our work was focused on aluminium based alloys with Fe, Nb and V additions. Samples of nominal composition Al 90 Fe 7 Nb 3 and Al 94 Fe 2 V 4 were studied in amorphous state and after annealing up to 873 K. From Moessbauer spectra taken on the samples in amorphous state the value of f-factor was determined as well as corresponding Debye temperatures were calculated. Annealing at higher temperatures induced nano and microcrystalline crystallization. Moessbauer spectra of samples annealed up to 573 K are fitted only by distribution of quadrupole doublets corresponding to the amorphous state. An increase of annealing temperature leads to the structural transformation, which consists in growth of nanometer sized aluminium nuclei. This is partly reflected in Moessbauer parameters. After annealing at 673 K intermetallic phase Al 3 Fe and other Al-Fe phases are created. In this case Moessbauer spectra are fitted by quadrupole doublets. During annealing up to 873 K large grains of Fe-Al phases are created. (authors)

  6. State of art in FE-based fuel performance codes

    International Nuclear Information System (INIS)

    Kim, Hyo Chan; Yang, Yong Sik; Kim, Dae Ho; Bang, Je Geon; Kim, Sun Ki; Koo, Yang Hyun

    2013-01-01

    Finite element (FE) method that is reliable and proven solution in mechanical field has been introduced into fuel performance codes for multidimensional analysis. The present state of the art in numerical simulation of FE-based fuel performance predominantly involves 2-D axisymmetric model and 3-D volumetric model. The FRAPCON and FRAPTRAN own 1.5-D and 2-D FE model to simulate PCMI and cladding ballooning. In 2-D simulation, the FALCON code, developed by EPRI, is a 2-D (R-Z and R-θ) fully thermal-mechanically coupled steady-state and transient FE-based fuel behavior code. The French codes TOUTATIS and ALCYONE which are 3-D, and typically used to investigate localized behavior. In 2008, the Idaho National Laboratory (INL) has been developing multidimensional (2-D and 3-D) nuclear fuel performance code called BISON. In this paper, the current state of FE-based fuel performance code and their models are presented. Based on investigation into the codes, requirements and direction of development for new FE-based fuel performance code can be discussed. Based on comparison of models in FE-based fuel performance code, status of art in the codes can be discussed. A new FE-based fuel performance code should include typical pellet and cladding models which all codes own. In particular, specified pellet and cladding model such as gaseous swelling and high burnup structure (HBS) model should be developed to improve accuracy of code as well as consider AC condition. To reduce computation cost, the approximated gap and the optimized contact model should be also developed. Nuclear fuel operates in an extreme environment that induces complex multiphysics phenomena, occurring over distances ranging from inter-atomic spacing to meters, and times scales ranging from microseconds to years. This multiphysics behavior is often tightly coupled, a well known example being the thermomechanical behavior. Adding to this complexity, important aspects of fuel behavior are inherently

  7. Domain observations of Fe and Co based amorphous wires

    International Nuclear Information System (INIS)

    Takajo, M.; Yamasaki, J.

    1993-01-01

    Domain observations were made on Fe and Co based amorphous magnetic wires that exhibit a large Barkhausen discontinuity during flux reversal. Domain patterns observed on the wire surface were compared with those found on a polished section through the center of the wire. It was confirmed that the Fe based wire consists of a shell and core region as previously proposed, however, there is a third region between them. This fairly thick transition region made up of domains at an angle of about 45 degree to the wire axis clearly lacking the closure domains of the previous model. The Co based wire does not have a clear core and shell domain structure. The center of the wire had a classic domain structure expected of uniaxial anisotropy with the easy axis normal to the wire axis. When a model for the residual stress quenched-in during cooling of large Fe bars is applied to the wire, the expected anisotropy is consistent with the domain patterns in the Fe based wire, however, shape anisotropy still plays a dominant role in defining the wire core in the Co based wire

  8. Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes.

    Science.gov (United States)

    Zhou, Du; Yuan, Xi; Gao, Haoxiang; Wang, Ailing; Liu, Jun; El Fakir, Omer; Politis, Denis J; Wang, Liliang; Lin, Jianguo

    2016-12-13

    The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques. This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

  9. Spectroscopic scanning tunneling microscopy insights into Fe-based superconductors

    International Nuclear Information System (INIS)

    Hoffman, Jennifer E

    2011-01-01

    In the first three years since the discovery of Fe-based high T c superconductors, scanning tunneling microscopy (STM) and spectroscopy have shed light on three important questions. First, STM has demonstrated the complexity of the pairing symmetry in Fe-based materials. Phase-sensitive quasiparticle interference (QPI) imaging and low temperature spectroscopy have shown that the pairing order parameter varies from nodal to nodeless s± within a single family, FeTe 1-x Se x . Second, STM has imaged C4 → C2 symmetry breaking in the electronic states of both parent and superconducting materials. As a local probe, STM is in a strong position to understand the interactions between these broken symmetry states and superconductivity. Finally, STM has been used to image the vortex state, giving insights into the technical problem of vortex pinning, and the fundamental problem of the competing states introduced when superconductivity is locally quenched by a magnetic field. Here we give a pedagogical introduction to STM and QPI imaging, discuss the specific challenges associated with extracting bulk properties from the study of surfaces, and report on progress made in understanding Fe-based superconductors using STM techniques.

  10. A new rhodamine-based fluorescent probe for the discrimination of Fe{sup 3+} from Fe{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    You, Qi Hua; Huang, Hua Bin; Zhuang, Zhi Xia; Wang, Xiao Ru [Dept. of Science and Technology for Inspection, Xiamen Huaxia University, Xiamen (China); Chan, Wing Hong [Dept. of of Chemistry, Hong Kong Bap tist University, Hong Kong (China)

    2016-11-15

    A new rhodamine-based fluorescent probe for the discrimination of Fe{sup 3+} from Fe{sup 2+} has been designed and investigated. The probe shows an immediate visual color change in response to Fe{sup 3+} and Cu{sup 2+}, while only Fe{sup 3+} triggers the fluorescent change of the probe. The existence of large amount of other metal ions shows negligible interference in the detection of Fe{sup 3+}. The association constant K{sub ass} of 4.64 × 10{sup 8} M{sup -2} (R{sup 2} = 0.994) and 5.38 × 10{sup 8} M{sup -2} (R{sup 2} = 0.991) of the complex was derived from UV/Vis and fluorescence titration assuming 1:2 stoichiometry of probe–Fe{sup 3+} complex, respectively.

  11. Magnetic and transport properties of Fe-based nanocrystalline materials

    Science.gov (United States)

    Barandiarán, J. M.

    1994-01-01

    Fe-rich amorphous alloys containing late transition metals like Nb, V, Zr,..., sometimes with the addition of Cu, can crystallize in ultrafine grains of a crystalline phase, a few nanometers in diameter, embedded in a disordered matrix. In such state they have shown excellent soft magnetic properties for technical applications, rising the interest for deep studies. In this paper, recent work on some Fe-Nb and Fe-Zr based alloys both in amorphous state and after several degrees of nanocrystallization is presented. The nanocrystallization process has been achieved by conventional heat treatments (about 1 h at temperatures around 400-500 °C in a controlled atmosphere furnance) as well as by Joule heating using an electrical current flowing through the sample. Magnetic measurements, electrical resistivity, x-rays diffraction and 57Fe Mössbauer spectroscopy were used in the study of the crystalline phases appearing after the thermal treatments. The basic magnetic and transport properties of the nanocrystals do not differ appreciably from their bulk values. The magnetic anisotropy, however, is very sensitive to grain size and to the intergranular magnetic coupling. The effect of such coupling is deduced from the coercivity changes at the Curie Temperature of the amorphous matrix remaining after nanocrystallization.

  12. Acetone sensors based on microsheet-assembled hierarchical Fe2O3 with different Fe3+ concentrations

    Science.gov (United States)

    Wang, Han; Yan, Lei; Li, Shuo; Li, Yu; Liu, Li; Du, Liting; Duan, Haojie; Cheng, Yali

    2018-02-01

    Several different morphologies of microsheet-assembled Fe2O3 have been fabricated by hydrothermal method using diverse concentrations of Fe3+ precursor solutions (0.025, 0.020, 0.015, 0.010 mol/L Fe3+). The as-synthesized materials have been characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and energy-dispersive X-ray spectrometry (EDS). The SEM images reflect that the morphologies of as-synthesized materials are affected by the concentrations of Fe3+ in precursor solutions. The less concentration of Fe3+, the more porous of Fe2O3 microflowers, and thinner of slices distributed on the surface. Furthermore, gas sensors based on these Fe2O3 microflowers manufactured and tested to various common gases. The optimum response value to 100 ppm acetone is 52 at the working temperature of 220 °C. Meanwhile, the Fe2O3 microflower sensors possess ultrafast response-recovery speed, which are 8 and 19 s, respectively. The possible sensing mechanism was mainly attributed to the high surface area, three-dimensional porous structure.

  13. Exploring FeSe-based superconductors by liquid ammonia method

    International Nuclear Information System (INIS)

    Ying Tian-Ping; Wang Gang; Jin Shi-Feng; Shen Shi-Jie; Zhang Han; Zhou Ting-Ting; Lai Xiao-Fang; Wang Wan-Yan; Chen Xiao-Long

    2013-01-01

    Our recent progress on the preparation of a series of new FeSe-based superconductors and the clarification of SC phases in potassium-intercalated iron selenides are reviewed here. By the liquid ammonia method, metals Li, Na, Ca, Sr, Ba, Eu, and Yb are intercalated in between FeSe layers and form superconductors with transition temperatures of 30 K∼46 K, which cannot be obtained by high-temperature routes. In the potassium-intercalated iron selenides, we demonstrate that at least two SC phases exist, K x Fe 2 Se 2 (NH 3 ) y (x ≈ 0.3 and 0.6), determined mainly by the concentration of potassium. NH 3 has little, if any, effect on superconductivity, but plays an important role in stabilizing the structures. All these results provide a new starting point for studying the intrinsic properties of this family of superconductors, especially for their particular electronic structures. (topical review - iron-based high temperature superconductors)

  14. Melting and casting of FeAl-based cast alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

    1998-11-01

    The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

  15. High-Tc Superconductors Based on FeAs Compounds

    CERN Document Server

    Izyumov, Yuri

    2010-01-01

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

  16. Roles of Co element in Fe-based bulk metallic glasses utilizing industrial FeB alloy as raw material

    Directory of Open Access Journals (Sweden)

    Shouyuan Wang

    2017-08-01

    Full Text Available A series of Fe-based bulk metallic glasses were fabricated by a conventional copper mold casting method using a kind of Fe-B industrial raw alloy. It is found that Fe-B-Y-Nb bulk metallic glass with 3 at% of Co addition possesses the best glass forming ability, thermal stability, hardness, magnetic property and anti-corrosion property. The hardness test result indicates a synchronically trend with glass-forming ability parameters. The excellent glass-forming ability and a combination of good mechanical and functional properties suggest that the alloys in this work might be good candidates for commercial use.

  17. Seasonal changes in Fe species and soluble Fe concentration in the atmosphere in the Northwest Pacific region based on the analysis of aerosols collected in Tsukuba, Japan

    Directory of Open Access Journals (Sweden)

    Y. Takahashi

    2013-08-01

    mineral dust concentrations during spring in East Asia. However, this factor does not contribute to the amount of soluble Fe to a larger degree than the effect of Fe speciation, or more strictly speaking the presence of Fe(III sulfate. Therefore, based on these results, the most significant factor influencing the amount of soluble Fe in the North Pacific region is the concentration of anthropogenic Fe species such as Fe(III sulfate that can be emitted from megacities in Eastern Asia.

  18. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Katiyar, Ajay, E-mail: ajay_k@ric.drdo.in [Research and Innovation Centre (DRDO), IIT Madras Research Park, Chennai 600113 (India); Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Dhar, Purbarun [Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 (India); Nandi, Tandra [Defence Materials and Stores Research and Development Establishment (DRDO), G.T. Road, Kanpur 208013 (India); Das, Sarit K. [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036 (India); Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001 (India)

    2017-08-15

    Highlights: • The magnetoviscous effect in ferrofluids in the presence of magnetic field is investigated. • Oxides of Fe and Ni are dispersed in oil to formulate the ferrofluids. • Drastic enhancement in the yield stress and viscosity under the magnetic field is observed for Fe{sub 3}O{sub 4}-based ferrofluids. • Viscoelastic properties of the formulated ferrofluids demonstrate the strong function of magnetic field. • The increase in temperature reduces the magneto-viscous effect in ferrofluids under the magnetic field. - Abstract: Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe{sub 3}O{sub 4}), Iron (III) oxide (Fe{sub 2}O{sub 3}) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto

  19. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-01-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications. PMID:27725780

  20. Topological Superconductivity on the Surface of Fe-Based Superconductors.

    Science.gov (United States)

    Xu, Gang; Lian, Biao; Tang, Peizhe; Qi, Xiao-Liang; Zhang, Shou-Cheng

    2016-07-22

    As one of the simplest systems for realizing Majorana fermions, the topological superconductor plays an important role in both condensed matter physics and quantum computations. Based on ab initio calculations and the analysis of an effective 8-band model with superconducting pairing, we demonstrate that the three-dimensional extended s-wave Fe-based superconductors such as Fe_{1+y}Se_{0.5}Te_{0.5} have a metallic topologically nontrivial band structure, and exhibit a normal-topological-normal superconductivity phase transition on the (001) surface by tuning the bulk carrier doping level. In the topological superconductivity (TSC) phase, a Majorana zero mode is trapped at the end of a magnetic vortex line. We further show that the surface TSC phase only exists up to a certain bulk pairing gap, and there is a normal-topological phase transition driven by the temperature, which has not been discussed before. These results pave an effective way to realize the TSC and Majorana fermions in a large class of superconductors.

  1. High pressure die casting of Fe-based metallic glass.

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-11

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  2. High pressure die casting of Fe-based metallic glass

    Science.gov (United States)

    Ramasamy, Parthiban; Szabo, Attila; Borzel, Stefan; Eckert, Jürgen; Stoica, Mihai; Bárdos, András

    2016-10-01

    Soft ferromagnetic Fe-based bulk metallic glass key-shaped specimens with a maximum and minimum width of 25.4 and 5 mm, respectively, were successfully produced using a high pressure die casting (HPDC) method, The influence of die material, alloy temperature and flow rate on the microstructure, thermal stability and soft ferromagnetic properties has been studied. The results suggest that a steel die in which the molten metal flows at low rate and high temperature can be used to produce completely glassy samples. This can be attributed to the laminar filling of the mold and to a lower heat transfer coefficient, which avoids the skin effect in the steel mold. In addition, magnetic measurements reveal that the amorphous structure of the material is maintained throughout the key-shaped samples. Although it is difficult to control the flow and cooling rate of the molten metal in the corners of the key due to different cross sections, this can be overcome by proper tool geometry. The present results confirm that HPDC is a suitable method for the casting of Fe-based bulk glassy alloys even with complex geometries for a broad range of applications.

  3. Ab initio study of C14 laves phases in Fe-based systems

    Directory of Open Access Journals (Sweden)

    Pavlu J.

    2012-01-01

    Full Text Available Structural properties and energetics of Fe-based C14 Laves phases at various compositions (i.e. Fe2Fe, Fe2X, X2Fe, X2X, where X stands for Si, Cr, Mo, W, Ta were investigated using the pseudopotential VASP (Vienna Ab initio Simulation Package code employing the PAW-PBE (Projector Augmented Wave - Perdew Burke-Ernzerhof pseudopotentials. Full relaxation was performed for all structures studied including the reference states of elemental constituents and the equilibrium structure parameters as well as bulk moduli were found. The structure parameters of experimentally found structures were very well reproduced by our calculations. It was also found that the lattice parameters and volumes of the unit cell decrease with increasing molar fraction of iron. Thermodynamic analysis shows that the Fe2X configurations of Laves phases are more stable than the X2Fe ones. Some of the X2Fe configurations are even unstable with respect to the weighted average of the Laves phases of elemental constituents. Our calculations predict the stability of Fe2Ta. On the other hand, Fe2Mo and Fe2W are slightly unstable (3.19 and 0.68 kJ.mol-1, respectively and hypothetical structures Fe2Cr and Fe2Si are found unstable as well.

  4. Acoustic properties of TiNiMoFe base alloys

    International Nuclear Information System (INIS)

    Gyunter, V.Eh.; Chernyshev, V.I.; Chekalkin, T.L.

    2000-01-01

    The regularity of changing the acoustic properties of the TiNi base alloys in dependence on the alloy composition and impact temperature is studied. It is shown that the oscillations of the TiNiMoFe base alloys within the temperature range of the B2 phase existence and possible appearance of the martensite under the load differ from the traditional materials oscillations. After excitation of spontaneous oscillations within the range of M f ≤ T ≤ M d there exists the area of long-term and low-amplitude low-frequency acoustic oscillations. It is established that free low-frequency oscillations of the TH-10 alloy sample are characterized by the low damping level in the given temperature range [ru

  5. Elucidation of reaction mechanism for m -cresol hydrodeoxygenation over Fe based catalysts: A kinetic study

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Yongchun; Wang, Yong

    2017-09-01

    Fe based catalysts are promising for hydrodeoxygenation (HDO) of lignin derived phenolics due to their high selectivity for aromatics. In this work, the reaction mechanism of m-cresol HDO on Fe catalysts and the kinetic consequence with Pd addition were elucidated by examining the effect of H2, H2O and m-cresol pressures on toluene formation rate on Fe and PdFe catalysts. A direct CO bond cleavage mechanism is proposed for HDO catalysis on both Fe and PdFe catalysts, while Pd provides a facilitated reaction pathway at the PdFe interface and therefore promotes the catalysis on Fe without changing the high selectivity towards aromatics.

  6. Epitaxial growth of Fe-based superconductor thin films

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Sven; Haenisch, Jens; Holzapfel, Bernhard [Institut fuer Technische Physik, Karlsruher Institut fuer Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2016-07-01

    The Fe-based superconductors (FBS), discovered in 2008, are not only interesting for possible applications due to their large upper critical fields and low anisotropies, but also for basic understanding of unconventional superconductivity. With their properties, they constitute a link between the classic low-T{sub c} superconductors (low anisotropies, low thermal fluctuations, s-wave type symmetry) and the oxocuprates (T{sub c} up to 55 K, large H{sub c2}, unconventional pairing). Their multi-band nature reminds of MgB{sub 2}. We prepare thin films of FBS in the so called 122 family, namely Co- and P-doped BaFe{sub 2}As{sub 2} to investigate application relevant properties, such as critical current density J{sub c}, by pulsed laser deposition using a frequency-tripled Nd:YAG laser (λ = 355 nm). Microstructure and chemical composition will be investigated by XRD, AFM and SEM, and electrical transport using a 14 T PPMS. The results are compared to literature data on films grown at different wavelengths.

  7. Effects of V and Cr on Laser Cladded Fe-Based Coatings

    Directory of Open Access Journals (Sweden)

    Haiyang Wang

    2018-03-01

    Full Text Available Fe-based coatings with high V and Cr content were obtained by laser cladding using Fe-based powder with different Cr3C2 and FeV50 content. The results showed that Fe-based coatings were uniform and dense. The constituent phases were mainly composed of α-Fe solid solution with the increase of Cr3C2 and FeV50, γ-Fe and V8C7 phases were achieved. The microstructure of the coatings exhibited a typical dendrite structure. The concentration of C, V and Cr were saturated in dendritic areas, and the other alloying elements were mainly dissolved in the interdendritic areas. The hardness and wear resistance of Fe-based coatings were enhanced with the Cr3C2 and FeV50 addition. The specimen with 15% Cr3C2 and 16% FeV50 had the highest hardness of 66.1 ± 0.6 HRC, which was 1.05 times higher than the sample with 4.5% Cr3C2 and 5% FeV50, and the wear resistance of the former was three times greater than the latter.

  8. Fe-based bulk amorphous alloys with iron contents as high as 82 at%

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jin-Feng; Liu, Xue; Zhao, Shao-Fan; Ding, Hong-Yu [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Yao, Ke-Fu, E-mail: kfyao@tsinghua.edu.cn [School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-07-15

    Fe-based bulk amorphous alloys (BAAs) with high Fe contents are advantageous due to their high saturation magnetization and low cost. However, preparing Fe-based BAAs with Fe contents higher than 80 at% is difficult due to their poor glass forming abilities (GFA). In this study, an Fe{sub 81}P{sub 8.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA with a diameter of 1 mm and a saturation magnetization of 1.56 T was successfully prepared using the fluxing and copper mold casting methods. In addition, by introducing a small amount of elemental Mo to the alloy, an Fe{sub 82}Mo{sub 1}P{sub 6.5}C{sub 5.5}B{sub 2}Si{sub 3} BAA rod with a diameter of 1 mm, a high saturation magnetization of 1.59 T, a high yield stress of 3265 MPa, and a clear plasticity of 1.3% was prepared in the same way. The cost effectiveness and good magnetic properties of these newly-developed Fe-based BAAs with Fe contents as high as 82 at% would be advantageous and promising for industrial applications. - Highlights: • Novel Fe-based BAA with no other metallic element except 81 at% Fe was prepared. • Fe-based bulk amorphous alloy (BAA) with the highest Fe content (82%) was prepared. • Very high saturation magnetization of 1.59 T has been achieved. • A new thought for designing Fe-based BAA with high Fe content was provided.

  9. Magnetoviscoelastic characteristics of superparamagnetic oxides (Fe, Ni) based ferrofluids

    Science.gov (United States)

    Katiyar, Ajay; Dhar, Purbarun; Nandi, Tandra; Das, Sarit K.

    2017-08-01

    Ferrofluids have been popular among the academic and scientific communities owing to their intelligent physical characteristics under external stimuli and are in fact among the first nanotechnology products to be employed in real world applications. However, studies on the magnetoviscoelastic behavior of concentrated ferrofluids, especially of superparamagnetic oxides of iron and nickel are rare. The present article comprises the formulation of magneto-colloids utilizing the three various metal oxides nanoparticles viz. Iron (II, III) oxide (Fe3O4), Iron (III) oxide (Fe2O3) and Nickel oxide (NiO) in oil. Iron (II, III) oxide based colloids demonstrate high magnetoviscous characteristics over the other oxides based colloids under external magnetic fields. The maximum magnitude of yield stress and viscosity is found to be 3.0 kPa and 2.9 kPa.s, respectively for iron (II, III) oxide based colloids at 2.6 vol% particle concentration and 1.2 T magnetic field. Experimental investigations reveal that the formulated magneto-nanocolloids are stable, even in high magnetic fields and almost reversible when exposed to rising and drop of magnetic fields of the same magnitude. Observations also reveal that the elastic behavior dominates over the viscous behavior with enhanced relaxation and creep characteristics under the magnetic field. The effect of temperature on viscosity and yield stress of magneto-nanocolloids under magnetic fields has also been discussed. Thus, the present findings have potential applications in various fields such as electromagnetic clutch and brakes of automotive, damping, sealing, optics, nanofinishing etc.

  10. MR imaging differentiation of Fe{sup 2+} and Fe{sup 3+} based on relaxation and magnetic susceptibility properties

    Energy Technology Data Exchange (ETDEWEB)

    Dietrich, Olaf [Ludwig-Maximilians-University Hospital Munich, Josef Lissner Laboratory for Biomedical Imaging, Institute for Clinical Radiology, Munich (Germany); Levin, Johannes [Ludwig-Maximilians-University Hospital Munich, Department of Neurology, Munich (Germany); German Center for Neurodegenerative Diseases (DZNE), Munich (Germany); Ahmadi, Seyed-Ahmad; Plate, Annika; Boetzel, Kai [Ludwig-Maximilians-University Hospital Munich, Department of Neurology, Munich (Germany); Reiser, Maximilian F.; Ertl-Wagner, Birgit [Ludwig-Maximilians-University Hospital Munich, Institute for Clinical Radiology, Munich (Germany); Giese, Armin [Ludwig-Maximilians-University Munich, Center for Neuropathology and Prion Research, Munich (Germany)

    2017-04-15

    The aim of this study is to evaluate the MR imaging behavior of ferrous (Fe{sup 2+}) and ferric (Fe{sup 3+}) iron ions in order to develop a noninvasive technique to quantitatively differentiate between both forms of iron. MRI was performed at 3 T in a phantom consisting of 21 samples with different concentrations of ferrous and ferric chloride solutions (between 0 and 10 mmol/L). A multi-echo spoiled gradient-echo pulse sequence with eight echoes was used for both T{sub 2}* and quantitative susceptibility measurements. The transverse relaxation rate, R{sub 2}* = 1/T{sub 2}*, was determined by nonlinear exponential fitting based on the mean signals in each sample. The susceptibilities, χ, of the samples were calculated after phase unwrapping and background field removal by fitting the spatial convolution of a unit dipole response to the measured internal field map. Relaxation rate changes, ΔR{sub 2}*(c{sub Fe}), and susceptibility changes, Δχ(c{sub Fe}), their linear slopes, as well as the ratios ΔR{sub 2}*(c{sub Fe}) / Δχ(c{sub Fe}) were determined for all concentrations. The linear slopes of the relaxation rate were (12.5 ± 0.4) s{sup -1}/(mmol/L) for Fe{sup 3+} and (0.77 ± 0.09) s{sup -1}/(mmol/L) for Fe{sup 2+} (significantly different, z test P < 0.0001). The linear slopes of the susceptibility were (0.088 ± 0.003) ppm/(mmol/L) for Fe{sup 3+} and (0.079 ± 0.006) ppm/(mmol/L) for Fe{sup 2+}. The individual ratios ΔR{sub 2}*/Δχ were greater than 40 s{sup -1}/ppm for all samples with ferric solution and lower than 20 s{sup -1}/ppm for all but one of the samples with ferrous solution. Ferrous and ferric iron ions show significantly different relaxation behaviors in MRI but similar susceptibility patterns. These properties can be used to differentiate ferrous and ferric samples. (orig.)

  11. Electrodeposited Fe-Co films prepared from a citric-acid-based plating bath

    OpenAIRE

    Yanai, Takeshi; Uto, H.; Shimokawa, Takaya; Nakano, Masaki; Fukunaga, Hirotoshi; Suzuki, K.

    2013-01-01

    Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research, we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the waste bath is restricted by environmental-protection regulations in Japan. We evaluated the effect of citric acid on the magnetic and structural properties of the films. The saturation magnetization of the Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasing ...

  12. Magnetic Properties of FeNi-Based Thin Film Materials with Different Additives

    Directory of Open Access Journals (Sweden)

    Cai Liang

    2014-07-01

    Full Text Available This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B.

  13. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.

    2014-07-04

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials attractive for sensor applications. Our findings show that FeNi deposited with Mo or Al yields magnetically soft materials and that depositing with B further increases the softness. The out-of-plane magnetic anisotropy of FeNi thin films is reduced by depositing with Al and completely removed by depositing with B. The effect of depositing with Mo is dependent on the Mo concentration. The coercivity of FeNiMo and FeNiAl is reduced to less than a half of that of FeNi, and a value as low as 40 A/m is obtained for FeNiB. The surfaces of the obtained FeNiMo, FeNiAl and FeNiB thin films reveal very different morphologies. The surface of FeNiMo shows nano-cracks, while the FeNiAl films show large clusters and fewer nano-cracks. When FeNi is deposited with B, a very smooth morphology is obtained. The crystal structure of FeNiMo strongly depends on the depositant concentration and changes into an amorphous structure at a higher Mo level. FeNiAl thin films remain polycrystalline, even at a very high concentration of Al, and FeNiB films are amorphous, even at a very low concentration of B. 2014 by the authors.

  14. Effect of Ti seed and spacer layers on structure and magnetic properties of FeNi thin films and FeNi-based multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Svalov, A.V., E-mail: andrey.svalov@ehu.es [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Kurlyandskaya, G.V. [Departamento de Electricidad y Electrónica, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain); Department of Magnetism and Magnetic Nanomaterials, Ural Federal University, 620002 Ekaterinburg (Russian Federation)

    2014-10-15

    Highlights: • Fe{sub 19}Ni{sub 81} films and FeNi-based multilayers were prepared by magnetron sputtering. • The samples were deposited onto glass substrates at room temperature. • Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. • The thick Cu seed increases the coercive force of the magnetic layer. • The thin Ti spacer restores the magnetic softness of the Cu/Ti/FeNi multilayers. - Abstract: The microstructure and magnetic properties of sputtered permalloy films and FeNi-based multilayers prepared by magnetron sputtering have been studied. X-ray diffraction measurements indicate that Ti/FeNi films exhibit good (1 1 1) texture and crystallinity. Ti/FeNi bilayers with high crystallographic quality have relatively low resistivity. The Ti seed layer does not influence the magnetic properties of FeNi film in Ti/FeNi bilayers, but the thick Cu seed layer leads to an increase of the coercive force of the magnetic layer. For the FeNi films deposited on thick Cu seed layer, the (0 1 0) and (0 0 2) diffraction peaks of hcp nickel were clearly observed. The thin Ti spacer between Cu and FeNi layers prevents the formation of the nickel phase and restores the magnetic softness of the FeNi layer in the Cu/Ti/FeNi sample. Obtained results can be important for the development of multilayer sensitive elements for giant magnetoimpedance or magnetoresistance detectors.

  15. Enhancement of plasticity of Fe-based bulk metallic glass by Ni substitution for Fe

    Energy Technology Data Exchange (ETDEWEB)

    Guo, S.F. [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Li, N.; Zhang, C. [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Liu, L., E-mail: sfguo2005@163.co [State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)

    2010-08-15

    Bulk metallic glasses (BMGs) (Fe{sub 1-x}Ni{sub x}){sub 71}Mo{sub 5}P{sub 12}C{sub 10}B{sub 2} (x = 0, 0.1 and 0.2) with a diameter of 3 mm were synthesized by copper mold casting. The effect of Ni substitution for Fe on the structure, thermal and mechanical properties has been studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and compressive testing. It was found that the substitution of Ni for Fe enhances the glass forming ability, and improves the plasticity of Fe{sub 71}Mo{sub 5}P{sub 12}C{sub 10}B{sub 2} BMG as indicated by the increase in the plastic strain from 3.1% (x = 0) to 5.2% (x = 0.2). The improvement of the plasticity is discussed in term of the reduction of glass transition temperature and the supercooled liquid region due to the substitution of Ni for Fe.

  16. Biodiesel production from soybean and Jatropha oils by magnetic CaFe2O4–Ca2Fe2O5-based catalyst

    International Nuclear Information System (INIS)

    Xue, Bao-jin; Luo, Jia; Zhang, Fan; Fang, Zhen

    2014-01-01

    Heterogeneous CaFe 2 O 4 –Ca 2 Fe 2 O 5 -based catalyst with weak magnetism was prepared by co-precipitation and calcination. It was characterized by various techniques including X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed desorption method. Its active components were identified as mainly Ca–Fe composite oxides such as CaFe 2 O 4 for transesterification. The magnetism was further strengthened by reducing its component of Fe 2 O 3 to Fe 3 O 4 –Fe under H 2 atmosphere for better magnetic separation. Both catalysts were used for the catalytic transesterification of soybean and Jatropha oils to biodiesel. The highest biodiesel yields for soybean oil of 85.4% and 83.5% were obtained over the weak and strong magnetic catalysts, respectively under the optimized conditions (373 K, 30 min, 15/1 methanol/oil molar ratio and 4 wt% catalyst). The catalysts could be recycled three times. Biodiesel production from pretreated Jatropha oil was tested with the magnetic CaFe 2 O 4 –Ca 2 Fe 2 O 5 –Fe 3 O 4 –Fe catalyst, and 78.2% biodiesel yield was obtained. The magnetic CaFe 2 O 4 –Ca 2 Fe 2 O 5 -based catalyst shows a potential application for the green production of biodiesel. - Highlights: • Magnetic catalyst was prepared by co-precipitation, calcination and reduction. • The catalyst was composed of CaFe 2 O 4 –Ca 2 Fe 2 O 5 –Fe 3 O 4 –Fe. • Biodiesel yields of 83.5% and 78.2% were achieved for soybean and Jatropha oils. • The catalyst was easily separated by a magnet and used for three cycles

  17. Fe/sup 57/ polarimetry based on quadrupole interaction

    Energy Technology Data Exchange (ETDEWEB)

    Gonser, U; Sakai, H; Keune, W [Universitaet des Saarlandes, Saarbruecken (F.R. Germany). Fachbereich Angewandte Physik

    1976-01-01

    A quadrupole Fe/sup 57/ polarimeter consisting of single crystals of LiNbO/sub 3/:Co/sup 57/ as source (polarizer) and of FeCO/sub 3/ (siderite) as absorber (analyzer) is described. The quadrupole interactions of the two materials are nearly equal in magnitude but opposite in sign and in addition the asymmetry parameter eta equal approximately 0.

  18. Superconducting spin valve effect in Fe/In based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Kataev, Vladislav; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences (Russian Federation)

    2015-07-01

    We report on magnetic and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. The Superconducting Spin Valve Effect (SSVE) assumes the T{sub c} difference between parallel (P) and antiparallel (AP) orientations of the Fe1 and Fe2 layers' magnetizations. The SSVE value oscillates and changes its sign when the Fe2 layer thickness d{sub Fe2} is varied from 0 to 5 nm. The SSVE value is positive, as expected, in the range 0.4 nm ≤ d{sub Fe2} ≤ 0.8 nm. For a rather broad range of thicknesses 1 nm ≤ d{sub Fe2} ≤ 2.6 nm the SSVE has negative sign assuming the inverse SSVE. Moreover, the magnitude of the inverse effect is larger than that of the positive direct effect. We attribute these oscillations to a quantum interference of the cooper pair wave functions in the magnetic part of the system. For most of the spin-valve samples from this set we experimentally realized the full switching between normal and superconducting states due to direct and inverse SSVE. The analysis of the experimental data has enabled the determination of all microscopic parameters of the studied system.

  19. Interaction of an Fe derivative of TMAP (Fe(TMAP)OAc) with DNA in comparison with free-base TMAP.

    Science.gov (United States)

    Ghaderi, Masoumeh; Bathaie, S Zahra; Saboury, Ali-Akbar; Sharghi, Hashem; Tangestaninejad, Shahram

    2007-07-01

    We investigated the interaction of meso-tetrakis (N-para-methylanilium) porphyrin (TMAP) in its free base and Fe(II) form (Fe(TMAP)OAc) as a new derivative, with high molecular weight DNA at different ionic strengths, using various spectroscopic methods and microcalorimetry. The data obtained by spectrophotometery, circular dichroism (CD), fluorescence quenching and resonance light scattering (RLS) have demonstrated that TMAP association with DNA is via outside binding with self-stacking manner, which is accompanied with the "end-on" type complex formation in low ionic strength. However, in the case of Fe(TMAP)OAc, predominant mode of interaction is groove binding and after increasing in DNA concentration, unstable stacking-type aggregates are formed. In addition, isothermal titration calorimetric measurements have indicated the exothermic process of porphyrins binding to DNA, but the exothermisity in metal derivative of porphyrin is less than the free base. It confirmed the formation of a more organized aggregate of TMAP on DNA surface. Interactions of both porphyrins with DNA show high sensitivity to ionic strength. By addition of salt, the downfield CD signal of TMAP aggregates is shifted to a higher wavelength, which indicates some changes in the aggregates position. In the case of Fe(TMAP)OAc, addition of salt leads to changes in the mode of binding from groove binding to outside binding with self-stacking, which is accompanied with major changes in CD spectra, possibly indicating the formation of "face-on" type complex.

  20. High Performance Fe-Co Based SOFC Cathodes

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent; Hansen, Karin Vels; Mogensen, Mogens Bjerg

    2010-01-01

    With the aim of reducing the temperature of the solid oxide fuel cell (SOFC), a new high-performance perovskite cathode has been developed. An area-specific resistance (ASR) as low as 0.12 Ωcm2 at 600 °C was measured by electrochemical impedance spectroscopy (EIS) on symmetrical cells. The cathode...... is a composite between (Gd0.6Sr0.4)0.99Fe0.8Co0.2O3-δ (GSFC) and Ce0.9Gd0.1O1.95 (CGO10). Examination of the microstructure of the cathodes by scanning electron microscopy (SEM) revealed a possibility of further optimisation of the microstructure in order to increase the performance of the cathodes. It also...... seems that an adjustment of the sintering temperature will make a lowering of the ASR value possible. The cathodes were compatible with ceria-based electrolytes but reacted to some extent with zirconia-based electrolytes depending on the sintering temperature....

  1. Effect of strain on voltage-controlled magnetism in BiFeO₃-based heterostructures.

    Science.gov (United States)

    Wang, J J; Hu, J M; Yang, T N; Feng, M; Zhang, J X; Chen, L Q; Nan, C W

    2014-04-01

    Voltage-modulated magnetism in magnetic/BiFeO3 heterostructures can be driven by a combination of the intrinsic ferroelectric-antiferromagnetic coupling in BiFeO3 and the antiferromagnetic-ferromagnetic exchange interaction across the heterointerface. However, ferroelectric BiFeO3 film is also ferroelastic, thus it is possible to generate voltage-induced strain in BiFeO3 that could be applied onto the magnetic layer across the heterointerface and modulate magnetism through magnetoelastic coupling. Here, we investigated, using phase-field simulations, the role of strain in voltage-controlled magnetism for these BiFeO3-based heterostructures. It is predicted, under certain condition, coexistence of strain and exchange interaction will result in a pure voltage-driven 180° magnetization reversal in BiFeO3-based heterostructures.

  2. Effect of strain on voltage-controlled magnetism in BiFeO3-based heterostructures

    Science.gov (United States)

    Wang, J. J.; Hu, J. M.; Yang, T. N.; Feng, M.; Zhang, J. X.; Chen, L. Q.; Nan, C. W.

    2014-01-01

    Voltage-modulated magnetism in magnetic/BiFeO3 heterostructures can be driven by a combination of the intrinsic ferroelectric-antiferromagnetic coupling in BiFeO3 and the antiferromagnetic-ferromagnetic exchange interaction across the heterointerface. However, ferroelectric BiFeO3 film is also ferroelastic, thus it is possible to generate voltage-induced strain in BiFeO3 that could be applied onto the magnetic layer across the heterointerface and modulate magnetism through magnetoelastic coupling. Here, we investigated, using phase-field simulations, the role of strain in voltage-controlled magnetism for these BiFeO3-based heterostructures. It is predicted, under certain condition, coexistence of strain and exchange interaction will result in a pure voltage-driven 180° magnetization reversal in BiFeO3-based heterostructures. PMID:24686503

  3. High energy spectra on Fe-based unconventional superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Nag, Pranab Kumar; Baumann, Danny; Schlegel, Ronny; Beck, Robert; Hess, Christian [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Wurmehl, Sabine; Buechner, Bernd [Leibniz-Institute for Solid State and Materials Research, IFW-Dresden, 01171 Dresden (Germany); Institut fuer Festkoerperphysik, TU Dresden, D-01062 Dresden (Germany); Wolf, Thomas [Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, Postfach 3640, D-76021 Karlsruhe (Germany)

    2015-07-01

    We have performed low-temperature scanning tunneling microscopy and spectroscopy on LiFeAs, Co doped NaFeAs and FeSe superconductors. The spectroscopy data routinely reveal important aspects of the electronic structure both very close to the Fermi level, i.e. the superconducting gap, and distinct features at higher energies. The latter appear in occupied states roughly between -0.3 eV and -0.5 eV in these materials, and allow specific comparison with ARPES band structure data.

  4. Magnetoimpedance of FeNi-based asymmetric sensitive elements

    Energy Technology Data Exchange (ETDEWEB)

    Chlenova, A.A., E-mail: chlenova.anna@gmail.com [Ural Federal University, Laboratory of Magnetic Sensorics, Lenin Ave. 51, 620083 Ekaterinburg, Russian Ferderation (Russian Federation); Immanuel Kant Baltic Federal University, Science and Technology Park “Fabrica”, Gaidara str. 6, Kaliningrad (Russian Federation); Svalov, A.V.; Kurlyandskaya, G.V. [Ural Federal University, Laboratory of Magnetic Sensorics, Lenin Ave. 51, 620083 Ekaterinburg, Russian Ferderation (Russian Federation); Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Volchkov, S.O. [Ural Federal University, Laboratory of Magnetic Sensorics, Lenin Ave. 51, 620083 Ekaterinburg, Russian Ferderation (Russian Federation)

    2016-10-01

    [Ti/FeNi]{sub 5}/Ti/Cu/Ti/[FeNi/Ti]{sub x} (x=0–5) multilayers were prepared by sputtering. Their magnetic properties and magnetoimpedance were studied focusing on future technological applications. Both (ΔZ/Z){sub max} and (ΔR/R){sub max} values showed a tendency to decrease with a decrease of the number of magnetic layers of the top multilayer. Such a parameter as an even or odd number of layers is important for the MI value. In the field interval of technological interest all [Ti/FeNi]{sub 5}/Ti/Cu/Ti/[FeNi/Ti]{sub x} structures show similar sensitivities of about 70%/Oe for ΔR/R ratios but the lower the number of magnetic layers in the top multilayer, the higher the operating frequency. - Highlights: • Giant magnetoimpedance effect. • Non-symmetric multilayers sructure. • Biosensing.

  5. Magnetoimpedance of FeNi-based asymmetric sensitive elements

    International Nuclear Information System (INIS)

    Chlenova, A.A.; Svalov, A.V.; Kurlyandskaya, G.V.; Volchkov, S.O.

    2016-01-01

    [Ti/FeNi] 5 /Ti/Cu/Ti/[FeNi/Ti] x (x=0–5) multilayers were prepared by sputtering. Their magnetic properties and magnetoimpedance were studied focusing on future technological applications. Both (ΔZ/Z) max and (ΔR/R) max values showed a tendency to decrease with a decrease of the number of magnetic layers of the top multilayer. Such a parameter as an even or odd number of layers is important for the MI value. In the field interval of technological interest all [Ti/FeNi] 5 /Ti/Cu/Ti/[FeNi/Ti] x structures show similar sensitivities of about 70%/Oe for ΔR/R ratios but the lower the number of magnetic layers in the top multilayer, the higher the operating frequency. - Highlights: • Giant magnetoimpedance effect. • Non-symmetric multilayers sructure. • Biosensing.

  6. Minor-Cu doped soft magnetic Fe-based FeCoBCSiCu amorphous alloys with high saturation magnetization

    Science.gov (United States)

    Li, Yanhui; Wang, Zhenmin; Zhang, Wei

    2018-05-01

    The effects of Cu alloying on the amorphous-forming ability (AFA) and magnetic properties of the P-free Fe81Co5B11C2Si1 amorphous alloy were investigated. Addition of ≤ 1.0 at.% Cu enhances the AFA of the base alloy without significant deterioration of the soft magnetic properties. The Fe80.5Co5B11C2Si1Cu0.5 alloy with the largest critical thickness for amorphous formation of ˜35 μm possesses a high saturation magnetization (Bs) of ˜1.78 T, low coercivity of ˜14.6 A/m, and good bending ductility upon annealing in a wide temperature range of 513-553 K with maintaining the amorphous state. The fabrication of the new high-Fe-content Fe-Co-B-C-Si-Cu amorphous alloys by minor doping of Cu gives a guideline to developing high Bs amorphous alloys with excellent AFA.

  7. Power loss separation in Fe-based composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Kollar, Peter, E-mail: peter.kollar@upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Safarik University, Park Angelinum 9, 04154 Kosice (Slovakia); Bircakova, Zuzana; Fuezer, Jan [Institute of Physics, Faculty of Science, Pavol Jozef Safarik University, Park Angelinum 9, 04154 Kosice (Slovakia); Bures, Radovan; Faberova, Maria [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Kosice (Slovakia)

    2013-02-15

    The frequency dependence of total losses measured in the frequency range from dc to 1 kHz of two Fe-based soft magnetic composites (prepared by compaction of an ASC 100.29 iron powder mixture with 10 vol% of commercial thermoset resin and of a Somaloy{sup Registered-Sign} 700 powder) was analyzed. We found out that hysteresis losses (per volume unit) are higher for the composite with lower volume concentration of iron particles (i.e. mixture of iron with resin) and consequently weaker magnetic interaction between particles. On the other hand, higher specific resistivity of the sample with lower magnetic fraction causes lower contribution of eddy current losses to the total losses. A linear dependence of the total energy losses on frequency was observed and from them the contribution of excess losses was obtained. The detailed study of the excess losses resulted in an explanation of the frequency dependence of these losses in composite materials. - Highlights: Black-Right-Pointing-Pointer It was observed that excess losses in SMC depend on the frequency linearly. Black-Right-Pointing-Pointer Two components of eddy current losses (inter- and intra-particle) were analyzed. Black-Right-Pointing-Pointer Larger amount of insulator causes the eddy current inside ferromagnetic particles.

  8. Flexible piezoelectric nanogenerators based on PVDF-TrFE nanofibers

    Science.gov (United States)

    Serairi, Linda; Gu, Long; Qin, Yong; Lu, Yingxian; Basset, Philippe; Leprince-Wang, Yamin

    2018-01-01

    In this paper, electrospun piezoelectric PVDF-TrFE nanofibers were used for the fabrication of two types of flexible nanogenerator (NG) devices based on the direct piezoelectric effect, allowing the conversion of mechanical energy into electrical energy. The first one is composed of quite well aligned thin film nanofibers of about 35 μm and the second one is composed of random nanofibers of about 50 μm. The influence of the applied stress and strain rate on the output for both types of NG was studied. It is shown that the pulse peaks generated by NG increase with the applied mechanical strain frequency, the generated output is also proportional to the applied stress amplitude. The first NG loaded in bending mode can generate a maximum voltage of 270 mV. By connecting two devices in series/parallel, the voltage/current value could be multiplied by two. The second NG which was biased in compression mode using a shaker controlled by a force sensor, can generate a potential of about 7 V under 3.6 N applied force.

  9. Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation

    KAUST Repository

    Pan, B.; Wang, Bo; Lubineau, Gilles

    2016-01-01

    Subset-based local and finite-element-based (FE-based) global digital image correlation (DIC) approaches are the two primary image matching algorithms widely used for full-field displacement mapping. Very recently, the performances

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  11. A 3x1 integrated pyroelectric sensor based on VDF/TrFE copolymer

    NARCIS (Netherlands)

    Setiadi, D.; Setiadi, D.; Sarro, P.M.; Regtien, Paulus P.L.

    1996-01-01

    This paper presents an integrated pyroelectric sensor based on a vinylidene fluoride¿trifluoroethylene (VDF/TrFE) copolymer. A silicon substrate that contains field-effect transistor (FET) readout electronics is coated with the VDF/TrFE copolymer film using a spin-coating technique. On-chip poling

  12. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    International Nuclear Information System (INIS)

    Gorny, Anton; Manickaraj, Jeyakumar; Cai, Zhonghou; Shankar, Sumanth

    2013-01-01

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al 13 Fe 4 , τ 5 -Al 8 Fe 2 Si and τ 6 -Al 9 Fe 2 Si 2 phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s −1 . Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ 5 -Al 8 SiFe 2 and τ 6 -Al 9 Fe 2 Si 2 . The τ 5 -Al 8 SiFe 2 phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ 6 -Al 9 Fe 2 Si 2 through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al 13 Fe 4 binary phase precludes the evolution of the τ 5 during solidification and subsequently transforms into the τ 6 phase during solidification. These observations are anomalous to the publications as prior art and simulation predictions of thermodynamic phase diagrams of these alloys, wherein, only one intermetallic phases in the

  13. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    International Nuclear Information System (INIS)

    Zhukova, V.; Korchuganova, O.A.; Aleev, A.A.; Tcherdyntsev, V.V.; Churyukanova, M.; Medvedeva, E.V.; Seils, S.; Wagner, J.; Ipatov, M.; Blanco, J.M.; Kaloshkin, S.D.; Aronin, A.; Abrosimova, G.; Orlova, N.

    2017-01-01

    Highlights: • High domain wall mobility of Fe-Ni-based microwires. • Enhancement of domain wall velocity and mobility in Fe-rich microwires after annealing. • Observation of areas enriched by Si and depleted by B after annealing. • Phase separation in annealed Fe-Ni based microwires in metallic nucleus and near the interface layer. - Abstract: We studied the magnetic properties and domain wall (DW) dynamics of Fe 47.4 Ni 26.6 Si 11 B 13 C 2 and Fe 77.5 Si 7.5 B 15 microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe 77.5 Si 7.5 B 15 , while DW velocity of samples Fe 47.4 Ni 26.6 Si 11 B 13 C 2 is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe 47.4 Ni 26.6 Si 11 B 13 C 2 sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe 47.4 Ni 26.6 Si 11 B 13 C 2 . Consequently we studied the structure of Fe 47.4 Ni 26.6 Si 11 B 13 C 2 sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  14. Nanosized catalysts based on Fe oxide for combustion of n-hexane

    International Nuclear Information System (INIS)

    Picasso, Gino; Hermoza, Emilia; Lopez, Alcides; Gomez, Gemma; Pina, Maria Pilar; Herguido, Javier

    2009-01-01

    In this work, nanosized catalysts on Fe oxide have been prepared for total combustion on n-hexane (2000 ppmV). The synthesis of Fe oxide have been performed following sol-gel procedure starting from precursors based on nitrate salts. According to XRD analysis, nanoparticles formed α-hematite and the average particle size estimated by TEM was 9 nm with formation of agglomerations of 140 nm. Moreover, different clays pillared with Al (Al-PILC), Ti (Ti-PILC) and Fe (Fe-PILC) have been synthesized. Some samples based on Fe-Mn equimolar mixed supported on Al-PILC (FeMn/Al-PILC) and on Ti-PILC (FeMn/Ti-PILC) have been prepared in order to study the cooperative effect of Mn. Experimental conditions of calcination were adjusted in order to obtain samples with high thermal stability. XRD analysis of pillared samples revealed the formation of stable pillars, except for Fe-PILC which described a delaminated structure. As a consequence of pillaring, an enhancement of total surface area compared to starting clay material is observed. Concerning surface area, the decreasing order series of pillared material was: Ti-PILC > Fe-PILC > Al-PILC. Depression of total surface area decreasing of basal spacing d 001 with no modification of basal structure of starting natural clay have been observed due to the incorporation of Fe-Mn active phase into the structures of Ti-PILC and Al-PILC. The Fe-Mn mixed phase supported over pillared material exhibited higher catalytic activity than the Fe-PILC sample, which was attributed to the cooperative effect of Mn. This effect could be associated with redox properties of Mn and improving of surface oxygen mobility. Delaminated structure and strong interaction of Fe with clay porous network into the Fe-PILC sample could be the reason of lower activities. However, higher performances were observed in the case of Fe oxide nanoparticles prepared with surfactant agent over bentonite, due to a lesser extent of Fe-porous structure interaction presented in

  15. Microstructural Characteristics and Tribological Behavior of HVOF-Sprayed Novel Fe-Based Alloy Coatings

    Directory of Open Access Journals (Sweden)

    Andrea Milanti

    2014-01-01

    Full Text Available Thermally-sprayed Fe-based coatings have shown their potential for use in wear applications due to their good tribological properties. In addition, these kinds of coatings have other advantages, e.g., cost efficiency and positive environmental aspects. In this study, the microstructural details and tribological performances of Fe-based coatings (Fe-Cr-Ni-B-C and Fe-Cr-Ni-B-Mo-C manufactured by High Velocity Oxygen Fuel (HVOF thermal spray process are evaluated. Traditional Ni-based (Ni-Cr-Fe-Si-B-C and hard-metal (WC-CoCr coatings were chosen as references. Microstructural investigation (field-emission scanning electron microscope FESEM and X-Ray diffractometry XRD reveals a high density and low oxide content for HVOF Fe-based coatings. Particle melting and rapid solidification resulted in a metastable austenitic phase with precipitates of mixed carbides and borides of chromium and iron which lead to remarkably high nanohardness. Tribological performances were evaluated by means of the ball on-disk dry sliding wear test, the rubber-wheel dry particle abrasion test, and the cavitation erosion wear test. A higher wear resistance validates Fe-based coatings as a future alternative to the more expensive and less environmentally friendly Ni-based alloys.

  16. Metamorphoses of electronic structure of FeSe-based superconductors (Review Article)

    International Nuclear Information System (INIS)

    Pustovit, Yu.V.; Kordyuk, A.A.

    2016-01-01

    The electronic structure of FeSe, the simplest iron-based superconductor (Fe-SC), conceals a potential of dramatic increase of Tc that realizes under pressure or in a single layer film. This is also the system where nematicity, the phenomenon of a keen current interest, is most easy to study since it is not accompanied by the antiferromagnetic transition like in all other Fe-SC. Here we overview recent experimental data on electronic structure of FeSe-based superconductors: isovalently doped crystals, intercalates, and single layer films, trying to clarify its topology and possible relation of this topology to superconductivity. We argue that the marked differences between the experimental and calculated band structures for all FeSe compounds can be described by a hoping selective renormalization model for a spin/orbital correlated state that may naturally ex-plain both the evolution of the band structure with temperature and nematicity.

  17. Estimation of lunar FeO abundance based on imaging by LRO Diviner

    International Nuclear Information System (INIS)

    Tang, Xiao; Zhang, Xue-Wei; Chen, Yuan; Zhang, Xiao-Meng; Cai, Wei; Wu, Yun-Zhao; Luo, Xiao-Xing; Jiang, Yun; Xu, Ao-Ao; Wang, Zhen-Chao

    2016-01-01

    Understanding the abundance and distribution characteristics of FeO on the surface of the Moon is important for investigating its evolution. The current high resolution maps of the global FeO abundance are mostly produced with visible and near infrared reflectance spectra. The Christiansen Feature (CF) in mid-infrared has strong sensitivity to lunar minerals and correlates to major elements composing minerals. This paper investigates the possibility of mapping global FeO abundance using the CF values from the Diviner Lunar Radiometer Experiment aboard the Lunar Reconnaissance Orbiter (LRO) mission. A high correlation between the CF values and FeO abundances from the Apollo samples was found. Based on this high correlation, a new global map (±60°) of FeO was produced using the CF map. The results show that the global FeO average is 8.2 wt.%, the highland average is 4.7 wt.%, the global modal abundance is 5.4 wt.% and the lunar mare mode is 15.7 wt.%. These results are close to those derived from data provided by Clementine, the Lunar Prospector Gamma Ray Spectrometer (LP-GRS) and the Chang'e-1 Interference Imaging Spectrometer (IIM), demonstrating the feasibility of estimating FeO abundance based on the Diviner CF data. The near global FeO abundance map shows an enrichment of lunar major elements. (paper)

  18. A novel fluorescence probe based on triphenylamine Schiff base for bioimaging and responding to pH and Fe3+

    International Nuclear Information System (INIS)

    Wang, Lei; Yang, Xiaodong; Chen, Xiuli; Zhou, Yuping; Lu, Xiaodan; Yan, Chenggong; Xu, Yikai; Liu, Ruiyuan; Qu, Jinqing

    2017-01-01

    A novel fluorescence probe 1 based on triphenylamine was synthesized and characterized by NMR, IR, high resolution mass spectrometry and elemental analysis. Its fluorescence was quenched when pH below 2. There was a linear relationship between the fluorescence intensity and pH value ranged from 2 to 7. And its fluorescence emission was reversibility in acidic and alkaline solution. Furthermore, it exhibited remarkable selectivity and high sensitivity to Fe 3+ and was able to detect Fe 3+ in aqueous solution with low detection limit of 0.511 μM. Job plot showed that the binding stoichiometry of 1 with Fe 3+ was 1:1. Further observations of 1 H NMR titration suggested that coordination interaction between Fe 3+ and nitrogen atom on C =N bond promoted the intramolecular charge transfer (ICT) or energy transfer process causing fluorescence quenching. Additionally, 1 was also able to be applied for detecting Fe 3+ in living cell and bioimaging. - Graphical abstract: Triphenylamine based fluorescence probe can detect pH and Fe 3+ simultaneously in aqueous solution and be applied for detecting Fe 3+ in living cell and bioimaging. - Highlights: • The fluorescence probe is sensitive to pH in strong acid conditions. • The fluorescence chemosensor can detect pH and Fe 3+ simultaneously. • The recognition is able to carry out in aqueous solution. • The probe can also be applied for detecting Fe 3+ in living cell and bioimaging. • The sensor is synthesized easily with one step.

  19. A novel ascorbic acid sensor based on the Fe3+/Fe2+ modulated photoluminescence of CdTe quantum dots@SiO2 nanobeads.

    Science.gov (United States)

    Ma, Qiang; Li, Yang; Lin, Zi-Han; Tang, Guangchao; Su, Xing-Guang

    2013-10-21

    In this paper, CdTe quantum dot (QD)@silica nanobeads were used as modulated photoluminescence (PL) sensors for the sensing of ascorbic acid in aqueous solution for the first time. The sensor was developed based on the different quenching effects of Fe(2+) and Fe(3+) on the PL intensity of the CdTe QD@ silica nanobeads. Firstly, the PL intensity of the CdTe QDs was quenched in the presence of Fe(3+). Although both Fe(2+) and Fe(3+) could quench the PL intensity of the CdTe QDs, the quenching efficiency were quite different for Fe(2+) and Fe(3+). The PL intensity of the CdTe QD@silica nanobeads can be quenched by about 15% after the addition of Fe(3+) (60 μmol L(-1)), while the PL intensity of the CdTe QD@silica nanobeads can be quenched about 49% after the addition of Fe(2+) (60 μmol L(-1)). Therefore, the PL intensity of the CdTe QD@silica nanobeads decreased significantly when Fe(3+) was reduced to Fe(2+) by ascorbic acid. To confirm the strategy of PL modulation in this sensing system, trace H2O2 was introduced to oxidize Fe(2+) to Fe(3+). As a result, the PL intensity of the CdTe QD@silica nanobeads was partly recovered. The proposed sensor could be used for ascorbic acid sensing in the concentration range of 3.33-400 μmol L(-1), with a detection limit (3σ) of 1.25 μmol L(-1) The feasibility of the proposed sensor for ascorbic acid determination in tablet samples was also studied, and satisfactory results were obtained.

  20. Acridine-based fluorescence chemosensors for selective sensing of Fe3+ and Ni2+ ions

    Science.gov (United States)

    Wang, Chaoyu; Fu, Jiaxin; Yao, Kun; Xue, Kun; Xu, Kuoxi; Pang, Xiaobin

    2018-06-01

    Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13 μM and 1.52 μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Job's plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.

  1. Observation of Pseudopartial Grain Boundary Wetting in the NdFeB-Based Alloy

    Science.gov (United States)

    Straumal, B. B.; Mazilkin, A. A.; Protasova, S. G.; Schütz, G.; Straumal, A. B.; Baretzky, B.

    2016-08-01

    The NdFeB-based alloys were invented in 1980s and remain the best-known hard magnetic alloys. In order to reach the optimum magnetic properties, the grains of hard magnetic Nd2Fe14B phase have to be isolated from one another by the (possibly thin) layers of a non-ferromagnetic Nd-rich phase. In this work, we observe that the few-nanometer-thin layers of the Nd-rich phase appear between Nd2Fe14B grains due to the pseudopartial grain boundary (GB) wetting. Namely, some Nd2Fe14B/Nd2Fe14B GBs are not completely wetted by the Nd-rich melt and have the high contact angle with the liquid phase and, nevertheless, contain the 2-4-nm-thin uniform Nd-rich layer.

  2. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    International Nuclear Information System (INIS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-01-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM -1 cm -2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  3. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    Science.gov (United States)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  4. Enhanced spin accumulation in Fe3O4 based spin injection devices below the Verwey transition

    Science.gov (United States)

    Bhat, Shwetha G.; Kumar, P. S. Anil

    2016-12-01

    Spin injection into GaAs and Si (both n and p-type) semiconductors using Fe3O4 is achieved with and without a tunnel barrier (MgO) via three-terminal electrical Hanle measurement. Interestingly, the magnitude of spin accumulation voltage (ΔV) in semiconductor is found to be associated with a drastic increment in ΔV in Fe3O4 based devices for temperature metal-to-insulator transition of Fe3O4 at T V. Observations from our elaborate investigations show that spin polarization of Fe3O4 has an explicit influence on the enhanced spin injection. It is argued that the theoretical prediction of half-metallicity of Fe3O4 above and below T V has to be reinvestigated.

  5. Fabrication and study of the electrical properties of PbO/Fe based ...

    African Journals Online (AJOL)

    Fabrication and study of the electrical properties of PbO/Fe based composite ... is aimed at fabrication and study of the electrical properties of cermets resistor, ... obtained and this largely depended on the composition of the materials used.

  6. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    Science.gov (United States)

    Zhukova, V.; Korchuganova, O. A.; Aleev, A. A.; Tcherdyntsev, V. V.; Churyukanova, M.; Medvedeva, E. V.; Seils, S.; Wagner, J.; Ipatov, M.; Blanco, J. M.; Kaloshkin, S. D.; Aronin, A.; Abrosimova, G.; Orlova, N.; Zhukov, A.

    2017-07-01

    We studied the magnetic properties and domain wall (DW) dynamics of Fe47.4Ni26.6Si11B13C2 and Fe77.5Si7.5B15 microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe77.5Si7.5B15, while DW velocity of samples Fe47.4Ni26.6Si11B13C2 is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe47.4Ni26.6Si11B13C2 sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe47.4Ni26.6Si11B13C2. Consequently we studied the structure of Fe47.4Ni26.6Si11B13C2 sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  7. The Pulse Thermal Processing of NdFeB-Based Nanocomposite Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Z. Q. [University of Texas; Wang, Z. L. [Georgia Institute of Technology; Liu, J. P. [University of Texas; Kadolkar, Puja [ORNL; Ott, Ronald D [ORNL

    2006-01-01

    Pulse-thermal processing (PTP) based on high-density plasma arc lamp technology has been utilized to crystallize melt-spun NdFeB-based amorphous ribbons to form magnetic nanocomposites consisting of Nd{sub 2}Fe{sub 14}B and {alpha}-Fe phases. After applying suitable pulses, the NdFeB-based ribbons were developed with hard magnetic properties. The highest coercivity can be obtained for ribbons with a thickness of 40 {micro}m after PTP treatments consisting of a 400 A pulse for 0.25 s for ten times. The correlation between PTP parameters and magnetic properties indicates that PTP is an effective approach to control the structure and properties of nanostructured magnetic materials.

  8. Electrospun nanofiber based colorimetric probe for rapid detection of Fe{sup 2+} in water

    Energy Technology Data Exchange (ETDEWEB)

    Ondigo, D.A. [Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140 (South Africa); Tshentu, Z.R. [Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140 (South Africa); Department of Chemistry, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth, 6031 (South Africa); Torto, N., E-mail: N.Torto@ru.ac.za [Department of Chemistry, Rhodes University, P.O. Box 94, Grahamstown 6140 (South Africa)

    2013-12-04

    Graphical abstract: -- Highlights: •Colorimetric probe for the detection of Fe{sup 2+} was developed. •Polymeric electrospun nanofibers were used as host for the signaling reagent. •The functionalized electrospun nanofibers exhibited a selective color change in the presence of Fe{sup 2+}. •The mechanism was based on spin crossover (SCO) from high spin Fe{sup 2+} to low spin Fe{sup 2+} upon interaction with the embedded ligand. -- Abstract: An imidazole derivative, 2-(2′-pyridyl)imidazole (PIMH), was developed as a colorimetric probe for the qualitative analysis of Fe{sup 2+} in aqueous solution. PIMH was then used to post-functionalize poly(vinylbenzyl chloride) (PVBC) nanofibers after electrospinning so as to afford a solid state colorimetric probe. Upon treatment with Fe{sup 2+} the probe displayed a distinctive color change both in liquid and solid platforms. The linear dynamic range for the colorimetric determination of Fe{sup 2+} was 0.0988–3.5 μg mL{sup −1}. The ligand showed a high chromogenic selectivity for Fe{sup 2+} over other cations with a detection limit of 0.102 μg mL{sup −1} in solution (lower than the WHO drinking water guideline limit of 2 mg L{sup −1}), and 2 μg mL{sup −1} in the solid state. The concentration of Fe{sup 2+} in a certified reference material (Iron, Ferrous, 1072) was found to be 2.39 ± 0.01 mg L{sup −1}, which was comparable with the certified value of 2.44 ± 0.12 mg L{sup −1}. Application of the probe to real samples spiked with Fe{sup 2+} achieved recoveries of over 97% confirming accuracy of the method and its potential for on-site monitoring.

  9. Design and performance of a pulse transformer based on Fe-based nanocrystalline core.

    Science.gov (United States)

    Yi, Liu; Xibo, Feng; Lin, Fuchang

    2011-08-01

    A dry-type pulse transformer based on Fe-based nanocrystalline core with a load of 0.88 nF, output voltage of more than 65 kV, and winding ratio of 46 is designed and constructed. The dynamic characteristics of Fe-based nanocrystalline core under the impulse with the pulse width of several microseconds were studied. The pulse width and incremental flux density have an important effect on the pulse permeability, so the pulse permeability is measured under a certain pulse width and incremental flux density. The minimal volume of the toroidal pulse transformer core is determined by the coupling coefficient, the capacitors of the resonant charging circuit, incremental flux density, and pulse permeability. The factors of the charging time, ratio, and energy transmission efficiency in the resonant charging circuit based on magnetic core-type pulse transformer are analyzed. Experimental results of the pulse transformer are in good agreement with the theoretical calculation. When the primary capacitor is 3.17 μF and charge voltage is 1.8 kV, a voltage across the secondary capacitor of 0.88 nF with peak value of 68.5 kV, rise time (10%-90%) of 1.80 μs is obtained.

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

    Czech Academy of Sciences Publication Activity Database

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

    2007-01-01

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

  11. First-principles-based study of transport properties of Fe thin films on Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Tomoya [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Kasai, Hideaki [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Nakanishi, Hiroshi [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Dino, Wilson Agerico [Department of Applied Physics, Osaka University, Suita, Osaka 565-0871 (Japan); Komori, Fumio [Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8587 (Japan)

    2004-12-08

    We investigate the transport properties of Fe thin films on Cu(111) based on first principles calculation. We calculate the electron current through these Fe thin films, which can be observed by using a double-tipped scanning tunnelling microscope. We find that the conductance is majority spin polarized. On the basis of the band structures for this system, we discuss the origin of these interesting transport properties.

  12. First-principles-based study of transport properties of Fe thin films on Cu surfaces

    International Nuclear Information System (INIS)

    Kishi, Tomoya; Kasai, Hideaki; Nakanishi, Hiroshi; Dino, Wilson Agerico; Komori, Fumio

    2004-01-01

    We investigate the transport properties of Fe thin films on Cu(111) based on first principles calculation. We calculate the electron current through these Fe thin films, which can be observed by using a double-tipped scanning tunnelling microscope. We find that the conductance is majority spin polarized. On the basis of the band structures for this system, we discuss the origin of these interesting transport properties

  13. Selective Hydrodeoxygenation of Alkyl Lactates to Alkyl Propionates with Fe-based Bimetallic Supported Catalysts.

    Science.gov (United States)

    Khokarale, Santosh Govind; He, Jian; Schill, Leonhard; Yang, Song; Riisager, Anders; Saravanamurugan, Shunmugavel

    2018-02-22

    Hydrodeoxygenation (HDO) of methyl lactate (ML) to methyl propionate (MP) was performed with various base-metal supported catalysts. A high yield of 77 % MP was obtained with bimetallic Fe-Ni/ZrO 2 in methanol at 220 °C and 50 bar H 2 . A synergistic effect of Ni increased the yield of MP significantly when using Fe-Ni/ZrO 2 instead of Fe/ZrO 2 alone. Moreover, the ZrO 2 support contributed to improve the yield as a phase transition of ZrO 2 from tetragonal to monoclinic occurred after metal doping giving rise to fine dispersion of the Fe and Ni on the ZrO 2 , resulting in a higher catalytic activity of the material. Interestingly, it was observed that Fe-Ni/ZrO 2 also effectively catalyzed methanol reforming to produce H 2 in situ, followed by HDO of ML, yielding 60 % MP at 220 °C with 50 bar N 2 instead of H 2 . Fe-Ni/ZrO 2 also catalyzed HDO of other short-chain alkyl lactates to the corresponding alkyl propionates in high yields around 70 %. No loss of activity of Fe-Ni/ZrO 2 occurred in five consecutive reaction runs demonstrating the high durability of the catalyst system. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Electrochemical Determination of Paracetamol Using Fe3O4/Reduced Graphene-Oxide-Based Electrode

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Anh Thu

    2018-01-01

    Full Text Available The synthesis of magnetic iron oxide/reduced graphene oxide (Fe3O4/rGO and its application to the electrochemical determination of paracetamol using Fe3O4/rGO modified electrode were demonstrated. The obtained materials were characterized by means of X-ray diffraction (XRD, nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS, transmission electron microscope (TEM, Fourier transform infrared spectroscopy (FTIR, and magnetic measurement. The results showed that Fe3O4/rGO composite exhibited high specific surface area, and its morphology consists of very fine spherical particles of Fe3O4 in nanoscales. Fe3O4/rGO was used as an electrode modifier for the determination of paracetamol by differential pulse-anodic stripping voltammetry (DP-ASV. The preparation of Fe3O4/rGO-based electrode and some factors affecting voltammetric responses were investigated. The results showed that Fe3O4/rGO is a potential electrode modifier for paracetamol detection by DP-ASV with a low limit of detection. The interfering effect of uric acid, ascorbic acid, and dopamine on the current response of paracetamol has been reported. The repeatability, reproducibility, linear range, and limit of detection were also addressed. The proposed method could be applied to the real samples with satisfactory results.

  15. Development of amperometric L-tyrosine sensor based on Fe-doped hydroxyapatite nanoparticles

    International Nuclear Information System (INIS)

    Kanchana, P.; Lavanya, N.; Sekar, C.

    2014-01-01

    A novel biosensor based on Fe-doped hydroxyapatite (Fe-HA) nanoparticles and tyrosinase has been developed for the detection of L-tyrosine. Nanostructured Fe-HA was synthesized by a simple microwave irradiation method, and its phase formation, morphology and magnetic property were examined by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Electrochemical performance of the nano Fe-HA/tyrosinase modified glassy carbon electrode (GCE) for detection of L-tyrosine was investigated by cyclic voltammetry (CV) and amperometric methods. The fabricated biosensor exhibited a linear response to L-tyrosine over a wide concentration range of 1.0 × 10 −7 to 1.0 × 10 −5 M with a detection limit of 245 nM at pH 7.0. In addition, the fabricated sensor showed an excellent selectivity, good reproducibility, long-term stability and anti-interference towards the determination of L-tyrosine. - Highlights: • A novel amperometric L-tyrosine biosensor has been fabricated using nanostructured Fe-HA. • The fabricated sensor exhibits a wide linear range, good stability and high reproducibility. • Fe-HA assists microenvironment and direct electron transfer between enzyme and electrode surface. • The nano Fe-HA and electrode fabrication procedure are simple and less expensive

  16. Formation and crystallization kinetics of Nd-Fe-B-based bulk amorphous alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Ge, Hongliang; Zhang, Pengyue; Li, Dongyun; Wang, Zisheng [China Jiliang University, Magnetism Key Laboratory of Zhejiang Province, Hangzhou (China)

    2014-06-15

    In order to improve the glass-forming ability (GFA) of Nd-Fe-B ternary alloys to obtain fully amorphous bulk Nd-Fe-B-based alloy, the effects of Mo and Y doping on GFA of the alloys were investigated. It was found that the substitution of Mo for Fe and Y for Nd enhanced the GFA of the Nd-Y-Fe-Mo-B alloys. It was also revealed that the GFA of the samples was optimized by 4 at.% Mo doping and increased with theYcontent. The fully amorphous structures were all formed in the Nd{sub 6-x}Y{sub x}Fe{sub 68}Mo{sub 4}B{sub 22} (x =1-5) alloy rods with 1.5 mm-diameter. After subsequent crystallization, the devitrified Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} alloy rod exhibited a uniform distribution of grains with a coercivity of 364.1 kA/m. The crystallization behavior of Nd{sub 3}Y{sub 3}Fe{sub 68}Mo{sub 4}B{sub 22} BMG was investigated in isothermal situation. The Avrami exponent n determined by JAM plot is lower than 2.5, implying that the crystallization is mainly governed by a growth of particles with decreasing nucleation rate. (orig.)

  17. A perspective on the Fe-based superconductors

    International Nuclear Information System (INIS)

    Wilson, John A

    2010-01-01

    FeSe is employed as reference material to elucidate the observed high T c superconducting behaviour of the related layered iron pnictides. The structural and ensuing semimetallic band structural forms are here rather unusual, with the resulting ground state details extremely sensitive to the precise shape of the Fe-X coordination unit. The superconductivity is presented as coming from a combination of resonant valence bond and excitonic insulator physics, and incorporating boson-fermion degeneracy. Although sourced in a very different fashion, the latter leads to some similarities with the high temperature superconducting (HTSC) cuprates. The excitonic insulator behaviour sees spin density wave, charge density wave/periodic structural distortion, and superconductive instabilities all vie for ground state status. The conflict leads to a very sensitive and complex set of properties, frequently mirroring HTSC cuprate behaviour. The delicate balance between ground states is made particularly difficult to unravel by the micro-inhomogeneity of structural form which it can engender. It is pointed out that several other notable superconductors, layered in form, semimetallic with indirect overlap and possessing homopolar bonding, would look to fall into the same general category, β-ZrNCl and MgB 2 and the high pressure forms of several elements, like sulfur, phosphorus, lithium and calcium, being cases in point. (topical review)

  18. In-gap bound states induced by interstitial Fe impurities in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Degang, E-mail: degangzhang@yahoo.com

    2015-12-15

    Highlights: • We provide an explanation for the interesting STM observation of the robust zero energy bound state on the interstitial Fe impurities in iron-based superconductors. - Abstract: Based on a two-orbit four-band tight binding model, we investigate the low-lying electronic states around the interstitial excess Fe ions in the iron-based superconductors by using T-matrix approach. It is shown that the local density of states at the interstitial Fe impurity (IFI) possesses a strong resonance inside the gap, which seems to be insensitive to the doping and the pairing symmetry in the Fe–Fe plane, while a single or two resonances appear at the nearest neighboring (NN) Fe sites. The location and height of the resonance peaks only depend on the hopping t and the pairing parameter Δ{sub I} between the IFI and the NN Fe sites. These in-gap resonances are originated in the Andreev’s bound states due to the quasiparticle tunneling through the IFI, leading to the change of the magnitude of the superconducting order parameter. When both t and Δ{sub I} are small, this robust zero-energy bound state near the IFI is consistent with recent scanning tunneling microscopy observations.

  19. Coercivity and nanostructure of melt-spun Ti-Fe-Co-B-based alloys

    Directory of Open Access Journals (Sweden)

    W. Y. Zhang

    2016-05-01

    Full Text Available Nanocrystalline Ti-Fe-Co-B-based alloys, prepared by melt spinning and subsequent annealing, have been characterized structurally and magnetically. X-ray diffraction and thermomagnetic measurements show that the ribbons consist of tetragonal Ti3(Fe,Co5B2, FeCo-rich bcc, and NiAl-rich L21 phases; Ti3(Fe,Co5B2, is a new substitutional alloy series whose end members Ti3Co5B2 and Ti3Fe5B2 have never been investigated magnetically and may not even exist, respectively. Two compositions are considered, namely Ti11+xFe37.5-0.5xCo37.5−0.5xB14 (x = 0, 4 and alnico-like Ti11Fe26Co26Ni10Al11Cu2B14, the latter also containing an L21-type alloy. The volume fraction of the Ti3(Fe,Co5B2 phase increases with x, which leads to a coercivity increase from 221 Oe for x = 0 to 452 Oe for x = 4. Since the grains are nearly equiaxed, there is little or no shape anisotropy, and the coercivity is largely due to the magnetocrystalline anisotropy of the tetragonal Ti3(Fe,Co5B2 phase. The alloy containing Ni, Al, and Cu exhibits a magnetization of 10.6 kG and a remanence ratio of 0.59. Our results indicate that magnetocrystalline anisotropy can be introduced in alnico-like magnets, adding to shape anisotropy that may be induced by field annealing.

  20. Effect of annealing on magnetic properties and structure of Fe-Ni based magnetic microwires

    Energy Technology Data Exchange (ETDEWEB)

    Zhukova, V. [Dpto. de Física de Materiales, Fac. Químicas, UPV/EHU, 20018 San Sebastian (Spain); Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Korchuganova, O.A.; Aleev, A.A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409 Moscow (Russian Federation); Tcherdyntsev, V.V.; Churyukanova, M. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Medvedeva, E.V. [Institute of Electrophysics, Ural Branch, Russian Academy of Sciences 620016 Yekaterinburg (Russian Federation); Seils, S.; Wagner, J. [Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Ipatov, M. [Dpto. de Física de Materiales, Fac. Químicas, UPV/EHU, 20018 San Sebastian (Spain); Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Blanco, J.M. [Dpto. de Física Aplicada, EUPDS, UPV/EHU, 20018 San Sebastian (Spain); Kaloshkin, S.D. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Aronin, A. [National University of Science and Technology «MISIS», 119049 Moscow (Russian Federation); Insitute of Solid State Physics, Moscow Region, 142432 Chernogolovka (Russian Federation); Abrosimova, G.; Orlova, N. [Insitute of Solid State Physics, Moscow Region, 142432 Chernogolovka (Russian Federation); and others

    2017-07-01

    Highlights: • High domain wall mobility of Fe-Ni-based microwires. • Enhancement of domain wall velocity and mobility in Fe-rich microwires after annealing. • Observation of areas enriched by Si and depleted by B after annealing. • Phase separation in annealed Fe-Ni based microwires in metallic nucleus and near the interface layer. - Abstract: We studied the magnetic properties and domain wall (DW) dynamics of Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} and Fe{sub 77.5}Si{sub 7.5}B{sub 15} microwires. Both samples present rectangular hysteresis loop and fast magnetization switching. Considerable enhancement of DW velocity is observed in Fe{sub 77.5}Si{sub 7.5}B{sub 15}, while DW velocity of samples Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} is less affected by annealing. The other difference is the magnetic field range of the linear region on dependence of domain wall velocity upon magnetic field: in Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} sample is considerably shorter and drastically decreases after annealing. We discussed the influence of annealing on DW dynamics considering different magnetoelastic anisotropy of studied microwires and defects within the amorphous state in Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2}. Consequently we studied the structure of Fe{sub 47.4}Ni{sub 26.6}Si{sub 11}B{sub 13}C{sub 2} sample using X-ray diffraction and the atom probe tomography. The results obtained using the atom probe tomography supports the formation of the B-depleted and Si-enriched precipitates in the metallic nucleus of Fe-Ni based microwires.

  1. Fe-based bulk metallic glasses used for magnetic shielding

    Energy Technology Data Exchange (ETDEWEB)

    Serban, Va; Codrean, C; UTu, D [Politehnica University of Timisoara, Depart for Materials Science and Welding, 1, M. Viteazu Bvd., 300222, Timisoara (Romania); ErcuTa, A, E-mail: serban@mec.upt.r [West University of Timisoara, Faculty of Physics, 4, Vasile Parvan Bdv., Timisoara 300223 (Romania)

    2009-01-01

    The casting in complex shapes (tubular) and the main magnetic properties of bulk metallic glasses (BMG) alloys from the ferromagnetic Fe-Cr-Ni-Ga-P-Si-C system, with a small addition of Ni (3%) were studied. Samples as rods and sockets having the thickness up to 1 mm were obtained from master alloys by melt injection by low cooling rates into a Cu mold and annealed in order to ensure adequate magnetic requirements. The structure was examined by X-ray diffraction (XRD) and the basic magnetic properties (coercivity, magnetic remanence, initial susceptibility, etc.) were determined by conventional low frequency induction method. The experimental investigations on producing of BMG ferromagnetic alloys with 3% Ni show the possibility to obtain magnetic shields of complex shape with satisfactory magnetic properties. The presence of Ni does not affect the glass forming ability, but reduce the shielding capacity.

  2. Torsion-induced magnetoimpedance in nanocrystalline Fe-based wires

    International Nuclear Information System (INIS)

    Santos, J.D.; Olivera, J.; Alvarez, P.; Sanchez, T.; Perez, M.J.; Sanchez, M.L.; Gorria, P.; Hernando, B.

    2007-01-01

    The magnetic field influence on the real and imaginary parts of axial-diagonal (ζ zz ) and off-diagonal (ζ φz ) components of the surface magnetoimpedance (MI) tensor has been studied in amorphous and nanocrystalline Fe 73.5 Si 13.5 B 9 Cu 1 Nb 3 wires. Twisted and untwisted wires were annealed at a temperature near to that of primary crystallization. The MI response has been measured at 1MHz and 5mA rms drive current in all the samples. Even though the higher values for both components of the MI tensor are achieved for the untwisted annealed wire, the most interesting features are observed in the torsion annealed wire

  3. Short-range order in Fe-based metallic glasses: Wide-angle X-ray scattering studies

    International Nuclear Information System (INIS)

    Babilas, Rafał; Hawełek, Łukasz; Burian, Andrzej

    2014-01-01

    The local atomic structure of the Fe 80 B 20 , Fe 70 Nb 10 B 20 and Fe 62 Nb 8 B 30 glasses prepared in the form of ribbons has been studied by wide-angle X-ray scattering. Structural information about the amorphous ribbons has been derived from analysis of the radial distribution functions using the least-squares curve-fitting method. The obtained structural parameters indicate that Fe–Fe, Fe–B, Fe–Nb and Nb–B contributions are involved in the near-neighbor coordination spheres. The possible similarities of the local atomic arrangement in the investigated glasses and the crystalline Fe 3 B, Fe 23 B 6 and bcc Fe structures are also discussed. - Graphical abstract: Pair distribution functions (a) and best-fit model and experimental radial distribution functions for Fe 80 B 20 (b), Fe 70 Nb 10 B 20 (c) and Fe 62 Nb 8 B 30 (d) metallic glasses. - Highlights: • The short-range ordering in the Fe-based metallic glasses is presented. • The results of RDF function have been analyzed using the least-squares method. • The Fe–Fe, Fe–B, Fe–Nb or Nb–B contributions are involved in coordination spheres. • The structural unit is distorted triangular prism containing B, Fe or Nb atoms. • Similarities of atomic arrangement in glassy and crystalline structures are discussed

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

    Directory of Open Access Journals (Sweden)

    V. B. Naik

    2012-12-01

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

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

    OpenAIRE

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

    2017-01-01

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

  6. Evolution of Fe based intermetallic phases in Al–Si hypoeutectic casting alloys: Influence of the Si and Fe concentrations, and solidification rate

    Energy Technology Data Exchange (ETDEWEB)

    Gorny, Anton; Manickaraj, Jeyakumar [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada); Cai, Zhonghou [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Shankar, Sumanth, E-mail: shankar@mcmaster.ca [Light Metal Casting Research Centre (LMCRC), Department of Mechanical Engineering, McMaster University, 1280 Main Street W, Hamilton, ON, Canada L8S 4L7 (Canada)

    2013-11-15

    Highlights: •Anomalous evolution of Fe based intermetallic phases in Al–Si–Fe alloys. •XRF coupled with nano-diffraction to confirm the nano-size Fe intermetallic phases. •Crystallography of the θ-Al{sub 13}Fe{sub 4}, τ{sub 5}-Al{sub 8}Fe{sub 2}Si and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} phases. •Peritectic reactions involving the Fe intermetallic phases in Al–Si–Fe alloys. -- Abstract: Al–Si–Fe hypoeutectic cast alloy system is very complex and reported to produce numerous Fe based intermetallic phases in conjunction with Al and Si. This publication will address the anomalies of phase evolution in the Al–Si–Fe hypoeutectic casting alloy system; the anomaly lies in the peculiarities in the evolution and nature of the intermetallic phases when compared to the thermodynamic phase diagram predictions and past publications of the same. The influence of the following parameters, in various combinations, on the evolution and nature of the intermetallic phases were analyzed and reported: concentration of Si between 2 and 12.6 wt%, Fe between 0.05 and 0.5 wt% and solidification rates of 0.1, 1, 5 and 50 K s{sup −1}. Two intermetallic phases are observed to evolve in these alloys under these solidification conditions: the τ{sub 5}-Al{sub 8}SiFe{sub 2} and τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2}. The τ{sub 5}-Al{sub 8}SiFe{sub 2} phase evolves at all levels of the parameters during solidification and subsequently transforms into the τ{sub 6}-Al{sub 9}Fe{sub 2}Si{sub 2} through a peritectic reaction when promoted by certain combinations of solidification parameters such as higher Fe level, lower Si level and slower solidification rates. Further, it is also hypothesized from experimental evidences that the θ-Al{sub 13}Fe{sub 4} binary phase precludes the evolution of the τ{sub 5} during solidification and subsequently transforms into the τ{sub 6} phase during solidification. These observations are anomalous to the publications as prior art and

  7. Coercivity enhancement in Ce-Fe-B based magnets by core-shell grain structuring

    Directory of Open Access Journals (Sweden)

    M. Ito

    2016-05-01

    Full Text Available Ce-based R2Fe14B (R= rare-earth nano-structured permanent magnets consisting of (Ce,Nd2Fe14B core-shell grains separated by a non-magnetic grain boundary phase, in which the relative amount of Nd to Ce is higher in the shell of the magnetic grain than in its core, were fabricated by Nd-Cu infiltration into (Ce,Nd2Fe14B hot-deformed magnets. The coercivity values of infiltrated core-shell structured magnets are superior to those of as-hot-deformed magnets with the same overall Nd content. This is attributed to the higher value of magnetocrystalline anisotropy of the shell phase in the core-shell structured infiltrated magnets compared to the homogeneous R2Fe14B grains of the as-hot-deformed magnets, and to magnetic isolation of R2Fe14B grains by the infiltrated grain boundary phase. First order reversal curve (FORC diagrams suggest that the higher anisotropy shell suppresses initial magnetization reversal at the edges and corners of the R2Fe14B grains.

  8. Gap symmetry and structure of Fe-based superconductors

    International Nuclear Information System (INIS)

    Hirschfeld, P J; Korshunov, M M; Mazin, I I

    2011-01-01

    The recently discovered Fe-pnictide and chalcogenide superconductors display low-temperature properties suggesting superconducting gap structures which appear to vary substantially from family to family, and even within families as a function of doping or pressure. We propose that this apparent nonuniversality can actually be understood by considering the predictions of spin fluctuation theory and accounting for the peculiar electronic structure of these systems, coupled with the likely 'sign-changing s-wave' (s ± ) symmetry. We review theoretical aspects, materials properties and experimental evidence relevant to this suggestion, and discuss which further measurements would be useful to settle these issues. Satisfactoriness has to be measured by a multitude of standards, of which some, for aught we know, may fail in any given case; and what is more satisfactory than any alternative in sight, may to the end be a sum of pluses and minuses, concerning which we can only trust that by ulterior corrections and improvements a maximum of the one and a minimum of the other may some day be approached. William James, Meaning of Truth

  9. Synthesis, microstructure and properties of BiFeO3-based multiferroic materials: A review

    Directory of Open Access Journals (Sweden)

    Bernardo, M. S.

    2014-02-01

    Full Text Available BiFeO3-based materials are currently one of the most studied multiferroics due to their possible applications at room temperature. However, among the large number of published papers there is much controversy. For example, possibility of synthesizing a pure BiFeO3 phase is still source of discussion in literature. Not even the nature of the binary Bi2O3-Fe2O3 diagram has been clarified yet. The difficulty in controlling the formation of parasite phases reaches the consolidation step. Accordingly, the sintering conditions must be carefully determined both to get dense materials and to avoid bismuth ferrite decomposition. However, the precise conditions to attain dense bismuth ferrite materials are frequently contradictory among different works. As a consequence, the reported properties habitually result opposed and highly irreproducible hampering the preparation of BiFeO3 materials suitable for practical applications. In this context, the purpose of the present review is to summarize the main researches regarding BiFeO3 synthesis, microstructure and properties in order to provide an easier understanding of these materials.Los materiales basados en BiFeO3 son en la actualidad uno de los multiferroicos más estudiados debido a sus posibles aplicaciones a temperatura ambiente. Sin embargo, entre la multitud de trabajos publicados referentes a estos materiales existe mucha controversia. Por ejemplo, la posibilidad de sintetizar una fase BiFeO3 pura es aún objeto de discusión en la bibliografía y la naturaleza de los diagramas de fases del sistema Bi2O3-Fe2O3 aún no está clara. La dificultad para controlar las fases parásitas se extiende al proceso de consolidación por lo que las condiciones de sinterización deben ser cuidadosamente controladas para obtener materiales densos y al mismo tiempo evitar la descomposición de la ferrita. No obstante, las condiciones precisas para obtener materiales densos de BiFeO3 son frecuentemente

  10. Stress and annealing induced changes in the Curie temperature of amorphous and nanocrystalline FeZr and FeNb based alloys

    International Nuclear Information System (INIS)

    Gorria, P.; Orue, I.; Fernandez-Gubieda, M.L.; Plazaola, F.; Zabala, N.; Barandiaran, J.M.

    1996-01-01

    The stress and annealing dependence of the Curie temperature in FeZrBCu alloys is presented. A change of about 50 /GPa has been observed. The change in amorphous matrix composition upon crystallization produces an expected increase in T C (about 200 C) which is similar to the experimentally observed increase. This behaviour is opposite to that observed in Fe-Nb based alloys. (orig.)

  11. A study of the Fe-based superconductor SmFeAsO{sub 1-x}F{sub x} by x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y; Chen, Y L; Cui, Y J; Cheng, C H; Zhao, Y [Key Laboratory of Magnetic Levitation Technologies and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, H [Department of Physics, Peking University, Beijing 100871 (China)], E-mail: yzhao@swjtu.edu.cn

    2009-01-15

    The electronic structure of the Fe-based superconductor SmFeAsO{sub 1-x}F{sub x} (x = 0 and 0.2) is studied with x-ray photoemission spectroscopy (XPS) through comparing the band structures of the nonsuperconducting parent material SmFeAsO and the superconducting SmFeAsO{sub 0.8}F{sub 0.2} (T{sub c} = 52.5 K). A small peak centered at 0.2 eV below the Fermi level, E{sub F}, in the valence band is observed in the parent material SmFeAsO, which is due to the low-spin state of the Fe 3d electrons. With fluorine doping, the peak at 0.2 eV disappears and a broad plateau forms near the Fermi level; in the meantime, the density of states at E{sub F} is slightly suppressed. The O 1s and Sm 3d core levels shift towards high energy by {approx}0.55 eV with fluorine doping, but in a sharp comparison, the Fe 2p and As 3d core levels do not shift significantly (the binding energy shift is less than 0.01 eV). It is deduced from the core-level shifts that the Fermi level of the system moves up by 0.55 eV by fluorine doping.

  12. Nd2Fe14C-based magnet with better permanent magnetic properties prepared by a simple mechanochemical method

    Science.gov (United States)

    Geng, Hongmin; Ji, Yuan; Zhang, Jingjing; Gao, Yuchao; Yan, Yu; Wang, Wenquan; Su, Feng; Du, Xiaobo

    2017-11-01

    Nd2Fe14C-based magnet is prepared by a mechanochemical method, namely high-energy ball-milling Nd2Fe11Bx (x = 0-0.15) alloy in heptane (C7H16), followed by annealing to 850 °C in vacuum. Under the action of high-energy ball-milling, Nd2Fe11Bx react with heptane to form NdH2+δ, Fe-(CB), C, etc. H2 is released and Nd2Fe17, Nd2Fe17Cx (x = 0-3), Nd2Fe14C, Nd carbides and α-Fe are formed in the subsequent annealing. C amount depends on ball-milling time t. Long time ball milling or high C content suppresses the formation of 2:17 phase and favors the formation of 2:14:1 phase in the final products. Excessive ball-milling results in the quick increase of α-Fe. The maximum of magnetically hard Nd2Fe14C is obtained at t = 4 h. For Nd2Fe11 samples, there exists considerable quantity of Nd carbides and α-Fe phase appears earlier and increases rapidly with extending the ball-milling time t. The addition of B element shortens the ball-milling time of the formation of maximum Nd2Fe14C and prominently suppresses the formation of Nd carbide and α-Fe. The optimum magnetic properties, coercivity iHc of 1193.7 kA/m, remanence Mr of 580.9 kA/m, maximum magnetic energy product (BH)max of 91.7 kJ/m3 is approaching to its theoretic value of 99.2 kJ/m3 for isotropic Nd2Fe14C magnet, are obtained in Nd2Fe11B0.06 alloy ball milled for 3.5 h.

  13. Magnetic Compton scattering study of Laves phase ZrFe2 and Sc doped ZrFe2: Experiment and Green function based relativistic calculations

    Science.gov (United States)

    Bhatt, Samir; Mund, H. S.; Kumar, Kishor; Bapna, Komal; Dashora, Alpa; Itou, M.; Sakurai, Y.; Ahuja, B. L.

    2018-05-01

    Spin momentum densities of ferromagnetic ZrFe2 and Zr0.8Sc0.2Fe2 have been measured using magnetic Compton scattering with 182.65 keV circularly polarized synchrotron radiations. Site specific spin moments, which are responsible for the formation of total spin moment, have been deduced from Compton line shapes. At room temperature, the computed spin moment of ZrFe2 is found to be slightly higher than that of Sc doped ZrFe2 which is in consensus with the magnetization data. To compare the experimental data, we have also computed magnetic Compton profiles (MCPs), total and partial spin projected density of states (DOS) and the site specific spin moments using spin-polarized relativistic Korringa-Kohn-Rostoker method. It is observed that the spin moment at Fe site is aligned antiparallel to that of Zr site in both ZrFe2 and Zr0.8Sc0.2Fe2. The MCP results when compared with vibrating sample magnetometer based magnetization data, show a very small contribution of orbital moment in the formation of total magnetic moments in both the compounds. The DOS of ferromagnetic ground state of ZrFe2 and Zr0.8Sc0.2Fe2 are interpreted on the basis of a covalent magnetic model beyond the Stoner rigid band model. It appears that on alloying between a magnetic and a non-magnetic partner (with low valence), a polarization develops on the non-magnetic atom which is anti-parallel to that of the magnetic atom.

  14. Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys

    International Nuclear Information System (INIS)

    Kumar, G.

    2005-01-01

    The aim of the present work is to characterize a metastable hard magnetic phase referred to as ''A1'' in Nd-Fe alloys, which forms as a part of the fine eutectic depending on the composition and cooling rate. In order to define the range of composition for the formation of A1, Nd 100-x Fe x (x=20,25,40) alloys are cooled at about 150 K/s. The effect of cooling rate on the formation of hard magnetic A1 is studied by investigating the Nd 80 Fe 20 alloys cooled at different rates. The Nd-richer regions are identified as dhcp Nd and fcc Nd-Fe solid solution. However, the Fe-richer regions also referred to as A1, are diffuse and give an average composition of Nd 56 Fe 44 . HRTEM images of the Fe-richer regions reveal the presence of 5-10 nm crystallites embedded in an amorphous phase. The demagnetization curves the hard magnetic Nd80Fe20 measured at temperatures above 30 K are typical of a hard magnetic material. The measurements of initial magnetization, field dependence of coercivity, and temperature dependence of coercivity suggest the Stoner-Wohlfarth type magnetization reversal process for the hard magnetic A1. The values of anisotropy constant are estimated by fitting the magnetization data to the law-of-approach to saturation. The temperature dependence of anisotropy constant and the coercivity indicate that the origin of coercivity is magnetic anisotropy

  15. Superconductivity in SnO: a nonmagnetic analog to Fe-based superconductors?

    Science.gov (United States)

    Forthaus, M K; Sengupta, K; Heyer, O; Christensen, N E; Svane, A; Syassen, K; Khomskii, D I; Lorenz, T; Abd-Elmeguid, M M

    2010-10-08

    We discovered that under pressure SnO with α-PbO structure, the same structure as in many Fe-based superconductors, e.g., β-FeSe, undergoes a transition to a superconducting state for p≳6 GPa with a maximum Tc of 1.4 K at p=9.3 GPa. The pressure dependence of Tc reveals a domelike shape and superconductivity disappears for p≳16 GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc as a function of pressure.

  16. Superconductivity in SnO: A Nonmagnetic Analog to Fe-Based Superconductors?

    DEFF Research Database (Denmark)

    Forthaus, M. K.; Sengupta, K.; Heyer, O.

    2010-01-01

    We discovered that under pressure SnO with α-PbO structure, the same structure as in many Fe-based superconductors, e.g., β-FeSe, undergoes a transition to a superconducting state for p≳6  GPa with a maximum Tc of 1.4 K at p=9.3  GPa. The pressure dependence of Tc reveals a domelike shape...... and superconductivity disappears for p≳16  GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc...

  17. Surface transport properties of Fe-based superconductors: The influence of degradation and inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Plecenik, T.; Gregor, M.; Sobota, R.; Truchly, M.; Satrapinskyy, L.; Kus, P.; Plecenik, A. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Kurth, F.; Holzapfel, B.; Iida, K. [Institute for Metallic Materials, IFW Dresden, P. O. Box 270116, D-01171 Dresden (Germany)

    2013-07-29

    Surface properties of Co-doped BaFe{sub 2}As{sub 2} epitaxial superconducting thin films were inspected by X-ray photoelectron spectroscopy, scanning spreading resistance microscopy (SSRM), and point contact spectroscopy (PCS). It has been shown that surface of Fe-based superconductors degrades rapidly if being exposed to air, what results in suppression of gap-like structure on PCS spectra. Moreover, SSRM measurements revealed inhomogeneous surface conductivity, what is consistent with strong dependence of PCS spectra on contact position. Presented results suggest that fresh surface and small probing area should be assured for surface sensitive measurements like PCS to obtain intrinsic properties of Fe-based superconductors.

  18. Damage induced by helium ion irradiation in Fe-based metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaonan; Mei, Xianxiu, E-mail: xxmei@dlut.edu.cn; Zhang, Qi; Li, Xiaona; Qiang, Jianbing; Wang, Younian

    2017-07-15

    The changes in structure and surface morphology of metallic glasses Fe{sub 80}Si{sub 7.43}B{sub 12.57} and Fe{sub 68}Zr{sub 7}B{sub 25} before and after the irradiation of He ions with the energy of 300 keV were investigated, and were compared with that of the tungsten. The results show that after the He{sup 2+} irradiation, metallic glass Fe{sub 68}Zr{sub 7}B{sub 25} still maintained amorphous. While a small amount of metastable β-Mn type phase nanocrystals formed in metallic glass Fe{sub 80}Si{sub 7.43}B{sub 12.57} at the fluence of 4.0 × 10{sup 17}ions/cm{sup 2} (19dpa). The nanocrystals transformed into α-Fe phase and tetragonal Fe{sub 2}B phase as the fluence increased to 1.0 × 10{sup 18}ions/cm{sup 2} (47dpa). Then the new orthogonal Fe{sub 3}B phase and β-Mn type phase nanocrystals appeared when the fluence increased further, and the quantities of nanocrystals increased. Blisters and cracks appeared on the surface of tungsten under the irradiation fluence of 1.0 × 10{sup 18}ions/cm{sup 2}, however only when the fluence was up to 1.6 × 10{sup 18}ions/cm{sup 2}, could cracks and spalling appear on the surfaces of metallic glasses. - Highlights: •Metallic glass Fe{sub 68}Zr{sub 7}B{sub 25} could maintain amorphous state after the irradiation. •A series of crystallization behaviors occurred in metallic glass Fe{sub 80}Si{sub 7.43}B{sub 12.57}. •The surface of tungsten appeared blisters at the fluence of 1.0 × 10{sup 18} ions/cm{sup 2}. •Surfaces of Fe-based metallic glasses cracked at the fluence of 1.6 × 10{sup 18}ions/cm{sup 2}.

  19. Low-temperature rapid synthesis and superconductivity of Fe-based oxypnictide superconductors.

    Science.gov (United States)

    Fang, Ai-Hua; Huang, Fu-Qiang; Xie, Xiao-Ming; Jiang, Mian-Heng

    2010-03-17

    Fe-based oxypnictide superconductors were successfully synthesized at lower reaction temperatures and with shorter reaction times made possible by starting with less stable compounds, which provide a larger driving force for reactions. Using ball-milled powders of intermediate compounds, phase-pure superconductors with T(c) above 50 K were synthesized at 1173 K in 20 min. This method is particularly advantageous for retaining F, a volatile dopant that enhances superconductivity. Bulk superconductivity and high upper critical fields up to 392 T in Sm(0.85)Nd(0.15)FeAsO(0.85)F(0.15) were demonstrated.

  20. Efficient FRET-based fuorescent ratiometric chemosensors for Fe3+ and its application in living cells

    International Nuclear Information System (INIS)

    Wang, Cuicui; Liu, Yaqi; Cheng, Junye; Song, Jianhua; Zhao, Yufen; Ye, Yong

    2015-01-01

    A series of novel FRET-based fluorescent ratiometric chemosensors (L 1 –L 6 ) were designed and synthesized. Sensor L 2 showed reversible and the best selective recognition toward Fe 3+ over other metal ions with a detection limit of 0.418 ppm, which can meet the selective requirements for practical application. Experiment results showed that the response behavior of L 2 toward Fe 3+ is pH independent in weak acid condition (pH 4.0–6.0). In addition, sensor L 2 was successfully applied for ratiometric visualization of Fe 3+ in living cells. - Highlights: • The detection limit of a new FRET probe for Fe 3+ was 0.418 ppm. • The probe exhibited high selectivity and sensitivity detection to Fe 3+ with a pH span of 4.0–6.0. • The significant changes in color could be used for naked-eye detection • The fluorescence imaging experiment demonstrated its value of practical application

  1. Polylactide-based polyurethane shape memory nanocomposites (Fe3O4/PLAUs) with fast magnetic responsiveness

    International Nuclear Information System (INIS)

    Gu, Shu-Ying; Jin, Sheng-Peng; Gao, Xie-Feng; Mu, Jian

    2016-01-01

    Polylactide-based polyurethane shape memory nanocomposites (Fe 3 O 4 /PLAUs) with fast magnetic responsiveness are presented. For the purpose of fast response and homogeneous dispersion of magnetic nanoparticles, oleic acid was used to improve the dispersibility of Fe 3 O 4 nanoparticles in a polymer matrix. A homogeneous distribution of Fe 3 O 4 nanoparticles in the polymer matrix was obtained for nanocomposites with low Fe 3 O 4 loading content. A small agglomeration was observed for nanocomposites with 6 wt% and 9 wt% loading content, leading to a small decline in the mechanical properties. PLAU and its nanocomposites have glass transition around 52 °C, which can be used as the triggering temperature. PLAU and its nanocomposites have shape fixity ratios above 99%, shape recovery ratios above 82% for the first cycle and shape recovery ratios above 91% for the second cycle. PLAU and its nanocomposites also exhibit a fast water bath or magnetic responsiveness. The magnetic recovery time decreases with an increase in the loading content of Fe 3 O 4 nanoparticles due to an improvement in heating performance for increased weight percentage of fillers. The nanocomposites have fast responses in an alternating magnetic field and have potential application in biomedical areas such as intravascular stent. (paper)

  2. Industrial wastewater advanced treatment via catalytic ozonation with an Fe-based catalyst.

    Science.gov (United States)

    Li, Xufang; Chen, Weiyu; Ma, Luming; Wang, Hongwu; Fan, Jinhong

    2018-03-01

    An Fe-based catalyst was used as a heterogeneous catalyst for the ozonation of industrial wastewater, and key operational parameters (pH and catalyst dosage) were studied. The results indicated that the Fe-based catalyst significantly improved the mineralization of organic pollutants in wastewater. TOC (total organic carbon) removal was high, at 78.7%, with a catalyst concentration of 200 g/L, but only 31.6% with ozonation alone. The Fe-based catalyst significantly promoted ozone decomposition by 70% in aqueous solution. Hydroxyl radicals (·OH) were confirmed to be existed directly via EPR (electron paramagnetic resonance) experiments, and ·OH were verified to account for about 34.4% of TOC removal with NaHCO 3 as a radical scavenger. Through characterization by SEM-EDS (field emission scanning electron microscope with energy-dispersive spectrometer), XRD (X-ray powder diffraction) and XPS (X-ray photoelectron spectroscopy), it was deduced that FeOOH on the surface of the catalyst was the dominant contributor to the catalytic efficiency. The catalyst was certified as having good stability and excellent reusability based on 50 successive operations and could be used as a filler simultaneously. Thereby, it is a promising catalyst for practical industrial wastewater advanced treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Magnetic properties of FeNi-based thin film materials with different additives

    KAUST Repository

    Liang, C.; Gooneratne, C.P.; Wang, Q.X.; Liu, Y.; Gianchandani, Y.; Kosel, Jü rgen

    2014-01-01

    This paper presents a study of FeNi-based thin film materials deposited with Mo, Al and B using a co-sputtering process. The existence of soft magnetic properties in combination with strong magneto-mechanical coupling makes these materials

  4. Selective Hydrodeoxygenation of Alkyl Lactates to Alkyl Propionates with Fe-based Bimetallic Supported Catalysts

    DEFF Research Database (Denmark)

    Khokarale, Santosh Govind; He, Jian; Schill, Leonhard

    2018-01-01

    Hydrodeoxygenation (HDO) of methyl lactate (ML) to methyl propionate (MP) was performed with various base-metal supported catalysts. A high yield of 77 % MP was obtained with bimetallic Fe-Ni/ZrO2 in methanol at 220 °C and 50 bar H2 . A synergistic effect of Ni increased the yield of MP...... of the material. Interestingly, it was observed that Fe-Ni/ZrO2 also effectively catalyzed methanol reforming to produce H2 in situ, followed by HDO of ML, yielding 60 % MP at 220 °C with 50 bar N2 instead of H2. Fe-Ni/ZrO2 also catalyzed HDO of other short-chain alkyl lactates to the corresponding alkyl...

  5. Nb-Based Nb-Al-Fe Alloys: Solidification Behavior and High-Temperature Phase Equilibria

    Science.gov (United States)

    Stein, Frank; Philips, Noah

    2018-03-01

    High-melting Nb-based alloys hold significant promise for the development of novel high-temperature materials for structural applications. In order to understand the effect of alloying elements Al and Fe, the Nb-rich part of the ternary Nb-Al-Fe system was investigated. A series of Nb-rich ternary alloys were synthesized from high-purity Nb, Al, and Fe metals by arc melting. Solidification paths were identified and the liquidus surface of the Nb corner of the ternary system was established by analysis of the as-melted microstructures and thermal analysis. Complementary analysis of heat-treated samples yielded isothermal sections at 1723 K and 1873 K (1450 °C and 1600 °C).

  6. Recent Advances in Layered Metal Chalcogenides as Superconductors and Thermoelectric Materials: Fe-Based and Bi-Based Chalcogenides.

    Science.gov (United States)

    Mizuguchi, Yoshikazu

    2016-04-01

    Recent advances in layered (Fe-based and Bi-based) chalcogenides as superconductors or functional materials are reviewed. The Fe-chalcogenide (FeCh) family are the simplest Fe-based high-Tc superconductors. The superconductivity in the FeCh family is sensitive to external or chemical pressure, and high Tc is attained when the local structure (anion height) is optimized. The Bi-chalcogenide (BiCh2) family are a new group of layered superconductors with a wide variety of stacking structures. Their physical properties are also sensitive to external or chemical pressure. Recently, we revealed that the emergence of superconductivity and the Tc in this family correlate with the in-plane chemical pressure. Since the flexibility of crystal structure and electronic states are an advantage of the BiCh2 family for designing functionalities, I briefly review recent developments in this family as not only superconductors but also other functional materials. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Fe-based MOFs for efficient adsorption and degradation of acid orange 7 in aqueous solution via persulfate activation

    International Nuclear Information System (INIS)

    Li, Xianghui; Guo, Weilin; Liu, Zhonghua; Wang, Ruiqin; Liu, Hua

    2016-01-01

    Graphical abstract: - Highlights: • Fe-based MILs were prepared via the facile solvothermal method. • MILs showed efficient removal rate through adsorption and degradation processes. • A possible catalytic degradation mechanism is proposed. - Abstract: Fe-based metal–organic frameworks (MOFs) including MIL-101(Fe), MIL-100(Fe), MIL-53(Fe), and MIL-88B(Fe) prepared via a facile solvothermal process were introduced as both adsorbents and catalysts to generate powerful radicals from persulfate for acid orange 7 (AO7) removal in aqueous solution. Various catalysts were described and characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectra. Because of the high specific surface area of the materials, we studied the adsorption isotherms of the four MILs by the fitting of Langmuir adsorption isotherm. Meanwhile, the catalytic activities in persulfate oxidation system were investigated. The results showed that the sequence of the materials ability in the combination of adsorption and degradation was MIL-101(Fe) > MIL-100(Fe) > MIL-53(Fe) > MIL-88B(Fe), which had a close connection with the activity of metal ion in active site of the catalysts and their different cages in size. Moreover, the reactive species in MILs/persulfate system were identified as sulfate radicals and hydroxyl radicals. The reaction mechanism for persulfate activation over MILs was also studied.

  8. A displacement based FE formulation for steady state problems

    NARCIS (Netherlands)

    Yu, Y.

    2005-01-01

    In this thesis a new displacement based formulation is developed for elasto-plastic deformations in steady state problems. In this formulation the displacements are the primary variables, which is in contrast to the more common formulations in terms of the velocities as the primary variables. In a

  9. Colloidal processing of Fe-based metalceramic composites with high content of ceramic reinforcement

    Directory of Open Access Journals (Sweden)

    Escribano, J. A.

    2013-12-01

    Full Text Available Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N , is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N in its composition.Las principales dificultades de procesamiento de materiales compuestos de matriz metálica por medio de técnicas convencionales pulvimetalúrgicas es la falta de dispersión entre fases dentro de la microestructura final. Este trabajo describe por primera vez el procesamiento de materiales compuestos de matriz metálica de Fe, con un alto contenido de un refuerzo cerámico (Ti (C, N, mediante técnicas coloidales. El procesamiento coloidal permite un mayor control sobre el empaquetamiento de polvos y una mejor homogeneización de las fases al mezclarse los polvos en un medio líquido. La estabilidad química del Fe en medio acuoso determina las condiciones de dispersión de la mezcla. Las suspensiones de Fe se formularon mediante la optimización del potencial zeta y de su reología, con el fin de dar forma a piezas compactas por colaje en molde de escayola. Los resultados preliminares mostrados demuestran la viabilidad del proceso, además de abrir nuevas vías al dise

  10. Improving the electrochemical properties of nanosized LiFePO4-based electrode by boron doping

    International Nuclear Information System (INIS)

    Trócoli, Rafael; Franger, Sylvain; Cruz, Manuel; Morales, Julián; Santos-Peña, Jesús

    2014-01-01

    Highlights: • Thermal treatment of boron phosphate with LiFePO 4 provides electrode materials with high performance in lithium half-cells: 160 mAh·g -1 (90% of theoretical capacity) under C/5 rate • The products are composites containing boron-modified LiFePO 4 , FePO 4 and an amorphous phase with ionic diffusion properties • The boron treatment affects textural, conductive and lithium diffusivity of the electrode material leading to higher performance • A limited boron-doping of the phospholivine structure is observed - Abstract: Electrode materials with homogeneous distribution of boron were obtained by heating mixtures of nanosized carbon-coated lithium iron phosphate and BPO 4 in 3-9% weight at 700 °C. The materials can be described as nanocomposites containing i) LiFePO 4 , possibly doped with a low amount of boron, ii) FePO 4 and iii) an amorphous layer based on Li 4 P 2 O 7 -derived material that surrounds the phosphate particles. The thermal treatment with BPO 4 also triggered changes in the carbon coating graphitic order. Galvanostatic and voltammetric studies in lithium half-cells showed smaller polarisation, higher capacity and better cycle life for the boron-doped composites. For instance, one of the solids, called B 6 -LiFePO 4 , provided close to 150 and 140 mAhg -1 (87% and 81% of theoretical capacity, respectively) under C/2.5 and C regimes after several cycles. Improved specific surface area, carbon graphitization, conductivity and lithium ion diffusivity in the boron-doped phospholivine network account for this excellent rate performance. The properties of an amorphous layer surrounding the phosphate particles also account for such higher performance

  11. Mass renormalization and unconventional pairing in multi-band Fe-based superconductors- a phenomenological approach

    Energy Technology Data Exchange (ETDEWEB)

    Drechsler, S.L.; Efremov, D.; Grinenko, V. [IFW-Dresden (Germany); Johnston, S. [Inst. of Quantum Matter, University of British Coulumbia, Vancouver (Canada); Rosner, H. [MPI-cPfS, Dresden, (Germany); Kikoin, K. [Tel Aviv University (Israel)

    2015-07-01

    Combining DFT calculations of the density of states and plasma frequencies with experimental thermodynamic, optical, ARPES, and dHvA data taken from the literature, we estimate both the high-energy (Coulomb, Hund's rule coupling) and the low-energy (el-boson coupling) electronic mass renormalization [H(L)EMR] for typical Fe-pnictides with T{sub c}<40 K, focusing on (K,Rb,Cs)Fe{sub 2}As{sub 2}, (Ca,Na)122, (Ba,K)122, LiFeAs, and LaFeO{sub 1-x}F{sub x}As with and without As-vacancies. Using Eliashberg theory we show that these systems can NOT be described by a very strong el-boson coupling constant λ ≥ ∝ 2, being in conflict with the HEMR as seen by DMFT, ARPES and optics. Instead, an intermediate s{sub ±} coupling regime is realized, mainly based on interband spin fluctuations from one predominant pair of bands. For (Ca,Na)122, there is also a non-negligible intraband el-phonon/orbital fluctuation intraband contribution. The coexistence of magnetic As-vacancies and high-T{sub c}=28 K for LaFeO{sub 1-x}F{sub x}As{sub 1-δ} excludes an orbital fluctuation dominated s{sub ++} scenario at least for that system. In contrast, the line nodal BaFe{sub 2}(As,P){sub 2} near the quantum critical point is found as a superstrongly coupled system. The role of a pseudo-gap is briefly discussed for some of these systems.

  12. Pack cementation diffusion coatings for Fe-base and refractory alloys. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1998-03-10

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels and refractory metal alloys. A new comprehensive theory to treat the multi-component thermodynamic equilibria in the gas phase for several coexisting solid phases was developed and used. Many different processes to deposit various types of coatings on several types of steels were developed: Cr-Si codeposition for low- or medium-carbon steels, Cr-Al codeposition on low-carbon steels to yield either a Kanthal-type composition (Fe-25Cr-4Al in wt.%) or else a (Fe, Cr){sub 3}Al surface composition. An Fe{sub 3}Al substrate was aluminized to achieve an FeAl surface composition, and boron was also added to ductilize the coating. The developmental Cr-lean ORNL alloys with exceptional creep resistance were Cr-Al coated to achieve excellent oxidation resistance. Alloy wires of Ni-base were aluminized to provide an average composition of Ni{sub 3}Al for use as welding rods. Several different refractory metal alloys based on Cr-Cr{sub 2}Nb have been silicided, also with germanium additions, to provide excellent oxidation resistance. A couple of developmental Cr-Zr alloys were similarly coated and tested.

  13. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Weiming [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Sun, Baoan [Department of Mechanical and Biomedical Engineering, City University of Hong Kong (Hong Kong); Zhao, Yucheng, E-mail: zhaoyc1972@163.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Li, Qiang [School of Physics Science and Technology, Xinjiang University, Urumqi, Xinjiang 830046 (China); Hou, Long; Luo, Ning [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Dun, Chaochao [Department of Physics, Wake Forest University, Winston Salem, NC 27109 (United States); Zhao, Chengliang [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Ma, Zhanguo [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Haishun, E-mail: liuhaishun@126.com [State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, School of Sciences, China University of Mining and Technology, Xuzhou 221116 (China); Shen, Baolong [School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

    2016-08-15

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe{sub 50}Ni{sub 30}P{sub 13}C{sub 7} metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  14. Non-repeatability of large plasticity for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Yang, Weiming; Sun, Baoan; Zhao, Yucheng; Li, Qiang; Hou, Long; Luo, Ning; Dun, Chaochao; Zhao, Chengliang; Ma, Zhanguo; Liu, Haishun; Shen, Baolong

    2016-01-01

    Serrated flow is an essential characteristic of the plastic deformation of metallic glasses. Under restricted loading conditions, the formation and expansion of shear bands act as the serrated flow of stress-strain curves in metallic glasses. In this work, serrated flows in Fe_5_0Ni_3_0P_1_3C_7 glassy samples with different plasticity were studied. The distribution histogram shows a monotonically decreasing trend during the initial deformation stage (i.e., the plastic deformation in the range of 0–8%), whereas in the following deformation stage (i.e., a plastic deformation of 8–14%), the stress drop frequency distribution presents both a monotonically decreasing distribution and a peak shape similar to chaotic dynamics. It is shown that the spatial evolution behavior of shear bands in Fe_5_0Ni_3_0P_1_3C_7 metallic glasses evolved from self-organized critical to chaotic dynamics in the form of serrated flow, which reveals the origin of discrete plasticity of Fe-based bulk metallic glasses. This study has potential applications for understanding the plastic deformation mechanism. - Highlights: • Two-stage deformation mechanism in Fe-based bulk metallic glasses. • Distribution of the stress drop amplitude is significantly different at two stages. • The stages are related to multiple shear bands and discrete plasticity.

  15. Fe-based nanocrystalline powder cores with ultra-low core loss

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiangyue, E-mail: wangxiangyue1986@163.com [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China); Lu, Zhichao; Lu, Caowei; Li, Deren [China Iron and Steel Research Institute Group, Beijing 100081 (China); Center of Advanced Technology and Materials Co., Ltd., Beijing 100081 (China)

    2013-12-15

    Melt-spun amorphous Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 15.5}B{sub 7} alloy strip was crushed to make flake-shaped fine powders. The passivated powders by phosphoric acid were mixed with organic and inorganic binder, followed by cold compaction to form toroid-shaped bonded powder-metallurgical magnets. The powder cores were heat-treated to crystallize the amorphous structure and to control the nano-grain structure. Well-coated phosphate-oxide insulation layer on the powder surface decreased the the core loss with the insulation of each powder. FeCuNbSiB nanocrystalline alloy powder core prepared from the powder having phosphate-oxide layer exhibits a stable permeability up to high frequency range over 2 MHz. Especially, the core loss could be reduced remarkably. At the other hand, the softened inorganic binder in the annealing process could effectively improve the intensity of powder cores. - Highlights: • Fe-based nanocrystalline powder cores were prepared with low core loss. • Well-coated phosphate-oxide insulation layer on the powder surface decreased the core loss. • Fe-based nanocrystalline powder cores exhibited a stable permeability up to high frequency range over 2 MHz. • The softened inorganic binder in the annealing process could effectively improve the intensity of powder cores.

  16. Recent advances on Fe- and Mn-based cathode materials for lithium and sodium ion batteries

    Science.gov (United States)

    Zhu, Xiaobo; Lin, Tongen; Manning, Eric; Zhang, Yuancheng; Yu, Mengmeng; Zuo, Bin; Wang, Lianzhou

    2018-06-01

    The ever-growing market of electrochemical energy storage impels the advances on cost-effective and environmentally friendly battery chemistries. Lithium-ion batteries (LIBs) are currently the most critical energy storage devices for a variety of applications, while sodium-ion batteries (SIBs) are expected to complement LIBs in large-scale applications. In respect to their constituent components, the cathode part is the most significant sector regarding weight fraction and cost. Therefore, the development of cathode materials based on Earth's abundant elements (Fe and Mn) largely determines the prospects of the batteries. Herein, we offer a comprehensive review of the up-to-date advances on Fe- and Mn-based cathode materials for LIBs and SIBs, highlighting some promising candidates, such as Li- and Mn-rich layered oxides, LiNi0.5Mn1.5O4, LiFe1-xMnxPO4, NaxFeyMn1-yO2, Na4MnFe2(PO4)(P2O7), and Prussian blue analogs. Also, challenges and prospects are discussed to direct the possible development of cost-effective and high-performance cathode materials for future rechargeable batteries.

  17. Novel high-strength Fe-based composite materials with large plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Werniewicz, Katarzna; Kuehn, Uta; Mattern, Norbert; Eckert, Juergen; Siegel, Uwe; Bartusch, Birgit; Schultz, Ludwig [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany); Kulik, Tadeusz [Warsaw University of Technology, Faculty of Materials Science and Engineering (Poland)

    2007-07-01

    Among glass-forming alloy systems reported so far, Fe-based bulk metallic glasses play a special role. Compared to other amorphous alloys e.g. Zr-, Ti-based, such glasses show superior mechanical strength. However, due to the general brittleness their wider application as structural materials is strongly restricted. The alternative approach to overcome this defect is to design BMG composites. In this work we present a series of new Fe-Cr-Mo-Ga-(Si,C) composite materials derived from an Fe-Cr-Mo-Ga-C-P-B glassy alloy, with the aim to improve the ductility of this high-strength material. The effect of the composition and the phase formation on the resulting mechanical properties was investigated. It has been found that the formation of a complex microstructure, which essentially consists of soft Ga-rich dendrites embedded in a hard Cr- and Mo-rich matrix, leads to a material with excellent compressive mechanical properties. While the obtained values of true strength are comparable with data reported for Fe-Cr-Mo-Ga-C-P-B BMG, the values of true strain are greatly improved for investigated composites.

  18. Development of FeCoB/Graphene Oxide based microwave absorbing materials for X-Band region

    International Nuclear Information System (INIS)

    Das, Sukanta; Chandra Nayak, Ganesh; Sahu, S.K.; Oraon, Ramesh

    2015-01-01

    This work explored the microwave absorption capability of Graphene Oxide and Graphene Oxide coated with FeCoB for stealth technology. Epoxy based microwave absorbing materials were prepared with 30% loading of Graphene Oxide, FeCoB alloy and Graphene Oxide coated with FeCoB. Graphene Oxide and FeCoB were synthesized by Hummer's and Co-precipitation methods, respectively. The filler particles were characterized by FESEM, XRD and Vibrating Sample Magnetometer techniques. Permittivity, permeability and reflection loss values of the composite absorbers were measured with vector network analyzer which showed a reflection loss value of −7.86 dB, at 10.72 GHz, for single layered Graphene Oxide/Epoxy based microwave absorbers which can be correlated to the absorption of about 83.97% of the incident microwave energy. Reflection loss value of FeCoB/Epoxy based microwave absorber showed −13.30 dB at 11.67 GHz, which corresponded to maximum absorption of 93.8%. However, reflection loss values of Graphene Oxide coated with FeCoB/Epoxy based single-layer absorber increased to −22.24 dB at 12.4 GHz which corresponds to an absorption of 99% of the incident microwave energy. - Highlights: • FeCoB coated Graphene Oxide (GO) was synthesized by co-precipitation method. • GO, FeCoB and GO@FeCoB based microwave absorbers were developed with Epoxy matrix. • GO and FeCoB/Epoxy absorbers showed −7.86 & −13.30 dB reflection loss, respectively. • Maximum Reflection loss of −22.24 dB was achieved with GO@FeCoB/Epoxy absorber

  19. Friction and wear properties of Cu and Fe-based P/M bearing materials

    International Nuclear Information System (INIS)

    Tufekci, Kenan; Kurbanoglu, Cahit; Durak, Ertugrul; Tunay, R. Fatih

    2006-01-01

    The performances of porous bearings under different operating conditions were experimentally investigated in this study. Material groups studied are 90%Cu + 10%Sn bronze and 1%C + % balance Fe iron-based self-lubricating P/M bearings at constant (85%) density. In the experiments, the variation of the coefficient of friction and wear ratio of those two different group materials for different sliding speeds, loads, and temperatures were investigated. As a result, the variation of the friction coefficient - temperature for both constant load, and constant sliding speed, friction coefficient - average bearing pressure, PV - wear loss and temperature-wear loss curves were plotted and compared with each other for two materials, separately. The test results showed that Cu-based bearings have better friction and wear properties than Fe-based bearings

  20. Transport and superconducting properties of Fe-based superconductors: a comparison between SmFeAsO1-xFx and Fe1+yTe1-xSex

    Science.gov (United States)

    Tropeano, M.; Pallecchi, I.; Cimberle, M. R.; Ferdeghini, C.; Lamura, G.; Vignolo, M.; Martinelli, A.; Palenzona, A.; Putti, M.

    2010-05-01

    In this paper we carry out a direct comparison between transport and superconducting properties—namely resistivity, magnetoresistivity, Hall effect, Seebeck effect, thermal conductivity, upper critical field—of two different families of Fe-based superconductors, which can be viewed in many respects as end members: SmFeAsO1 - xFx with the largest Tc and the largest anisotropy and Fe1 + yTe1 - xSex, with the largest Hc2, the lowest Tc and the lowest anisotropy. In the case of the SmFeAsO1 - xFx series, we find that a single-band description allows us to extract an approximate estimation of band parameters such as carrier density and mobility from experimental data, although the behaviour of the Seebeck effect as a function of doping demonstrates that a multiband description would be more appropriate. On the contrary, experimental data for the Fe1 + y(Te1 - x, Sex) series exhibit a strongly compensated behaviour, which can be described only within a multiband model. In the Fe1 + y(Te1 - x, Sex) series, the role of the excess Fe, tuned by Se stoichiometry, is found to be twofold: on one hand it dopes electrons in the system and on the other hand it introduces localized magnetic moments, responsible for Kondo like scattering and likely pairbreaking of Cooper pairs. Hence, Fe excess also plays a crucial role in determining superconducting properties such as the Tc and the upper critical field Hc2. The huge Hc2 values of the Fe1 + yTe1 - xSex samples are described by a dirty limit law, opposed to the clean limit behaviour of the SmFeAsO1 - xFx samples. Hence, magnetic scattering by excess Fe seems to drive the system in the dirty regime, but its detrimental pairbreaking role seems not to be as severe as predicted by theory. This issue has yet to be clarified, addressing the more fundamental issue of the interplay between magnetism and superconductivity.

  1. Electrospun ZnFe{sub 2}O{sub 4}-based nanofiber composites with enhanced supercapacitive properties

    Energy Technology Data Exchange (ETDEWEB)

    Agyemang, Frank Ofori; Kim, Hern, E-mail: hernkim@mju.ac.kr

    2016-09-15

    Highlights: • Electrospun ZnFe{sub 2}O{sub 4}-based nanofibers were successfully fabricated. • The electrochemical properties of ZnFe{sub 2}O{sub 4} were enhanced by addition of ZnO and Fe{sub 2}O{sub 3.} • A specific capacitance of 590 F g{sup −1} was achieved from a CV curve at a scan rate of 5 mV s{sup −1.} • The electrode materials poses excellent cycling stability even after 3000 cycles. - Abstract: Herein, we are reporting a facile method to synthesis ZnFe{sub 2}O{sub 4}-based nanofibers (ZnFe{sub 2}O{sub 4}, ZnO–ZnFe{sub 2}O{sub 4} and Fe{sub 2}O{sub 3}–ZnFe{sub 2}O{sub 4}) via the electrospinning technique using zinc acetonate and ferric acetonate as the metal oxide precursor and polyvinyl pyrrolidone (PVP) as the polymer. The as-prepared electrospun nanofiber composites were calcined at 500 °C to obtain crystalline porous nanofibers. The effect of different compositions on the morphology of each sample as well as their electrochemical properties when employed as electrode materials was studied. The results show that the as-prepared electrodes exhibited excellent performance with their specific capacitances calculated from the CV curves as 590, 490 and 450 F g{sup −1} for Fe{sub 2}O{sub 3}–ZnFe{sub 2}O{sub 4}, ZnO–ZnFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4} respectively at a scan rate of 5 mV s{sup −1}. Excellent stability of the electrodes was also observed even after 3000 cycles. The results obtained suggest these electrode materials might be promising candidates for supercapacitor application.

  2. Phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC and the formation of TiC in Fe3Al-based alloys

    International Nuclear Information System (INIS)

    Kobayashi, Satoru; Schneider, Andre; Zaefferer, Stefan; Frommeyer, Georg; Raabe, Dierk

    2005-01-01

    In the context of the development of high-strength Fe 3 Al-based alloys, phase equilibria among α-Fe(Al, Cr, Ti), liquid and TiC phases in the Fe-Al-Cr-Ti-C quinary system and the formation of TiC were determined. A pseudo-eutectic trough (L α + L + TiC) exists at 1470 deg C at around Fe-26Al-5Cr-2Ti-1.7C on the vertical section between Fe-26Al-5Cr (α) and Ti-46C (TiC) in at.%. Large faceted TiC precipitates form from the melt after the formation of primary α phase even in hypoeutectic alloys. The TiC formation is thought to be due to the composition change of the liquid towards the hypereutectic compositions by solidification of the primary α. In order to remove the faceted TiC, which are unfavourable for strengthening the material, two different processing routes have been successfully tested: (i) solidification with an increased rate to reduce the composition variation of the liquid during solidification, and (ii) unidirectional solidification to separate the light TiC precipitates from the melt

  3. Fermi surface deformation in a simple iron-based superconductor, FeSe

    Science.gov (United States)

    Coldea, Amalia; Watson, Matthew; Kim, Timur; Haghighirad, Amir; McCollam, Alix; Hoesch, Moritz; Schofield, Andrew

    2015-03-01

    One of the outstanding problems in the field superconductivity is the identification of the normal state out of which superconductivity emerges. FeSe is one of the simplest and most intriguing iron-based superconductors, since in its bulk form it undergoes a structural transition before it becomes superconducting, whereas its single-layer form is believed to be a high-temperature superconductor. The nature of the structural transition, occurring in the absence of static magnetism, is rather unusual and how the electronic structure is stabilized by breaking of the rotational symmetry is the key to understand the superconductivity in bulk FeSe. Here we report angle-resolved photoemission spectroscopy measurements on FeSe that gives direct access to the band structure and orbital-dependent effects. We complement our studies on bulk FeSe with low-temperature angular-dependent quantum oscillation measurements using applied magnetic fields that are sufficiently strong to suppress superconductivity and reach the normal state. These studies reveal a strong deformation of Fermi surface through the structural transition driven by electronic correlations and orbital-dependent effects. . This work was supported by EPSRC, UK (EP/I004475/1), Diamond Light Source, UK and HFML, Nijmegen.

  4. Review on α-Fe2O3 based negative electrode for high performance supercapacitors

    Science.gov (United States)

    Nithya, V. D.; Arul, N. Sabari

    2016-09-01

    Supercapacitor is an electrochemical energy storage device which has drawn attention of the researchers in recent years due to its high power density and long cycle life. Recently, an enormous effort has been imposed to improve the energy density of supercapacitor and might be attained through asymmetric cell configuration that offer wider potential window. Until now, a significant advancement has been achieved in the fabrication of positive electrodes for asymmetric cell. Nevertheless, the electrochemical performance of negative electrode materials is less explored, especially Hematite (α-Fe2O3). The α-Fe2O3 has been proved to be a promising negative electrode in supercapacitor application due to its wide operating potential, high redox activity, low cost, abundant availability and eco-friendliness. In this review, we have chosen α-Fe2O3 as the negative electrode and discussed its latest research progress with emphasis on various surface engineering synthesis strategies such as, carbon, polymer, metal-metal oxide, and ternary based α-Fe2O3 composites for supercapacitor. Besides, the importance of their synergistic effects over the supercapacitive performance in terms of specific capacitance, energy density, power density, cycling life and rate capability are highlighted. Also, an extensive analysis of the literature about its symmetric/asymmetric cell performance is explored.

  5. Ab initio based kinetic Monte-Carlo simulations of phase transformations in FeCrAl

    International Nuclear Information System (INIS)

    Olsson, Paer

    2015-01-01

    Document available in abstract form only, full text follows: Corrosion and erosion in lead cooled reactors can be a serious issue due to the high operating temperature and the necessary flow rates. FeCrAl alloys are under consideration as cladding or as coating for stainless steel cladding tubes for lead cooled reactor concepts. The alumina scale that is formed, as Al segregates to the surface and Fe and Cr rich oxides break off, offers a highly protective layer against lead corrosion in a large range of temperatures. However, there are concerns about the phase stability of the alloy under irradiation conditions and of possible induced alpha-prime precipitation. Here a theoretical model of the ternary FeCrAl alloy is presented, based on density functional theory predictions and linked to a kinetic Monte-Carlo simulation framework. The effect of Al on the FeCr miscibility properties are discussed and the coupling of irradiation induced defects with the solutes are treated. Simulations of the micro-structure evolution are tentatively compared to available experiments. (authors)

  6. Microstructure and composition in rapidly quenched NdFeB-based hard magnet alloys

    International Nuclear Information System (INIS)

    Nguyen, T.D.; Krishnan, K.M.; Lewis, L.H.; Zhu, Y.; Welch, D.O.

    1996-01-01

    A detailed study of the microstructure and composition in hot-pressed (MQ-2) and die-upset (MQ-3) magnet alloys based on the Nd 2 Fe 14 B composition, utilizing high resolution and analytical transmission electron microscopy, is reported. The initial magnetic properties of the two samples show different behaviors, which are attributed to the difference in the anisotropy of the grain structure and the grain boundaries. The hot-pressed sample shows faceted grains of the 2-14-1 phase, while die-upset sample shows plate-like grains, together with larger equiaxed grains that contain a speckling of precipitates in the grain interior. The grain structure and composition remain rather similar in the two samples. The grain boundary phase averages ∼1 endash approx-gt 10 nm in width. The thicker grain boundaries are Nd-rich, while the thinner grain boundaries in the hot-pressed sample exhibit an Fe-rich composition near that of the NdFe 3 phase. Nd-rich phases are found at the grain boundary junctions of both samples, with the Nd:Fe ratio near 7:3 in the die-upset sample, and up to 3:2 in the hot-pressed sample. The significance of the microstructure and the grain boundary phases on the magnetic behavior in the two samples is discussed. copyright 1996 American Institute of Physics

  7. Moessbauer study on the formation process of Fe-K composition in iron-based catalyst for dehydrogenation of ethylbenzene

    International Nuclear Information System (INIS)

    Jiang Keyu; Zhao Zhenjie; Yang Xielong

    2001-01-01

    Fe-K spinel structure is the predecessor of active phase of potassium promoted iron-based catalyst for dehydrogenation of ethylbenzene. Moessbauer spectroscopy has been used to study the formation process of Fe-K spinel structure which depends on the catalyst composition and preparing condition. The results may prove useful for production of industrial catalyst

  8. YSZ-based sensor using Cr-Fe-based spinel-oxide electrodes for selective detection of CO.

    Science.gov (United States)

    Anggraini, Sri Ayu; Fujio, Yuki; Ikeda, Hiroshi; Miura, Norio

    2017-08-22

    A selective carbon monoxide (CO) sensor was developed by the use of both of CuCrFeO 4 and CoCrFeO 4 as the sensing electrode (SE) for yttria-stabilized zirconia (YSZ)-based potentiometric sensor. The sensing-characteristic examinations of the YSZ-based sensors using each of spinel oxides as the single-SE sensor showed that CuCrFeO 4 -SE had the ability to detect CO, hydrocarbons and NO x gases, while CoCrFeO 4 -SE was sensitive to hydrocarbons and NO x gases. Thus, when both SEs were paired as a combined-SEs sensor, the resulting sensor could generate a selective response to CO at 450 °C under humid conditions. The sensor was also capable of detecting CO in the concentration range of 20-700 ppm. Its sensing mechanism that was examined via polarization-curve measurements was confirmed to be based on mixed-potential model. The CO response generated by the combined-SEs sensor was unaffected by the change of water vapor concentration in the range of 1.3-11.5 vol% H 2 O. Additionally, the sensing performance was stable during 13 days tested. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Schiff Base Ligand Coated Gold Nanoparticles for the Chemical Sensing of Fe(III Ions

    Directory of Open Access Journals (Sweden)

    Abiola Azeez Jimoh

    2015-01-01

    Full Text Available New Schiff base-coated gold nanoparticles (AuNPs of type AuNP@L (where L: thiolated Schiff base ligand have been synthesized and characterized using various spectroscopic techniques. The AuNPs and AuNP@L were imaged by transmission electron microscopy (TEM and were confirmed to be well-dispersed, uniformly distributed, spherical nanoparticles with an average diameter of 8–10 nm. Their potential applications for chemosensing were investigated in UV-Vis and fluorescence spectroscopic studies. The AuNP@L exhibited selectivity for Fe3+ in an ethanol/water mixture (ratio 9 : 1 v/v. The absorption and emission spectral studies revealed a 1 : 1 binding mode for Fe3+, with binding constants of 8.5×105 and 2.9×105 M−1, respectively.

  10. Giant electroresistance of super-tetragonal BiFeO3-based ferroelectric tunnel junctions.

    Science.gov (United States)

    Yamada, Hiroyuki; Garcia, Vincent; Fusil, Stéphane; Boyn, Sören; Marinova, Maya; Gloter, Alexandre; Xavier, Stéphane; Grollier, Julie; Jacquet, Eric; Carrétéro, Cécile; Deranlot, Cyrile; Bibes, Manuel; Barthélémy, Agnès

    2013-06-25

    Ferroelectric tunnel junctions enable a nondestructive readout of the ferroelectric state via a change of resistance induced by switching the ferroelectric polarization. We fabricated submicrometer solid-state ferroelectric tunnel junctions based on a recently discovered polymorph of BiFeO3 with giant axial ratio ("T-phase"). Applying voltage pulses to the junctions leads to the highest resistance changes (OFF/ON ratio >10,000) ever reported with ferroelectric tunnel junctions. Along with the good retention properties, this giant effect reinforces the interest in nonvolatile memories based on ferroelectric tunnel junctions. We also show that the changes in resistance scale with the nucleation and growth of ferroelectric domains in the ultrathin BiFeO3 (imaged by piezoresponse force microscopy), thereby suggesting potential as multilevel memory cells and memristors.

  11. Electro-Synthetic Optimization of Host Material Based on MIL-100(Fe

    Directory of Open Access Journals (Sweden)

    Witri Wahyu Lestari

    2016-05-01

    Full Text Available Electro-synthesis of Metal-Organic Frameworks types of MIL-100(Fe (MIL = Material Institute of Lavoisier in ethanol: water (1: 1 with electrolyte TBATFB 0.1 M has been optimized by varying voltage (12, 13, 14 and 15 Volt and temperature (room temperature, 40, 60 and 80 °C. The product showed light brown powder which upon activation becomes dark brown. Optimum condition achieved during use voltage of 15 Volts and at a temperature of 40 °C with 33% yield. The obtained material was characterized by XRD and compared to CCDC 640536 simulated patterns to confirm the phase purity of the product. As comparison hydrothermal and reflux method have been carried out. Characterization by FTIR has also undertaken to ensure the coordination between the metal cation (Fe3+ and the BTC ligand (BTC = 1,3,5-Benzene Tri Carboxylate. Meanwhile pore analysis using SAA confirmed that MIL-100(Fe obtained by electrolysis method has a BET surface area reached till 569.191 m²/g with a total pore volume of 0.4540 cc/g and an average pore diameter reached 16 Å. Based on SEM analysis, morphology material show particle size between 0.4-8.6 μm and has a thermal stability up to 350 °C according thermo-gravimetric analysis. Due to the presence of Lewis acid sites on Fe-trimeric unit, porosity features on MIL-100(Fe and a fairly high thermal stability, this material is potentially used as the host material for the catalyst in the conversion reactions model for green diesel production.

  12. Repositioning the knee joint in human body FE models using a graphics-based technique.

    Science.gov (United States)

    Jani, Dhaval; Chawla, Anoop; Mukherjee, Sudipto; Goyal, Rahul; Vusirikala, Nataraju; Jayaraman, Suresh

    2012-01-01

    Human body finite element models (FE-HBMs) are available in standard occupant or pedestrian postures. There is a need to have FE-HBMs in the same posture as a crash victim or to be configured in varying postures. Developing FE models for all possible positions is not practically viable. The current work aims at obtaining a posture-specific human lower extremity model by reconfiguring an existing one. A graphics-based technique was developed to reposition the lower extremity of an FE-HBM by specifying the flexion-extension angle. Elements of the model were segregated into rigid (bones) and deformable components (soft tissues). The bones were rotated about the flexion-extension axis followed by rotation about the longitudinal axis to capture the twisting of the tibia. The desired knee joint movement was thus achieved. Geometric heuristics were then used to reposition the skin. A mapping defined over the space between bones and the skin was used to regenerate the soft tissues. Mesh smoothing was then done to augment mesh quality. The developed method permits control over the kinematics of the joint and maintains the initial mesh quality of the model. For some critical areas (in the joint vicinity) where element distortion is large, mesh smoothing is done to improve mesh quality. A method to reposition the knee joint of a human body FE model was developed. Repositions of a model from 9 degrees of flexion to 90 degrees of flexion in just a few seconds without subjective interventions was demonstrated. Because the mesh quality of the repositioned model was maintained to a predefined level (typically to the level of a well-made model in the initial configuration), the model was suitable for subsequent simulations.

  13. A solvent-dependent fluorescent detection method for Fe(3+) and Hg(2+) based on a rhodamine B derivative.

    Science.gov (United States)

    Li, Xutian; Yin, Yue; Deng, Junjie; Zhong, Huixian; Tang, Jian; Chen, Zhi; Yang, Liting; Ma, Li-Jun

    2016-07-01

    A new rhodamine B-benzofurazan based fluorescent probe (1) for Fe(3+) and Hg(2+) was synthesized. In aqueous solution containing 30% (v/v) ethanol, probe 1 shows a high selective fluorescent enhancement recognition to Fe(3+) with a binding ratio of 1:1 (probe 1: Fe(3+)), when the concentration of Fe(3+) is less than that of the probe. When the concentration of Fe(3+) is higher than that of the probe, it shows fluorescent "turn-on" response to Fe(3+) by opening the rhodamine spirolactam with a binding ratio of 1:2 (probe 1: Fe(3+)). Furthermore, probe 1 displays a high selectivity and a hypersensitivity (detection limit is 4.4nM) to Hg(2+) with a binding ratio of 1:1 in ethanol. NMR and UV-vis experiments indicate that the different fluorescent recognition signals to Fe(3+) and Hg(2+) are derived from different binding modes of 1-Fe(3+) and 1-Hg(2+). Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Investigation on microstructure and mechanical properties of Mo2FeB2 based cermets with and without PVA

    Science.gov (United States)

    Shen, Yupeng; Huang, Zhifu; Jian, Yongxin; Yang, Ming; Li, Kemin

    2018-03-01

    Mo2FeB2 based cermets with and without PVA have been investigated by x-ray diffractometry (XRD), x-ray photoelectron spectroscope (XPS) and scanning electron microscopy (SEM). The density and transverse rupture strength (TRS) of green compact, relative density, hardness (HRA), fracture toughness (KIC) and TRS of Mo2FeB2 based cermets were also measured. The results indicate that, compared with the Mo2FeB2 based cermets without PVA, the density of green compact with PVA can be improved slightly at the same pressure. However, the much higher TRS is obtained for the green compact without PVA. Meanwhile, Mo2FeB2 particles exhibit the finer and less congruity feature for Mo2FeB2 based cermets without PVA. In addition, the higher relative density, hardness, fracture toughness and TRS can be acquired for the cermets without PVA. Obviously, considering the mechanical properties and preparation period of Mo2FeB2 based cermets, no adding PVA is the optimized process of powder molding in the manufacture of Mo2FeB2 based cermets.

  15. Model's sparse representation based on reduced mixed GMsFE basis methods

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Lijian, E-mail: ljjiang@hnu.edu.cn [Institute of Mathematics, Hunan University, Changsha 410082 (China); Li, Qiuqi, E-mail: qiuqili@hnu.edu.cn [College of Mathematics and Econometrics, Hunan University, Changsha 410082 (China)

    2017-06-01

    In this paper, we propose a model's sparse representation based on reduced mixed generalized multiscale finite element (GMsFE) basis methods for elliptic PDEs with random inputs. A typical application for the elliptic PDEs is the flow in heterogeneous random porous media. Mixed generalized multiscale finite element method (GMsFEM) is one of the accurate and efficient approaches to solve the flow problem in a coarse grid and obtain the velocity with local mass conservation. When the inputs of the PDEs are parameterized by the random variables, the GMsFE basis functions usually depend on the random parameters. This leads to a large number degree of freedoms for the mixed GMsFEM and substantially impacts on the computation efficiency. In order to overcome the difficulty, we develop reduced mixed GMsFE basis methods such that the multiscale basis functions are independent of the random parameters and span a low-dimensional space. To this end, a greedy algorithm is used to find a set of optimal samples from a training set scattered in the parameter space. Reduced mixed GMsFE basis functions are constructed based on the optimal samples using two optimal sampling strategies: basis-oriented cross-validation and proper orthogonal decomposition. Although the dimension of the space spanned by the reduced mixed GMsFE basis functions is much smaller than the dimension of the original full order model, the online computation still depends on the number of coarse degree of freedoms. To significantly improve the online computation, we integrate the reduced mixed GMsFE basis methods with sparse tensor approximation and obtain a sparse representation for the model's outputs. The sparse representation is very efficient for evaluating the model's outputs for many instances of parameters. To illustrate the efficacy of the proposed methods, we present a few numerical examples for elliptic PDEs with multiscale and random inputs. In particular, a two-phase flow model in

  16. A Polycarboxyl-Decorated FeIII -Based Xerogel-Derived Multifunctional Composite (Fe3 O4 /Fe/C) as an Efficient Electrode Material towards Oxygen Reduction Reaction and Supercapacitor Application.

    Science.gov (United States)

    Devi, Bandhana; Venkateswarulu, Mangili; Kushwaha, Himmat Singh; Halder, Aditi; Koner, Rik Rani

    2018-05-02

    Low cost, non-noble metal catalysts with a good oxygen reduction reaction (ORR) activity comparable to that of platinum and also having good energy storage properties are highly desirable but challenging. Several challenges are associated with the development of such materials. Herein, we demonstrate a new polycarboxyl-functionalised Fe III -based gel material, synthesised following a solvothermal method and the development of its composite (Fe 3 O 4 /Fe/C) by annealing at optimised temperature. The developed composite displayed excellent electrocatalytic activity for the oxygen reduction reaction with an onset potential of 0.87 V (vs. RHE) and a current density value of -5 mA cm -2 , which are comparable with commercial 20 wt % Pt/C. In addition, as one of the most desirable properties, the composite exhibits a better methanol tolerance and greater durability than Pt/C. The same material was explored as an energy storage material for supercapacitors, which showed a specific capacitance of 245 F g -1 at a current density of 1 A g -1 . It is expected that this Fe 3 O 4 /Fe/C composite with a disordered graphitised carbon matrix will pave a horizon for developing energy conversion and energy storage devices. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. In Situ Synthesis and Characterization of Fe-Based Metallic Glass Coatings by Electrospark Deposition Technique

    Science.gov (United States)

    Burkov, Alexander A.; Pyachin, S. A.; Ermakov, M. A.; Syuy, A. V.

    2017-02-01

    Crystalline FeWMoCrBC electrode materials were prepared by conventional powder metallurgy. Metallic glass (MG) coatings were produced by electrospark deposition onto AISI 1035 steel in argon atmosphere. X-ray diffraction and scanning electron microscopy verified the amorphous structure of the as-deposited coatings. The coatings have a thickness of about 40 microns and a uniform structure. The results of dry sliding wear tests against high-speed steel demonstrated that Fe-based MG coatings had a lower friction coefficient and more than twice the wear resistance for 20 km sliding distance with respect to AISI 1035 steel. High-temperature oxidation treatment of the metal glass coatings at 1073 K in air for 12 h revealed that the oxidation resistance of the best coating was 36 times higher than that for bare AISI 1035 steel. These findings are expected to broaden the applications of electrospark Fe-based MG as highly protective and anticorrosive coatings for mild steel.

  18. Electroplated Fe-Co-Ni films prepared from deep-eutectic-solvent-based plating baths

    Directory of Open Access Journals (Sweden)

    Takeshi Yanai

    2016-05-01

    Full Text Available We fabricated soft magnetic films from DES-based plating baths, and investigated magnetic properties of the plated films. The plating baths were obtained by stirring the mixture of choline chloride, ethylene glycol, FeCl2 ⋅ 4H2O, NiCl2 ⋅ 6H2O and CoCl2 ⋅ 6H2O. The composition of the electroplated film depended on the amount of the reagent in the plating bath, and we consequently obtained the films with various composition. The current efficiency of the plating process shows high values (> 88 % in the wide composition range. The soft magnetic films with low coercivity were obtained at the Fe compositions of ≈ 30 at.% and > 80 at.%, and we found that low coercivity could be realized by the control of the film composition. We also found that the Fe-rich films prepared from DES-based plating bath have some advantages as a soft magnetic phase for a nanocomposite magnet due to their high saturation magnetization and very fine crystal structure.

  19. Impact of potassium promoter on Cu–Fe based mixed alcohols synthesis catalyst

    International Nuclear Information System (INIS)

    Ding, Mingyue; Tu, Junling; Qiu, Minghuang; Wang, Tiejun; Ma, Longlong; Li, Yuping

    2015-01-01

    Highlights: • Adding K facilitated the immigration of bulky iron species to surface layers. • Adding potassium strengthened the interaction of Fe–K on the surface layers. • Increasing K content facilitated the formation of C 2 + OH. • A maximum in catalytic activity is obtained at 0.5 wt.% of potassium loading. - Abstract: Impacts of K promoter on microstructures of a precipitated Cu–Fe based catalyst were studied by N 2 -physisorption (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and hydrogen temperature-programmed desorption/reduction (H 2 -TPD/TPR). Mixed alcohols synthesis (MAS) was carried out in a fixed-bed reactor. The results indicated that incorporation of K in the Cu–Fe based catalyst decreased the surface area of the particles, whereas promoted the immigration of bulky iron species to surface layers and strengthened the interaction of surface Fe–Cu. The increase of K concentration weakened the H 2 chemisorption and restrained the reduction of both the Cu and Fe species. The catalytic activity and mixed alcohols selectivity increased accompanied with a gradually increasing K concentration, and reached the highest values as the amount of K increased to 0.5 wt.%. Subsequently, the MAS activity and selectivity C 2 + OH presented a decreasing trend. In addition, the increase of K concentration facilitated the formation of heavy hydrocarbons

  20. Shape-Memory Effect and Pseudoelasticity in Fe-Mn-Based Alloys

    Science.gov (United States)

    La Roca, P.; Baruj, A.; Sade, M.

    2017-03-01

    Several Fe-based alloys are being considered as potential candidates for applications which require shape-memory behavior or superelastic properties. The possibility of using fabrication methods which are well known in the steel industry is very attractive and encourages a large amount of research in the field. In the present article, Fe-Mn-based alloys are mainly addressed. On the one hand, attention is paid to the shape-memory effect where the alloys contain (a) a maximum amount of Mn up to around 30 wt%, (b) several possible substitutional elements like Si, Cr, Ni, Co, and Nb and (c) some possible interstitial elements like C. On the other hand, superelastic alloys are analyzed, mainly the Fe-Mn-Al-Ni system discovered a few years ago. The most noticeable properties resulting from the martensitic transformations which are responsible for the mentioned properties, i.e., the fcc-hcp in the first case and the bcc-fcc in the latter are discussed. Selected potential applications are also analyzed.

  1. Formation of centimeter Fe-based bulk metallic glasses in low vacuum environment

    Energy Technology Data Exchange (ETDEWEB)

    Pan Jie; Chen Qi; Li Ning [State Key Lab of Materials Processing and Mould Technology, Department of Materials Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China); Liu Lin [State Key Lab of Materials Processing and Mould Technology, Department of Materials Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan (China)], E-mail: lliu2000@public.wh.hb.cn

    2008-09-08

    The formation of a Fe{sub 43.7}Co{sub 7.3}Cr{sub 14.7}Mo{sub 12.6}C{sub 15.5}B{sub 4.3}Y{sub 1.9} bulk metallic glass (BMG) was attempted in low vacuum environment and in air using commercial raw materials. The glass forming ability of the Fe-based alloys was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and differential thermal analyzer (DTA). It was found that cylindric rods with diameters ranging from 10 mm to 5 mm could be successfully fabricated by copper-mold casting in the pressures from 1.5 Pa to 10{sup 5} Pa (10{sup 5} Pa = 1 atm). All BMGs exhibit a distinct glass transition and wide supercooled liquid region. The preparation condition seems not significantly affected by the thermodynamic parameters of BMG, such as supercooled liquid region, glass transition temperature and melting process. The oxygen content of the alloys prepared in different vacuum conditions was measured by a LECO oxygen analyzer, which revealed that the oxygen content was less than 100 ppm for all BMGs prepared, even in air. The good glass forming ability and excellent oxidation resistance for the present Fe-based alloy are discussed.

  2. Ordinary and triplet superconducting spin valve effect in Fe/Pb based systems

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Krupskaya, Yulia; Kataev, Vladislav; Hess, Christian; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute of RAS, Kazan (Russian Federation); Fominov, Yakov [L. D. Landau Institute for Theoretical Physics of RAS, Moscow (Russian Federation)

    2015-07-01

    We report on experimental evidence for the occurrence of the long range triplet correlations (LRTC) of the superconducting (SC) condensate in the spin-valve heterostructures CoO{sub x}/Fe1/Cu/Fe2/Pb. The LRTC generation in this layer sequence is accompanied by a T{sub c} suppression near the orthogonal mutual orientation of the Fe1 and Fe2 layers' magnetization. This T{sub c} drop reaches its maximum of 60mK at the Fe2 layer thickness d{sub Fe2} = 0.6 nm and falls down when d{sub Fe2} is increased. The modification of the Fe/Pb interface by using a thin Cu layer between Fe and Pb layers reduces the SC transition width without preventing the interaction between Pb and Fe2 layers. The dependence of the SSVE magnitude on Fe1 layer thickness d{sub Fe1} reveals maximum of the effect when d{sub Fe1} and d{sub Fe2} are equal and the d{sub Fe2} value is minimal. Using the optimal d{sub Fe1}, d{sub Fe2} and the intermediate Cu layer we realized almost full switching from normal to SC state due to SSVE.

  3. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    Energy Technology Data Exchange (ETDEWEB)

    Rodionova, V. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); National University of Science and Technology “MISIS”, Leninsky prospect 4, Moscow 119049 (Russian Federation); Baraban, I.; Chichay, K.; Litvinova, A. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); Perov, N. [Institute of Physics & Technology and STP “Fabrika” Immanuel Kant Baltic Federal University, A. Nevskogo 14, Kaliningrad 236041 (Russian Federation); Faculty of Physics, Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991 (Russian Federation)

    2017-01-15

    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of “classic” Fe{sub 77.5}Si{sub 7.5}B{sub 15} alloy with positive magnetostriction coefficient.

  4. Infiltrated SrTiO3:FeCr-based anodes for metalsupported SOFC

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Persson, Åsa Helen; Nielsen, Jimmi

    2012-01-01

    The concept of using highly electronically conducting backbones with subsequent infiltration of electrocatalytic active materials, has recently been used to develop an alternative SOFC design based on a ferritic stainless steel support. The metal-supported SOFC is comprised of porous and highly e...... changes occurring in the anode layer during testing. The results indicate that the STN component in the anode seems to have a positive effect on the corrosion stability of the FeCr-particles in the anode layer.......) and FeCr. Electrochemical characterization and post test SEM analysis have been used to get an insight into the possible degradation mechanisms of this novel electrode infiltrated with Gd-doped CeO2 and Ni. Accelerated oxidation/corrosion experiments have been conducted to evaluate the microstructural...

  5. The stress components effect on the Fe-based microwires magnetostatic and magnetostrictive properties

    International Nuclear Information System (INIS)

    Rodionova, V.; Baraban, I.; Chichay, K.; Litvinova, A.; Perov, N.

    2017-01-01

    For glass-coated amorphous ferromagnetic Fe-based microwires both joint and separate effect of metallic nucleus diameter, d, and the ratio of metallic nucleus diameter to the total diameter of microwire in glass shell, d/D, on magnetic properties is investigated. Thereby the contribution of both shell-induced stresses, associated with the ratio of diameters, and internal nucleus stresses (residual, quenching), associated with the diameter of the nucleus are estimated. A strong and non-monotonic effect of the metallic nucleus diameter and metallic nucleus diameter/total microwire diameter ratio on magnetostatic and magnetostrictive properties was established. For analysis, we considered magnetically bi-stable microwires of “classic” Fe_7_7_._5Si_7_._5B_1_5 alloy with positive magnetostriction coefficient.

  6. Neutron irradiation effects on magnetic properties of Fe-based ferromagnetic metallic glasses

    International Nuclear Information System (INIS)

    Miglierini, M.; Nasu, Saburo; Skorvanek, I.; Sitek, J.

    1992-01-01

    Transmission 57 Fe Moessbauer spectroscopy, J-H quasistatic hysteresis loop and AC susceptibility measurements are used to study effects of neutron irradiation on magnetic properties of Fe-based-ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transition from the ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. The presence of Ni in the samples reduces the effects of radiation damage as revealed also from position lifetime data. Possible sources of a radiation damage are discussed using the results of γ-ray spectroscopy. (author)

  7. Neutron irradiation effects on magnetic properties of Fe-based ferromagnetic metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, M.; Nasu, Saburo (Osaka Univ., Toyonaka (Japan). Faculty of Science); Skorvanek, I.; Sitek, J.

    1992-04-01

    Transmission {sup 57}Fe Moessbauer spectroscopy, J-H quasistatic hysteresis loop and AC susceptibility measurements are used to study effects of neutron irradiation on magnetic properties of Fe-based-ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transition from the ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. The presence of Ni in the samples reduces the effects of radiation damage as revealed also from position lifetime data. Possible sources of a radiation damage are discussed using the results of {gamma}-ray spectroscopy. (author).

  8. Microscopic Analysis and Electrochemical Behavior of Fe-Based Coating Produced by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Jinlin Chen

    2017-10-01

    Full Text Available The effect of laser cladding on the surface microstructure and corrosion properties of coated/uncoated specimens were investigated. Fe-based alloy coating was produced on 35CrMo steel by laser cladding. The phase composition, microstructure, interface element distribution, microhardness and corrosion resistance of the cladding coating were measured. The results show that the cladding layer is mainly composed of α-Fe phases, the microstructure presents a gradient distribution, and a good metallurgical bond is formed at the boundary with the substrate. Microhardness profiles show that the average microhardness of the cladding coating is about 2.1 times higher than that of the uncoated specimen. In addition, the electrochemical results show that the coated specimen exhibits far better corrosion resistance than to the uncoated specimen.

  9. Electroplated Fe-Co-Ni films prepared in ammonium-chloride-based plating baths

    Science.gov (United States)

    Yanai, T.; Koda, K.; Kaji, J.; Aramaki, H.; Eguchi, K.; Takashima, K.; Nakano, M.; Fukunaga, H.

    2018-05-01

    We electroplated Fe-Co-Ni films in ammonium-chloride-based plating baths, and investigated the effect of the Co content on the magnetic properties and the structural ones of the as-plated films. The coercivity increased abruptly when the Co content become more than 60 at.%. As the rough surfaces were observed in the high Co content region, we considered that degradation of the surface is a factor of the abrupt increase in the coercivity. From the XRD analysis, we found that another factor of the abrupt increase is fcc-bcc phase transformation, and concluded that we need to keep the fcc structure to obtain Fe-Co-Ni films with low coercivity.

  10. Mechanical properties of Fe3Al-based alloys with addition of carbon, niobium and titanium

    International Nuclear Information System (INIS)

    Zhang Zhengrong; Liu Wenxi

    2006-01-01

    Several Fe 3 Al-based iron aluminides with the addition of alloying elements carbon, niobium and titanium were produced by vacuum induction melting (VIM) and hot spinning forging. Analytic techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used in studying the microstructure and fracture manner of these alloys. The results show that due to the addition of alloying elements, the superlattice dislocations tend towards multiple slipping, leaving behind on their slip plane ribbons of square-shaped slip-induced antiphase boundaries. The elongation of Fe 3 Al in tension at room temperature increased to about 10% by the addition of suitable alloying elements, the usage of thermo-mechanical processing that has the function of refining grains and substructures, and subsequent annealing

  11. New carbazole-based Schiff base: Colorimetric chemosensor for Fe{sup 3+} and fluorescent turn-on chemosensor for Fe{sup 3+} and Cr{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Weiju; Yang, Lianlian; Fang, Min; Wu, Zhenyu; Zhang, Qing; Yin, Fangfang; Huang, Qiang; Li, Cun, E-mail: cun_li@126.com

    2015-02-15

    Two novel carbazole-based Schiff-bases L1 and L2 have been synthesized and characterized by {sup 1}H NMR, {sup 13}C NMR, FT-IR spectroscopy and elemental analysis. L1 can selectively detect Fe{sup 3+} by UV–vis spectroscopy and Fe{sup 3+}/Cr{sup 3+} by fluorescent spectroscopy in CH{sub 3}CN among various metal ions. The addition of Fe{sup 3+} ions to a L1 solution results in a significant blue-shift from 410 nm to 378 nm accompanied with color change from yellowish green to colorless. Upon excitation at 380 nm, the addition of Fe{sup 3+} or Cr{sup 3+} causes a 13-fold or 11-fold fluorescence enhancement. The binding stoichiometry ratio of L1–Fe{sup 3+} and L1–Cr{sup 3+} is recognized as 2:1 by the method of Job's plot, and the possible binding mode of the system also proposes. The results indicate that L1 is an ideal chemosensor for Fe{sup 3+} and Cr{sup 3+} recognition. However, L2 without hydroxyl in ortho imino group cannot selectively recognize the tasted metal ions, indicating that the introduction of the appropriate coordination binding site to receptor can improve efficiently the selectivity of chemosensor. - Highlights: • We designed and synthesized two new carbazole-based Schiff bases L1 and L2. • L1 could selectively recognize Fe{sup 3+} but L2 could not, which suggested that increase recognition site helped to improve the selectivity of probe. • L1 not only could serve as a highly selective visual chemosensor for Fe{sup 3+} ion without the aid of any instruments, but also could be used as a fluorescent chemosensor for Fe{sup 3+} and Cr{sup 3+}.

  12. Knowledge Based Cloud FE simulation - data-driven material characterization guidelines for the hot stamping of aluminium alloys

    Science.gov (United States)

    Wang, Ailing; Zheng, Yang; Liu, Jun; El Fakir, Omer; Masen, Marc; Wang, Liliang

    2016-08-01

    The Knowledge Based Cloud FEA (KBC-FEA) simulation technique allows multiobjective FE simulations to be conducted on a cloud-computing environment, which effectively reduces computation time and expands the capability of FE simulation software. In this paper, a novel functional module was developed for the data mining of experimentally verified FE simulation results for metal forming processes obtained from KBC-FE. Through this functional module, the thermo-mechanical characteristics of a metal forming process were deduced, enabling a systematic and data-driven guideline for mechanical property characterization to be developed, which will directly guide the material tests for a metal forming process towards the most efficient and effective scheme. Successful application of this data-driven guideline would reduce the efforts for material characterization, leading to the development of more accurate material models, which in turn enhance the accuracy of FE simulations.

  13. Enhanced high-frequency microwave absorption of Fe3O4 architectures based on porous nanoflake

    DEFF Research Database (Denmark)

    Wang, Xiaoliang; Liu, Yanguo; Han, Hongyan

    2017-01-01

    Hierarchical Fe3O4 architectures assembled with porous nanoplates (p-Fe3O4) were synthesized. Due to the strong shape anisotropy of the nanoplates, the p-Fe3O4 exhibits increased microwave resonance towards high frequency range. The improved microwave absorption properties of the p-Fe3O4, includi...

  14. Enhanced high-frequency microwave absorption of Fe3O4 architectures based on porous nanoflake

    DEFF Research Database (Denmark)

    Wang, Xiaoliang; Liu, Yanguo; Han, Hongyan

    2017-01-01

    Hierarchical Fe3O4 architectures assembled with porous nanoplates (p-Fe3O4) were synthesized. Due to the strong shape anisotropy of the nanoplates, the p-Fe3O4 exhibits increased microwave resonance towards high frequency range. The improved microwave absorption properties of the p-Fe3O4, including...

  15. Effective Adsorption and Removal of Phosphate from Aqueous Solutions and Eutrophic Water by Fe-based MOFs of MIL-101.

    Science.gov (United States)

    Xie, Qiying; Li, Yan; Lv, Zhaoling; Zhou, Hang; Yang, Xiangjun; Chen, Jing; Guo, Hong

    2017-06-12

    Although many efforts have been devoted to the adsorptive removal of phosphate from aqueous solutions and eutrophic water, it is still highly desirable to develop novel adsorbents with high adsorption capacities. In this study, Fe-based metal-organic frameworks (MOFs), MIL-101 and NH 2 -MIL-101, are fabricated through a general facile strategy. Their performance as an adsorbent for phosphate removal is investigated. Experiments are performed to study the effects of various factors on the phosphate adsorption, including adsorbent dosage, contact time and co-existing ions. Both MIL-101(Fe) and NH 2 -MIL-101(Fe) show highly effective removal of phosphates from aqueous solutions, and the concentration of phosphates decrease sharply from the initial 0.60 mg·L -1 to 0.045 and 0.032 mg·L -1 , respectively, within just 30 min of exposure. The adsorption kinetics and adsorption isotherms reveal that NH 2 -MIL-101(Fe) has higher adsorption capacity than MIL-101(Fe) possibly due to the amine group. Furthermore, the Fe-based MOFs also exhibit a high selectivity towards phosphate over other anions such as chloride, bromide, nitrate and sulfate. Particularly, the prepared Fe-based MIL-101 materials are also capable of adsorbing phosphate in an actual eutrophic water sample and display better removal effect.

  16. Comparison of subset-based local and FE-based global digital image correlation: Theoretical error analysis and validation

    KAUST Repository

    Pan, B.

    2016-03-22

    Subset-based local and finite-element-based (FE-based) global digital image correlation (DIC) approaches are the two primary image matching algorithms widely used for full-field displacement mapping. Very recently, the performances of these different DIC approaches have been experimentally investigated using numerical and real-world experimental tests. The results have shown that in typical cases, where the subset (element) size is no less than a few pixels and the local deformation within a subset (element) can be well approximated by the adopted shape functions, the subset-based local DIC outperforms FE-based global DIC approaches because the former provides slightly smaller root-mean-square errors and offers much higher computation efficiency. Here we investigate the theoretical origin and lay a solid theoretical basis for the previous comparison. We assume that systematic errors due to imperfect intensity interpolation and undermatched shape functions are negligibly small, and perform a theoretical analysis of the random errors or standard deviation (SD) errors in the displacements measured by two local DIC approaches (i.e., a subset-based local DIC and an element-based local DIC) and two FE-based global DIC approaches (i.e., Q4-DIC and Q8-DIC). The equations that govern the random errors in the displacements measured by these local and global DIC approaches are theoretically derived. The correctness of the theoretically predicted SD errors is validated through numerical translation tests under various noise levels. We demonstrate that the SD errors induced by the Q4-element-based local DIC, the global Q4-DIC and the global Q8-DIC are 4, 1.8-2.2 and 1.2-1.6 times greater, respectively, than that associated with the subset-based local DIC, which is consistent with our conclusions from previous work. © 2016 Elsevier Ltd. All rights reserved.

  17. A dansyl-rhodamine chemosensor for Fe(III) based on off-on FRET.

    Science.gov (United States)

    Piao, Jingyu; Lv, Jia; Zhou, Xin; Zhao, Tong; Wu, Xue

    2014-07-15

    A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe(3+) based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe(3+) to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off-on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job's plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe(3+). The association constant was estimated to be 2.72×10(3) M(-1) according to the Benesi-Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Simultaneous study of sputtering and secondary ion emission of binary Fe-based alloys

    International Nuclear Information System (INIS)

    Riadel, M.M.; Nenadovic, T.; Perovic, B.

    1976-01-01

    The sputtering and secondary ion emission of binary Fe-based alloys of simple phase diagrams have been studied simultaneously. A series FeNi and FeCr alloys in the concentration range of 0-100% have been bombarded by 4 keV Kr + ions in a secondary ion mass spectrometer. The composition of the secondary ions has been analysed and also a fraction of the sputtered material has been collected and analysed by electron microprobe. The surface topography of the etched samples has been studied by scanning electron microscope. The relative sputtering coefficients of the metals have been determined, and the preferential sputtering of the alloying component of lower S have been proved. The etching pictures of samples are in correlation with the sputtering rates. Also the degree of secondary ionization has been calculated from the simultaneously measured ion emission and sputtering data. α + shows the change in the concentration range of the melting point minimum. This fact emphasizes the connection between the physico-chemical properties of alloys and their secondary emission process. From the dependence of the emitted homo- and hetero-cluster ions, conclusions could be shown concerning the production mechanism of small metallic aggregates

  19. A dansyl-rhodamine chemosensor for Fe(III) based on off-on FRET

    Science.gov (United States)

    Piao, Jingyu; Lv, Jia; Zhou, Xin; Zhao, Tong; Wu, Xue

    2014-07-01

    A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe3+ based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe3+ to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off-on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job's plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe3+. The association constant was estimated to be 2.72 × 103 M-1 according to the Benesi-Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field.

  20. Supramolecular architecture based on [Fe(CN)6]3- metallotectons and melaminium synthons

    Science.gov (United States)

    Krichen, Firas; Walha, Siwar; Lhoste, Jérôme; Bulou, Alain; Kabadou, Ahlem; Goutenoire, François

    2017-10-01

    Assembly involving [Fe(CN)6]3- metallotectons as building units and melaminium organic cation has been envisioned in order to elaborate a hybrid supramolecular based on ionic H-bonds with formula {(H-mel)4[Fe(CN)6]Cl} (H-mel+: melaminium cation). The compound has been prepared by diffusion method and characterized by single-crystal X-ray diffraction, EDX analysis, and Raman-IR spectroscopies with assignment from ab initio calculations. The melaminium exhibit self cationic coupling with cyclic hydrogen bonds to give a one dimensional {[H-mel]+}∝ synthon. Therefore, these cationic ribbons are inter-linked via hydrogen bonds by the anionic tectons [Fe(CN)6]3- and chlorine anion resulting on a 3D network. Molecular hirshfeld surfaces revealed that the crystal structure has been supported mainly by Nsbnd H⋯N and Nsbnd H⋯Cl intermolecular Hydrogen bonds and by favoured C⋯C and C⋯N weak interactions.

  1. Effect of transient annealing on patterned CoFeB-based magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Kuo-Ming; Huang, Chao-Hsien; Lin, Shiao-Chi; Wu, Jong-Ching [Department of Physics and Taiwan SPIN Research Center, National Changhua University of Education, Changhua 50007 (China); Kao, Ming-Jer; Tsai, Ming-Jinn [Industrial Technology Research Institute, Hsinchu 31040 (China); Horng, Lance

    2007-12-15

    In this study, the transient annealing effect on the switching behavior of microstructured Co{sub 60}Fe{sub 20}B{sub 20}-based magnetic tunnel junctions has been studied through magnetoresistance measurements (R-H loop). Elliptical shape of devices with long/short axis of 4/2 micrometers was patterned out of sheet film stack of: Ta(20)/PtMn(15)/CoFeB(3)/Al(0.7)-oxide/CoFeB(2)/Ru(8)/Ta(40) (thickness unit in nanometers) after a conventional long time field cooling annealing. The transient annealing was then executed by sample loading into a furnace with pre-set temperatures ranging from 100 to 400 C for only 5 minutes in the absence of any external magnetic field. The vortex-like reverse of free layer in as-etched MTJ evidently changes to single-domain-like reverser after 200{proportional_to}250 C transient annealing. The magnetoresistance was found to increase with increasing annealing temperatures up to 265 C and then slowly decrease at higher annealing temperatures. The transient thermal annealing creates obvious efforts to repair magnetic properties of MTJ cell befor 265 C annealing and results in less damage at temperature of 350 C and 400 C. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Effect of transient annealing on patterned CoFeB-based magnetic tunnel junctions

    International Nuclear Information System (INIS)

    Wu, Kuo-Ming; Huang, Chao-Hsien; Lin, Shiao-Chi; Wu, Jong-Ching; Kao, Ming-Jer; Tsai, Ming-Jinn; Horng, Lance

    2007-01-01

    In this study, the transient annealing effect on the switching behavior of microstructured Co 60 Fe 20 B 20 -based magnetic tunnel junctions has been studied through magnetoresistance measurements (R-H loop). Elliptical shape of devices with long/short axis of 4/2 micrometers was patterned out of sheet film stack of: Ta(20)/PtMn(15)/CoFeB(3)/Al(0.7)-oxide/CoFeB(2)/Ru(8)/Ta(40) (thickness unit in nanometers) after a conventional long time field cooling annealing. The transient annealing was then executed by sample loading into a furnace with pre-set temperatures ranging from 100 to 400 C for only 5 minutes in the absence of any external magnetic field. The vortex-like reverse of free layer in as-etched MTJ evidently changes to single-domain-like reverser after 200∝250 C transient annealing. The magnetoresistance was found to increase with increasing annealing temperatures up to 265 C and then slowly decrease at higher annealing temperatures. The transient thermal annealing creates obvious efforts to repair magnetic properties of MTJ cell befor 265 C annealing and results in less damage at temperature of 350 C and 400 C. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Optimization of Sintering Time and Holding Time for 3D Printing of Fe-Based Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Wenzheng Wu

    2018-06-01

    Full Text Available Fe-based metallic glasses are amorphous alloys with high strength, high hardness, and excellent corrosion resistance; however, the immaturity of processing methods has prevented their wide application in industrial production. Fe-based metallic glass parts were manufactured employing pneumatic injection additive manufacturing in this study. An evenly dispersed and stable Fe-based metallic glass powder slurry with a solids content of 50% was prepared firstly. Then the Fe-based metallic glass parts were printed. The printed parts were dried, debinded, and sintered for strengthening. The deformations of the printed parts and sintered parts relative to the original model were then analyzed by a 3D scanning reconstruction method. The slightly average bulging and sunken deformation of the printed parts and sintered parts confirmed the good printing accuracy of the pneumatic injection manufacture system. The effects of the sintering temperature and holding time on the properties of the sintered parts were studied. For a sintering temperature of 580 °C and holding time of 1 h, the surface quality of the sintered parts was better. The sintering of 3D-printed Fe-based metallic glass parts was preliminarily realized in this study, and the feasibility of preparing Fe-based metallic glass using pneumatic injection additive manufacture was verified.

  4. Superconducting spin valves based on epitaxial Fe/V-hybrid thin film heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Gregor

    2010-12-10

    This study presents a systematic investigation of the SSV effect in FM/SC/FM and FM/N/FM/SC heterostructures. Before investigating the actual SSV effect, we first pre-analyzed structural, magnetic and superconducting properties of the Fe/V system. In these preliminary studies we demonstrated, that epitaxial Fe/V heterostructures of superior crystalline quality can be grown by DC sputter deposition. With a Fe/V interface thickness of only one monolayer, the chemical separation of the Fe and V layers is extremely sharp. Moreover, the magnetic investigation showed that from thicknesses of two Fe(001) monolayers on the Fe layers in the superlattice possess a magnetic moment. Furthermore, we demonstrated the interlayer exchange coupling as oscillatory function of the V interlayer thickness. The investigations of the superconducting parameters of the Fe/V system revealed a non-monotonic T{sub S} vs. d{sub Fe} dependence in sample series (1). This observation proves the presence of the FM/SC proximity effect. The studies of various heterostructures of the design AFM/FM/SC/FM revealed a strong counteracting influence on the SSV effect, the stray field effect. The sample containing Fe{sub 25}V{sub 75} alloy layers, has the highest ratio of Cooper pair coherence length and superconductor thickness (ξ{sub S})/(d{sub S}), and its superconducting transition temperature is comparable to the sample with Fe{sub 35}V{sub 65} alloy layers. Nevertheless, the SSV effect in sample Fe{sub 25}V{sub 75} with alloy layers is much smaller than in sample with Fe{sub 35}V{sub 65} alloy layers. For a high-performance superconducting spin valve based on a FM1/SC/FM2 heterostructure at least four parameters have to be optimized simultaneously. 1. The magnetic domain size in FM1 and FM2 has to be as large as possible in order to reduce the stray field effect resulting from magnetization components in the FM domain walls perpendicular to the SC layer. 2. When using ferromagnetic alloys as

  5. Computational and Experimental Design of Fe-Based Superalloys for Elevated-Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter K. [Univ. of Tennessee, Knoxville, TN (United States); Fine, Morris E. [Northwestern Univ., Evanston, IL (United States); Ghosh, Gautam [Northwestern Univ., Evanston, IL (United States); Asta, Mark D. [Univ. of California, Berkeley, CA (United States); Liu, Chain T. [Auburn Univ., AL (United States); Sun, Zhiqian [Univ. of Tennessee, Knoxville, TN (United States); Huang, Shenyan [Univ. of Tennessee, Knoxville, TN (United States); Teng, Zhenke [Univ. of Tennessee, Knoxville, TN (United States); Wang, Gongyao [Univ. of Tennessee, Knoxville, TN (United States)

    2012-04-13

    Analogous to nickel-based superalloys, Fe-based superalloys, which are strengthened by coherent B2- type precipitates are proposed for elevated-temperature applications. During the period of this project, a series of ferritic superalloys have been designed and fabricated by methods of vacuum-arc melting and vacuum-induction melting. Nano-scale precipitates were characterized by atom-probe tomography, ultrasmall- angle X-ray scattering, and transmission-electron microscopy. A duplex distribution of precipitates was found. It seems that ferritic superalloys are susceptible to brittle fracture. Systematic endeavors have been devoted to understanding and resolving the problem. Factors, such as hot rolling, precipitate volume fractions, alloy compositions, precipitate sizes and inter-particle spacings, and hyperfine cooling precipitates, have been investigated. In order to understand the underlying relationship between the microstructure and creep behavior of ferric alloys at elevated temperatures, in-situ neutron studies have been carried out. Based on the current result, it seems that the major role of β' with a 16%-volume fraction in strengthening ferritic alloys is not load sharing but interactions with dislocations. The oxidation behavior of one ferritic alloy, FBB8 (Fe-6.5Al-10Ni-10Cr-3.4Mo-0.25Zr-0.005B, weight percent), was studied in dry air. It is found that it possesses superior oxidation resistance at 1,023 and 1,123 K, compared with other creep-resistant ferritic steels [T91 (modified 9Cr-1Mo, weight percent) and P92 (9Cr-1.8W-0.5Mo, weight percent)]. At the same time, the calculation of the interfacial energies between the -iron and B2-type intermetallics (CoAl, FeAl, and NiAl) has been conducted.

  6. Shape memory and pseudoelastic properties of Fe-Mn-Si and Ti-Ni based alloys

    International Nuclear Information System (INIS)

    Guenin, G.

    1997-01-01

    The aim of this presentation is to analyse and discuss some recent advances in shape memory and pseudoelastic properties of different alloys. Experimental work in connection with theoretical ones will be reviewed. The first part is devoted to the microstructural origin of shape memory properties of Fe-Mn-Si based alloys (γ-ε transformation); the second part is a synthetic analysis of the effects of thermomechanical treatments on shape memory and pseudoelastic effects in Ti-Ni alloys, with some focus on the behaviour of the R phase introduced. (orig.)

  7. Fabrication of a solenoid-type inductor with Fe-based soft magnetic core

    International Nuclear Information System (INIS)

    Lei Chong; Zhou Yong; Gao Xiaoyu; Ding Wen; Cao Ying; Choi, Hyung; Won, Jonghwa

    2007-01-01

    A solenoid-type inductor was fabricated by MEMS (Microelectromechanical systems) technique. The fabrication process uses UV-LIGA, dry etching, fine polishing, and electroplating technique to achieve high performance of the solenoid-type inductor. Fe-based soft magnetic thin film was sputtered as the magnetic core, and polyimide was used as the insulation materials. The inductor was in size of 4x4 mm with coil width of 20 μm and space of 35 μm. The inductance is 1.61 μH at a frequency of 5 MHz with the maximum quality factor of 1.42

  8. New high strength technologically ecological and expedient economically advantageous alloys on Fe-C base

    International Nuclear Information System (INIS)

    Kolev, B.V.

    2003-01-01

    The paper presents framework a part of by now obtained results of the authors studies in the period 1967(68) - 2002 about possibilities for obtaining new high-strength and wear resistant cast alloys on, Fe-C base (complex alloyed steels and cast irons of different systems with different structure, reflected in over 125 articles, 15 inventions (patents) and other scientific studies. The paper includes summarized results and discussion. Key words: new austenite steels and cast irons, mechanical characteristics, wear resistance. (Original)

  9. A high performance hybrid battery based on aluminum anode and LiFePO4 cathode.

    Science.gov (United States)

    Sun, Xiao-Guang; Bi, Zhonghe; Liu, Hansan; Fang, Youxing; Bridges, Craig A; Paranthaman, M Parans; Dai, Sheng; Brown, Gilbert M

    2016-01-28

    A novel hybrid battery utilizing an aluminum anode, a LiFePO4 cathode and an acidic ionic liquid electrolyte based on 1-ethyl-3-methylimidazolium chloride (EMImCl) and aluminum trichloride (AlCl3) (EMImCl-AlCl3, 1-1.1 in molar ratio) with or without LiAlCl4 is proposed. The hybrid ion battery delivers an initial high capacity of 160 mA h g(-1) at a current rate of C/5. It also shows good rate capability and cycling performance.

  10. Comparison of effect of TDS and Fe in uranium measurement in LED and Xe lamp based fluorimeter

    International Nuclear Information System (INIS)

    Sahoo, S.K.; Mohapatra, S.; Lenka, P.; Dubey, J.S.; Patra, A.C.; Thakur, V.K.; Ravi, P.M.; Tripathi, R.M.

    2014-01-01

    In the present study, the effect of TDS and Fe on uranium fluorescence in water samples is studied by fluorometric techniques based on LED and xenon lamp systems. Fluorimeters are calibrated with uranium standards to establish the relationship between concentration and fluorescence response. Known concentration of uranium standard solution is measured in both LED and Xe lamp based fluorimeter after spiking with a series of concentration of Fe and TDS solution. Most often high levels of TDS are caused by the presence of K, CI, Na, etc. Thus here the effect of TDS is studied with NaCI solution but the effect may differ with the presence other elements. Details of the optimization procedure and measurement of uranium concentration in fluorometric technique are given elsewhere. In LED based system, sodium pyrophosphate with phosphoric acid is used as the complexing agent while sodium polysilicate is used in Xe lamp based system. Fe standard solution of 0.1 to 10 ppm was spiked with known uranium standard and analysed in both the fluorimeters. The fluorescence response gradually decreased upto 50% with 10 ppm of Fe in the solution in the LED based system whereas there was a gradual decrease of fluorescence response with increase in Fe concentration and it was 60% with 10 ppm of Fe. Thus both the instruments show nearly equal response with the increasing concentration of Fe in sample solution. Therefore, in case of high TDS and Fe content in the sample, precautions should be taken during measurement of uranium in water samples directly by fluorimetric techniques

  11. The influence of reduced graphene oxide on electrical conductivity of LiFePO4-based composite as cathode material

    International Nuclear Information System (INIS)

    Arifin, Muhammad; Aimon, Akfiny Hasdi; Winata, Toto; Abdullah, Mikrajuddin; Iskandar, Ferry

    2016-01-01

    LiFePO 4 is fascinating cathode active materials for Li-ion batteries application because of their high electrochemical performance such as a stable voltage at 3.45 V and high specific capacity at 170 mAh.g −1 . However, their low intrinsic electronic conductivity and low ionic diffusion are still the hindrance for their further application on Li-ion batteries. Therefore, the efforts to improve their conductivity are very important to elevate their prospecting application as cathode materials. Herein, we reported preparation of additional of reduced Graphene Oxide (rGO) into LiFePO 4 -based composite via hydrothermal method and the influence of rGO on electrical conductivity of LiFePO 4 −based composite by varying mass of rGO in composition. Vibration of LiFePO 4 -based composite was detected on Fourier Transform Infrared Spectroscopy (FTIR) spectra, while single phase of LiFePO 4 nanocrystal was observed on X-Ray Diffraction (XRD) pattern, it furthermore, Scanning Electron Microscopy (SEM) images showed that rGO was distributed around LiFePO4-based composite. Finally, the 4-point probe measurement result confirmed that the optimum electrical conductivity is in additional 2 wt% rGO for range 1 to 2 wt% rGO

  12. Effect of Fe content on the friction and abrasion properties of copper base overlay on steel substrate by TIG welding

    Institute of Scientific and Technical Information of China (English)

    Lü Shixiong; Song Jianling; Liu Lei; Yang Shiqin

    2009-01-01

    Copper base alloy was overlaid onto 35CrMnSiA steel plate by tungsten inert gas (TIG) welding method. The heat transfer process was simulated, the microstructures of the copper base overlay were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), and the friction and abrasion properties of the overlay were measured. The results show that the Fe content increases in the overlay with increasing the welding current. And with the increase of Fe content in the overlay, the friction coefficient increases and the wear mechanism changes from oxidation wear to abrasive wear and plough wear, which is related to the size and quantity of Fe grains in the overlay. While with the increase of Fe content in the overlay, the protection of oxidation layer against the oxidation wear on the melted metal decreases.

  13. Development of Fe-B Based Bulk Metallic Glasses: Morphology of Residual Phases in Fe50Ni16Mo6B18Zr10 Glass

    Directory of Open Access Journals (Sweden)

    Tiburce A. Aboki

    2013-04-01

    Full Text Available Iron-boron based bulk metallic glasses (BMG development has been initiated using Fe40Ni38Mo4B18 as precursor. Addition of zirconium up to 10 atomic % along with the reduction of Ni proportion improves the glass forming ability (GFA, which is optimum when Ni is suppressed in the alloy. However melting instability occurred during the materials fabrication resulting in the formation of residual crystalline phases closely related to the amorphous phase. Microstructure study shows an evolution from amorphous structure to peculiar acicular structure, particularly for Fe50Ni16Mo6B18Zr10, suggesting the amorphous structure as interconnected atomic sheets like “atomic mille feuilles” whose growth affects the alloys’ GFA.

  14. Mechanical and Thermal Properties of Palm-Based Polyurethane Composites Filled with Fe3O4, PANI and PANI/ Fe3O4

    International Nuclear Information System (INIS)

    Hao, L.C.; Sahrim Ahmad; Khairiah Badri

    2011-01-01

    In-situ polymerization method was used to prepare palm-based polyurethane (PU) composites loading with 15 wt % magnetite (Fe 3 O 4 ), poly aniline (PANI) and Fe 3 O 4 coated with PANI labeled as PU15, PP and PPM, respectively. FTIR spectroscopy analysis indicated a shift in the carbonyl, C=O and NH in PP. The shift of the peak indicated that there was hydrogen bonding between the C=O (proton acceptor) of urethane with NH (proton-donator) of PANI. PPM gave the highest impact and flexural strengths at 4875 kJ/ m 2 and 42 MPa, respectively but with the lowest flexural modulus (1050 MPa). Two-stage degradation behavior was observed in the TGA thermo gram. (author)

  15. Fault feature analysis of cracked gear based on LOD and analytical-FE method

    Science.gov (United States)

    Wu, Jiateng; Yang, Yu; Yang, Xingkai; Cheng, Junsheng

    2018-01-01

    At present, there are two main ideas for gear fault diagnosis. One is the model-based gear dynamic analysis; the other is signal-based gear vibration diagnosis. In this paper, a method for fault feature analysis of gear crack is presented, which combines the advantages of dynamic modeling and signal processing. Firstly, a new time-frequency analysis method called local oscillatory-characteristic decomposition (LOD) is proposed, which has the attractive feature of extracting fault characteristic efficiently and accurately. Secondly, an analytical-finite element (analytical-FE) method which is called assist-stress intensity factor (assist-SIF) gear contact model, is put forward to calculate the time-varying mesh stiffness (TVMS) under different crack states. Based on the dynamic model of the gear system with 6 degrees of freedom, the dynamic simulation response was obtained for different tooth crack depths. For the dynamic model, the corresponding relation between the characteristic parameters and the degree of the tooth crack is established under a specific condition. On the basis of the methods mentioned above, a novel gear tooth root crack diagnosis method which combines the LOD with the analytical-FE is proposed. Furthermore, empirical mode decomposition (EMD) and ensemble empirical mode decomposition (EEMD) are contrasted with the LOD by gear crack fault vibration signals. The analysis results indicate that the proposed method performs effectively and feasibility for the tooth crack stiffness calculation and the gear tooth crack fault diagnosis.

  16. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths

    Science.gov (United States)

    Jiao, Z. B.; Luan, J. H.; Miller, M. K.; Yu, C. Y.; Liu, C. T.

    2016-01-01

    The precipitation of nanoparticles plays a key role in determining the properties of many structural materials, and the understanding of their formation and stabilization mechanisms has been a long standing interest in the material field. However, the critical issues involving the group precipitation of various nanoparticles and their cooperative hardening mechanism remain elusive in the newly discovered Fe-based alloys with nanostructures. Here we quantitatively elucidate the nucleation mechanism, evolution kinetics and hardening effects of the group-precipitated nanoparticles in the Fe-Cu-Ni-Al-based alloys by atom probe tomography together with both first-principles and thermodynamic calculations. Our results provide the compelling evidence for two interesting but complex group precipitation pathways of nanoparticles, i.e., the Cu-rich and NiAl-based precipitations. The co-existence of the two precipitation pathways plays a key role in age hardening kinetics and ultimately enhances the hardening response, as compared to the single particle type of strengthening, therefore providing an effective new approach for strengthening materials for structural applications. PMID:26892834

  17. Analysis of the low-frequency magnetoelectric performance in three-phase laminate composites with Fe-based nanocrystalline ribbon

    International Nuclear Information System (INIS)

    Chen, Lei; Li, Ping; Wen, Yumei; Zhu, Yong

    2013-01-01

    The theoretical analysis of magnetoelectric (ME) performance in three-phase Terfenol-D/PZT/FeCuNbSiB (MPF) laminate composite is presented in this paper. The ME couplings at low frequency for ideal and less than ideal interface couplings are studied, respectively, and our analysis predicts that (i) the ME voltage coefficient for ideal interface coupling increases with the increasing layers (n) of Fe-based nanocrystalline ribbon FeCuNbSiB (Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 ) while the sizes of PZT (Pb(Zr 1−x Ti x )O 3 ) and Terfenol-D (Tb 1−x Dy x Fe 2−y ) are kept constant, and then it tends to be a constant when the layers of FeCuNbSiB are >100; (ii) by introducing the interface coupling factor k and considering the degradation of d 33m,f with n, the ME voltage coefficient for a less than ideal interface condition is predicted. As the FeCuNbSiB layer increases, it first increases and reaches to a maximum value, and then slowly decreases. Various MPF laminates are fabricated and tested. It is found that the theoretical predictions for the consideration of actual boundary conditions at the interface are in agreement with the experimental observations. This study plays a guiding role for the design of MPF composite in real applications. (paper)

  18. EIT image reconstruction based on a hybrid FE-EFG forward method and the complete-electrode model.

    Science.gov (United States)

    Hadinia, M; Jafari, R; Soleimani, M

    2016-06-01

    This paper presents the application of the hybrid finite element-element free Galerkin (FE-EFG) method for the forward and inverse problems of electrical impedance tomography (EIT). The proposed method is based on the complete electrode model. Finite element (FE) and element-free Galerkin (EFG) methods are accurate numerical techniques. However, the FE technique has meshing task problems and the EFG method is computationally expensive. In this paper, the hybrid FE-EFG method is applied to take both advantages of FE and EFG methods, the complete electrode model of the forward problem is solved, and an iterative regularized Gauss-Newton method is adopted to solve the inverse problem. The proposed method is applied to compute Jacobian in the inverse problem. Utilizing 2D circular homogenous models, the numerical results are validated with analytical and experimental results and the performance of the hybrid FE-EFG method compared with the FE method is illustrated. Results of image reconstruction are presented for a human chest experimental phantom.

  19. Fabrication of PVDF-TrFE based bilayered PbTiO{sub 3}/PVDF-TrFE films capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Nurbaya, Z., E-mail: nurbayazainal@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, 54100 Kuala Lumpur (Malaysia); Wahid, M. H.; Rozana, M. D. [Faculty of Applied Sciences, Department of Polymer, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Annuar, I. [UiTM Sarawak Kampus Kota Samarahan, Jalan Meranek, 94300 Sarawak (Malaysia); Alrokayan, S. A. H.; Khan, H. A. [Department of Biochemistry, College of Science, Bldg. 5, King Saud University (KSU) P.O: 2454 Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-Sci Tech Centre (NST), Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    Development of high performance capacitor is reaching towards new generation where the ferroelectric materials take places as the active dielectric layer. The motivation of this study is to produce high capacitance device with long life cycle. This was configured by preparing bilayered films where lead titanate as an active dielectric layer and stacked with the top dielectric layer, poly(vinyledenefluoride-trifluoroethylene). Both of them are being referred that have one in common which is ferroelectric behavior. Therefore the combination of ceramic and polymer ferroelectric material could perform optimum dielectric characteristic for capacitor applications. The fabrication was done by simple sol-gel spin coating method that being varied at spinning speed property for polymer layers, whereas maintaining the ceramic layer. The characterization of PVDF-TrFE/PbTiO3 was performed according to metal-insulator-metal stacked capacitor measurement which includes structural, dielectric, and ferroelectric measurement.

  20. Fabrication of PVDF-TrFE based bilayered PbTiO3/PVDF-TrFE films capacitor

    Science.gov (United States)

    Nurbaya, Z.; Wahid, M. H.; Rozana, M. D.; Annuar, I.; Alrokayan, S. A. H.; Khan, H. A.; Rusop, M.

    2016-07-01

    Development of high performance capacitor is reaching towards new generation where the ferroelectric materials take places as the active dielectric layer. The motivation of this study is to produce high capacitance device with long life cycle. This was configured by preparing bilayered films where lead titanate as an active dielectric layer and stacked with the top dielectric layer, poly(vinyledenefluoride-trifluoroethylene). Both of them are being referred that have one in common which is ferroelectric behavior. Therefore the combination of ceramic and polymer ferroelectric material could perform optimum dielectric characteristic for capacitor applications. The fabrication was done by simple sol-gel spin coating method that being varied at spinning speed property for polymer layers, whereas maintaining the ceramic layer. The characterization of PVDF-TrFE/PbTiO3 was performed according to metal-insulator-metal stacked capacitor measurement which includes structural, dielectric, and ferroelectric measurement.

  1. PVC-membrane potentiometric sensors based on a recently synthesized Schiff base for Fe(III ion

    Directory of Open Access Journals (Sweden)

    S. Yousef Ebrahimipur

    2012-12-01

    Full Text Available A potentiometric iron sensor based on the use 3-(2-diethylamino-ethylimino-1,3-dihydro-indol-2-one (DEDIO as an ionophore in poly(vinyl chloride (PVC matrix, is reported. The plasticized membrane sensor exhibits a Nernstian response for Fe(III ions over a wide concentration range (2.0 × 10-6 - 5.0 × 10-2 M with a super Nernstian slope of 26(plus or minus 1 mV per decade. It has a fast response time of less than 12 s and can be used for ten weeks without any considerable divergences in its potentials the electrode can be used in the pH range 4.5-8.0. The proposed sensor shows fairly good discriminating ability towards Fe(III ion in comparison with a large number of alkali, alkaline earth, transition and heavy metal ions. The sensor was used as indicator electrode in potentiometric titration of Fe(III ions vs. EDTA.DOI: http://dx.doi.org/10.4314/bcse.v26i1.7

  2. Studies of Fe-Co based perovskite cathodes with different A-site cations

    DEFF Research Database (Denmark)

    Kammer Hansen, K.

    2006-01-01

    Iron-cobalt based perovskite cathodes with different A-site cations ((Ln(0.6)Sr(0.4))(0.99)Fe0.8Co0.2O3-delta, where Ln is La, Pr, Sm or Gd) have been synthesised, characterised by a powder XRD, dilatometry, 4-point DC conductivity measurements, and electrochemical impedance spectroscopy (EIS......) on cone shaped electrodes. In addition to this scanning electron microscopy (SEM) was used to characterise the bars. XRD revealed that only the La-containing perovskite was hexagonal. The Pr and Sm perovskites were orthorhombic. The gadolinium-based perovskite was a two phase system consisting...... of an orthorhombic and a cubic perovskite phase. The thermal expansion coefficient (TEC) increased systematically with a decrease in the size of the A-site cation until the gadoliniurn-containing perovskite where the TEC decreases abruptly. The total electric conductivity was the highest for the La-based perovskite...

  3. Photochemistry of Fe(Iii)-Carboxylates in Polysaccharide-Based Materials with Tunable Mechanical Properties

    Science.gov (United States)

    Giammanco, Giuseppe E.

    We present the formulation and study of light-responsive materials based on carboxylate-containing polysaccharides. The functional groups in these natural polymers allow for strong interactions with transition metal ions such as Fe(III). The known photochemistry of hydroxycarboxylic acids in natural waters inspired us in exploring the visible light induced photochemistry of the carboxylates in these polysaccharides when coordinated to Fe(III) ions. Described in this dissertation are the design and characterization of the Fe(III)-polysaccharide materials, specifically the mechanistic aspects of the photochemistry and the effects that these reactions have on the structure of the polymer materials. We present a study of the quantitative photochemistry of different polysaccharide systems, where the presence of uronic acids was important for the photoreaction to take place. Alginate (Alg), pectate (Pec), hyaluronic acid (Hya), xanthan gum (Xan), and a polysaccharide extracted from the Noni fruit (NoniPs), were among the natural uronic acid-containing polysaccharide (UCPS) systems we analyzed. Potato starch, lacking of uronate groups, did not present any photochemistry in the presence of Fe(III); however, we were able to induce a photochemical response in this polysaccharide upon chemical manipulation of its functional groups. Important structure-function relationships were drawn from this study. The uronate moiety present in these polysaccharides is then envisioned as a tool to induce response to light in a variety of materials. Following this approach, we report the formulation of materials for controlled drug release, able to encapsulate and release different drug models only upon illumination with visible light. Furthermore, hybrid hydrogels were prepared from UPCS and non-responsive polymers. Different properties of these materials could be tuned by controlling the irradiation time, intensity and location. These hybrid gels were evaluated as scaffolds for tissue

  4. The investigation of Fe-Mn-based alloys with shape memory effect by small-angle scattering of polarized neutrons

    International Nuclear Information System (INIS)

    Kopitsa, G.P.; Runov, V.V.; Grigoriev, S.V.; Bliznuk, V.V.; Gavriljuk, V.G.; Glavatska, N.I.

    2003-01-01

    The small-angle polarized neutron scattering (SAPNS) technique has been used to study a nuclear and magnetic homogeneity in the distribution of both substituent (Si, Cr, Ni) and interstitial (C, N) alloying elements on the mesoscopic range in Fe-Mn-based alloys with shape memory effect (SME). The four groups of alloys with various basic compositions: FeMn 18 (wt%), FeMn 20 Si 6 , FeMn 20 Cr 9 N 0.2 and FeMn 17 Cr 9 Ni 4 Si 6 were investigated. It was found that the small-angle scattering of neutrons and depolarization on these alloys are very small altogether. The scattering did not exceed 1.5% from the incident beam and depolarization ∼2% for all samples. It means that these alloys are well nuclear and magnetically homogeneous on the scale of 10-1000 A. However, the difference in the homogeneity depending on the compositions still takes place. Thus, the adding of Si in FeMn 18 and FeMn 20 Cr 9 N 0.2 alloys improves the homogeneity pronouncedly. At once, the effect of the doping by C or N atoms on the homogeneity in FeMn 20 Si 6 and FeMn 17 Cr 9 Ni 4 Si 6 alloys is multivalued and depend on the presence of substitutional atoms (Ni and Cr). The capability of SAPNS as a method for the study of mesoscopic homogeneity in materials with SME and testing of the quality of their preparation is discussed

  5. Corrosion behaviour of Fe-Mn-Si based shape memory steels trained by cold rolling

    International Nuclear Information System (INIS)

    Soederberg, O.; Liu, X.W.; Ullakko, K.; Lindroos, V.K.

    1999-01-01

    Fe-Mn-Si based high nitrogen steels have been studied in recent years for potential industrial applications. These steels show good shape memory properties, high strength and excellent ductility. In the present study, the effects of training history on the corrosion properties of Fe-Mn-Si-Cr-Ni based high nitrogen steels were investigated. The corrosion behaviour of shape memory alloys was analyzed by implementing anodic polarisation measurements and immersion tests. The shape memory steels in annealed, deformed and recovered conditions were studied to examine the training effect on their corrosion behaviour. The features of the anodic polarisation curves indicated a general corrosion type of these steels. The experimental results showed that Cr and Mn had a marked influence on the corrosion behaviour of the steels, followed by Ni, N and V. It was also apparent that the deformation during the shape memory training by cold rolling decreased the corrosion stability, and the recovery heating reduced further their corrosion resistance. However, further studies are needed in order to better understand the corrosion behaviour of the investigated alloys. (orig.)

  6. Thermal Conductivity and Wear Behavior of HVOF-Sprayed Fe-Based Amorphous Coatings

    Directory of Open Access Journals (Sweden)

    Haihua Yao

    2017-10-01

    Full Text Available To protect aluminum parts in vehicle engines, metal-based thermal barrier coatings in the form of Fe59Cr12Nb5B20Si4 amorphous coatings were prepared by high velocity oxygen fuel (HVOF spraying under two different conditions. The microstructure, thermal transport behavior, and wear behavior of the coatings were characterized simultaneously. As a result, this alloy shows high process robustness during spraying. Both Fe-based coatings present dense, layered structure with porosities below 0.9%. Due to higher amorphous phase content, the coating H-1 exhibits a relatively low thermal conductivity, reaching 2.66 W/(m·K, two times lower than the reference stainless steel coating (5.85 W/(m·K, indicating a good thermal barrier property. Meanwhile, the thermal diffusivity of amorphous coatings display a limited increase with temperature up to 500 °C, which guarantees a steady and wide usage on aluminum alloy. Furthermore, the amorphous coating shows better wear resistance compared to high carbon martensitic GCr15 steel at different temperatures. The increased temperature accelerating the tribological reaction, leads to the friction coefficient and wear rate of coating increasing at 200 °C and decreasing at 400 °C.

  7. Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy

    Science.gov (United States)

    Wang, Changshuai; Su, Haijun; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang

    2017-09-01

    Solidification characteristics and segregation behavior of a P-containing Ni-Fe-Cr-based alloy, considered as boiler and turbine materials in 700 °C advanced ultra-supercritical coal-fired power plants, have been investigated by differential thermal analysis and directional solidification quenching technique. Results reveal that P decreases the solidus temperature, but only has negligible influence on liquidus temperature. After P was added, the solidification sequence has no apparent change, but the width of the mushy zone increases and dendritic structures become coarser. Moreover, P increases the amount and changes the morphology of MC carbide. Energy-dispersive spectroscopy analysis reveals that P has obvious influence on the segregation behavior of the constitute elements with equilibrium partition coefficients (ki) far away from unity, whereas has negligible effect on the constituent elements with ki close to unity and has more influence on the final stage of solidification than at early stage. The distribution profiles reveal that P atoms pile up ahead of the solid/liquid (S/L) interface and strongly segregate to the interdendritic liquid region. The influence of P on solidification characteristics and segregation behavior of Ni-Fe-Cr-based alloy could be attributed to the accumulation of P ahead of the S/L interface during solidification.

  8. Low temperature London penetration depth and superfluid density in Fe-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

    The superconducting gap symmetry of the Fe-based superconductors was studied by measurements and analysis of London penetration depth and super uid density. Tunnel diode resonator technique for these measurements was implemented in a dilution refrigerator allowing for the temperatures down to 50 mK. For the analysis of the super uid density, we used both experimental studies of Al-coated samples and original thermodynamic approach based on Rutgers relation. In three systems studied, we found that the superconducting gap at the optimal doping is best described in multi-gap full gap scenario. By performing experiments on samples with arti cially introduced disorder with heavy ion irradiation, we show that evolution of the superconducting transition temperature and of the super uid density are consistent with full-gap sign changing s superconducting state. The superconducting gap develops strong modulation both in the under-doped and the over-doped regimes. In the terminal hole-doped KFe{sub 2}As{sub 2}, both temperature dependence of the super uid density and its evolution with increase of the scattering rate are consistent with symmetry imposed vertical line nodes in the superconducting gap. By comparative studies of hole-doped (Ba,K)Fe{sub 2}As{sub 2} and electron-doped Ca10-3-8, we show that the superconducting gap modulation in the under-doped regime is intrinsic and is not induced by the coexisting static magnetic order.

  9. Characterization of Fe-based alloy coating deposited by supersonic plasma spraying

    International Nuclear Information System (INIS)

    Piao, Zhong-yu; Xu, Bin-shi; Wang, Hai-dou; Wen, Dong-hui

    2013-01-01

    Highlights: • Fe-based coating exhibited few oxides, high density and bond strength. • Amorphous/nanocrystalline phases were found in the coating. • Formation mechanism of excellent coating was investigated. -- Abstract: The objective of the present study is to characterize the Fe-based alloy coating deposited by the supersonic plasma spraying process. The condition of the melting particles was in situ monitored. The microstructure of the coating was examined by scanning electron microscope and high resolution transmission electron microscope. The phase composition was examined by X-ray diffraction. The microhardness and porosity were also measured, respectively. Results show the prepared coatings have excellent properties, such as few oxides, high microhardness and a low porosity amount. At the same time, a mass of amorphous/nanocrystalline phases was found in the coating. The mechanism of the formation of amorphous/nanocrystalline phases was investigated. The appropriate material composition of spraying material and flash set process of plasma spraying are the key factors. Moreover, the mechanism for oxidation resistance is also investigated, where the separation between melting metal and oxygen by the formation of SiO 2 films is the key factor

  10. Shape recovery characteristics of biaxially prestrained Fe-Mn-Si-based shape memory alloy

    International Nuclear Information System (INIS)

    Wada, M.; Naoi, H.; Yasuda, H.; Maruyama, T.

    2008-01-01

    Fe-Mn-Si-based shape memory alloy has already been used practically for steel pipe joints. In most of the applications including the steel pipe joints, it is possible to estimate the reduction of diameter from the experimental data of the shape recovery after uniaxial stretching of the alloy materials. However, studies on shape recovery effects after biaxial stretching are important for the extensive applications of the alloy. In this study, we investigated the shape recovery strain after uniaxial and biaxial stretching and the microstructures of the alloy in order to see the effects of uniaxial and biaxial prestrain on the stress-induced martensitic transformation. Amounts of shape recovery strain in the biaxially prestrained specimens are smaller than those in the uniaxially prestrained specimens. Transmission electron microscopy revealed that reverse transformations of stress-induced martensitic ε-phase are prevented by slip bands formed at the same time in the biaxially prestrained specimens, but not in the uniaxially prestrained specimens. The technological data and interpretations presented in this study should be useful in forming design guidelines for promoting the extensive applications of Fe-Mn-Si-based shape memory alloy

  11. The synthesis of higher alcohols from CO2 hydrogenation with Co, Cu, Fe-based catalysts

    International Nuclear Information System (INIS)

    Ji, Qinqin

    2017-01-01

    CO 2 is a clean carbon source for the chemical reactions, many researchers have studied the utilization of CO 2 . Higher alcohols are clean fuel additives. The synthesis of higher alcohols from CO hydrogenation has also been studied by many researchers, but there are few literatures about the synthesis of higher alcohols from CO 2 hydrogenation, which is a complex and difficult reaction. The catalysts that used for higher alcohols synthesis need at least two active phases and good cooperation. In our study, we tested the Co. Cu. Fe spinel-based catalysts and the effect of supports (CNTs and TUD-1) and promoters (K, Na, Cs) to the HAS reaction. We found that catalyst CuFe-precursor-800 is beneficial for the synthesis of C2+ hydrocarbons and higher alcohols. In the CO 2 hydrogenation, Co acts as a methanation catalyst rather than acting as a FT catalyst, because of the different reaction mechanism between CO hydrogenation and CO 2 hydrogenation. In order to inhibit the formation of huge amount of hydrocarbons, it is better to choose catalysts without Co in the CO 2 hydrogenation reaction. Compared the functions of CNTs and TUD-1, we found that CNTs is a perfect support for the synthesis of long-chain products (higher alcohols and C2+ hydrocarbons). The TUD-1 support are more suitable for synthesis of single-carbon products (methane and methanol).The addition of alkalis as promoters does not only lead to increase the conversion of CO 2 and H 2 , but also sharply increased the selectivity to the desired products, higher alcohols. The catalyst 0.5K30CuFeCNTs owns the highest productivities (370.7 g.kg -1 .h -1 ) of higher alcohols at 350 C and 50 bar. (author) [fr

  12. A new multifunctional Schiff base as a fluorescence sensor for Fe{sup 2+} and F{sup −} ions, and a colorimetric sensor for Fe{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Chin-Feng [School of Medical Applied Chemistry, Chung Shan Medical University, Taichung City 40201, Taiwan (China); Chang, Ya-Ju; Chien, Chih-Yu; Sie, Yi-Wun; Hu, Ching-Han [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China); Wu, An-Tai, E-mail: antai@cc.ncue.edu.tw [Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan (China)

    2016-10-15

    A multifunctional Schiff base fluorescent sensor (receptor L) was prepared and its metal ions and anions sensing properties were investigated. Receptor L exhibited an excellent selective fluorescence response toward Fe{sup 2+} and F{sup −}. It also showed colorimetric response (from colorless to yellow) toward Fe{sup 3+} among a series of ions. Moreover, the detection limits of receptor L for Fe{sup 2+} and F{sup −} were determined to be 0.3 ppm and 25.7 ppb, respectively. The two detection limit values were sufficiently low to detect nano-molar concentration of Fe{sup 2+} and F{sup −}.

  13. Ultrasensitive ppb-level NO2 gas sensor based on WO3 hollow nanosphers doped with Fe

    Science.gov (United States)

    Zhang, Ziyue; haq, Mahmood; Wen, Zhen; Ye, Zhizhen; Zhu, Liping

    2018-03-01

    WO3 mesoporous hollow nanospheres doped with Fe synthesized by a facile method have mesoporous hollow nanospherical like morphology, small grain size (10 nm), high crystalline quality and ultrahigh surface area (165 m2/g). XRD spectra and Raman spectra indicate the Fe doping leading to the smaller cell parameters as compared to pure WO3, and the slight distortion in the crystal lattice produces a number of defects, making it a better candidate for gas sensing. XPS analysis shows that Fe-doped WO3 mesoporous hollow nanospheres have more oxygen vacancies than pure WO3, which is beneficial to the adsorption of oxygen and NO2 and its surface reaction. The gas sensor based on Fe-WO3 exhibited excellent low ppb-level (10 ppb) NO2 detecting performance and outstanding selectivity.

  14. A physics-based crystallographic modeling framework for describing the thermal creep behavior of Fe-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Wei [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Capolungo, Laurent [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Patra, Anirban [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Tome, Carlos [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-02

    This Report addresses the Milestone M2MS-16LA0501032 of NEAMS Program (“Develop hardening model for FeCrAl cladding), with a deadline of 09/30/2016. Here we report a constitutive law for thermal creep of FeCrAl. This Report adds to and complements the one for Milestone M3MS-16LA0501034 (“Interface hardening models with MOOSE-BISON”), where we presented a hardening law for irradiated FeCrAl. The last component of our polycrystal-based constitutive behavior, namely, an irradiation creep model for FeCrAl, will be developed as part of the FY17 Milestones, and the three regimes will be coupled and interfaced with MOOSE-BISON.

  15. Sol-gel based optical sensor for determination of Fe (II): a novel probe for iron speciation.

    Science.gov (United States)

    Samadi-Maybodi, Abdolraouf; Rezaei, Vida; Rastegarzadeh, Saadat

    2015-02-05

    A highly selective optical sensor for Fe (II) ions was developed based on entrapment of a sensitive reagent, 2,4,6-tri(2-pyridyl)-s-triazine (TPTZ), in a silica sol-gel thin film coated on a glass substrate. The thin films fabricated based on tetraethoxysilane (TEOS) as precursor, sol-gel pH∼3, water:alkoxyde ratio of 4:1 and TPTZ concentration of 0.112 mol L(-1). The influence of sol-gel parameters on sensing behavior of the fabricated sensor was also investigated. The fabricated sensor can be used for determination of Fe (II) ion with an outstanding high selectivity over a dynamic range of 5-115 ng mL(-1) and a detection limit of 1.68 ng mL(-1). It also showed reproducible results with relative standard deviation of 3.5% and 1.27% for 10 and 90 ng mL(-1) of Fe (II), respectively, along with a fast response time of ∼120 s. Total iron also was determined after reduction of Fe (III) to Fe (II) using ascorbic acid as reducing agent. Then, the concentration of Fe (III) was calculated by subtracting the concentration of Fe (II) from the total iron concentration. Interference studies showed a good selectivity for Fe (II) with trapping TPTZ into sol-gel matrix and appropriately adjusting the structure of doped sol-gel. The sensor was compared with other sensors and was applied to determine iron in different water samples with good results. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. A rhodamine–dansyl conjugate as a FRET based sensor for Fe{sup 3+} in the red spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Puhui, E-mail: pxie2007@yahoo.com.cn [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Guo, Fengqi, E-mail: fqguo@zzu.edu.cn [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Xia, Ruirui; Wang, Yao [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China); Yao, Denghui [College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001 (China); Yang, Guoyu; Xie, Lixia [College of Sciences, Henan Agricultural University, Zhengzhou 450002 (China)

    2014-01-15

    A new fluorescent resonance energy transfer (FRET) based fluorescent probe (compound 1) containing a dansyl unit as a donor and rhodamine 101 as an acceptor was developed to detect Fe{sup 3+} from other transition metal ions through ratiometric sensing in organic-aqueous solutions. Fe{sup 3+} induced a ring-opening reaction of the spirolactam rhodamine moiety of 1 resulting in the formation of a fluorescent derivative that can serve as the FRET acceptor. Ratiometric sensing of Fe{sup 3+} was accomplished by plotting the fluorescence intensity ratio at 605 nm and 515 nm versus ferric ion concentration. The probe displayed a linear response to Fe{sup 3+} in the range of 5.5–25 μM with a detection limit of 0.64 μM. A 1:1 stoichiometry for the 1–Fe{sup 3+} complex was formed with an association constant of 1.74×10{sup 4} M{sup −1}. The probe also exhibited a large Stokes shift (225 nm) which can eliminate backscattering effects of excitation light. -- Highlights: • A new colorimetric and fluorescent “off–on” chemosensor for Fe{sup 3+} was synthesized. • It can respond to Fe{sup 3+} in the red spectral region based on a FRET mechanism. • Its ratiometric sensing for Fe{sup 3+} can be accomplished with a signal to noise ratio of 214. • The large Stokes shift (225 nm) can rule out the excitation backscattering effects.

  17. Electric field control of magnetism using BiFeO3-based heterostructures

    International Nuclear Information System (INIS)

    Heron, J. T.; Schlom, D. G.; Ramesh, R.

    2014-01-01

    Conventional CMOS based logic and magnetic based data storage devices require the shuttling of electrons for data processing and storage. As these devices are scaled to increasingly smaller dimensions in the pursuit of speed and storage density, significant energy dissipation in the form of heat has become a center stage issue for the microelectronics industry. By taking advantage of the strong correlations between ferroic orders in multiferroics, specifically the coupling between ferroelectric and magnetic orders (magnetoelectricity), new device functionalities with ultra-low energy consumption can be envisioned. In this article, we review the advances and highlight challenges toward this goal with a particular focus on the room temperature magnetoelectric multiferroic, BiFeO 3 , exchange coupled to a ferromagnet. We summarize our understanding of the nature of exchange coupling and the mechanisms of the voltage control of ferromagnetism observed in these heterostructures

  18. The Suitability of Pozzolan as Admixing Aggregate for Fe0-Based Filters

    Directory of Open Access Journals (Sweden)

    Arnaud Igor Ndé-Tchoupé

    2018-04-01

    Full Text Available Continuous gravity-fed column experiments using the methylene blue (MB discoloration method were performed to characterize the suitability of a pozzolan (PZ specimen as alternative admixing aggregate for metallic iron filters (Fe0-filters. Investigated systems were: (i pure sand, (ii pure PZ, (iii pure Fe0, (iv Fe0/sand, (v Fe0/PZ, and (vi Fe0/sand/PZ. The volumetric proportion of Fe0 was 25%. The volumetric proportions of the Fe0/sand/PZ system was 25/45/30. The initial MB concentration was 2.0 mg·L−1, 6.0 g of Fe0 was used, and the experiments lasted for 46 days. The individual systems were fed with 3.9 to 8.4 L (7.80 to 16.69 mg of MB and were characterized by the time-dependent changes of: (i the pH value, (ii the iron breakthrough, (iii the MB breakthrough, and (iv the hydraulic conductivity. Results showed that the Fe0/sand/PZ system was the most efficient. This ternary system was also the most permeable and therefore the most sustainable. The suitability of MB as a powerful operative indicator for the characterization of processes in the Fe0/H2O system was confirmed. The tested PZ is recommended as an alternative material for efficient but sustainable Fe0 filters.

  19. Properties of nanoparticles prepared from NdFeB-based compound for magnetic hyperthermia application.

    Science.gov (United States)

    Périgo, E A; Silva, S C; de Sousa, E M B; Freitas, A A; Cohen, R; Nagamine, L C C M; Takiishi, H; Landgraf, F J G

    2012-05-04

    Nanoparticles were prepared from a NdFeB-based alloy using the hydrogen decrepitation process together with high-energy ball milling and tested as heating agent for magnetic hyperthermia. In the milling time range evaluated (up to 10 h), the magnetic moment per mass at H = 1.59 MA m(-1) is superior than 70 A m(2) kg(-1); however, the intrinsic coercivity might be inferior than 20 kA m(-1). The material presents both ferromagnetic and superparamagnetic particles constituted by a mixture of phases due to the incomplete disproportionation reaction of Nd(2)Fe(14)BH(x) during milling. Solutions prepared with deionized water and magnetic particles exposed to an AC magnetic field (H(max) ~ 3.7 kA m(-1) and f = 228 kHz) exhibited 26 K ≤ ΔT(max) ≤ 44 K with a maximum estimated specific absorption rate (SAR) of 225 W kg(-1). For the pure magnetic material milled for the longest period of time (10 h), the SAR was estimated as ~2500 W kg(-1). In vitro tests indicated that the powders have acceptable cytotoxicity over a wide range of concentration (0.1-100 µg ml(-1)) due to the coating applied during milling.

  20. Microstructure evolution of Fe-based nanostructured bainite coating by laser cladding

    International Nuclear Information System (INIS)

    Guo, Yanbing; Li, Zhuguo; Yao, Chengwu; Zhang, Ke; Lu, Fenggui; Feng, Kai; Huang, Jian; Wang, Min; Wu, Yixiong

    2014-01-01

    Highlights: • The laser cladding and isothermal holding are used to fabricate nanobainite coating. • Fine prior austenite is obtained to accelerate the bainite transformation. • Low transformation temperature results in fine bainite ferrite and film austenite. • Retained austenite volume fraction in bainite coating is determined by XRD. • Evolution of carbon content in austenite and ferrite is analyzed. - Abstract: A Fe-based coating with nano-scale bainitic microstructure was fabricated using laser cladding and subsequent isothermal heat treatment. The microstructure of the coating was observed and analyzed using optical microscope (OM), field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The results showed that nanostructured bainitic ferrite and carbon-enriched retained austenite distributed uniformly in the coating. Blocky retained austenite was confined to the prior austenite grain boundaries resulting from the elements segregation. The bainitic microstructure obtained at 250 °C had a finer scale compared with that obtained at 300 °C. The volume fraction of austenite increased with increasing transformation temperature for the fully transformed bainitic coating. The bainitic transformation was accelerated as a result of the fine prior austenite generated during the laser cladding. The evolution of the carbon contents in bainitic ferrite and retained austenite revealed the diffusionless mechanism of the bainitic transformation

  1. Synthesis of Fe-based amorphous composite coatings with low purity materials by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Qingjun [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)]. E-mail: sduzhu@yahoo.com.cn; Qu Shiyao [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Wang Xinhong [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Zou Zengda [School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

    2007-06-30

    Amorphous composite coatings Fe{sub 38}Ni{sub 30-X}Si{sub 16}B{sub 14}V{sub 2}M {sub X} (X = 0, 1, 2) (M contains Al, Ti, Mo, and C) were prepared with low purity of raw materials by laser cladding. X-ray diffraction and transmission electron microscopy results show that the coating have an amorphous structure with a few crystalline phase on it. The amorphous phase is the primary phase. The glass forming ability as well as the microhardness of the Fe-based alloy made from low purity raw materials can be much enhanced by adding small amount of multi-components. However, the elements addition has its optimal quantity. When X is equal to 1, the microstructure of the coating contains 97.93% amorphous phase and 2.07% crystalline phase on it. As a result, the microhardness of the coating reaches maximum. With further increasing of the additions, the amorphous phase in the coating lessens instead of augment and the crystalline phase begins to accumulate, which result in the decrease of the microhardness.

  2. A Highly Selective Room Temperature NH3 Gas Sensor based on Nanocrystalline a-Fe2O3

    Directory of Open Access Journals (Sweden)

    Priyanka A. PATIL

    2017-05-01

    Full Text Available Nanocrystalline a-Fe2O3 powder was synthesized by simple, inexpensive sol-gel method. The obtained powder was calcined at 700 0C in air atmosphere for 2 hours. The structural and morphological properties of calcined powder were studied by X-ray diffraction (XRD and Field Emission Scanning Electron Microscopy (FESEM respectively. Thermal properties of dried gel were studied by Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC. The XRD pattern of the powder confirmed the a-Fe2O3 (hematite phase of iron oxide with average crystalline size of 30.87 nm calculated from Scherrer equation. The FESEM images showed uniform wormlike morphology of a-Fe2O3 powder. TGA result indicated that a-Fe2O3 is thermodynamically stable. Room temperature NH3 sensing characteristics of a-Fe2O3 were studied for various concentration levels (250-2500 ppm of NH3 at various humid conditions. The sensor based on a-Fe2O3 exhibited good selectivity and excellent sensitivity (S=92 towards 1000 ppm of NH3 with quick response of 4 sec and fast recovery of 9 sec. Room temperature sensing mechanism is also discussed.

  3. SrFe12O19 based ceramics with ultra-low dielectric loss in the millimetre-wave band

    Science.gov (United States)

    Yu, Chuying; Zeng, Yang; Yang, Bin; Wylde, Richard; Donnan, Robert; Wu, Jiyue; Xu, Jie; Gao, Feng; Abrahams, Isaac; Reece, Mike; Yan, Haixue

    2018-04-01

    Non-reciprocal devices such as isolators and circulators, based mainly on ferromagnetic materials, require extremely low dielectric loss in order for strict power-link budgets to be met for millimetre (mm)-wave and terahertz (THz) systems. The dielectric loss of commercial SrFe12O19 hexaferrite was significantly reduced to below 0.002 in the 75-170 GHz band by thermal annealing. While the overall concentration of Fe2+ and oxygen vacancy defects is relatively low in the solid, their concentration at the surface is significantly higher, allowing for a surface sensitive technique such as XPS to monitor the Fe3+/Fe2+ redox reaction. Oxidation of Fe2+ and a decrease in oxygen vacancies are found at the surface on annealing, which are reflected in the bulk sample by a small change in the unit cell volume. The significant decrease in the dielectric loss property can be attributed to the decreased concentration of charged defects such as Fe2+ and oxygen vacancies through the annealing process, which demonstrated that thermal annealing could be effective in improving the dielectric performance of ferromagnetic materials for various applications.

  4. Anisotropic energy-gaps of iron-based superconductivity from intra-band quasiparticle interference in LiFeAs

    Energy Technology Data Exchange (ETDEWEB)

    Rost, A.W. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); Allan, M.P. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Mackenzie, A.P. [SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); Xie, Y. [CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Davis, J.C. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); SUPA, School of Physics and Astronomy, Univ. of St Andrews, St Andrews, Fife KY16 9SS (United Kingdom); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Kavli Institute at Cornell for Nanoscale Science, Cornell, Ithaca, NY 14853 (United States); Kihou, K.; Lee, C.H.; Iyo, A.; Eisaki, H. [AIST, Tsukuba, Ibaraki 305-8568 (Japan); Chuang, T.M. [LASSP, Department of Physics, Cornell, Ithaca, NY 14853 (United States); CMPMS Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Inst. of Physics, Academica Sinica, Nankang, Taipei 11529, Taiwan (China)

    2012-07-01

    Cooper pairing in the Fe-based superconductors is thought to occur due to the projection of the antiferromagnetic interactions between iron atoms onto the complex momentum-space electronic structure. A key consequence is that distinct anisotropic energy gaps {Delta}{sub i}(k) with specific relative orientations should occur on the different electronic bands i. To determine this previously unresolved gap structure high-precision spectroscopy is required. Here we introduce the STM technique of intra-band Bogolyubov quasiparticle scattering interference (QPI) to iron-based superconductor studies, focusing on LiFeAs. We identify the QPI signatures of three hole-like dispersions and, by introducing a new QPI technique, determine the magnitude and relative orientations of corresponding anisotropic {Delta}{sub i}(k). Intra-band Bogolyubov QPI therefore yields the spectroscopic information required to identify the mechanism of superconductivity in Fe-based superconductors.

  5. The rheological responds of the superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, Xiaohui; Pei, Lei; Xuan, Shouhu, E-mail: xuansh@ustc.edu.cn; Yan, Qifan; Gong, Xinglong, E-mail: gongxl@ustc.edu.cn

    2017-05-01

    In this work, a superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres was developed and the influence of the particle structure on the rheological properties was investigated. The Fe{sub 3}O{sub 4} hollow nanospheres which were prepared by using the hydrothermal method presented the superparamagnetic characteristic, and the magnetic fluid thereof showed well magnetorheological (MR) effect. The stable magnetic fluid had a high yield stress even at low shear rate and its maximal yield stress was dramatically influenced by the measurement gap. In comparison to the Fe{sub 3}O{sub 4} nanoparticles based magnetic fluid (MF), the Fe{sub 3}O{sub 4} hollow nanospheres based MF exhibited better MR effect and higher stability since the unique hollow nanostructure. The shear stress of the hollow nanospheres is about 1.85 times larger than the nanoparticles based MF because it formed stronger chains structure under applying a magnetic field. To further investigate the enhancing mechanism, a molecule dynamic simulation was conducted to analyze the shear stress and the structure evolution of the Fe{sub 3}O{sub 4} hollow nanospheres based MF and the simulation matched well with the experimental results. - Highlights: • A superparamagnetic fluid based on Fe{sub 3}O{sub 4} hollow nanospheres was investigated. • The stable magnetic fluid had a high yield stress even at low shear rate. • The shear stress of the hollow nanospheres is large. • A molecule dynamic simulation was conducted to analyze the shear stress.

  6. Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

    Directory of Open Access Journals (Sweden)

    Y.-B. Huang

    2012-12-01

    Full Text Available The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission spectroscopy measurements of the superconducting gap in the Fe-based high-temperature superconductors. We show that the superconducting gap is Fermi surface dependent and nodeless with small anisotropy, or more precisely, a function of the momentum location in the Brillouin zone. We show that while this observation seems inconsistent with weak coupling approaches for superconductivity in these materials, it is well supported by strong coupling models and global superconducting gaps. We also suggest that a smaller lifetime of the superconducting Cooper pairs induced by the momentum dependent interband scattering inherent to these materials could affect the residual density of states at low energies, which is critical for a proper evaluation of the superconducting gap.

  7. Growth of carbon nanotubes by Fe-catalyzed chemical vapor processes on silicon-based substrates

    Science.gov (United States)

    Angelucci, Renato; Rizzoli, Rita; Vinciguerra, Vincenzo; Fortuna Bevilacqua, Maria; Guerri, Sergio; Corticelli, Franco; Passini, Mara

    2007-03-01

    In this paper, a site-selective catalytic chemical vapor deposition synthesis of carbon nanotubes on silicon-based substrates has been developed in order to get horizontally oriented nanotubes for field effect transistors and other electronic devices. Properly micro-fabricated silicon oxide and polysilicon structures have been used as substrates. Iron nanoparticles have been obtained both from a thin Fe film evaporated by e-gun and from iron nitrate solutions accurately dispersed on the substrates. Single-walled nanotubes with diameters as small as 1 nm, bridging polysilicon and silicon dioxide “pillars”, have been grown. The morphology and structure of CNTs have been characterized by SEM, AFM and Raman spectroscopy.

  8. Preliminary Results from Duplex Procedure for Obtain of Fe Based Materials for Automotive Applications

    Science.gov (United States)

    Crăciun, R. C.; Stanciu, S.; Geantă, V.; Voiculescu, I.; Manole, V.; Gârneţ, I. A.; Alexandru, A.; Cimpoesu, N.; Săndulache, F.

    2017-06-01

    Abstract Iron based materials still represent a high percentage from metallic materials used in industry, in general, and in automotive industry, in particular. In this case we used a duplex process in order to obtain the FeMnSiAl experimental alloy for a more efficient use of various units. In the first stage iron, manganese, silicon and aluminum were melted and mixed together using arc melting technology and for the second stage the alloy was re-melt for homogeneity in an induction furnace. Chemical composition, after each melting step, was analyzed using EDS Bruker detector for various areas and microstructural characterization using SEM, VegaTescan LMH II with SE detector, equipment. This alloy is proposed as a metallic approach of mechanical dumpers used in automotive industry for low and medium impact contacts.

  9. Rapid magnetic hardening by rapid thermal annealing in NdFeB-based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Chu, K.-T.; Jin, Z Q; Chakka, Vamsi M; Liu, J P [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States)

    2005-11-21

    A systematic study of heat treatments and magnetic hardening of NdFeB-based melt-spun nanocomposite ribbons have been carried out. Comparison was made between samples treated by rapid thermal annealing and by conventional furnace annealing. Heating rates up to 200 K s{sup -1} were adopted in the rapid thermal processing. It was observed that magnetic hardening can be realized in an annealing time as short as 1 s. Coercivity of 10.2 kOe in the nanocomposites has been obtained by rapid thermal annealing for 1 s, and prolonged annealing did not give any increase in coercivity. Detailed results on the effects of annealing time, temperature and heating rate have been obtained. The dependence of magnetic properties on the annealing parameters has been investigated. Structural characterization revealed that there is a close correlation between magnetic hardening and nanostructured morphology. The coercivity mechanism was also studied by analysing the magnetization minor loops.

  10. Creep resistance in a new alloy based on Fe3Al

    International Nuclear Information System (INIS)

    Morris, D.G.

    1994-01-01

    Iron aluminide alloys based on the composition Fe 3 Al are receiving considerable attention as structural materials for applications at high temperatures in view of their excellent resistance to oxidation and corrosion as well as reasonable mechanical properties. Recently, problems associated with poor ductility at room temperature have been alleviated by small additions of Cr and by microstructure control, as well by as the realization that the low ductility is, in part, extrinsic behavior due to environmental attack. These materials suffer also from a loss of their good strength at temperatures above about 600 C, and recent attention has led also to the development of creep resistant alloys. The present report considers a new alloy developed for improved creep resistance which shows also good oxidation and erosion resistance. Effort has been devoted to an examination of the dislocation structures that characterize deformation, both cold and hot, during fast tensile straining as well as during creep testing

  11. FE-simulation of the initial stages of rafting in nickel-base superalloys

    International Nuclear Information System (INIS)

    Bioermann, H.; Feng Hua; Mughrabi, H.

    2000-01-01

    In the present work, the model of Socrate and Parks which takes into account the plastic deformation and which applies the method of finite elements (FE) using an energy-perturbation approach will be extended by the introduction of a further contribution to the driving force for rafting, cf. This additional driving force is based on the local variation of the hydrostatic stresses arising from the anisotropic distribution of dislocations after deformation, in combination with the different lattice parameters of the two phases γ and γ'. It is an alternative formulation of the driving force introduced recently. With the present model, the initial stages of rafting and the build-up of internal stresses and strains are determined. (orig.)

  12. Analytical expression for initial magnetization curve of Fe-based soft magnetic composite material

    Energy Technology Data Exchange (ETDEWEB)

    Birčáková, Zuzana, E-mail: zuzana.bircakova@upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 04154 Košice (Slovakia); Kollár, Peter; Füzer, Ján [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 04154 Košice (Slovakia); Bureš, Radovan; Fáberová, Mária [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Košice (Slovakia)

    2017-02-01

    The analytical expression for the initial magnetization curve for Fe-phenolphormaldehyde resin composite material was derived based on the already proposed ideas of the magnetization vector deviation function and the domain wall annihilation function, characterizing the reversible magnetization processes through the extent of deviation of magnetization vectors from magnetic field direction and the irreversible processes through the effective numbers of movable domain walls, respectively. As for composite materials the specific dependences of these functions were observed, the ideas were extended meeting the composites special features, which are principally the much higher inner demagnetizing fields produced by magnetic poles on ferromagnetic particle surfaces. The proposed analytical expression enables us to find the relative extent of each type of magnetization processes when magnetizing a specimen along the initial curve. - Highlights: • Analytical expression of the initial curve derived for SMC. • Initial curve described by elementary magnetization processes. • Influence of inner demagnetizing fields on magnetization process in SMC.

  13. Fe K-Edge X-ray absorption near-edge spectroscopy (XANES) and X-ray diffraction (XRD) analyses of LiFePO4 and its base materials

    Science.gov (United States)

    Latif, C.; Negara, V. S. I.; Wongtepa, W.; Thamatkeng, P.; Zainuri, M.; Pratapa, S.

    2018-03-01

    XANES analysis has been performed with the aim of knowing the Fe oxidation state in a synthesized LiFePO4 and its base materials. XANES measurements were performed at SLRI on energy around Fe K-edge. An XRD analysis has also been performed with the aim of knowing the phase composition, lattice parameters and crystallite size of the LiFePO4 as well as the base materials. From the XRD analysis, it was found that the dominating phase in the iron sand sample was Fe3O4 and the only phase found after calcination was LiFePO4. The latter phase exhibited crystallite size of 100 nm and lattice parameters a = 10.169916 Å, b = 5.919674 Å, c = 4.627893 Å. Qualitative analysis of XANES data revealed that the oxidation number of Fe in the sample before calcination was greater than that after calcination and Fe in the natural iron sand, indicated by the E0 values of 7129.2 eV, 7120.6 eV and 7124.4 eV respectively.

  14. A novel fluorescence probe based on triphenylamine Schiff base for bioimaging and responding to pH and Fe{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Yang, Xiaodong; Chen, Xiuli [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Zhou, Yuping [Guangdong Provincial key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Lu, Xiaodan; Yan, Chenggong; Xu, Yikai [Medical Imaging Center, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Liu, Ruiyuan, E-mail: ruiyliu@smu.edu.cn [Guangdong Provincial key Laboratory of New Drug Screening, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515 (China); Qu, Jinqing, E-mail: cejqqu@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China)

    2017-03-01

    A novel fluorescence probe 1 based on triphenylamine was synthesized and characterized by NMR, IR, high resolution mass spectrometry and elemental analysis. Its fluorescence was quenched when pH below 2. There was a linear relationship between the fluorescence intensity and pH value ranged from 2 to 7. And its fluorescence emission was reversibility in acidic and alkaline solution. Furthermore, it exhibited remarkable selectivity and high sensitivity to Fe{sup 3+} and was able to detect Fe{sup 3+} in aqueous solution with low detection limit of 0.511 μM. Job plot showed that the binding stoichiometry of 1 with Fe{sup 3+} was 1:1. Further observations of {sup 1}H NMR titration suggested that coordination interaction between Fe{sup 3+} and nitrogen atom on C =N bond promoted the intramolecular charge transfer (ICT) or energy transfer process causing fluorescence quenching. Additionally, 1 was also able to be applied for detecting Fe{sup 3+} in living cell and bioimaging. - Graphical abstract: Triphenylamine based fluorescence probe can detect pH and Fe{sup 3+} simultaneously in aqueous solution and be applied for detecting Fe{sup 3+} in living cell and bioimaging. - Highlights: • The fluorescence probe is sensitive to pH in strong acid conditions. • The fluorescence chemosensor can detect pH and Fe{sup 3+} simultaneously. • The recognition is able to carry out in aqueous solution. • The probe can also be applied for detecting Fe{sup 3+} in living cell and bioimaging. • The sensor is synthesized easily with one step.

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

    Science.gov (United States)

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

    2000-12-01

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

  16. Role of Sn impurity on electronic topological transitions in 122 Fe-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Haranath, E-mail: hng@rrcat.gov.in [Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094 (India); Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Sen, Smritijit [Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094 (India); Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2016-08-25

    We show that only a few percentage of Sn doping at the Ba site on BaFe{sub 2}As{sub 2}, can cause electronic topological transition, namely, the Lifshitz transition. A hole like d{sub xy} band of Fe undergoes electron like transition due to 4% Sn doping. Lifshitz transition is found in BaFe{sub 2}As{sub 2} system around all the high symmetry points. Our detailed first principles simulation predicts absence of any Lifshitz transition in other 122 family compounds like SrFe{sub 2}As{sub 2}, CaFe{sub 2}As{sub 2} in agreement with experimental observations. This work bears practical significance due to the facts that a few percentage of Sn impurity is in-built in tin-flux grown single crystals method of synthesizing 122 materials and inter-relationship among the Lifshitz transition, magnetism and superconductivity. - Highlights: • Electronic topological transition due to Sn contamination in BaFe{sub 2}As{sub 2}. • Hole like Fe-d{sub xy} band converts into electron like in 3% Sn contaminated BaFe{sub 2}As{sub 2}. • Electron like Fe-d{sub xz}, d{sub yz} bands moves above Fermi Level at X,Y points. • No Lifshitz transition found in Sn-contaminated Sr-122, Ca-122 systems.

  17. Development of Fe/Nb-based solar photocatalysts for water treatment: impact of different synthesis routes on materials properties.

    Science.gov (United States)

    Ribeiro, Marília C M; Amorim, Camila C; Moreira, Regina F P M; Oliveira, Luiz C A; Henriques, Andréia B; Leão, Mônica M D

    2018-04-27

    Semiconductors based on Fe/Nb oxides can present both solar sensitivity and high catalytic activity. However, there is still a lack regarding the comparison between different routes to produce Fe/Nb-based solar photocatalysts and the evaluation of the impact of the synthesis operating conditions on the material properties. In this work, Fe/Nb 2 O 5 ratio, type of precipitating agent, presence/absence of washing stage, and temperature of calcination were verified to be the most relevant parameters in the synthesis by the co-precipitation method. These factors led to remarkable differences in the properties and performance of the photocatalysts produced by each distinct synthesis route. Composition, iron species present in the materials, crystallinity characteristics, and pH of the catalysts were affected, leading to different photocatalytic activities under UV-Vis light. Due to their characteristics, the synthesized materials are potential photocatalysts for application in solar processes. Graphical abstract ᅟ.

  18. Synthesis and densification of Cu added Fe-based BMG composite powders by gas atomization and electrical explosion of wire

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.C., E-mail: jckimpml@ulsan.ac.k [University of Ulsan, School of Materials Science and Engineering, Ulsan 680-749 (Korea, Republic of); Ryu, H.J.; Kim, J.S. [University of Ulsan, School of Materials Science and Engineering, Ulsan 680-749 (Korea, Republic of); Kim, B.K.; Kim, Y.J. [Department of Powder Materials, Korea Institute of Materials Science, Changwon 641-831 (Korea, Republic of); Kim, H.J. [Advanced Materials Division, Korea Institute of Industrial Technology, Incheon 406-130 (Korea, Republic of)

    2009-08-26

    In this study, the Fe-based (Fe-C-Si-B-P-Cr-Mo-Al) BMG powders were produced by the high pressure gas atomization process, and they were combined with the ductile Cu powders produced by the electrical explosion of wire (EEW). The Fe-based amorphous powders and Cu added BMG composite powders were compacted by the spark plasma sintering (SPS) processes into cylindrical shape. In the SPS press, the as-prepared powders were sintered at 793 K and 843 K. The relative density increased to 98% when the pressure increased up to 500 MPa by optimum control of the SPS process parameters. The micro-Vickers hardness was over 1100 Hv.

  19. XMCD study of the local magnetic and structural properties of microcrystalline NdFeB-based alloys

    Science.gov (United States)

    Menushenkov, A. P.; Ivanov, V. G.; Shchetinin, I. V.; Zhukov, D. G.; Menushenkov, V. P.; Rudnev, I. A.; Ivanov, A. A.; Wilhelm, F.; Rogalev, A.; Savchenko, A. G.

    2017-01-01

    X-ray Magnetic Circular Dichroism (XMCD) technique was used to investigate local magnetic properties of microcrystalline Nd10.4Zr4.0Fe79.2B6.4 samples, oriented along either easy or hard magnetization direction. The Nd L 2,3 and Fe K edge XMCD spectra were measured at room temperature under a magnetic field of T. A very strong dependence of XMCD spectra on the sample orientation has been observed at the Nd L 2,3-edges, whereas the Fe K-edge XMCD spectra are found to be practically isotropic. This result indicates that magnetic anisotropy of NdFeB-based alloys originates from the Nd sublattice. In addition, element selective magnetization curves have been recorded by measuring the intensity of XMCD signals as a function of an applied magnetic field up to T. To find a correlation between local and macroscopic magnetic properties of studied samples we compared these data with magnetization curves, measured by vibrating sample magnetometer up to T. Results are important for understanding the origin of high-coercivity state in NdFeB-based intermetallic compounds.

  20. Electron-irradiation induced changes in structural and magnetic properties of Fe and Co based metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kane, S.N., E-mail: kane_sn@yahoo.com [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Satalkar, M., E-mail: satalkar.manvi@gmail.com [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Ghosh, A.; Shah, M. [School of Physics, D.A. University, Khandwa Road Campus, Indore 452001 (India); Ghodke, N. [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001 (India); Pramod, R.; Sinha, A.K.; Singh, M.N.; Dwivedi, J. [Raja Ramanna Centre for Advanced Technology, P.O. CAT, Indore 452013 (India); Coisson, M.; Celegato, F.; Vinai, F.; Tiberto, P. [INRIM, Electromagnetism Division, Strada Delle Cacce 91, I-10135 TO (Italy); Varga, L.K. [RISSPO, Hungarian Academy of Sciences, P.O. Box 49, 1525 Budapest (Hungary)

    2014-12-05

    Highlights: • Enhancement of Ms by low electron irradiation dose in Fe-based alloy. • Variation of magnetic properties by electron irradiation induced ordered phase. • Electron irradiation alters TM-TM distance and, magnetic properties. - Abstract: Electron-irradiation induced changes in structural and, magnetic properties of Co{sub 57.6}Fe{sub 14.4}Si{sub 4.8}B{sub 19.2}Nb{sub 4}, Fe{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4} and, Co{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4} metallic glasses were studied using magnetic hysteresis and, synchrotron X-ray diffraction measurements. Results reveal composition dependent changes of magnetic properties in electron irradiated metallic glasses. A low electron irradiation dose (15 kGy) enhances saturation magnetization (up to 62%) in Fe-based alloy (Fe{sub 72}Si{sub 4.8}B{sub 19.2}Nb{sub 4}). Synchrotron XRD measurements reveal that electron irradiation transforms the amorphous matrix to a more ordered phase, accountable for changes in magnetic properties.

  1. Multi-scale Modelling of bcc-Fe Based Alloys for Nuclear Applications

    International Nuclear Information System (INIS)

    Malerba, Lorenzo

    2008-01-01

    Understanding the basic mechanisms that determine microstructure changes in neutron irradiated steels is vital for a safe lifetime management of existing nuclear reactors and a safe design of future nuclear options. Low-alloyed ferritic steels containing Cu, Ni, Mn and Si as principal solute atoms are used as structural materials for current reactor vessels. The microstructural evolution under irradiation in alloys is decided by the interplay between defect formation and thermodynamic driving forces, together determining the appearance of phase transformations (precipitation, segregation,...) and favouring or delaying the nucleation and growth of point-defect clusters, their diffusion and their mutual recombination or removal at sinks. A reliable description of the production, evolution and accumulation of radiation damage must therefore start from the atomic level and requires being able to describe multicomponent systems for timescales ranging from few picoseconds to years. This goal demands firstly the fabrication of interatomic potentials for alloys that must be both consistent with the thermodynamic properties of the system and capable of reproducing correctly the characteristic solute-point defect interactions, versus ab initio or experimental data. Secondly the performance of extensive molecular dynamics (MD) simulations, to grasp the main mechanisms of defect production, diffusion, mutual interaction, and interaction with solute atoms and impurities. Thirdly, the development of simulation tools capable of describing the microstructure evolution beyond the time-frame and length-scale of MD, while reproducing as much as possible the atomic-level origin of the mechanisms governing the evolution of the system, including phase changes. In this presentation the results of recent efforts made in this direction in the case of Fe-Cu, Fe-Cr and Fe-Ni alloys, as basic model alloys for the description of steels of technological relevance, are highlighted. In particular

  2. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    International Nuclear Information System (INIS)

    Lavorato, G.C.; Fiore, G.; Castellero, A.; Baricco, M.; Moya, J.A.

    2012-01-01

    Amorphous alloys with composition (at%) Fe 48 Cr 15 Mo 14 C 15 B 6 Gd 2 (alloy A) and Fe 48 Cr 15 Mo 14 C 15 B 6 Y 2 (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness (∼13 GPa) and the Young modulus (∼180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  3. Preparation and characterization of Fe-based bulk metallic glasses in plate form

    Energy Technology Data Exchange (ETDEWEB)

    Lavorato, G.C. [INTECIN (FIUBA-CONICET), Paseo Colon 850, Capital Federal (Argentina); Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Fiore, G.; Castellero, A.; Baricco, M. [Dipartimento di Chimica IFM and NIS, Universita di Torino, Torino (Italy); Moya, J.A., E-mail: jmoya.fi.uba@gmail.com [IESIING, Facultad de Ingenieria e Informatica, UCASAL, Salta (Argentina); CONICET (Argentina)

    2012-08-15

    Amorphous alloys with composition (at%) Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Gd{sub 2} (alloy A) and Fe{sub 48}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Y{sub 2} (alloy B) were prepared either using pure elements (A and B1) and a commercial AISI430 steel as a base material (B2). When prepared from pure elements both alloys (A and B1) could be cast in plate form with a fixed thickness of 2 mm and variable lengths between 10 and 20 mm by means of copper-mold injection in air atmosphere. In the case of alloy B2, prepared using commercial grade raw materials, rods of 2 mm diameter were obtained. X-ray diffraction and scanning electron microscopy observations confirmed that an amorphous structure was obtained in all the as-cast samples. A minor fraction of crystalline phases (oxides and carbides) was detected on the as-cast surface. Differential scanning calorimetry measurements showed a glass transition temperature at 856 K for alloy A and 841 K for alloy B1, and an onset crystallization temperature of 887 K for alloy A and 885 K for alloy B1. In the case of alloy B2 a slightly different crystallization sequence was observed. Values of hardness ({approx}13 GPa) and the Young modulus ({approx}180 GPa) were measured by nanoindentation for both the alloys. The effects of adverse casting conditions (such as air atmosphere, non-conventional injection copper mold casting and partial replacement of pure elements with commercial grade raw materials) on the glass formation and properties of the alloy are discussed.

  4. Synthesis of Fe-Al-Ti Based Intermetallics with the Use of Laser Engineered Net Shaping (LENS

    Directory of Open Access Journals (Sweden)

    Monika Kwiatkowska

    2015-04-01

    Full Text Available The Laser Engineered Net Shaping (LENS technique was combined with direct synthesis to fabricate L21-ordered Fe-Al-Ti based intermetallic alloys. It was found that ternary Fe-Al-Ti alloys can be synthesized using the LENS technique from a feedstock composed of a pre-alloyed Fe-Al powder and elemental Ti powder. The obtained average compositions of the ternary alloys after the laser deposition and subsequent annealing were quite close to the nominal compositions, but the distributions of the elements in the annealed samples recorded over a large area were inhomogeneous. No traces of pure Ti were observed in the deposited alloys. Macroscopic cracking and porosity were observed in all investigated alloys. The amount of porosity in the samples was less than 1.2 vol. %. It seems that the porosity originates from the porous pre-alloyed Fe-Al powders. Single-phase (L21, two-phase (L21-C14 and multiphase (L21-A2-C14 Fe-Al-Ti intermetallic alloys were obtained from the direct laser synthesis and annealing process. The most prominent feature of the ternary Fe-Al-Ti intermetallics synthesized by the LENS method is their fine-grained structure. The grain size is in the range of 3–5 μm, indicating grain refinement effect through the highly rapid cooling of the LENS process. The Fe-Al-Ti alloys synthesized by LENS and annealed at 1000 °C in the single-phase B2 region were prone to an essential grain growth. In contrast, the alloys annealed at 1000 °C in the two-phase L21-C14 region exhibited almost constant grain size values after the high-temperature annealing.

  5. Highly Sensitive Colorimetric Assay for Determining Fe3+ Based on Gold Nanoparticles Conjugated with Glycol Chitosan

    Directory of Open Access Journals (Sweden)

    Kyungmin Kim

    2017-01-01

    Full Text Available A highly sensitive and simple colorimetric assay for the detection of Fe3+ ions was developed using gold nanoparticles (AuNPs conjugated with glycol chitosan (GC. The Fe3+ ion coordinates with the oxygen atoms of GC in a hexadentate manner (O-Fe3+-O, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the bound Fe3+ was coordinated to the oxygen atoms of the ethylene glycol in GC, which resulted in a significant color change from light red to dark midnight blue due to aggregation. Using this GC-AuNP probe, the quantitative determination of Fe3+ in biological, environmental, and pharmaceutical samples could be achieved by the naked eye and spectrophotometric methods. Sensitive response and pronounced color change of the GC-AuNPs in the presence of Fe3+ were optimized at pH 6, 70°C, and 300 mM NaCl concentration. The absorption intensity ratio (A700/A510 linearly correlated to the Fe3+ concentration in the linear range of 0–180 μM. The limits of detection were 11.3, 29.2, and 46.0 nM for tap water, pond water, and iron supplement tablets, respectively. Owing to its facile and sensitive nature, this assay method for Fe3+ ions can be applied to the analysis of drinking water and pharmaceutical samples.

  6. Cluster-based bulk metallic glass formation in Fe-Si-B-Nb alloy systems

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, C L; Wang, Q; Li, F W; Li, Y H; Wang, Y M; Dong, C [State Key Laboratory of Materials Modification, Dalian University of Technology (DUT), Dalian 116024 (China); Zhang, W; Inoue, A, E-mail: dong@dlut.edu.c [Institute for Materials Research (IMR), Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

    2009-01-01

    Bulk metallic glass formations have been explored in Fe-B-Si-Nb alloy system using the so-called atomic cluster line approach in combination with minor alloying guideline. The atomic cluster line refers to a straight line linking binary cluster to the third element in a ternary system. The basic ternary compositions in Fe-B-Si system are determined by the inetersection points of two cluster lines, namely Fe-B cluster to Si and Fe-Si cluster to B, and then further alloyed with 3-5 at. % Nb for enhancing glass forming abilities. BMG rods with a diameter of 3 mm are formed under the case of minor Nb alloying the basic intersecting compositions of Fe{sub 8}B{sub 3}-Si with Fe{sub 12}Si-B and Fe{sub 8}B{sub 2}-Si with Fe{sub 9}Si-B. The BMGs also exhibit high Vickers hardness (H{sub v}) of 1130-1164 and high Young's modulous (E) of 170-180 GPa

  7. {Fe6O2}-Based Assembly of a Tetradecanuclear Iron Nanocluster

    Directory of Open Access Journals (Sweden)

    Svetlana G. Baca

    2011-01-01

    Full Text Available The tetradecanuclear FeIII pivalate nanocluster [Fe14O10(OH4(Piv18], comprising a new type of metal oxide framework, has been solvothermally synthesized from a hexanuclear iron pivalate precursor in dichlormethane/acetonitrile solution. Magnetic measurements indicate the presence of very strong antiferromagnetic interactions in the cluster core.

  8. Ferroelectric domain switching dynamics and memristive behaviors in BiFeO3-based magnetoelectric heterojunctions

    Science.gov (United States)

    Huang, Weichuan; Liu, Yukuai; Luo, Zhen; Hou, Chuangming; Zhao, Wenbo; Yin, Yuewei; Li, Xiaoguang

    2018-06-01

    The ferroelectric domain reversal dynamics and the corresponding resistance switching as well as the memristive behaviors in epitaxial BiFeO3 (BFO, ~150 nm) based multiferroic heterojunctions were systematically investigated. The ferroelectric domain reversal dynamics could be described by the nucleation-limited-switching model with the Lorentzian distribution of logarithmic domain-switching times. By engineering the domain states, multi and even continuously tunable resistances states, i.e. memristive states, could be non-volatilely achieved. The resistance switching speed can be as fast as 30 ns in the BFO-based multiferroic heterojunctions with a write voltage of ~20 V. By reducing the thickness of BFO, the La0.6Sr0.4MnO3/BFO (~5 nm)/La0.6Sr0.4MnO3 multiferroic tunnel junction (MFTJ) shows an even a quicker switching speed (20 ns) with a much lower operation voltage (~4 V). Importantly, the MFTJ exhibits a tunable interfacial magnetoelectric coupling related to the ferroelectric domain switching dynamics. These findings enrich the potential applications of multiferroic BFO based devices in high-speed, low-power, and high-density memories as well as future neuromorphic computational architectures.

  9. A Comparative Study of the Microstructure, Mechanical Properties and Corrosion Resistance of Ni- or Fe- Based Composite Coatings by Laser Cladding

    Science.gov (United States)

    Wan, M. Q.; Shi, J.; Lei, L.; Cui, Z. Y.; Wang, H. L.; Wang, X.

    2018-04-01

    Ni- and Fe-based composite coatings were laser cladded on 40Cr steel to improve the surface mechanical property and corrosion resistance, respectively. The microstructure and phase composition were analyzed by x-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) equipped with an energy-dispersive spectrometer (EDS). The micro-hardness, tribological properties and electrochemical corrosion behavior of the coatings were evaluated. The results show that the thickness of both the coatings is around 0.7 mm, the Ni-based coating is mainly composed of γ-(Ni, Fe), FeNi3, Ni31Si12, Ni3B, CrB and Cr7C3, and the Fe-based coating is mainly composed of austenite and (Fe, Cr)7C3. Micro-hardness of the Ni-based composite coating is about 960 HV0.3, much higher than that of Fe-based coating (357.4 HV0.3) and the 40Cr substrate (251 HV0.3). Meanwhile, the Ni-based composite coating possesses better wear resistance than the Fe-based coating validated by the worn appearance and the wear loss. Electrochemical results suggested that Ni-based coating exhibited better corrosion resistance than the Fe-based coating. The 40Cr substrate could be well protected by the Ni-based coating.

  10. Analysis of the Glass-Forming Ability of Fe-Er Alloys, Based on Thermodynamic Modeling

    Science.gov (United States)

    Arutyunyan, N. A.; Zaitsev, A. I.; Dunaev, S. F.; Kalmykov, K. B.; El'nyakov, D. D.; Shaposhnikov, N. G.

    2018-05-01

    The Fe-Er phase diagram and thermodynamic properties of all its phases are assessed by means of self-consistent analysis. To refine the data on phase equilibria in the Fe-Er system, an investigation is performed in the 10-40 at % range of Er concentrations. The temperature-concentration dependences of the thermodynamic properties of a melt are presented using the model of ideal associated solutions. Thermodynamic parameters of each phase are obtained, and the calculated results are in agreement with available experimental data. The correlation between the thermodynamic properties of liquid Fe-Er alloys and their tendency toward amorphization are studied. It is shown that compositions of amorphous alloys prepared by melt quenching coincide with the ranges of concentration with the predominance of Fe3Er and FeEr2 associative groups that have large negative entropies of formation.

  11. Phase formation and crystallization behavior of melt spun Sm-Fe-based alloys

    International Nuclear Information System (INIS)

    Shield, J.E.

    1999-01-01

    The phase formation and microstructures of Sm-Fe alloys have been investigated at Sm levels of 11 and 17 atomic percent and with alloying additions of Ti and C. At lower Sm content, virtually phase pure SmFe 7 formed, while higher Sm content resulted in the formation of SmFe 7 , SmFe 2 and amorphous phases. The addition of Ti and C resulted in greater stability and a larger volume fraction of the amorphous phase. The binary Sm-Fe alloys at both Sm levels had tremendously variable microstructures, with large discrepancies in grain size and phase distribution from region to region. The addition of Ti and C tended to result in a more homogeneous microstructure, as well as a refinement in the microstructural scale. (orig.)

  12. Fe based amorphous and compounds metallic alloys for magnetic and structural use

    International Nuclear Information System (INIS)

    Lavorato, G; Bassi, F; De Rosa, H; Moya, J

    2008-01-01

    Massive amorphous metals (thicker than 1mm) are new types of material that could have a wide range of future applications due to a unique combination of their physical properties, mechanics and magnetics. Among these are the elevated tension of fracture and hardness, and excellent soft magnetic properties. Since 1960, when an amorphous metallic alloy was first discovered, progress has continued on the application possibilities for these materials. One of their main limitations, maximum obtainable thickness, has continued to increase, since at first thicknesses of a few microns were obtained. Now amorphous alloys more than 70 mm thick are obtained using different metallic elements. Since 1995 massive amorphous metals can be produced using Fe as the base element. At first they were made in order to achieve good soft magnetic properties (thicknesses of ∼5 mm) and later a renewed interest in their use as structural material led to the development of materials with thicknesses of 16 mm and paramagnetics at room temperature. Increasing the toughness of these materials is also a challenge and investigators have proposed several solutions, among them is the development of composite materials where dendrites from a solid solution act as crack stoppers of fissures that are spread by an amorphous matrix. This work presents the results of studies with two types of synthesized materials using the rapid cooling technique from injection copper mold casting at air temperature: 1) a massive amorphous metallic alloy with composition (Fe 0.375 Co 0 .375 B 0.2 Si 0.05 )96Nb 4 (at.%) and 2) a composite of solid solution dendrites α-(FeCo) scattered in an amorphous matrix with a composition similar to alloy 1. Using the samples obtained structural studies were made (optic and electronic microscopy SEM, XRD, EDAX, DTA), magnetic studies (coercive field and saturation magnetization) and mechanical studies (Vickers microhardness). The fully amorphous alloy could be obtained with a

  13. Oxide Dispersion Strengthened Fe(sub 3)Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    Energy Technology Data Exchange (ETDEWEB)

    Kad, B.K.

    1999-07-01

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe3Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100C in the power generation industry. A particular 'in service application' anomaly of Fe3Al-based alloys is that the environmental resistance is maintained up to 1200C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism.

  14. Study of Fe-Ni-Si-B alloy and films on its base by X-ray photospectroscopy method

    International Nuclear Information System (INIS)

    Kozlenko, V.G.; Parfenenok, M.A.; Pukhov, I.K.; Shaposhnikov, A.N.; Shirkov, A.V.

    1983-01-01

    By the method of X ray photoelectron spectroscopy the chemical composition of Fe-Ni-Si-B alloy and films on its base prepared by ion-plasma sputtering is investigated. The identity of chemical bonds in film samples and initial target is revealed, realized are in them mostly Fe-B, Ni-C, Si-Si interatomic bonds. It is shown that lono. films contact with atmosphere is the cause of difference of film composition in the near-surface region (up to 100 nm) from its main volume composition

  15. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    Directory of Open Access Journals (Sweden)

    J. Rogge

    2015-07-01

    Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  16. Tetragonal Ce-based Ce-Sm(Fe, Co, Ti){sub 12} alloys for permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Cid, Andres; Salazar, Daniel [BCMaterials, Bizkaia Science and Tecnology Park, 48160 Derio (Spain); Gabay, Aleksandr M.; Hadjipanayis, George C. [Department of Physics and Astronomy, University of Delaware, Newark, DE, 19716 (United States); Barandiaran, Jose Manuel [BCMaterials, Bizkaia Science and Tecnology Park, 48160 Derio (Spain); Department of Electricity and Electronics, University Basque Country (UPV/EHU), 48080 Bilbao (Spain)

    2016-12-15

    Abundance and relatively low cost of Ce provide a great incentive for its use in rare-earth permanent magnets. It has been recently reported that the tetragonal Ce(Fe,Co,Ti)12 compounds may exhibit application-worthy intrinsic magnetic properties. In this work the effect of the α-Fe phase formation due to the evaporation of Sm during alloy fabrication has been studied, as a previous step in the attempt to convert the intrinsic magnetic properties into functional properties of a permanent magnet. Ce{sub 0.5}Sm{sub 0.5}Fe{sub 9}Co{sub 2}Ti alloys based on the ThMn12-type crystal structure have been synthesized via melt-spinning with different Sm content. Coercive fields between 2.8 and 1.4 kOe have been found for α-Fe phase contents between 8 and 46% in volume, showing the influence of the α-Fe phase on the coercivity and exchange coupling between the hard and soft phase. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Wear and Corrosion Resistance of Fe Based Coatings by HVOF Sprayed on Gray Cast-Iron for Automotive Application

    Directory of Open Access Journals (Sweden)

    M.S. Priyan

    2014-12-01

    Full Text Available In this study, commercially available FeSiNiCr and FeBCr alloy powders were designed with suitable compositions, gas atomized and then coated on gray cast-iron substrate. The microstructures of the feed stock Fe based alloy powders and the coatings were investigated by means of optical microscopy (OM, X-Ray diffraction (XRD, Thermogravimetric analysis (TGA and Scanning Electron Microscopy (SEM. In the present study, both the coating materials experienced two-body wear mechanisms. The results showed that for loads of 0.05 N, 0.1 N and 0.2 N, the wear resistance of FeBCr coating was less than FeSiNiCr by 44 %, 40 % and 31 %, respectively. The results indicated that the coated substrates exhibited lower corrosion current densities and lower corrosion rates, when placed in 20 wt.% H2SO4 solutions. In addition, the use of optimal spraying parameters/conditions gave improvements to the corrosion resistance of the substrates that had been treated with the crystalline coating.

  18. Fe3C-based oxygen reduction catalysts: synthesis, hollow spherical structures and applications in fuel cells

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei

    2015-01-01

    We present a detailed study of a novel Fe3C-based spherical catalyst with respect to synthetic parameters, nanostructure formation, ORR active sites and fuel cell demonstration. The catalyst is synthesized by high temperature autoclave pyrolysis using decomposing precursors. Below 500 °C, melamine...

  19. Upper critical fields and critical current densities of Fe-based superconductors as compared to those of other technical superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pallecchi, I., E-mail: ilaria.pallecchi@spin.cnr.it [CNR-SPIN, Corso Perrone 24, 16152 Genova (Italy); Tropeano, M. [Columbus Superconductors S.p.A, Via delle Terre Rosse 30, 16133 Genova (Italy); Lamura, G. [CNR-SPIN, Corso Perrone 24, 16152 Genova (Italy); Pani, M. [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Palombo, M. [Columbus Superconductors S.p.A, Via delle Terre Rosse 30, 16133 Genova (Italy); Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy); Palenzona, A. [Dipartimento di Chimica e Chimica Industriale, Universita di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Putti, M. [CNR-SPIN, Corso Perrone 24, 16152 Genova (Italy); Dipartimento di Fisica, Universita di Genova, Via Dodecaneso 33, 16146 Genova (Italy)

    2012-11-20

    Three years since the discovery by the Hosono's group of Fe-based superconductors, an enormous number of compounds, belonging to several different families have been discovered and fundamental properties have been deeply investigated in order to clarify the interplay between magnetisms and superconductivity in these compounds. Indeed, the actual potential of these compounds for practical applications remains still unclear. Fe-based superconductors are midway between high temperature superconductors (HTSCs) and MgB{sub 2}. In Fe-based superconductors the critical current is rather independent of the field, similarly to HTSCs, as a consequence of the exceptionally high upper critical field and strong pinning associated with nm-scale local modulations of the order parameter. They exhibit low anisotropy of the critical current with respect to the crystalline directions, as in the case of MgB{sub 2}, which allows current flow along the c-axis. However, Fe-based superconductor polycrystalline materials currently available still exhibit electromagnetic granularity, like the HTSCs, which suppresses superconducting current flow over long length. Whether the nature of such granularity is extrinsic, as due to spurious phases or cracks between grains or intrinsic, as related to misalignment of adjacent grains, is under debate. These aspects will be reviewed in the light of the recent literature.

  20. Adsorption of methyl violet from aqueous solution using gum xanthan/Fe3O4 based nanocomposite hydrogel

    CSIR Research Space (South Africa)

    Mittal, H

    2016-08-01

    Full Text Available This research paper reports the utilization of gum xanthan-grafted-polyacrylic acid and Fe(sub3)O(sub4) magnetic nanoparticles based nanocomposite hydrogel (NCH) for the highly effective adsorption of methyl violet (MV) from aqueous solution...

  1. On the nature of the variation of martensitic transformation hysteresis and SME characteristics in Fe-Ni-base alloys

    International Nuclear Information System (INIS)

    Koval, Yu.N.; Monastyrsky, G.E.

    1995-01-01

    The purpose of this paper is to summarize the various investigations, both by the authors and other works, concerning with the martensitic transformation and SME in Fe-Ni-base alloys. The thermal hysteresis dependence on the alloying elements and thermal treatments are surveyed. The contribution and effect on SME characteristics of widely used alloying elements such as Ti, Nb, Ni, Al, Co, Ta and peculiarities of thermal treatment are discussed. It is noted the main goal of these treatments is to reduce the symmetry of transformation by the ordering or precipitation of a fine coherent phase. The physical principles of transformation hysteresis manipulation in Fe-base alloys is discussed and it concluded that the thermal cycling behavior of Fe-base alloys is very complex and is not clearly understood at present. On the other hand, it is pointed out that thermal cycling is an effective method for control and improvement of SME in these alloys. It is concluded that Fe-base alloys are highly evolved shape memory materials-having a wide working range, good workability and are relatively cheap. In addition, the properties are easily controlled by suitably alloying, aging and thermal cycling. (orig.)

  2. Effect of molybdenum and chromium additions on the mechanical properties of Fe3Al-based alloys

    International Nuclear Information System (INIS)

    Sun Yangshan; Xue Feng; Mei Jianping; Yu Xingquan; Zhang Lining

    1995-01-01

    Iron aluminides based on Fe 3 Al offer excellent oxidation and sulfidation resistance, with lower material cost and density than stainless steels. However, their potential use as structural material has been hindered by limited ductility and a sharp drop in strength above 600 C. Recent development efforts have indicated that adequate engineering ductility of 10--20% and tensile yield strength of as high as 500 MPa can be achieved through control of composition and microstructure. These improved tensile properties make Fe 3 Al-based alloys more competitive against conventional austenic and ferritic steels. The improvement of high temperature mechanical properties has been achieved mainly by alloying processes. Molybdenum has been found to be one of the most important alloying elements for strengthening Fe 3 Al-based alloys at high temperatures. However, the RT(room temperature) ductility decreases with the increase of a molybdenum addition. On the other hand, a chromium addition to Fe 3 Al-based alloys is very efficient for improving RT ductility but not beneficial to yield strength at temperatures to 800 C. The purpose of the present paper is to report the effects of combined additions of molybdenum and chromium on mechanical properties at ambient temperature and high temperature of 600 C

  3. Demonstration of Security Benefits of Renewable Generation at FE Warren Air Force Base

    International Nuclear Information System (INIS)

    Warwick, William M.; Myers, Kurt; Seifert, Gary

    2010-01-01

    Report detailing field demonstration of security benefits of renewable generation at FE Warren Air Force Base. The 2006 National Defense Appropriations Act directed the Department of Defense (DOD) to coordinate the testing of a wind turbine (new to the U.S. market) at an Air Force installation as a follow on to analyses conducted by the Pacific Northwest National Laborabory (PNNL) as part of the 2005 DOD Renewable Assessment. The earlier study simulated the performance of renewable power produced from wind turbines, solar photovoltaics and geothermal energy as part of a Base-wide energy security solution. The simulation concluded that integration of renewable generating resources with emergency generators, typically diesel-fired, could significantly enhance energy security and extend power supplies during prolonged commercial grid power outages. A simulation is insufficient to convince skeptics of the reliability of renewable resources, especially those that produce power only intermittently, like wind and solar. Therefore, Congress requested a field demonstration be performed using a wind turbine because wind power is the most erratic of all renewable resources. Following this direction, the Air Force identified a site for the wind turbine demonstration and contracted with the Idaho National Laboratory (INL) and PNNL to conduct the demonstration and implement other provisions in the appropriation bill. INL identified a wind turbine that met the legislative requirements (the Gamesa G-80), and with the support of PNNL and the Air Force, selected FE Warren Air Force Base for the demonstration. FE Warren has an excellent wind resource and was already a host to two wind turbines and could accommodate a third. The G-80 is rated at 2 MWs versus the two existing 660 kW turbines, consequently wind production would more than double. Procurement, siting, and acceptance testing of the new turbine was completed in early 2010. The field test was conducted in late April 2010

  4. Crystallization and atomic diffusion behavior of high coercive Ta/Nd-Fe-B/Ta-based permanent magnetic thin film

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Na; Zhang, Xiao; You, Caiyin; Fu, Huarui [Xi' an University of Technology, School of Materials Science and Engineering, Xi' an (China); Shen, Qianlong [Logistics University of People' s Armed Police Force, Tianjin (China)

    2017-06-15

    A high coercivity of about 20.4 kOe was obtained through post-annealing the sputtered Ta/Nd-Fe-B/Ta-based permanent magnetic thin films. Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses were performed to investigate the crystallization and atomic diffusion behaviors during post-annealing. The results show that the buffer and capping Ta layers prefered to intermix with Fe and B atoms, and Nd tends to be combined with O atoms. The preferred atomic combination caused the appearance of the soft magnetic phase of Fe-Ta-B, resulting in a kink of the second quadratic magnetic hysteresis loop. The preferred atomic diffusion and phase formation of the thin films were well explained in terms of the formation enthalpy of the various compounds. (orig.)

  5. Effect of pre-deformation temperature on reverse transformation characteristic in Fe-Mn-Si based alloys

    International Nuclear Information System (INIS)

    Wang, D.; Xing, X.; Chen, J.; Dong, Z.; Liu, W.

    2000-01-01

    Two alloys of A: Fe-28Mn-6Si-5Cr(wt.%) and B: Fe-13Mn-5Si-12Cr-6Ni(wt.%) with different Ms temperatures were selected to be subjected to tensile deformation under different temperatures. The effect of deformation temperature on shape memory effect (SME) and the reverse transformation kinetics were studied respectively. It was found that: (1) The best SME could be obtained by deformation at Ms temperature; (2) The As temperature varied with deformation temperature. The lower the deformation temperature was, the lower the As temperature would be; (3) Some non-transformation related strain recovery between deformation temperature and As temperature was observed to be resulted from the retraction of stacking faults. The facts that the variation of As temperature with deformation temperature, as well as the non-transformation strain recovery imply that the γ→ε martensitic transformation in Fe-Mn-Si based shape memory alloys exhibits quasithermoelastic property. (orig.)

  6. Modeling Equilibrium Fe Isotope Fractionation in Fe-Organic Complexes: Implications for the use of Fe Isotopes as a Biomarker and Trends Based on the Properties of Bound Ligands

    Science.gov (United States)

    Domagal-Goldman, S.; Kubicki, J. D.

    2006-05-01

    Fe Isotopes have been proposed as a useful tracer of biological and geochemical processes. Key to understanding the effects these various processes have on Fe isotopes is accurate modeling of the reactions responsible for the isotope fractionations. In this study, we examined the theoretical basis for the claims that Fe isotopes can be used as a biomarker. This was done by using molecular orbital/density functional theory (MO/DFT) calculations to predict the equilibrium fractionation of Fe isotopes due to changes in the redox state and the bonding environment of Fe. Specifically, we predicted vibrational frequencies for iron desferrioxamine (Fe-DFOB), iron triscatechol (Fe(cat)3), iron trisoxalate (Fe(ox)3), and hexaaquo iron (Fe(H2O)6) for complexes containing both ferrous (Fe2+) and ferric (Fe3+) iron. Using these vibrational frequencies, we then predicted fractionation factors between these six complexes. The predicted fractionation factors resulting from changes in the redox state of Fe fell in the range 2.5- 3.5‰. The fractionation factors resulting from changes in the bonding environment of Fe ranged from 0.2 to 1.4‰. These results indicate that changes in the bonding strength of Fe ligands are less important to Fe isotope fractionation processes than are changes to the redox state of Fe. The implications for use of Fe as a tracer of biological processes is clear: abiological redox changes must be ruled out in a sample before Fe isotopes are considered as a potential biomarker. Furthermore, the use of Fe isotopes to measure the redox state of the Earths surface environment through time is supported by this work, since changes in the redox state of Fe appear to be the more important driver of isotopic fractionations. In addition to the large differences between redox-driven fractionations and ligand-driven fractionations, we will also show general trends in the demand for heavy Fe isotopes as a function of properties of the bound ligand. This will help the

  7. Tuning glass formation and brittle behaviors by similar solvent element substitution in (Mn,Fe)-based bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tao [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Li, Ran, E-mail: liran@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Xiao, Ruijuan [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Gang [State Key Laboratory for Mechanical Behavior of Materials, School of Materials Science and Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, Jianfeng [School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001 (China); Zhang, Tao, E-mail: zhangtao@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2015-02-25

    A family of Mn-rich bulk metallic glasses (BMGs) was developed through the similar solvent elements (SSE) substitution of Mn for Fe in (Mn{sub x}Fe{sub 80−x})P{sub 10}B{sub 7}C{sub 3} alloys. The effect of the SSE substitution on glass formation, thermal stability, elastic constants, mechanical properties, fracture morphologies, Weibull modulus and indentation fracture toughness was discussed. A thermodynamics analysis provided by Battezzati et al. (L. Battezzati, E. Garrone, Z. Metallkd. 75 (1984) 305–310) was adopted to explain the compositional dependence of the glass-forming ability (GFA). The elastic moduli follow roughly linear correlations with the substitution concentration of Mn in (Mn{sub x}Fe{sub 80−x})P{sub 10}B{sub 7}C{sub 3} BMGs. The introduction of Mn to replace Fe significantly decreases the plasticity of the resulting BMGs and the Weibull modulus of the fracture strength. A super-brittle Mn-based BMGs of (Mn{sub 55}Fe{sub 25})P{sub 10}B{sub 7}C{sub 3} BMGs were found with the indentation fracture toughness (K{sub c}) of 1.91±0.04 MPa m{sup 1/2}, the lowest value among all kinds of BMGs so far. The atomic and electronic structure of the selected BMGs were simulated by the first principles molecular dynamics calculations based on density functional theory, which provided a possible understanding of the brittleness caused by the similar chemical element replacement of Mn for Fe.

  8. Emissions from a Diesel Engine using Fe-based Fuel Additives and a Sintered Metal Filtration System.

    Science.gov (United States)

    Bugarski, Aleksandar D; Hummer, Jon A; Stachulak, Jozef S; Miller, Arthur; Patts, Larry D; Cauda, Emanuele G

    2016-03-01

    A series of laboratory tests were conducted to assess the effects of Fe-containing fuel additives on aerosols emitted by a diesel engine retrofitted with a sintered metal filter (SMF) system. Emission measurements performed upstream and downstream of the SMF system were compared, for cases when the engine was fueled with neat ultralow sulfur diesel (ULSD) and with ULSD treated with two formulations of additives containing Fe-based catalysts. The effects were assessed for four steady-state engine operating conditions and one transient cycle. The results showed that the SMF system reduced the average total number and surface area concentrations of aerosols by more than 100-fold. The total mass and elemental carbon results confirmed that the SMF system was indeed very effective in the removal of diesel aerosols. When added at the recommended concentrations (30 p.p.m. of iron), the tested additives had minor adverse impacts on the number, surface area, and mass concentrations of filter-out (FOut) aerosols. For one of the test cases, the additives may have contributed to measurable concentrations of engine-out (EOut) nucleation mode aerosols. The additives had only a minor impact on the concentration and size distribution of volatile and semi-volatile FOut aerosols. Metal analysis showed that the introduction of Fe with the additives substantially increased Fe concentration in the EOut, but the SMF system was effective in removal of Fe-containing aerosols. The FOut Fe concentrations for all three tested fuels were found to be much lower than the corresponding EOut Fe concentrations for the case of untreated ULSD fuel. The results support recommendations that these additives should not be used in diesel engines unless they are equipped with exhaust filtration systems. Since the tested SMF system was found to be very efficient in removing Fe introduced by the additives, the use of these additives should not result in a measurable increase in emissions of de novo generated

  9. Stabilized FE simulation of prototype thermal-hydraulics problems with integrated adjoint-based capabilities

    International Nuclear Information System (INIS)

    Shadid, J.N.; Smith, T.M.; Cyr, E.C.; Wildey, T.M.; Pawlowski, R.P.

    2016-01-01

    A critical aspect of applying modern computational solution methods to complex multiphysics systems of relevance to nuclear reactor modeling, is the assessment of the predictive capability of specific proposed mathematical models. In this respect the understanding of numerical error, the sensitivity of the solution to parameters associated with input data, boundary condition uncertainty, and mathematical models is critical. Additionally, the ability to evaluate and or approximate the model efficiently, to allow development of a reasonable level of statistical diagnostics of the mathematical model and the physical system, is of central importance. In this study we report on initial efforts to apply integrated adjoint-based computational analysis and automatic differentiation tools to begin to address these issues. The study is carried out in the context of a Reynolds averaged Navier–Stokes approximation to turbulent fluid flow and heat transfer using a particular spatial discretization based on implicit fully-coupled stabilized FE methods. Initial results are presented that show the promise of these computational techniques in the context of nuclear reactor relevant prototype thermal-hydraulics problems.

  10. Development of Novel Fe-Based Coating Systems for Internal Combustion Engines

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.; Dröder, K.; Hoffmeister, H.-W.; Mahlfeld, G.; Schläfer, T.

    2018-04-01

    Nowadays, combustion engines are the most common way to power vehicles. Thereby, losses occur due to cooling, exhaust gas and friction. With regard to frictional losses, highest potentials for optimization can be found in the tribological system of the inner surface of combustion chamber and piston ring. Besides friction, corrosive stress increases, e.g., due to utilization of exhaust gas recovery. In order to save energy, reduce emissions and enhance the life span of combustion engines, the demand for innovative coating material systems, especially for the inner surface of combustion chamber, increases. This study focuses on the development of innovative iron-based coating materials for the combustion chamber. As a first step, the plasma transferred wire arc and rotating single wire arc (RSW) technologies were compared using 0.8% C-steel as a reference. Subsequently, RSW was used for coating deposition using an innovative iron-based feedstock material. In order to improve wear and corrosion resistance, boron and chromium were added to the feedstock material. After deposition, different honing topographies were manufactured and compared under tribological load. Furthermore, electrochemical corrosion tests were conducted using an electrolyte simulating the exhaust gas concentrate. Especially with regard to corrosion, the novel coating system FeCrBMn showed promising results.

  11. Stabilized FE simulation of prototype thermal-hydraulics problems with integrated adjoint-based capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Shadid, J.N., E-mail: jnshadi@sandia.gov [Sandia National Laboratories, Computational Mathematics Department (United States); Department of Mathematics and Statistics, University of New Mexico (United States); Smith, T.M. [Sandia National Laboratories, Multiphysics Applications Department (United States); Cyr, E.C. [Sandia National Laboratories, Computational Mathematics Department (United States); Wildey, T.M. [Sandia National Laboratories, Optimization and UQ Department (United States); Pawlowski, R.P. [Sandia National Laboratories, Multiphysics Applications Department (United States)

    2016-09-15

    A critical aspect of applying modern computational solution methods to complex multiphysics systems of relevance to nuclear reactor modeling, is the assessment of the predictive capability of specific proposed mathematical models. In this respect the understanding of numerical error, the sensitivity of the solution to parameters associated with input data, boundary condition uncertainty, and mathematical models is critical. Additionally, the ability to evaluate and or approximate the model efficiently, to allow development of a reasonable level of statistical diagnostics of the mathematical model and the physical system, is of central importance. In this study we report on initial efforts to apply integrated adjoint-based computational analysis and automatic differentiation tools to begin to address these issues. The study is carried out in the context of a Reynolds averaged Navier–Stokes approximation to turbulent fluid flow and heat transfer using a particular spatial discretization based on implicit fully-coupled stabilized FE methods. Initial results are presented that show the promise of these computational techniques in the context of nuclear reactor relevant prototype thermal-hydraulics problems.

  12. Development of Novel Fe-Based Coating Systems for Internal Combustion Engines

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Königstein, T.; Dröder, K.; Hoffmeister, H.-W.; Mahlfeld, G.; Schläfer, T.

    2018-02-01

    Nowadays, combustion engines are the most common way to power vehicles. Thereby, losses occur due to cooling, exhaust gas and friction. With regard to frictional losses, highest potentials for optimization can be found in the tribological system of the inner surface of combustion chamber and piston ring. Besides friction, corrosive stress increases, e.g., due to utilization of exhaust gas recovery. In order to save energy, reduce emissions and enhance the life span of combustion engines, the demand for innovative coating material systems, especially for the inner surface of combustion chamber, increases. This study focuses on the development of innovative iron-based coating materials for the combustion chamber. As a first step, the plasma transferred wire arc and rotating single wire arc (RSW) technologies were compared using 0.8% C-steel as a reference. Subsequently, RSW was used for coating deposition using an innovative iron-based feedstock material. In order to improve wear and corrosion resistance, boron and chromium were added to the feedstock material. After deposition, different honing topographies were manufactured and compared under tribological load. Furthermore, electrochemical corrosion tests were conducted using an electrolyte simulating the exhaust gas concentrate. Especially with regard to corrosion, the novel coating system FeCrBMn showed promising results.

  13. Steel — ab Initio: Quantum Mechanics Guided Design of New Fe-Based Materials

    Science.gov (United States)

    Prahl, Ulrich; Bleck, Wolfgang; Saeed-Akbari, Alireza

    This contribution reports the results of the collaborative research unit SFB 761 "Steel — ab initio", a cooperative project between RWTH Aachen University and the Max-Planck-Institute for Iron Research in Düsseldorf (MPIE) financed by the German Research Foundation (DFG). For the first time, it is exploited how ab initio approaches may lead to a detailed understanding and thus to a specific improvement of material development. The challenge lies in the combination of abstract natural science theories with rather engineering-like established concepts. Aiming at the technological target of the development of a new type of structural materials based on Fe-Mn-C alloys, the combination of ab initio and engineering methods is new, but could be followed quite successfully. Three major topics are treated in this research unit: a) development of a new method for material- and process-development based on ab initio calculations; b) design of a new class of structural materials with extraordinary property combinations; c) acceleration of development time and reduction of experimental efforts and complexity for material- and process-development. In the present work, an overview of the results of the first five years as well as an outlook for the upcoming three-year period is given.

  14. A Simple Small Size and Low Cost Sensor Based on Surface Plasmon Resonance for Selective Detection of Fe(III

    Directory of Open Access Journals (Sweden)

    Nunzio Cennamo

    2014-03-01

    Full Text Available A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM and Surface Plasmon Resonance (SPR transduction, in connection with a Plastic Optical Fiber (POF, has been developed for the selective detection of Fe(III. DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO, having high binding affinity for Fe(III, is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III. The selectivity of the sensor was also proved by interference tests.

  15. A simple small size and low cost sensor based on surface plasmon resonance for selective detection of Fe(III).

    Science.gov (United States)

    Cennamo, Nunzio; Alberti, Giancarla; Pesavento, Maria; D'Agostino, Girolamo; Quattrini, Federico; Biesuz, Raffaela; Zeni, Luigi

    2014-03-07

    A simple, small size, and low cost sensor based on a Deferoxamine Self Assembled Monolayer (DFO-SAM) and Surface Plasmon Resonance (SPR) transduction, in connection with a Plastic Optical Fiber (POF), has been developed for the selective detection of Fe(III). DFO-SAM sensors based on appropriate electrochemical techniques can be frequently found in the scientific literature. In this work, we present the first example of a DFO-SAM sensor based on SPR in an optical fiber. The SPR sensing platform was realized by removing the cladding of a plastic optical fiber along half the circumference, spin coating a buffer of Microposit S1813 photoresist on the exposed core, and finally sputtering a thin gold film. The hydroxamate siderophore deferoxamine (DFO), having high binding affinity for Fe(III), is then used in its immobilized form, as self-assembled monolayer on the gold layer surface of the POF sensor. The results showed that the DFO-SAM-POF-sensor was able to sense the formation of the Fe(III)/DFO complex in the range of concentrations between 1 μm and 50 μm with a linearity range from 0 to 30 μm of Fe(III). The selectivity of the sensor was also proved by interference tests.

  16. Hydrogen storage performance of Ti-V-based BCC phase alloys with various Fe content

    International Nuclear Information System (INIS)

    Yu, X.B.; Feng, S.L.; Wu, Z.; Xia, B.J.; Xu, N.X.

    2005-01-01

    The effect of Fe content on hydrogen storage characteristics of Ti-10Cr-18Mn-(32-x)V-xFe (x = 0, 2, 3, 4, 5) alloys has been investigated at 353 K. The X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images of the alloys present BCC and C14 two-phase structures for all of the Fe-containing alloys. With the increasing Fe content, the lattice parameters of the BCC phase decrease, which results in an increase of the hydrogen desorption plateau pressure of the alloys. Among the studied alloys, Ti-10Cr-18Mn-27V-5Fe alloy exhibits the smallest PCT plateau slope and a more suitable plateau pressure (0.1 MPa equ <1 MPa). The maximum and effective capacities of the alloy are 3.32 wt.% and 2.26 wt.%, respectively, which are higher than other reported Fe-containing BCC phase alloys. In addition, the V/Fe ratio in this alloy is close to that of (VFe) alloy, whose cost is much lower than that of pure V

  17. Effects of Be, Sr, Fe and Mg interactions on the microstructure and mechanical properties of aluminum based aeronautical alloys

    Science.gov (United States)

    Ibrahim, Mohamed Fawzy

    The present work was carried out on a series of heat-treatable aluminum-based aeronautical alloys containing various amounts of magnesium (Mg), iron (Fe), strontium (Sr) and beryllium (Be). Tensile test bars (dendrite arm spacing ~ 24mum) were solutionized for either 5 or 12 hours at 540°C, followed by quenching in warm water (60°C). Subsequently, these quenched samples were aged at 160°C for times up to 12 hours. Microstructural assessment was performed. All heat-treated samples were pulled to fracture at room temperature using a servo-hydraulic tensile testing machine. The results show that Be causes partial modification of the eutectic silicon (Si) particles similar to that reported for Mg addition. Addition of 0.8 wt.% Mg reduced the eutectic temperature by ~10°C. During solidification of alloys containing high levels of Fe and Mg, without Sr, a peak corresponding to the formation of a Be-Fe phase (Al8Fe2BeSi) was detected at 611°C. The Be-Fe phase precipitates in a script-like morphology. A new quinary eutectic-like reaction was observed to take place near the end of solidification of high Mg, high Fe, Be-containing alloys. This new reaction is composed mainly of fine particles of Si, Mg2Si, pi-Al 8Mg3FeSi6 and (Be-Fe) phases. The volume fraction of this reaction decreased with the addition of Sr. The addition of Be has a noticeable effect on decreasing the beta-phase length, or volume fraction, this effect may be limited by adding Sr. Beryllium addition also results in the precipitation of the beta-phase in a nodular form, which reduces the harmful effects of these intermetallics on the alloy mechanical properties. Increasing both Mg and Fe levels led to an increase in the amount of the pi-phase; increasing the iron content led to an increase in the volume fraction of the partially soluble beta- and pi-phases, while Mg2Si particles were completely dissolved. The beta-phase platelets were observed to undergo changes in their morphology due to the

  18. Effect of Co content on structure and magnetic behaviors of high induction Fe-based amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Rajat K., E-mail: rajat@nmlindia.org; Panda, Ashis K.; Mitra, Amitava

    2016-11-15

    The replacement of Fe with Co is investigated in the (Fe{sub 1−x}Co{sub x}){sub 79}Si{sub 8.5}B{sub 8.5}Nb{sub 3}Cu{sub 1} (x=0, 0.05, 0.2, 0.35, 0.5) amorphous alloys. The alloys are synthesized in the forms of ribbons by single roller melt spinning technique, and the structural and magnetic properties of annealed ribbons are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), B–H curve tracer, respectively. All as-cast alloys are structurally amorphous, however, their magnetic properties are varying with Co addition. The Co addition within 5–20 at% results in moderate thermal stability, saturation induction, Curie temperature and lowest coercivity, while 35 at% Co causes highest saturation induction, coercivity, Curie temperature and lowest thermal stability. On devitrification, the magnetic properties change with the generation of α-FeCo nanocrystallites and (FeCo){sub 23}B{sub 6}, Fe{sub 2}B phases during primary and secondary crystallization stages, respectively. A small amount Co is advantageous for maintaining finer nanocrystallites in amorphous matrix even after annealing at 600 °C, leading to high saturation magnetization (>1.5 T) and low coercivity (~35 A/m). The improved magnetic properties at elevated temperatures indicate these alloys have a potential for high frequency transformer core applications. - Highlights: • The structural and magnetic behaviors of Fe based amorphous alloys have been investigated with the effect of Co content. • The Co has no adverse effect on amorphization of alloys. • A small amount Co causes the superior improvement of magnetic properties at elevated temperatures. • Therefore, it is important not only for academic research but also for industrial applied research.

  19. Structural and magnetic characterization of Fe2CrSi Heusler alloy nanoparticles as spin injectors and spin based sensors

    Science.gov (United States)

    Saravanan, G.; Asvini, V.; Kalaiezhily, R. K.; Parveen, I. Mubeena; Ravichandran, K.

    2018-05-01

    Half-metallic ferromagnetic [HMF] nanoparticles are of considerable interest in spintronics applications due to their potential use as a highly spin polarized current source. HMF exhibits a semiconductor in one spin band at the Fermi level Ef and at the other spin band they poses strong metallic nature which shows 100 % spin polarization at Ef. Fe based full Heusler alloys are primary interest due to high Curie temperature. Fe2CrSi Heusler alloys are synthesized using metallic powders of Fe, Cr and Si by mechanical alloying method. X-Ray diffractions studies were performed to analyze the structural details of Fe2CrSi nanoparticles with High resolution scanning electron microscope (HRSEM) studies for the morphological details of nanoparticles and magnetic properties were studied using Vibrating sample magnetometer (VSM). XRD Data analysis conforms the Heusler alloy phase showing the existence of L21 structure. Magnetic properties are measured for synthesized samples exhibiting a soft magnetic property possessing low coercivity (HC = 60.5 Oe) and saturation magnetic moment of Fe2CrSi is 3.16 µB, which is significantly higher than the ideal value of 2 µB from the Slater-Pauling rule due to room temperature measurement. The change in magnetic properties are half-metallic nature of Fe2CrSi is due to the shift of the Fermi level with respect to the gap were can be used as spin sensors and spin injectors in magnetic random access memories and other spin dependent devices.

  20. Low cost, Lightweight, FeS2-Based Photovoltaic Devices by On Demand Ink Jet Printing

    Data.gov (United States)

    National Aeronautics and Space Administration — This research projects seeks to develop novel synthesis for iron pyrite, FeS2, nanocrystals and nanorods. The synthesis of the material includes investigating the...

  1. Magnetic and microstructural properties of thin NdFeB based films and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Bommer, Lars; Goll, Dagmar [Max-Planck-Institut fuer Metallforschung, Stuttgart (Germany)

    2010-07-01

    The magnetic and microstructural properties of NdFeB and NdFeB/Fe thin films and nanostructures are presented. Samples with Cr buffer and protection layer (minimum thickness: d=50 nm) have been produced by ion beam sputtering at elevated temperatures (T{sub s}=700 C) using Al{sub 2}O{sub 3} and MgO(001) single crystal substrates. Films deposited on Al{sub 2}O{sub 3} substrates show c-axis growth in out-of-plane direction down to thicknesses of the NdFeB film of d=10 nm with coercivities up to {mu}{sub 0}H{sub c}=1 T. The texture of films deposited on MgO(001) substrates is less pronounced and films below d=20 nm show no hard magnetic behavior. For comparison, films were deposited at room temperature on Al{sub 2}O{sub 3} and MgO(001) followed by post-annealing in Ar atmosphere (T{sub pa}=525-650 C) leading to coercivities as high as {mu}{sub 0}H{sub c}=1.2 T but with isotropic behavior. By TEM images the grain structure of the NdFeB samples is studied. Bilayers of NdFeB (d=50 nm) and Fe (d=0-20 nm) show fully exchange coupled behavior. From the temperature dependence of the coercivity the microstructural parameters of all samples have been determined. Furthermore NdFeB periodical patterns were produced by means of electron beam lithography with dot sizes of 1000 nm and 500 nm, respectively.

  2. Local atomic order in nanocrystalline Fe-based alloys obtained by mechanical alloying

    International Nuclear Information System (INIS)

    Jartych, E.

    2003-01-01

    Using the 57 Fe Moessbauer spectroscopy, a local atomic order in nanocrystalline alloys of iron with Al, Ni, W and Mo has been determined. Alloys were prepared by mechanical alloying method. Analysis of Moessbauer spectra was performed on the basis of the local environment model in terms of Warren-Cowley parameters. It was shown that impurity atoms are not randomly distributed in the volume of the first and the second co-ordination spheres of 57 Fe nuclei and they form clusters

  3. The C60(FeCp22-Based Cell Proliferation Accelerator

    Directory of Open Access Journals (Sweden)

    Andrei Soldatov

    2013-01-01

    Full Text Available We studied structural and magnetic proprieties of the fulleride C60(FeCp22. The influence of fulleride particles on the cell proliferative activity was also investigated. We found that the proliferative activity of the RINmF5 cells increases (53% versus control in presence of the C60(FeCp22 nanosized particles. Moreover, it was registered that the cell culture became multilayered and secreted basophile matrix.

  4. Synthesis and magnetic properties of Ta/NdFeB-based composite microwires

    Energy Technology Data Exchange (ETDEWEB)

    Szary, P., E-mail: philipp.szary@uni.lu; Périgo, E. A.; Michels, A. [Physics and Materials Science Research Unit, University of Luxembourg, 162 Avenue de la Faïencerie, L-1511 Luxembourg, Grand Duchy of Luxembourg (Luxembourg); Luciu, I.; Duday, D.; Wirtz, T.; Choquet, P. [Science and Analysis of Materials (SAM), Centre de Recherche Public—Gabriel Lippmann, 41, rue du Brill, L-4422 Belvaux, Grand Duchy of Luxembourg (Luxembourg)

    2015-05-07

    Magnetic NdFeB-based microwire composites have been prepared by the direct current magnetron sputtering technique in a specifically designed sputtering chamber for thin-film deposition in wire geometry. As substrate wire material, we have employed steel and Ta. Annealing of the substrate wires during the deposition process was performed by ohmic heating through the application of a direct current. Samples were characterized by means of vibrating sample magnetometry (VSM) and scanning electron microscopy. Best properties have been encountered when using Ta wires as core (substrate) material. The VSM data show a dramatic impact of the current applied during the deposition process on the magnetic properties. For higher current values, i.e., higher annealing temperatures, the wires exhibit a reversal process that is typical for a two-phase system. Moreover, an increase of the coercive field (and remanent magnetization) is observed, which is ascribed to a modification of the magnetic phase present in the sample due to the annealing. We find an indication for the formation of a magnetic easy-axis direction which is azimuthally oriented around the wire axis.

  5. Self-lubricating tribological characterization of lead free Fe-Cu based plain bearing material

    Directory of Open Access Journals (Sweden)

    Shuhaib Mushtaq

    2017-03-01

    Full Text Available The negative impact of lead on environment and thereby its reciprocity on the health of mankind, there is a growing emphasis on resisting the usage of lead in bearings. Owing to this, new bearing materials that provide comparable tribological performance to that of lead containing alloys are being developed. In this study, lead free Fe-Cu based powders with addition of elements such as tin, molybdenum disulfide and Nano boron nitride (BN have been developed by powder metallurgy (PM technique in order to improve the tribological and mechanical properties. The powder mixtures were compressed at a pressure of 500 MPa, and then sintered in dry hydrogen atmosphere at 9000C for 50 minutes. The mechanical and tribological properties obtained due to addition of the said elements is presented in this study. The tribological behavior of the selected alloys is analyzed by reciprocating-sliding tests under dry conditions. The morphology of wear scars and the microstructure of the wear surfaces were investigated. The material with 2.5 wt.% of Sn exhibited the highest value of hardness, the material with 7.5 wt.% of Nano BN comparably shows the low coefficient of friction and wear rate as compared with 5 wt.% of Nano BN.

  6. Thermoplastic deformation of ferromagnetic CoFe-based bulk metallic glasses

    Science.gov (United States)

    Wu, Chenguang; Hu, Renchao; Man, Qikui; Chang, Chuntao; Wang, Xinmin

    2017-12-01

    The superplastic deformation behavior of the ferromagnetic Co31Fe31Nb8B30 bulk metallic glass (BMG) in the supercooled liquid region was investigated. At a given temperature, the BMG exhibits a Newtonian behavior at low strain rates but a non-Newtonian behavior at high strain rates. The high thermal stability of this glassy alloy system offers an enough processing window to thermoplastic forming (TPF), and the strong processing ability was examined by simple micro-replication experiments. It is demonstrated that the TPF formability on length scales ranging down to nanometers can be achieved in the selected experimental condition. Based on the analysis of deformation behavior, the nearly full density sample (i.e. nearly 100%), was produced from water-atomized glassy powders and consolidated by the hot-pressing technique. The sample exhibits good soft-magnetic and mechanical properties, i.e., low coercive force of 0.43 Oe, high initial permeability of 4100 and high Vickers hardness 1398. These results suggest that the hot-pressing process opens up possibilities for the commercial exploitation of BMGs in engineering applications.

  7. Synthesis of encapsulated pigments based on Fe, Co and Si by route of polymeric precursors

    International Nuclear Information System (INIS)

    Macedo, D.S.S.M.; Macedo Neto, O.C.; Paskocimas, C.A.; Varela, M.L.N.

    2012-01-01

    The objective is to apply the polymeric precursor method to obtain encapsulated pigments, the basis of oxides of iron and cobalt deposited on silica. The method has advantages such as reduction of time and reproducibility in the conventional methods, and also improves optical properties, thermal stability and morphology. The synthesis was based on the dissolution of the citric acid (complexing agent), addition of oxides of iron and cobalt (ions chromophores) polymerization of ethylene glycol and silica coating. The mixture was pre-calcined to form the precursor powder was analyzed by TG and DTA. Was then split, and calcined at different temperatures (700 ° C - 900 ° C) and analyzed by BET, DRX, MEV and UV-Visible. The pigments were stable thermally, with surface area ranging between 3,09 and 7,65 m² / g, formation of crystalline phases of cobalt ferrite (CoFe 2 O 4 ) and Cristobalite (SiO 2 ) and agglomerates of particles slightly rounded. (author)

  8. Fatigue crack initiation in nickel-based superalloys studied by microstructure-based FE modeling and scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Fried M.

    2014-01-01

    Full Text Available In this work stage I crack initiation in polycrystalline nickel-based superalloys is investigated by analyzing anisotropic mechanical properties, local stress concentrations and plastic deformation on the microstructural length scale. The grain structure in the gauge section of fatigue specimens was characterized by EBSD. Based on the measured data, a microstructure-based FE model could be established to simulate the strain and stress distribution in the specimens during the first loading cycle of a fatigue test. The results were in fairly good agreement with experimentally measured local strains. Furthermore, the onset of plastic deformation was predicted by identifying shear stress maxima in the microstructure, presumably leading to activation of slip systems. Measurement of plastic deformation and observation of slip traces in the respective regions of the microstructure confirmed the predicted slip activity. The close relation between micro-plasticity, formation of slip traces and stage I crack initiation was demonstrated by SEM surface analyses of fatigued specimens and an in-situ fatigue test in a large chamber SEM.

  9. Quality monitoring methods of initial and terminal manufacture of LiFePO4 based lithium ion batteries by capillary electrophoresis.

    Science.gov (United States)

    Xie, Xia; Yang, Yang; Zhou, Henghui; Li, Meixian; Zhu, Zhiwei

    2018-03-01

    Magnetic impurities of lithium ion battery degrade both the capacity and cycling rates, even jeopardize the safety of the battery. During the material manufacture of LiFePO 4 , two opposite and extreme cases (trace impurity Fe(II) with high content of Fe(III) background in FePO 4 of initial end and trace Fe(III) with high content of Fe(II) background in LiFePO 4 of terminal end) can result in the generation of magnetic impurities. Accurate determination of impurities and precise evaluation of raw material or product are necessary to ensure reliability, efficiency and economy in lithium ion battery manufacture. Herein, two kinds of rapid, simple, and sensitive capillary electrophoresis (CE) methods are proposed for quality monitoring of initial and terminal manufacture of LiFePO 4 based lithium ion batteries. The key to success includes the smart use of three common agents 1,10-phenanthroline (phen), EDTA and cetyltrimethyl ammonium bromide (CTAB) in sample solution or background electrolyte (BGE), as well as sample stacking technique of CE feature. Owing to the combination of field-enhanced sample injection (FESI) technique with high stacking efficiency, detection limits of 2.5nM for Fe(II) and 0.1μM for Fe(III) were obtained corresponding to high content of Fe(III) and Fe(II), respectively. The good recoveries and reliability demonstrate that the developed methods are accurate approaches for quality monitoring of LiFePO 4 manufacture. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Oxygen rocking aqueous batteries utilizing reversible topotactic oxygen insertion/extraction in iron-based perovskite oxides Ca(1-x)La(x)FeO(3-δ).

    Science.gov (United States)

    Hibino, Mitsuhiro; Kimura, Takeshi; Suga, Yosuke; Kudo, Tetsuichi; Mizuno, Noritaka

    2012-01-01

    Developments of large-scale energy storages with not only low cost and high safety but also abundant metals are significantly demanded. While lithium ion batteries are the most successful method, they cannot satisfy all conditions. Here we show the principle of novel lithium-free secondary oxygen rocking aqueous batteries, in which oxygen shuttles between the cathode and anode composed of iron-based perovskite-related oxides Ca(0.5)La(0.5)FeO(z) (2.5 ≤ z ≤ 2.75 and 2.75 ≤ z ≤ 3.0). Compound Ca(0.5)La(0.5)FeO(z) can undergo two kinds of reduction and reoxidation of Fe(4+)/Fe(3+) and Fe(3+)/Fe(2+), that are accompanied by reversible and repeatable topotactic oxygen extraction and reinsertion during discharge and charge processes.

  11. Pyrazolone as a recognition site: Rhodamine 6G-based fluorescent probe for the selective recognition of Fe3+ in acetonitrile-aqueous solution.

    Science.gov (United States)

    Parihar, Sanjay; Boricha, Vinod P; Jadeja, R N

    2015-03-01

    Two novel Rhodamine-pyrazolone-based colorimetric off-on fluorescent chemosensors for Fe(3+) ions were designed and synthesized using pyrazolone as the recognition moiety and Rhodamine 6G as the signalling moiety. The photophysical properties and Fe(3+) -binding properties of sensors L(1) and L(2) in acetonitrile-aqueous solution were also investigated. Both sensors successfully exhibit a remarkably 'turn-on' response, toward Fe(3+) , which was attributed to 1: 2 complex formation between Fe(3+) and L(1) /L(2) . The fluorescent and colorimetric response to Fe(3+) can be detected by the naked eye, which provides a facile method for the visual detection of Fe(3+) . Copyright © 2014 John Wiley & Sons, Ltd.

  12. Factors influencing shape memory effect and phase transformation behaviour of Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Li, H.; Dunne, D.; Kennon, N.

    1999-01-01

    The objective of this research work was to investigate the factors influencing the shape memory effect and phase transformation behaviour of three Fe-Mn-Si based shape memory alloys: Fe-28Mn-6Si, Fe-13Mn-5Si-10Cr-6Ni and Fe-20Mn-6Si-7Cr-1Cu. The research results show that the shape memory capacity of Fe-Mn-Si based shape memory alloys varies with annealing temperature, and this effect can be explained in terms of the effect of annealing on γ ε transformation. The nature and concentration of defects in austenite are strongly affected by annealing conditions. A high annealing temperature results in a low density of stacking faults, leading to a low nucleation rate during stress induced γ→ε transformation. The growth of ε martensite plates is favoured rather than the formation of new ε martensite plates. Coarse martensite plates produce high local transformation strains which can be accommodated by local slip deformation, leading to a reduction in the reversibility of the martensitic transformation and to a degradation of the shape memory effect. Annealing at low temperatures (≤673 K) for reasonable times does not eliminate complex defects (dislocation jogs, kinks and vacancy clusters) created by hot and cold working strains. These defects can retard the movement and rearrangement of Shockley partial dislocations, i.e. suppress γ→ε transformation, also leading to a degradation of shape memory effect. Annealing at about 873 K was found to be optimal to form the dislocation structures which are favourable for stress induced martensitic transformation, thus resulting in the best shape memory behaviour. (orig.)

  13. MWCNT-Fe{sub 3}O{sub 4}-based immuno-PCR for the early screening of nasopharyngeal carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Chia-Ching, Liu [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei 100, Taiwan (China); Subramaniam, Sadhasivam [Department of Microbial Biotechnology, Bharathiar University, Coimbatore 641 046 (India); Sivasubramanian, Savitha [Department of Biotechnology, Sree Sastha Institute of Engineering and Technology, Chennai (India); Feng-Huei, Lin, E-mail: double@ntu.edu.tw [Institute of Biomedical Engineering, College of Medicine and College of Engineering, National Taiwan University, Taipei 100, Taiwan (China); Division of Biomedical Engineering and Nanomedicine Research, National Health Research Institutes, Miaoli 350, Taiwan (China)

    2016-04-01

    Nasopharyngeal carcinoma (NPC) is the most prevalent form of malignancy in southeast China and its development is meticulously related to EBV pathogenesis. The current screening techniques are unsatisfactory in terms of the sensitivity and hence most of the NPC patients are diagnosed at an advanced stage. Herein, we report the multi-walled carbon nanotubes (MWCNTs) combined with iron oxide nanoparticles as a sensing surface for the early screening of nasopharyngeal carcinoma (NPC) by immuno-PCR (iPCR). The MWCNT-Fe{sub 3}O{sub 4} nanocomposite was characterized by Fourier transform infrared spectra (FTIR), Raman spectra, X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The characterization techniques had confirmed the successful formation of MWCNT-Fe{sub 3}O{sub 4} nanocomposites. The MWCNT-Fe{sub 3}O{sub 4}-based iPCR was effectively tested for the quantification of anti-EBV antibodies in human serum and the limit of detection (LOD) was compared with ELISA. The limit of detection by iPCR was valid until 1:10,000,000 fold dilution of NPC{sup +ve} human serum, whereas ELISA can detect the anti-EBV antibodies in human serum up to 1:100,000 fold dilution. The MWCNT-Fe{sub 3}O{sub 4} offers an excellent surface area for the antigen-antibody binding and hence greater sensitivity was achieved. - Highlights: • MWCNT-Fe{sub 3}O{sub 4} nanocomposite offers more surface area and effortless separation • The iPCR offers an exceptional LOD, which is significantly higher than the other analytical techniques reported • LOD of anti-EBV abs by ELISA was significant only until 1:100000 fold dilution • The proposed iPCR design could be extremely useful for the population-based screening.

  14. Multi-scale modelling of radiation damage in Fe-Cr based on ab initio electronic structure calculations

    International Nuclear Information System (INIS)

    Olsson, Paer

    2004-04-01

    The efficiency of fast neutron reactors, such as for fusion, breeding and transmutation, depend strongly on the neutron radiation resistance of the materials used in the reactors. The binary Fe-Cr alloy, which has many attractive properties in this regard, is the base for the best steels of today which are, however, still not up to the required standards. Therefore, substantial effort has been devoted to finding new materials that can cope with the demands better. Experimental studies must be complemented with extensive theoretical modelling in order to understand the effects that different alloying elements has on the resistance properties of materials. To this end, the first steps of multi-scale modelling has been taken, starting out with ab initio calculations of the electronic structure of the complete concentration range range of the disordered binary Fe-C alloy. The mixing enthalpy of Fe-Cr has been quantitatively predicted and has, together with data from literature, been used in order to fit two sets of interatomic potentials for the purpose of simulating defect evolution with molecular dynamics and kinetic Monte-Carlo codes. These dedicated Fe-Cr alloy potentials are new and represent important additions to the pure element potentials that can be found in literature

  15. Colorimetric sensing of oxalate based on its inhibitory effect on the reaction of Fe (III) with curcumin nanoparticles

    Science.gov (United States)

    Pourreza, Nahid; Lotfizadeh, Neda; Golmohammadi, Hamed

    2018-03-01

    In this research, a new colorimetric method for the determination of oxalate using curcumin nanoparticles (CURNs) in the presence Fe (III) is introduced. The method is based on the inhibitory effect of oxalate ion on the reaction of (CURNs) with Fe (III) in acidic media. This reaction was monitored by measuring the increase in absorbance of CURNs-Fe3 + complex in the presence of oxalate ion at 427 nm. The effect of different parameters such as the pH of the sample solution, concentration of Fe (III), concentration of CURNs and the reaction time was examined and optimized. Under optimum experimental conditions, the absorption intensity was linear with the concentration of oxalate in the range of 0.15 to 1.70 μg mL- 1. The limit of detection (LOD) was 0.077 μg mL- 1 and the relative standard deviations (RSD) for 8 replicate measurements of 0.40 and 1.05 μg mL- 1 of oxalate were 4.20% and 2.74%, respectively. The developed method was successfully employed to the determination of oxalate in water, food and urine samples with satisfactory results.

  16. Bio-based hyperbranched polyurethane/Fe3O4 nanocomposites: smart antibacterial biomaterials for biomedical devices and implants

    International Nuclear Information System (INIS)

    Das, Beauty; Karak, Niranjan; Mandal, Manabendra; Upadhyay, Aadesh; Chattopadhyay, Pronobesh

    2013-01-01

    The fabrication of a smart magnetically controllable bio-based polymeric nanocomposite (NC) has immense potential in the biomedical domain. In this context, magneto-thermoresponsive sunflower oil modified hyperbranched polyurethane (HBPU)/Fe 3 O 4 NCs with different wt.% of magnetic nanoparticles (Fe 3 O 4 ) were prepared by an in situ polymerization technique. Fourier-transform infrared, x-ray diffraction, vibrating sample magnetometer, scanning electron microscope, transmission electron microscope, thermal analysis and differential scanning calorimetric were used to analyze various physico-chemical structural attributes of the prepared NC. The results showed good interfacial interactions between HBPU and well-dispersed superparamagnetic Fe 3 O 4 , with an average diameter of 7.65 nm. The incorporation of Fe 3 O 4 in HBPU significantly improved the thermo-mechanical properties along with the shape-memory behavior, antibacterial activity, biocompatibility as well as biodegradability in comparison to the pristine system. The cytocompatibility of the degraded products of the NC was also verified by in vitro hemolytic activity and MTT assay. In addition, the in vivo biocompatibility and non-immunological behavior, as tested in Wistar rats after subcutaneous implantation, show promising signs for the NC to be used as antibacterial biomaterial for biomedical device and implant applications. (paper)

  17. Fabrication and Properties of Iron-based Soft Magnetic Composites Coated with NiZnFe2O4

    Directory of Open Access Journals (Sweden)

    WU Shen

    2017-07-01

    Full Text Available This paper focuses on iron-based soft magnetic composites which were synthesized by utilizing the sol-gel method prepared Ni-Zn ferrite particles as insulating compound to coat iron powder, and the influence of NiZnFe2O4 content and molding pressure on the magnetic properties was studied. The morphology, magnetic properties and density of Ni-Zn ferrite insulated compacts were investigated. Scanning electron microscope,line-scan EDX analysis and distribution maps show that the iron particle surface is covered with a thin layer of uniform Ni-Zn ferrites. The existing of the insulating layer can effectively improve the electrical resistivity of soft magnetic composites. Magnetic measurements show that the real part of permeability decreases with the increase of the Ni-Zn ferrite content, and the sample with 3%(mass fraction, the same below Ni-Zn ferrite has an acceptable real part and minimum imaginary part of permeability in comparison with other samples. Results show that the addition of NiZnFe2O4 can dramatically decrease the internal magnetic loss, the magnetic loss of coated samples decreases by 83.8% as compared with that of uncoated samples at 100kHz. The density of the Fe-3%NiZnFe2O4 compacts reaches 7.14g/cm3 and the saturation magnetization is 1.47T when the molding pressure is 1000MPa.

  18. Isotropic and anisotropic nanocrystalline NdFeB-based magnets prepared by spark plasma sintering and hot deformation

    International Nuclear Information System (INIS)

    Liu, Z.W.; Huang, Y.L.; Huang, H.Y.; Zhong, X.C.; Yu, Y.H.; Zeng, D.C.

    2011-01-01

    Isotropic and anisotropic NdFeB permanent magnets were prepared by Spark Plasma Sintering (SPS) and SPS followed hot deformation (HD), respectively, using melt spun NdFeB ribbons with various compositions as starting materials. It is found that, based on RE-rich composition, SPSed magnets sintered at low temperatures (<700 C) almost maintained the uniform fine grain structure inherited from rapid quenching. At higher temperatures, a distinct two-zone (coarse grain and fine grain zones) structure was formed in the SPSed magnets. The SPS temperature and pressure have important effects on the grain structure, which led to the variations in the magnetic properties. By employing low SPS temperature and high pressure, high-density magnets with negligible coarse grain zone and an excellent combination of magnetic properties can be obtained. For single phase NdFeB alloy, because of the deficiency of Nd-rich phases, it is relatively difficult to consolidate micro-sized melt spun powders into high density bulk magnet, but generally a larger particle size is beneficial to achieve better magnetic properties. Anisotropic magnets with a maximum energy product of approx. equal to 38 MGOe were produced by the SPS+HD process. HD did not lead to obvious grain growth and the two-zone structure still existed in the hot deformed magnets. The results indicated that nanocrystalline NdFeB magnets without significant grain growth and with excellent properties could be obtained by SPS and HD processes. (author)

  19. Multi-scale modelling of radiation damage in Fe-Cr based on ab initio electronic structure calculations

    Energy Technology Data Exchange (ETDEWEB)

    Olsson, Paer

    2004-04-01

    The efficiency of fast neutron reactors, such as for fusion, breeding and transmutation, depend strongly on the neutron radiation resistance of the materials used in the reactors. The binary Fe-Cr alloy, which has many attractive properties in this regard, is the base for the best steels of today which are, however, still not up to the required standards. Therefore, substantial effort has been devoted to finding new materials that can cope with the demands better. Experimental studies must be complemented with extensive theoretical modelling in order to understand the effects that different alloying elements has on the resistance properties of materials. To this end, the first steps of multi-scale modelling has been taken, starting out with ab initio calculations of the electronic structure of the complete concentration range range of the disordered binary Fe-C alloy. The mixing enthalpy of Fe-Cr has been quantitatively predicted and has, together with data from literature, been used in order to fit two sets of interatomic potentials for the purpose of simulating defect evolution with molecular dynamics and kinetic Monte-Carlo codes. These dedicated Fe-Cr alloy potentials are new and represent important additions to the pure element potentials that can be found in literature.

  20. Selective recognition of 6-mercaptopurine based on luminescent metal-organic frameworks Fe-MIL-88NH₂.

    Science.gov (United States)

    Sun, Zhengjuan; Liu, Yali; Li, Yuanfang

    2015-03-15

    A novel and rapid spectrofluorometry method for the recognition of 6-mercaptopurine (6-MP) has been developed based on luminescent metal-organic frameworks Fe-MIL-88NH2 as fluorescent probe. The strong fluorescence of Fe-MIL-88NH2 at 430 nm could be quenched by 6-MP directly, and the Fe-MIL-88NH2 shows high selectivity for 6-MP compared to other thiol-containing amino acids such as homocysteine (Hcy), cysteine (Cys), glutathione (GSH), etc. Under optimal conditions, the relative fluorescence intensity was linearly proportional to the concentration of 6-MP in the range of 5-600 μM with the detection limit at 1.17 μM (S/N=3). Furthermore, the present approach has been successfully applied to the determination of 6-MP in human serum samples. The possible fluorescence quenching mechanism has also been investigated, where it is revealed that the quenching was attributed to competition of absorption of the light source energy as well as electron transfer between Fe-MIL-88NH2 and 6-MP. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Rates of proton transfer to Fe-S-based clusters: comparison of clusters containing {MFe(mu(2)-S)(2)}n+ and {MFe(3)(mu(3)-S)(4)}n+ (M = Fe, Mo, or W) cores.

    Science.gov (United States)

    Bates, Katie; Garrett, Brendan; Henderson, Richard A

    2007-12-24

    The rates of proton transfer from [pyrH]+ (pyr = pyrrolidine) to the binuclear complexes [Fe2S2Cl4]2- and [S2MS2FeCl2]2- (M = Mo or W) are reported. The reactions were studied using stopped-flow spectrophotometry, and the rate constants for proton transfer were determined from analysis of the kinetics of the substitution reactions of these clusters with the nucleophiles Br- or PhS- in the presence of [pyrH]+. In general, Br- is a poor nucleophile for these clusters, and proton transfer occurs before Br- binds, allowing direct measure of the rate of proton transfer from [pyrH]+ to the cluster. In contrast, PhS- is a better nucleophile, and a pathway in which PhS- binds preferentially to the cluster prior to proton transfer from [pyrH]+ usually operates. For the reaction of [Fe2S2Cl4]2- with PhS- in the presence of [pyrH]+ both pathways are observed. Comparison of the results presented in this paper with analogous studies reported earlier on cuboidal Fe-S-based clusters allows discussion of the factors which affect the rates of proton transfer in synthetic clusters including the nuclearity of the cluster core, the metal composition, and the nature of the terminal ligands. The possible relevance of these findings to the protonation sites of natural Fe-S-based clusters, including FeMo-cofactor from nitrogenase, are presented.

  2. Corrosion aspects of Ni-Cr-Fe based and Ni-Cu based steam generator tube materials

    International Nuclear Information System (INIS)

    Dutta, R.S.

    2009-01-01

    This paper reviews corrosion related issues of Ni-Cr-Fe based (in a general sense) and Ni-Cu based steam generator tube materials for nuclear power plants those have been dealt with for last more than four decades along with some updated information on corrosion research. The materials include austenitic stainless steels (SSs), Alloy 600, Monel 400, Alloy 800 and Alloy 690. Compatibility related issues of these alloys are briefly discussed along with the alloy chemistry and microstructure. For austenitic SSs, stress corrosion cracking (SCC) behaviour in high temperature aqueous environments is discussed. For Alloy 600, intergranular cracking in high temperature water including hydrogen-induced intergranular cracking is highlighted along with the interactions of material in various environments. In case of Monel 400, intergranular corrosion and pitting corrosion at ambient temperature and SCC behaviour at elevated temperature are briefly described. For Alloy 800, the discussion covers SCC behaviour, surface characterization and microstructural aspects of pitting, whereas hydrogen-related issues are also highlighted for Alloy 690.

  3. A Physically-Based Equivalent Circuit Model for the Impedance of a LiFePO4/Graphite 26650 Cylindrical Cell

    DEFF Research Database (Denmark)

    Scipioni, Roberto; Jørgensen, Peter Stanley; Graves, Christopher R.

    2017-01-01

    In this work an Equivalent Circuit Model (ECM) is developed and used to model impedance spectra measured on a commercial 26650 LiFePO4/Graphite cylindrical cell. The ECM is based on measurements and modeling of impedance spectra recorded separately on cathode (LiFePO4) and anode (Graphite) samples...

  4. Nano-structured variable capacitor based on P(VDF-TrFE) copolymer and carbon nanotubes

    Science.gov (United States)

    Lakbita, I.; El-Hami, K.

    2018-02-01

    A newly organic capacitor was conceived with a variable capacitance using the inverse piezoelectric effect. The device consists of two parallel plates of carbon nanotubes (CNTs), known for their large surface area, high sensitivity and high electric conductivity, separated by a thin film of a dielectric layer of Polyinylidene fluoride and trifluoroehtylene (P(VDF-TrFE)) promising material for piezoelectric and ferroelectric properties. The obtained architecture is the CNT/PVDF-TrFE/CNT capacitor device. In this study, an ultra-thin film of P(VDF-TrFE) (54/46) with thickness of 20 nm was elaborated on highly oriented pyrolytic graphite (HOPG) by spin-coating. The morphology of the ultra-thin film and the mechanical behavior of CNT/P(VDF-TrFE)/CNT system were studied using the atomic force microscopy (AFM) combined with a lock-in amplifier in contact mode. All changes in applied voltage induce a change in thin film thickness according to the inverse piezoelectric effect that affect, consequently the capacitance. The results showed that the ratio of capacitance change ΔC to initial capacitance C0 is ΔC/C0=5%. This value is sufficient to use P(VDF-TrFE) as variable organic capacitor.

  5. Production and characterization of stainless steel based Fe-Cr-Ni-Mn-Si(-Co) shape memory alloys

    International Nuclear Information System (INIS)

    Otubo, J.

    1995-01-01

    It is well known that the Fe based alloys can exhibit shape memory effect due to the γ to ε martensitic transformation. The effect may not be as striking as observed in the NiTi alloy but it might become attractive from the practical point of view. In this work, two compositions of Fe-Cr-Ni-Mn-Si(-Co) stainless steel based shape memory alloy, prepared by the VIM technique, will be presented. The results are good with shape recovery of 95% for a pre-strain of 4% after some training cycles. In terms of workability the alloys produced are worse than the usual AISI304. However, adjusting the thermo-mechanical processing, it is perfectly possible to produce wire as thin as 1,20mm in dia. or down. (orig.)

  6. A study of coFeB magnetic yoke based on planar electromagnet

    Science.gov (United States)

    Qin, L.; Li, Q.; Yuan, Yong J.

    2017-07-01

    This paper studies the fabrication of a novel planar electromagnet consisting of a planar copper coil and a magnetic yoke. CoFeB was used as the magnetic yoke material instead of the traditional permanent magnets. The planar electromagnet was fabricated and optimized to maximize the electromagnetic force, especially with varying CoFeB thickness. The micro-planar electromagnet was fabricated successfully by the traditional micro-electro-mechanical-system (MEMS) techniques and XRD, VSM were used to characterize the performance of the electromagnet. The planar electromagnet exhibits superior perpendicular magnetic anisotropy (PMA) and 0.006 emu of MS was achieved following 2 min deposition of CoFeB thin film. By integrating with other micro apparatuses, it is anticipated that the planar electromagnet will have potential applications in areas such as biosensors, biological medicine, drug delivery, chemical analysis and environmental monitoring.

  7. Repair effect on patterned CoFeB-based magnetic tunneling junction using rapid thermal annealing

    International Nuclear Information System (INIS)

    Wu, K.-M.; Wang, Y.-H.; Chen, Wei-Chuan; Yang, S.-Y.; Shen, Kuei-Hung; Kao, M.-J.; Tsai, M.-J.; Kuo, C.-Y.; Wu, J.-C.; Horng, Lance

    2007-01-01

    Rapid thermal treatment without applying magnetic field reconstructing magnetic property of Co 60 Fe 20 B 20 was studied through magnetoresistance (R-H) measurement. In this paper, we report that the switching behaviors of CoFeB were obviously improved through rapid thermal annealing for only a brief 5 min. The squareness and reproduction of minor R-H loops were enhanced from 100 deg. C to 250 deg. C . Tunneling magnetoresistance (TMR) that is about 35% in the as-etched cells increases up to 44% after 250 deg. C rapid annealing and still shows about 25% TMR even after 400 deg. C treating. Therefore, repair purpose annealing is some what different from crystallizing purpose annealing. Applying magnetic field during repair annealing was not necessary. Brief thermal treatment improves CoFeB switching behavior indeed, and causes less damage at high temperature

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  9. ''Some features of γ-ε martensitic transformation and shape memory effect in Fe-Mn-Si based alloys''

    International Nuclear Information System (INIS)

    Gulyaev, A.A.

    1995-01-01

    In the present paper several important aspects concerning the shape memory behavior of the ε-martensite in the cost-saving Fe-Mn-Si-based alloys and its application are reported. Some kinetic features of the γ-ε martensitic transformation are discussed. The effects of the composition, volume change induced by the transformation, strength of austenite, temperature of pre strain on the shape memory effect have been investigated. (orig.)

  10. Exchange bias effect in L10-ordered FePt and FeCo-based bilayer structure: effect of increasing applied field

    Science.gov (United States)

    Singh, Sadhana; Kumar, Dileep; Bhagat, Babli; Choudhary, R. J.; Reddy, V. R.; Gupta, Ajay

    2018-02-01

    The applied magnetic field (H APP) dependence of the exchange bias (EB) is studied in an exchange-coupled thin-film bilayer composed of a hard ferromagnetic FePt layer in the proximity of a soft ferromagnetic FeCo layer. FePt/FeCo structure is deposited in an ultra-high vacuum chamber, where the FePt layer was first annealed at 823 K for 30 min and subsequently cooled to room temperature in the presence of an in-plane magnetic field, H MAX ~ 1.5 kOe to promote L10-ordered hard magnetic phase with magnetic moments aligned in one of the in-plane directions in the FePt layer. In-situ magneto-optical Kerr effect measurements during different stages of bilayer growth and detailed ex-situ superconducting quantum interference device-vibrating sample magnetometer measurements jointly revealed that due to the interplay between exchange coupling at the interface and dipolar energies of the saturated hard FePt layer, a hysteresis loop of FeCo layer shifts along the magnetic field axis. A clear dependence of EB field (H EB) on increasing maximum value of the H APP during the hysteresis loop measurement is understood in terms of the magnetic state of soft and hard magnetic layers, where EB increases with increasing H APP until the hard layer moment remains undisturbed in its remanence state. As soon as the field was sufficient to rotate the spins of the FePt layer, the loop became symmetric with respect to the field axis.

  11. Enhanced algae removal by Ti-based coagulant: comparison with conventional Al- and Fe-based coagulants.

    Science.gov (United States)

    Xu, Jie; Zhao, Yanxia; Gao, Baoyu; Zhao, Qian

    2018-05-01

    The water eutrophication caused by cyanobacteria seasonally proliferates, which is a hot potato to be resolved for water treatment plants. This study firstly investigated coagulation performance of titanium tetrachloride (TiCl 4 ) for Microcystis aeruginosa synthetic water treatment. Results show complete algal cell removal by TiCl 4 coagulation without damage to cell membrane integrity even under harsh conditions; 60 mg/L TiCl 4 was effective in removing the microcystins up to 85%. Furthermore, besides having stronger UV 254 removal capability and the higher removal of fluorescent substances over Al- and Fe-based coagulants, TiCl 4 coagulant required more compact coagulation and sedimentation tanks due to its significantly improved floc growth and sedimentation speed. Meanwhile, its' short hydraulic retention time avoided algal cell breakage and subsequent algal organic matter release. Microcystin concentrations were kept at a low level during sludge storage period, indicating that the TiCl 4 flocs could prevent algal cells from natural lysis. To facilitate water recycling without secondary contamination, the algae-containing sludge after TiCl 4 coagulation ought to be disposed within 12 days at 20 °C and 8 days at 35 °C.

  12. Effects of Cu substitution for Fe on the glass-forming ability and soft magnetic properties for Fe-based bulk metallic glasses

    International Nuclear Information System (INIS)

    Dou, Lintao; Liu, Haishun; Hou, Long; Xue, Lin; Yang, Weiming; Zhao, Yucheng; Chang, Chuntao

    2014-01-01

    The effects of Cu substitution for Fe on the glass-forming ability (GFA) and soft magnetic properties for Fe 72−x Cu x B 20 Si 4 Nb 4 (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) bulk metallic glasses (BMGs) are investigated. It is found that the investigated BMGs exhibit large GFA as well as excellent soft magnetic properties, and proper substitution of Fe by Cu improves the saturation magnetization, coercive force, and effective permeability without obvious deterioration of the GFA. - Highlights: • Fully glassy rods of Fe 72−x Cu x B 20 Si 4 Nb 4 BMGs were produced above 1 mm in diameter. • Investigated BMGs exhibit large glass-forming ability and excellent soft magnetic properties. • Proper Cu substitution improves magnetic properties without obvious deterioration of glass-forming ability

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  14. Copper(II) cyanido-bridged bimetallic nitroprusside-based complexes: Syntheses, X-ray structures, magnetic properties, 57Fe Moessbauer spectroscopy and thermal studies

    International Nuclear Information System (INIS)

    Travnicek, Zdenek; Herchel, Radovan; Mikulik, Jiri; Zboril, Radek

    2010-01-01

    Three heterobimetallic cyanido-bridged copper(II) nitroprusside-based complexes of the compositions [Cu(tet)Fe(CN) 5 NO].H 2 O (1), where tet=N,N'-bis(3-aminopropyl)ethylenediamine, [Cu(hto)Fe(CN) 5 NO].2H 2 O (2), where hto=1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9 ]octadecane and [Cu(nme) 2 Fe(CN) 5 NO].H 2 O (3), where nme=N-methylethylenediamine, were synthesized and characterized by elemental analyses, 57 Fe Moessbauer and FTIR spectroscopies, thermal analysis, magnetic measurements and single-crystal X-ray analysis. The products of thermal degradation processes of 2 and 3 were studied by XRD, 57 Fe Moessbauer spectroscopy, SEM and EDS, and they were identified as mixtures of CuFe 2 O 4 and CuO. - Three heterobimetallic cyano-bridged copper(II) nitroprusside-based complexes of the general compositions of [Cu(L)Fe(CN) 5 NO].xH 2 O, where L=N,N'-bis(3-aminopropyl)ethylenediamine (complex 1), 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1 6,9 ]-octadecane (complex 2) and N-methylethylenediamine (complex 3), were synthesized, and fully structurally and magnetically characterized. SEM, EDS, XRD and 57 Fe Moessbauer experiments were used for characterization of thermal decomposition products of complexes 2 and 3.

  15. Entomopathogenic fungi-based mechanisms for improved Fe nutrition in sorghum plants grown on calcareous substrates.

    Directory of Open Access Journals (Sweden)

    Silvia Raya-Díaz

    Full Text Available Although entomopathogenic fungi (EPF are best known for their ability to protect crops against insect pests, they may have other beneficial effects on their host plants. These effects, which include promoting plant growth and conferring resistance against abiotic stresses, have been examined in recent years to acquire a better understanding of them. The primary purposes of the present study were (i to ascertain in vitro whether three different strains of EPF (viz., Metarhizium, Beauveria and Isaria would increase the Fe bioavailability in calcareous or non-calcareous media containing various Fe sources (ferrihydrite, hematite and goethite and (ii to assess the influence of the EPF inoculation method (seed dressing, soil treatment or leaf spraying on the extent of the endophytic colonization of sorghum and the improvement in the Fe nutrition of pot-grown sorghum plants on an artificial calcareous substrate. All the EPFs studied were found to increase the Fe availability during the in vitro assay. The most efficient EPF was M. brunneum EAMa 01/58-Su, which lowered the pH of the calcareous medium, suggesting that it used a different strategy (organic acid release than the other two fungi that raised the pH of the non-calcareous medium. The three methods used to inoculate sorghum plants with B. bassiana and M. brunneum in the pot experiment led to differences in re-isolation from plant tissues and in the plant height. These three inoculation methods increased the leaf chlorophyll content of young leaves when the Fe deficiency symptoms were most apparent in the control plants (without fungal inoculation as well as the Fe content of the above-ground biomass in the plants at the end of the experiment. The total root lengths and fine roots were also increased in response to fungal applications with the three inoculation methods. However, the soil treatment was the most efficient method; thus, its effect on the leaf chlorophyll content was the most

  16. Effect of crystallization condition on the Microwave properties of Fe-based amorphous alloy flakes and polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Byoung-Gi [Department of Advanced Metallic Materials, Korea Institute of Materials Science, 531 Changwondaero, Changwon, Kyungnam (Korea, Republic of); Hong, Soon-Ho; Sohn, Keun Yong; Park, Won-Wook [School of Nano Engineering, Inje University, 607 Obang-dong, Kimhae, Kyungnam (Korea, Republic of); Kwon, Sang-Kyun; Song, Yong-Sul [Amosense Co., 185-1 Sucham-ri, Tongjin-myun, Gimposi, Kyungkido (Korea, Republic of); Lee, Taek-Dong, E-mail: bgmoon@kims.re.k [Department of Materials Science and Engineering, Korea Insititute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon (Korea, Republic of)

    2009-01-01

    The electromagnetic (EM) wave absorption properties with a variation of crystallization temperature have been investigated in a sheet-type absorber made of the amorphous Fe{sub 73}Si{sub 16}B{sub 7}Nb{sub 3}Cu{sub 1}Finemet powder. With the variation of the annealing temperature, the magnetic and dielectric properties of the crystallized Fe-based absorber with a nano-structure were changed. The complex permittivity increased with increasing the annealing temperature, whereas the complex permeability was maximized after annealing at 530 deg. C for 1 hour. The absolute value of the reflection parameter, |S{sub 11}|, increased with increasing annealing temperature of the nanocrystalline alloy powder. On the contrary, the transmission one, |S{sub 21}|, showed the highest value after annealing at 530 deg. C for 1 hour, which is regarded as the optimum temperature for the improvement of EM wave absorption properties.

  17. Electrochemical detection of short HIV sequences on chitosan/Fe3O4 nanoparticle based screen printed electrodes

    International Nuclear Information System (INIS)

    Tran, Lam Dai; Nguyen, Binh Hai; Van Hieu, Nguyen; Tran, Hoang Vinh; Nguyen, Huy Le; Nguyen, Phuc Xuan

    2011-01-01

    In this study, a novel CS/Fe 3 O 4 nanobiocomposite-based platform for electrochemical detection of HIV-1 was developed. The most attractive feature of this system is a suitable microenvironment (Fe 3 O 4 nanoparticles) which could contribute to electron transfer and thus sensitivity enhancement when using methylene blue (MB) as an external mediator and Square Wave Voltammetry (SWV), Electrochemical Impedance Spectroscopy (EIS) techniques. The proposed screen printed electrode (SPE) had a low detection limit (as low as 50 pM), acceptable stability and good reproducibility, which would be valuable for clinical diagnosis. In addition, this sensing interface may be feasibly adapted for multiplexed detection of other species of bacterial pathogens.

  18. Structural phase transitions in Iron - based superconductors BaFe2-xCrxAs2 under high pressure

    International Nuclear Information System (INIS)

    Uhoya, W.O.; Montgomery, J.M.; Samudrala, G.K.; Tsoi, G.M.; Vohra, Y.K.; Sefar, A.S.

    2011-01-01

    Pure BaFe 2 As 2 with the ThCr 2 Si 2 -type crystal structure under ambient conditions is known to superconduct under high pressure and undergo an isostructural phase transition from tetragonal to collapsed tetragonal phase which is accompanied by anomalous compressibility effects. Presently, there is no reported work on the crystal structure on any of the chemically doped 122- iron based superconductors under high pressure. We have carried out the electrical resistance measurements and high pressure X-ray diffraction studies on Chromium doped samples of BaFe 2-x Cr x As 2 (x = 0, 0.05, 0.15, 0.4, 0.61) to a pressure of 75 GPa and a temperature of 10K using a synchrotron source and designer diamond anvils, so as to investigate the influence of chemical doping and high pressure on crystal structure and superconductivity

  19. Exosome purification based on PEG-coated Fe3O4 nanoparticles.

    Science.gov (United States)

    Chang, Ming; Chang, Yaw-Jen; Chao, Pei Yu; Yu, Qing

    2018-01-01

    Cancer cells secrete many exosomes, which facilitate metastasis and the later growth of cancer. For early cancer diagnosis, the detection of exosomes is a crucial step. Exosomes exist in biological fluid, such as blood, which contains various proteins. It is necessary to remove the proteins in the biological fluid to avoid test interference. This paper presented a novel method for exosome isolation using Fe3O4 magnetic nanoparticles (MNPs), which were synthesized using the chemical co-precipitation method and then coated with polyethylene glycol (PEG). The experimental results showed that the diameter of the PEG-coated Fe3O4 nanoparticles was about 20 nm, while an agglomerate of MNPs reached hundreds of nanometers in size. In the protein removal experiments, fetal bovine serum (FBS) was adopted as the analyte for bioassays of exosome purification. PEG-coated Fe3O4 MNPs reduced the protein concentration in FBS to 39.89% of the original solution. By observing a particle size distribution of 30~200 nm (the size range of various exosomes), the exosome concentrations were kept the same before and after purification. In the gel electrophoresis experiments, the bands of CD63 (~53 kDa) and CD9 (~22 kDa) revealed that exosomes existed in FBS as well as in the purified solution. However, the bands of the serum albumins (~66 kDa) and the various immunoglobulins (around 160 ~ 188 kDa) in the purified solution's lane explained that most proteins in FBS were removed by PEG-coated Fe3O4 MNPs. When purifying exosomes from serum, protein removal is critical for further exosome investigation. The proposed technique provides a simple and effective method to remove proteins in the serum using the PEG-coated Fe3O4 MNPs.

  20. A sensitive and selective sensor for biothiols based on the turn-on fluorescence of the Fe-MIL-88 metal-organic frameworks-hydrogen peroxide system.

    Science.gov (United States)

    Sun, Zheng Juan; Jiang, Jun Ze; Li, Yuan Fang

    2015-12-21

    Herein, we present a novel strategy based on a "turn-on" fluorescence system made up of metal-organic frameworks Fe-MIL-88 and H2O2 for detecting biothiols in human serum. The nonfluorescent Fe-MIL-88 gives weak fluorescence in the presence of H2O2. Interestingly, it was found that biothiols such as glutathione (GSH), cysteine (Cys) or homocysteine (Hcy) could induce fluorescence turn-on of the Fe-MIL-88/H2O2 system. Under optimal conditions, the relative fluorescence intensity exhibited a good linear relationship in the range from 50 nM-10 μM for GSH (r = 0.994), 50 nM-10 μM for Cys (r = 0.990), and 50 nM-10 μM (r = 0.992) for Hcy; the detection limits of GSH, Cys and Hcy were 30 nM, 40 nM, and 40 nM respectively. Mechanism investigation reveals that biothiols could associate with Fe-MIL-88 via hydrogen bonding and electrostatic interaction followed by redox reaction between biothiols and Fe(3+) present in the Fe-MIL-88, Fe(3+) was thus reduced to Fe(2+), and then Fe(2+) could efficiently catalyze the decomposition of H2O2 to yield ˙OH radicals through the Fenton reaction. Besides, biothiols were able to reduce H2O2 to produce ˙OH radicals directly. Thus the Fe-MIL-88 as well as biothiols could cooperatively contribute to the activation of H2O2 to generate higher amounts of ˙OH radicals, which in turn oxidize the free ligand terephthalic acid (BDC) outside or within the Fe-MIL-88 structure to strongly fluorescent hydroxylated terephthalic acid (OHBDC), thereby turning on the fluorescence.

  1. The role of zeolites in the deactivation of multifunctional fischer-tropsch synthesis catalysts: the interaction between HZSM-5 and Fe-based Ft-catalysts

    Directory of Open Access Journals (Sweden)

    P. C. Zonetti

    2013-12-01

    Full Text Available In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis.

  2. The role of zeolites in the deactivation of multifunctional Fischer-Tropsch Synthesis catalysts: the interaction between HZSM-5 and Fe-based FT-catalysts

    International Nuclear Information System (INIS)

    Zonetti, P.C.; Gaspar, A.B.; Mendes, F.M.T.; Appel, L.G.; Avillez, R. R. de; Sousa-Aguiar, E.F.

    2013-01-01

    In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis. (author)

  3. The role of zeolites in the deactivation of multifunctional Fischer-Tropsch Synthesis catalysts: the interaction between HZSM-5 and Fe-based FT-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Zonetti, P.C.; Gaspar, A.B.; Mendes, F.M.T.; Appel, L.G., E-mail: lucia.appel@int.gov.br [Instituto Nacional de Tecnologia (INT/MCT), Rio de Janeiro, RJ (Brazil); Avillez, R. R. de [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), RJ (Brazil); Sousa-Aguiar, E.F. [Centro de Pesquisa Leopoldo Americo Miguez de Mello (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2013-10-15

    In order to produce gasoline directly from syngas, HZSM-5 can be added to the Fischer-Tropsch catalyst. However, this catalytic system shows an important deactivation rate. Aiming at describing this phenomenon, Fe-based catalysts and physical mixtures containing these catalysts and HZSM-5 were employed in this reaction. All these systems were characterized using the following techniques: XRD, XPS, TPR and TPD of CO. This work shows that HZSM-5 interacts with the Fe-based Fischer-Tropsch catalyst during the reduction step, decreasing the Fe concentration on the catalytic surface and thus lowering the activity of the catalytic system in the Fischer-Tropsch Synthesis. (author)

  4. Understanding of the mode of action of Fe(III)-EDDHA as iron chlorosis corrector based on its photochemical and redox behavior.

    Science.gov (United States)

    Gómez-Gallego, Mar; Pellico, Daniel; Ramírez-López, Pedro; Mancheño, María J; Romano, Santiago; de la Torre, María C; Sierra, Miguel A

    2005-10-07

    The very low reduction potential of the chelate Fe(III)-EDDHA (EDDHA = ethylenediamine N,N'-bis(2-hydroxy)phenylacetic acid) makes it unreactive in photochemically or chemically induced electron transfer processes. The lack of reactivity of this complex toward light invalidates photodegradation as an alternative mechanism for environmental elimination. However, in spite of its low reduction potential, the biological reduction of Fe(III)-EDDHA is very effective. Based on electrochemical measurements, it is proposed that Fe(III)-EDDHA itself is not the substrate of the enzyme ferric chelate reductase. Likely, at the more acidic pH in the vicinity of the roots, the ferric chelate in a closed form (FeL-) could generate a vacant coordination site that leads to an open hexacoordinate species (FeHL) where the reduction of the metal by the enzyme takes place.

  5. A dual-responsive colorimetric and fluorescent chemosensor based on diketopyrrolopyrrole derivative for naked-eye detection of Fe3 + and its practical application

    Science.gov (United States)

    Zhang, Shanshan; Sun, Tao; Xiao, Dejun; Yuan, Fang; Li, Tianduo; Wang, Enhua; Liu, Haixia; Niu, Qingfen

    2018-01-01

    A novel dual-responsive colorimetric and fluorescent chemosensor L based on diketopyrrolopyrrole derivative for Fe3 + detection was designed and synthesized. In presence of Fe3 +, sensor L displayed strong colorimetric response as amaranth to rose pink and significant fluorescence enhancement and chromogenic change, which served as a naked-eye indicator by an obvious color change from purple to red. The binding constant for L-Fe3 + complex was found as 2.4 × 104 with the lower detection limit of 14.3 nM. The sensing mechanism was investigated in detail by fluorescence measurements, IR and 1H NMR spectra. Sensor L for Fe3 + detection also exhibited high anti-interference performance, good reversibility, wide pH response range and instantaneous response time. Furthermore, the sensor L has been used to quantify Fe3 + ions in practical water samples with good recovery.

  6. Contribution to the Study of the Relation between Microstructure and Electrochemical Behavior of Iron-Based FeCoC Ternary Alloys

    Directory of Open Access Journals (Sweden)

    Farida Benhalla-Haddad

    2012-01-01

    Full Text Available This work deals with the relation between microstructure and electrochemical behavior of four iron-based FeCoC ternary alloys. First, the arc-melted studied alloys were characterized using differential thermal analyses and scanning electron microscopy. The established solidification sequences of these alloys show the presence of two primary crystallization phases (δ(Fe and graphite as well as two univariante lines : peritectic L+(Fe↔(Fe and eutectic L↔(Fe+Cgraphite. The ternary alloys were thereafter studied in nondeaerated solution of 10−3 M NaHCO3 + 10−3 M Na2SO4, at 25°C, by means of the potentiodynamic technique. The results indicate that the corrosion resistance of the FeCoC alloys depends on the carbon amount and the morphology of the phases present in the studied alloys.

  7. The importance of Fe interface states for ferromagnet-semiconductor based spintronic devices

    Science.gov (United States)

    Chantis, Athanasios

    2009-03-01

    I present our recent theoretical studies of the bias-controlled spin injection, detection sensitivity and tunneling anisotropic magnetoresistance in ferromagnetic-semiconductor tunnel junctions. Using first-principles electron transport methods we have shown that Fe 3d minority-spin surface (interface) states are responsible for at least two important effects for spin electronics. First, they can produce a sizable Tunneling Anisotropic Magnetoresistance in magnetic tunnel junctions with a single Fe electrode. The effect is driven by a Rashba shift of the resonant surface band when the magnetization changes direction. This can introduce a new class of spintronic devices, namely, Tunneling Magnetoresistance junctions with a single ferromagnetic electrode that can function at room temperatures. Second, in Fe/GaAs(001) magnetic tunnel junctions they produce a strong dependence of the tunneling current spin-polarization on applied electrical bias. A dramatic sign reversal within a voltage range of just a few tenths of an eV is found. This explains the observed sign reversal of spin-polarization in recent experiments of electrical spin injection in Fe/GaAs(001) and related reversal of tunneling magnetoresistcance through vertical Fe/GaAs/Fe trilayers. We also present a theoretical description of electrical spin-detection at a ferromagnet/semiconductor interface. We show that the sensitivity of the spin detector has strong bias dependence which, in the general case, is dramatically different from that of the tunneling current spin-polarization. We show that in realistic ferromagnet/semiconductor junctions this bias dependence can originate from two distinct physical mechanisms: 1) the bias dependence of tunneling current spin-polarization, which is of microscopic origin and depends on the specific properties of the interface, and 2) the macroscopic electron spin transport properties in the semiconductor. Our numerical results show that the magnitude of the voltage signal

  8. Supervised chaos genetic algorithm based state of charge determination for LiFePO4 batteries in electric vehicles

    Science.gov (United States)

    Shen, Yanqing

    2018-04-01

    LiFePO4 battery is developed rapidly in electric vehicle, whose safety and functional capabilities are influenced greatly by the evaluation of available cell capacity. Added with adaptive switch mechanism, this paper advances a supervised chaos genetic algorithm based state of charge determination method, where a combined state space model is employed to simulate battery dynamics. The method is validated by the experiment data collected from battery test system. Results indicate that the supervised chaos genetic algorithm based state of charge determination method shows great performance with less computation complexity and is little influenced by the unknown initial cell state.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  10. Room-temperature ferromagnetic transitions and the temperature dependence of magnetic behaviors in FeCoNiCr-based high-entropy alloys

    Science.gov (United States)

    Na, Suok-Min; Yoo, Jin-Hyeong; Lambert, Paul K.; Jones, Nicholas J.

    2018-05-01

    High-entropy alloys (HEAs) containing multiple principle alloying elements exhibit unique properties so they are currently receiving great attention for developing innovative alloy designs. In FeCoNi-based HEAs, magnetic behaviors strongly depend on the addition of alloying elements, usually accompanied by structural changes. In this work, the effect of non-magnetic components on the ferromagnetic transition and magnetic behaviors in equiatomic FeCoNiCrX (X=Al, Ga, Mn and Sn) HEAs was investigated. Alloy ingots of nominal compositions of HEAs were prepared by arc melting and the button ingots were cut into discs for magnetic measurements as functions of magnetic field and temperature. The HEAs of FeCoNiCrMn and FeCoNiCrSn show typical paramagnetic behaviors, composed of solid solution FCC matrix, while the additions of Ga and Al in FeCoNiCr exhibit ferromagnetic behaviors, along with the coexistence of FCC and BCC phases due to spinodal decomposition. The partial phase transition in both HEAs with the additions of Ga and Al would enhance ferromagnetic properties due to the addition of the BCC phase. The saturation magnetization for the base alloy FeCoNiCr is 0.5 emu/g at the applied field of 20 kOe (TC = 104 K). For the HEAs of FeCoNiCrGa and FeCoNiCrAl, the saturation magnetization significantly increased to 38 emu/g (TC = 703 K) and 25 emu/g (TC = 277 K), respectively. To evaluate the possibility of solid solution FCC and BCC phases in FeCoNiCr-type HEAs, we introduced a parameter of valence electron concentration (VEC). The proposed rule for solid solution formation by the VEC was matched with FeCoNiCr-type HEAs.

  11. Characterization of a Fe-based alloy system for an AFCI metallic waste form - 16134

    International Nuclear Information System (INIS)

    Williamson, Mark J.; Sindelar, Robert L.

    2009-01-01

    The AFCI waste management program aims to provide a minimum volume stable waste form for high level radioactive waste from the various process streams. The AFCI Integrated Waste Management Strategy document has identified a Fe-Zr metallic waste form (MWF) as the baseline alloy for disposal of Tc metal, undissolved solids, and TRUEX fission product wastes. Several candidate alloys have been fabricated using vacuum induction melting to investigate the limits of waste loading as a function of Fe and Zr content. Additional melts have been produced to investigate source material composition. These alloys have been characterized using SEM/EDS and XRD. Phase assemblage and specie partitioning of Re metal (surrogate for Tc) and noble metal FP elements into the phases is reported. (authors)

  12. Strength of "Light" Ferritic and Austenitic Steels Based on the Fe - Mn - Al - C System

    Science.gov (United States)

    Kaputkina, L. M.; Svyazhin, A. G.; Smarygina, I. V.; Kindop, V. E.

    2017-01-01

    The phase composition, the hardness, the mechanical properties at room temperature, and the resistance to hot (950 - 1000°C) and warm (550°C) deformation are studied for cast deformable "light" ferritic and austenitic steels of the Fe - (12 - 25)% Mn - (0 - 15)% Al - (0 - 2)% C system alloyed additionally with about 5% Ni. The high-aluminum high-manganese low-carbon and carbonless ferritic steels at a temperature of about 0.5 T melt have a specific strength close to that of the austenitic steels and may be used as weldable scale-resistant and wear-resistant materials. The high-carbon Fe - (20 - 24)% Mn - (5 - 9)% Al - 5% Ni - 1.5% C austenitic steels may be applied as light high-strength materials operating at cryogenic temperatures after a solution treatment and as scale- and heat-resistant materials in an aged condition.

  13. Martensitic Transformation and Superelasticity in Fe-Mn-Al-Based Shape Memory Alloys

    Science.gov (United States)

    Omori, Toshihiro; Kainuma, Ryosuke

    2017-12-01

    Ferrous shape memory alloys showing superelasticity have recently been obtained in two alloy systems in the 2010s. One is Fe-Mn-Al-Ni, which undergoes martensitic transformation (MT) between the α (bcc) parent and γ' (fcc) martensite phases. This MT can be thermodynamically understood by considering the magnetic contribution to the Gibbs energy, and the β-NiAl (B2) nanoprecipitates play an important role in the thermoelastic MT. The temperature dependence of critical stress for the MT is very small (about 0.5 MPa/°C) due to the small entropy difference between the parent and martensite phases in the Fe-Mn-Al-Ni alloy, and consequently, superelasticity can be obtained in a wide temperature range from cryogenic temperature to about 200 °C. Microstructural control is of great importance for obtaining superelasticity, and the relative grain size is among the most crucial factors.

  14. High performance screen printable lithium-ion battery cathode ink based on C-LiFePO4

    International Nuclear Information System (INIS)

    Sousa, R.E.; Oliveira, J.; Gören, A.; Miranda, D.; Silva, M.M.; Hilliou, Loic; Costa, C.M.; Lanceros-Mendez, S.

    2016-01-01

    Highlights: • C-LiFePO 4 paste was been prepared for screen-printing technique. • The inks produced have a Newtonian viscosity of 3 Pa.s for this printing technique. • C-LiFePO 4 inks present a 48.2 mAh.g −1 after 50 cycles at 5C. • This ink is suitable in the development of printed lithium ion batteries. - Abstract: Lithium-ion battery cathodes have been fabricated by screen-printing through the development of C-LiFePO 4 inks. It is shown that shear thinning polymer solutions in N-methyl-2-pyrrolidone (NMP) with Newtonian viscosity above 0.4 Pa s are the best binders for formulating a cathode paste with satisfactory film forming properties. The paste shows an elasticity of the order of 500 Pa and, after shear yielding, shows an apparent viscosity of the order of 3 Pa s for shear rates corresponding to those used during screen-printing. The screen-printed cathode produced with a thickness of 26 μm shows a homogeneous distribution of the active material, conductive additive and polymer binder. The total resistance and diffusion coefficient of the cathode are ∼ 450 Ω and 2.5 × 10 −16 cm 2 s −1 , respectively. The developed cathodes show an initial discharge capacity of 48.2 mAh g −1 at 5C and a discharge value of 39.8 mAh g −1 after 50 cycles. The capacity retention of 83% represents 23% of the theoretical value (charge and/or discharge process in twenty minutes), demonstrating the good performance of the battery. Thus, the developed C-LiFePO 4 based inks allow to fabricate screen-printed cathodes suitable for printed lithium-ion batteries.

  15. Mechanism-Based FE Simulation of Tool Wear in Diamond Drilling of SiCp/Al Composites.

    Science.gov (United States)

    Xiang, Junfeng; Pang, Siqin; Xie, Lijing; Gao, Feinong; Hu, Xin; Yi, Jie; Hu, Fang

    2018-02-07

    The aim of this work is to analyze the micro mechanisms underlying the wear of macroscale tools during diamond machining of SiC p /Al6063 composites and to develop the mechanism-based diamond wear model in relation to the dominant wear behaviors. During drilling, high volume fraction SiC p /Al6063 composites containing Cu, the dominant wear mechanisms of diamond tool involve thermodynamically activated physicochemical wear due to diamond-graphite transformation catalyzed by Cu in air atmosphere and mechanically driven abrasive wear due to high-frequency scrape of hard SiC reinforcement on tool surface. An analytical diamond wear model, coupling Usui abrasive wear model and Arrhenius extended graphitization wear model was proposed and implemented through a user-defined subroutine for tool wear estimates. Tool wear estimate in diamond drilling of SiC p /Al6063 composites was achieved by incorporating the combined abrasive-chemical tool wear subroutine into the coupled thermomechanical FE model of 3D drilling. The developed drilling FE model for reproducing diamond tool wear was validated for feasibility and reliability by comparing numerically simulated tool wear morphology and experimentally observed results after drilling a hole using brazed polycrystalline diamond (PCD) and chemical vapor deposition (CVD) diamond coated tools. A fairly good agreement of experimental and simulated results in cutting forces, chip and tool wear morphologies demonstrates that the developed 3D drilling FE model, combined with a subroutine for diamond tool wear estimate can provide a more accurate analysis not only in cutting forces and chip shape but also in tool wear behavior during drilling SiC p /Al6063 composites. Once validated and calibrated, the developed diamond tool wear model in conjunction with other machining FE models can be easily extended to the investigation of tool wear evolution with various diamond tool geometries and other machining processes in cutting different

  16. Temperature-dependent rigidity and magnetism of polyamide 6 nanocomposites based on nanocrystalline Fe-Ni alloy of various geometries

    Directory of Open Access Journals (Sweden)

    M. A. A. Mohamed

    2016-10-01

    Full Text Available The focus of this study is to explore the potential use of Polyamide 6 nanocomposite reinforced with nanocrystalline (nc Fe20Ni80 alloy (Fe20Ni80/PA6 PNC in electromagnetic applications and provide understanding of how the alloy particle geometry is controlling the nanocomposite’s physical properties. Thermomechanical rigidity, room-temperature soft magnetic performance and thermal soft magnetic stability of Fe20Ni80/PA6 PNCs based on spherical-sea urchin alloy particles (UMB2-SU and necklace-like alloy chains (UMB2-NC have been investigated. Both PNCs have considerably superior bulk properties compared to neat PA6 and UMB2-SU exhibits the most remarkable overall performance. Morphological observations disclose two relevant phenomena: i improved dispersion and distribution of the SU alloy particles than the NC ones within PA6 matrix, leading to stronger filler-matrix interfacial interactions within the UMB2-SU as compared to the UMB2-NC and ii presence of constraint polymer regions in between alloy segments within the UMB2-SU that provide secondary reinforcing and soft magnetic mechanisms. Such phenomena along with the lower alloy crystallite size and PA6 γ-crystal type content within the UMB2-SU than in the UMB2-NC, are considered the main responsible factors for the distinctive performance of UMB2-SU. Overall, compared to various ferromagnetic nanocrystalline metallic materials, the research proposes the SU nc Fe20Ni80 alloy as a valuable nanofiller in polymers for electromagnetic applications.

  17. Electronic correlations in hole- and electron-doped Fe-based superconductors

    Science.gov (United States)

    Hardy, Frederic; Boehmer, Anna; Schweiss, Peter; Wolf, Thomas; Heid, Rolf; Eder, Robert; Fisher, Robert A.; Meingast, Christoph

    2015-03-01

    High-temperature superconductivity in the cuprates occurs at the crossover from a highly-correlated Mott insulating state to a weaker correlated Fermi liquid as a function of hole doping. The iron pnictides were initially thought to be fairly weakly correlated. However, we have recently shown using transport and thermodynamic measurements that KFe2As2 is strongly correlated. Both the Sommerfeld coefficient and the Pauli susceptibility are strongly enhanced with respect to their bare DFT values. These correlations are even further enhanced in RbFe2As2andCsFe2As2. The temperature dependence of both the susceptibility and the thermal expansion provides strong experimental evidence for the existence of a coherence-incoherence crossover; similar to what is found in heavy-fermion compounds. Whereas the correlations in the cuprates result from a large value of the Hubbard U, recent works have stressed the particular relevance of Hund's coupling in the pnictides. Our data may be interpreted in terms of a close proximity of KFe2As2 to an orbital-selective Mott transition. We now have good thermodynamic data covering both the hole and electron sides of the BaFe2As2 system and we will discuss how these correlations are modified by doping.

  18. Composites Based on Core-Shell Structured HBCuPc@CNTs-Fe3O4 and Polyarylene Ether Nitriles with Excellent Dielectric and Mechanical Properties

    Science.gov (United States)

    Pu, Zejun; Zhong, Jiachun; Liu, Xiaobo

    2017-10-01

    Core-shell structured magnetic carbon nanotubes (CNTs-Fe3O4) coated with hyperbranched copper phthalocyanine (HBCuPc) (HBCuPc@CNTs-Fe3O4) hybrids were prepared by the solvent-thermal method. The results indicated that the HBCuPc molecules were decorated on the surface of CNTs-Fe3O4 through coordination behavior of phthalocyanines, and the CNTs-Fe3O4 core was completely coaxial wrapped by a functional intermediate HBCuPc shell. Then, polymer-based composites with a relatively high dielectric constant and low dielectric loss were fabricated by using core-shell structured HBCuPc@CNTs-Fe3O4 hybrids as fillers and polyarylene ether nitriles (PEN) as the polymer matrix. The cross-sectional scanning electron microscopy (SEM) images of composites showed that there is almost no agglomeration and internal delamination. In addition, the rheological analysis reveals that the core-shell structured HBCuPc@CNTs-Fe3O4 hybrids present better dispersion and stronger interface adhesion with the PEN matrix than CNTs-Fe3O4, thus resulting in significant improvement of the mechanical, thermal and dielectric properties of polymer-based composites.

  19. Studies of selected synthesis procedures of the conducting LiFePO{sub 4}-based composite cathode materials for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ojczyk, W.; Marzec, J.; Swierczek, K.; Zajac, W.; Molenda, J. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Molenda, M.; Dziembaj, R. [Faculty of Chemistry, Jagiellonian University, ul. R. Ingardena 3, 30-060 Krakow (Poland)

    2007-11-15

    In this paper technological aspects of a synthesis of phospho-olivine LiFePO{sub 4} based composite cathode materials for lithium batteries are presented. An effective synthesis route yielding a highly conductive composite cathode material was developed. The structural, electrical and electrochemical properties of these materials were investigated. It was shown that the enhanced conductivity of the cathode material is due to the presence of a thin layer of the reduced material which has metallic properties, which is formed on the grain surfaces of the phospho-olivine. We propose a synthesis route yielding LiFePO{sub 4}/Fe{sub 2}P composite material. (author)

  20. Oxide Dispersion Strengthened Fe3Al-Based Alloy Tubes: Application Specific Development for the Power Generation Industry

    Energy Technology Data Exchange (ETDEWEB)

    Kad, B.K.

    2002-02-08

    A detailed and comprehensive research and development methodology is being prescribed to produce Oxide Dispersion Strengthened (ODS)-Fe{sub 3}Al thin walled tubes, using powder extrusion methodologies, for eventual use at operating temperatures of up to 1100% in the power generation industry. A particular ''in service application'' anomaly of Fe{sub 3}Al-based alloys is that the environmental resistance is maintained up to 1200 C, well beyond where such alloys retain sufficient mechanical strength. Grain boundary creep processes at such high temperatures are anticipated to be the dominant failure mechanism. Thus, the challenges of this program are manifold: (1) to produce thin walled ODS-Fe{sub 3}Al tubes, employing powder extrusion methodologies, with (2) adequate increased strength for service at operating temperatures, and (3) to mitigate creep failures by enhancing the as-processed grain size in ODS-Fe{sub 3}Al tubes. Our research progress till date has resulted in the successful batch production of typically 8 Ft. lengths of 1-3/8 inch diameter, 1/8 inch wall thickness, ODS-Fe{sub 3}Al tubes via a proprietary single step extrusion consolidation process. The process parameters for such consolidation methodologies have been prescribed and evaluated as being routinely reproducible. Such processing parameters (i.e., extrusion ratios, temperature, can design etc.) were particularly guided by the need to effect post-extrusion recrystallization and grain growth at a sufficiently low temperature, while still meeting the creep requirement at service temperatures. Static recrystallization studies show that elongated grains (with their long axis parallel to the extrusion axis), typically 200-2000 {micro}m in diameter, and several millimeters long can be obtained routinely, at 1200 C. The growth kinetics are affected by the interstitial impurity content in the powder batches. For example complete recrystallization, across the tube wall thickness, is

  1. Properties of arc-sprayed coatings from Fe-based cored wires for high-temperature applications

    Science.gov (United States)

    Korobov, Yu. S.; Nevezhin, S. V.; Filiрpov, M. A.; Makarov, A. V.; Malygina, I. Yu.; Fantozzi, D.; Milanti, A.; Koivuluoto, H.; Vuoristo, P.

    2017-12-01

    Equipment of a thermal power plant is subjected to high temperature oxidation and wear. This raises operating costs through frequent repair of worn parts and high metal consumption. The paper proposes a possible solution to this problem through arc spraying of protective coatings. Cored wires of the Fe-Cr-C basic alloying system are used as a feedstock. Additional alloying by Al, B, Si, Ti and Y allows one to create wear- and heat-resistant coatings, which are an attractive substitute of more expensive Co- and Ni-based materials.

  2. The effect of chemical composition and granulation of Fe - based fillers on properties of metal resinous composite

    International Nuclear Information System (INIS)

    Janecki, J.; Dasiewicz, J.; Pawelec, Z.

    2000-01-01

    In this paper the authors present metal-resinous composites with Fe based fillers of various element constitution and granulation. The analysis of influence of filler type on coefficient of linear thermal expansion of composite materials was performed. Friction and wear tests (composite-bronze and composite-steel pairs) were carried out. It was stated that the thinner granulation of main filler has a positive effect on coefficient of linear thermal expansion and friction/wear characteristics. The presence of copper, nickel and molybdenum in the filler is beneficial for some properties of the composite. (author)

  3. MICROSTRUCTURE AND TENSILE PROPERTIES OF Fe3Al-BASED ALLOYS WITH VC AND TiC ADDITIONS

    Institute of Scientific and Technical Information of China (English)

    W.L.Xu; Y.S.Sun; S.S.Ding

    2001-01-01

    Microstructure and tensile properties of Fe3Al-based alloys with additions of TiC andVC particles have been investigated.Results show that the formation of TiC particlesresults in the refinement of the macrostructure of as-cast ingots.Although the additionof VC particles does not cause significant change of the as-cast microstructure,themicrostructure of the alloy after hot-working and recrystallization has been found tobe refined.The formation of both VC and TiC particles results in the increase of yieldstrength,especially at high temperature of 600℃.

  4. Sintering of Mo2FeB2 based cermet and its layered composites containing Sic fibers

    International Nuclear Information System (INIS)

    Rao, D.; Upadhyaya, G.S.

    2001-01-01

    In the present investigation Mo 2 FeB 2 based cermet (KH-C50) and its composites containing SiC fibers were sintered in two different atmospheres namely hydrogen and vacuum. It was observed that vacuum sintered samples have remarkably lower porosities than the hydrogen sintered ones. Two different sintering cycles were employed for each of the atmosphere and properties of the material were studied. Introduction of fibers in the composite imparts shrinkage anisotropy during sintering. Fiber containing cermets have rather poor densification and transverse rupture strength (TRS). TRS, macro and microhardness, and boride grain size measurements were also carried out for the cermets sintered in different atmospheres. (author)

  5. Magneto-Impedance behavior of Co-Fe-Nb-Si-B-based ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Partha; Mohanta, O.; Pal, S.K.; Panda, A.K. [National Metallurgical Laboratory, Council of Scientific and Industrial Research, Jamshedpur 831007 (India); Mitra, A., E-mail: amitra@nmlindia.or [National Metallurgical Laboratory, Council of Scientific and Industrial Research, Jamshedpur 831007 (India)

    2010-04-15

    The giant magneto-impedance of melt spun Co{sub x}Fe{sub 72-x}Nb{sub 4}Si{sub 4}B{sub 20}(x=10, 20, 36, 50) amorphous and nanostructured ribbons have been investigated. Alloys have been optimized at the driving current amplitude, frequency and found that amorphous ribbon of nominal composition of Co{sub 36}Fe{sub 36}Nb{sub 4}Si{sub 4}B{sub 20} shown maximum GMI ratio of 13%. The behaviour of the driving current amplitude on the GMI behaviour was studied and the sample was optimized for driving current amplitude, I{sub ac}=10 mA. The frequency dependence of the GMI behaviour was studied for the ribbon sample Co{sub 36}Fe{sub 36}Nb{sub 4}Si{sub 4}B{sub 20} at frequency in the range of 100 kHz-1.2 MHz of the optimized driving current amplitude and it was found that the sample showed the maximum GMI behaviour at f=700 kHz. The optimized samples were Joule heated at the current density J=0-35 A/m{sup 2} for a period of 1 min. The GMI ratio initially increased then progressively deteriorated with J, but after a certain range it shows up to 16% of improvement in the magneto-impedance value due the increase of nanocrystalline volume fraction. The asymmetry in the GMI profile was observed for the sample Joule heated at J=1-5 A/m{sup 2} for 1 min.

  6. Fe-based bulk metallic glasses with a larger supercooled liquid region and high ductility

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, K.Q. [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110178 (China)], E-mail: kqqiu@yahoo.com.cn; Pang, J.; Ren, Y.L.; Zhang, H.B. [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110178 (China); Ma, C.L.; Zhang, T. [School of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083 (China)

    2008-12-20

    Bulk metallic glasses (BMGs) with compositions of Fe{sub 61.5-x}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}M{sub x} (x = 2, 3; M = Ni, Nb) were fabricated by copper mold casting using raw industrial materials. The X-ray diffraction (XRD), differential scanning calorimetry (DSC), mechanical tester and scanning electron microscope (SEM) were employed to check the phase constituent, the thermal stability, the mechanical properties and the fracture surfaces of as-cast samples. The results indicate that the BMGs with diameters of 1.5-3 mm were fabricated for the alloys investigated. The largest supercooled liquid region (SLR) up to 76 K was found for Fe{sub 58.5}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}Ni{sub 3} BMG. The BMGs with Ni addition exhibit not only high fracture strengths reaching 3770 MPa for x = 2 and 3980 MPa for x = 3 alloys, respectively, but also apparently plastic strains up to 0.67% and 0.93%, respectively. The fracture surfaces of the Fe{sub 61.5-x}Co{sub 3}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 0.5}Ni{sub x} (x = 2, 3) alloys with plasticity show narrow ridges characteristic of venous patterns combining with tearing flow between the ridges. While the Nb containing alloys show not only a lower SLR below 60 K but also a lower stress below 2400 MPa, as well as almost no plastic strain before fracture.

  7. The influence of reduced graphene oxide on electrical conductivity of LiFePO{sub 4}-based composite as cathode material

    Energy Technology Data Exchange (ETDEWEB)

    Arifin, Muhammad; Aimon, Akfiny Hasdi; Winata, Toto; Abdullah, Mikrajuddin [Physics of Electronic Materials Research Division, Department of Physics, Institut Teknologi Bandung, Bandung 40132 Indonesia (Indonesia); Iskandar, Ferry, E-mail: ferry@fi.itb.ac.id [Physics of Electronic Materials Research Division, Department of Physics, Institut Teknologi Bandung, Bandung 40132 Indonesia (Indonesia); Research Center for Nanoscience and Nanotechnology Institut Teknologi Bandung, Bandung 40132 Indonesia (Indonesia)

    2016-02-08

    LiFePO{sub 4} is fascinating cathode active materials for Li-ion batteries application because of their high electrochemical performance such as a stable voltage at 3.45 V and high specific capacity at 170 mAh.g{sup −1}. However, their low intrinsic electronic conductivity and low ionic diffusion are still the hindrance for their further application on Li-ion batteries. Therefore, the efforts to improve their conductivity are very important to elevate their prospecting application as cathode materials. Herein, we reported preparation of additional of reduced Graphene Oxide (rGO) into LiFePO{sub 4}-based composite via hydrothermal method and the influence of rGO on electrical conductivity of LiFePO{sub 4}−based composite by varying mass of rGO in composition. Vibration of LiFePO{sub 4}-based composite was detected on Fourier Transform Infrared Spectroscopy (FTIR) spectra, while single phase of LiFePO{sub 4} nanocrystal was observed on X-Ray Diffraction (XRD) pattern, it furthermore, Scanning Electron Microscopy (SEM) images showed that rGO was distributed around LiFePO4-based composite. Finally, the 4-point probe measurement result confirmed that the optimum electrical conductivity is in additional 2 wt% rGO for range 1 to 2 wt% rGO.

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

    Directory of Open Access Journals (Sweden)

    Elhassan Benhsina

    2016-02-01

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

  9. Brazing Inconel 625 Using Two Ni/(Fe)-Based Amorphous Filler Foils

    Science.gov (United States)

    Chen, Wen-Shiang; Shiue, Ren-Kae

    2012-07-01

    For MBF-51 filler, the brazed joint consists of interfacial grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr-rich matrix. In contrast, the VZ-2106 brazed joint is composed of interfacial Nb6Ni16Si7 precipitates as well as grain boundary borides, coarse Nb6Ni16Si7, and Ni/Cr/Fe-rich matrix. The maximum tensile strength of 443 MPa is obtained from the MBF-51 brazed specimen. The tensile strengths of VZ-2106 brazed joints are approximately 300 MPa. Both amorphous filler foils demonstrate potential in brazing IN-625 substrate.

  10. Elevated temperature study of Nd-Fe-B--based magnets with cobalt and dysprosium additions

    International Nuclear Information System (INIS)

    Gauder, D.R.; Froning, M.H.; White, R.J.; Ray, A.E.

    1988-01-01

    This paper discusses the elevated temperature performance of Nd-Fe-B magnets containing 0--15 wt. % cobalt substitutions for iron and 0--10 wt. % dysprosium substitutions for neodymium. Test samples were prepared using conventional powder metallurgy techniques. Elevated temperature hysteresis loop and open-circuit measurements were performed on the samples to investigate irreversible losses and long term aging losses at 150 0 C. Magnets with high amounts of both cobalt and dysprosium exhibited lower losses of coercivity and magnetization. Dysprosium had more influence on the elevated temperature performance of the material than did cobalt

  11. Transformation condition in a Fe-based shape memory alloy under thermomechanical loadings

    International Nuclear Information System (INIS)

    Nishimura, F.; Watanabe, T.; Tanaka, K.

    2000-01-01

    The martensitic transformation start conditions in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy (SMA) are studied in the stress-temperature space. The martensite start condition is represented by an oval cone, which is not governed by the von Mises type condition. The subsequent martensite start condition is also investigated. The martensite start stress increases both in the initial loading and in the subsequent loading, with the progress of prior martensitic transformation. The concept of linear hardening in plasticity explains well the experimental results. On the contrary, the subsequent martensite start stress returns to the initial value with the progress of the reverse transformation. (orig.)

  12. External influence on magnetic properties of Fe-based nanocrystalline alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, Jozef [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia)]. E-mail: jozef.sitek@stuba.sk; Degmova, Jarmila [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Sedlackova, Katarina [Department of Nuclear Physics and Technology, Faculty of Electrical Engineering and Information Technology, Slovak University of Technology, Ilkovicova 3, 812 19 Bratislava (Slovakia); Butvin, Pavol [Institute of Physics, Slovak Academy of Sciences, Dubravska cesta 9, 845 11 Bratislava (Slovakia)

    2006-09-15

    Amorphous and nanocrystalline ribbons of NANOPERM, FINEMET and HITPERM were studied by Moessbauer spectroscopy (MS) after the influence of external factors: different annealing atmospheres, tensile stress and several kinds of corrosion. MS is a suitable tool for such studies because the spectral parameters are very sensitive to changes in the vicinity of the probe -{sup 57}Fe nuclei. The most sensitive parameters were hyperfine magnetic field in crystalline component, average hyperfine field in amorphous component and direction of net magnetic moments. Influence of external factors modified also the structure of the alloys, i.e. new or modified phases were identified by MS phase analysis.

  13. External influence on magnetic properties of Fe-based nanocrystalline alloys

    International Nuclear Information System (INIS)

    Sitek, Jozef; Degmova, Jarmila; Sedlackova, Katarina; Butvin, Pavol

    2006-01-01

    Amorphous and nanocrystalline ribbons of NANOPERM, FINEMET and HITPERM were studied by Moessbauer spectroscopy (MS) after the influence of external factors: different annealing atmospheres, tensile stress and several kinds of corrosion. MS is a suitable tool for such studies because the spectral parameters are very sensitive to changes in the vicinity of the probe - 57 Fe nuclei. The most sensitive parameters were hyperfine magnetic field in crystalline component, average hyperfine field in amorphous component and direction of net magnetic moments. Influence of external factors modified also the structure of the alloys, i.e. new or modified phases were identified by MS phase analysis

  14. Magnetic monolayers on semiconducting substrates. An in situ FMR study of Fe-based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zakeri Lori, K.

    2007-10-18

    The growth, magnetic anisotropy, g-factor, and magnetization of Fe monolayers grown on GaAs(001), InAs(001), and InP(001) are investigated by a combination of in situ ferromagnetic resonance and SQUID magnetometry as a function of temperature and film thickness. The effect of stress caused by the lattice mismatch and the surface reconstruction on the magnetic anisotropy is quantified. An in-plane spin reorientation transition as a function of film thickness is observed at room temperature for all systems. A magneto-elastic model is used to explain the direction of the easy axis, the spin reorientation transition, and the contributions to the magnetic anisotropy terms using the stress components measured directly by in situ IV-low-energy electron diffraction. While the model gives a quantitative explanation of the out-of-plane magnetic anisotropy, changes of the electronic interface structure have to be taken into account for the in-plane magnetic anisotropy. The influence of Ag and Au buffer and cap layers on the magnetic anisotropy terms are determined. The temperature dependence of the total magnetic anisotropy, as well as the surface-interface and volume contribution to the magnetic anisotropy are determined for Fe monolayers on GaAs(001). It is demonstrated that the temperature dependence of the magnetic anisotropy is correlated with the temperature dependence of the magnetization according to the Callen-Callen model. The temperature dependence of the volume contribution to the perpendicular magnetic anisotropy is fully explained by the temperature dependence of the magneto-elastic anisotropy. A temperature-driven morphological transformation occurring at a temperature higher than 550 K depending on the film thickness is observed. The thin Fe3Si binary Heusler structure epitaxially grown on MgO(001) is investigated. In addition to the structural properties, magnetic anisotropy, magnetization, g-factor, spin, and orbital magnetism, the magnetic relaxation

  15. Amorphization of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Pană, O. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath Street, 400293, Cluj-Napoca (Romania); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

    2016-11-01

    Amorphization of Fe{sub 75}Si{sub 20}B{sub 5} (at.%) alloy has been attempted both by wet and dry mechanical alloying starting from a mixture of elemental powders. Powder amorphization was not achieved even after 140 hours of dry mechanical alloying. Using the same milling parameters, when wet mechanical alloying was used, the powder amorphization was achieved after 40 h of milling. Our assumption regarding the powder amorphization capability enhancement by contamination with carbon was proved by X-ray Photoelectron Spectroscopy (XPS) measurements which revealed the presence of carbon in the chemical composition of the wet mechanically alloyed sample. Using shorter milling times and several process control agents (PCA) (ethanol, oleic acid and benzene) with different carbon content it was proved that the milling duration required for powder amorphization is linked to the carbon content of the PCA. Differential Scanning Calorimetry (DSC), thermomagnetic (TG) and X-ray Diffraction (XRD) measurements performed to the heated samples revealed the fact that, the crystallisation occurs at 488 °C, thus leading to the formation of Fe{sub 3}Si and Fe{sub 2}B. Thermogravimetry measurements performed under H{sub 2} atmosphere, showed the same amount of contamination with C, which is about 2.3 wt%, for the amorphous samples regardless of the type of PCA. Saturation magnetisation of the wet milled samples decreases upon increasing milling time. In the case of the amorphous samples wet milled with benzene up to 20 h and with oleic acid up to 30 h, the saturation magnetisation has roughly the same value, indicating the same degree of contamination. The XRD performed on the samples milled using the same parameters, revealed that powder amorphization can be achieved even via dry milling, just by adding the equivalent amount of elemental C calculated from the TG plots. This proves that in this system by considering the atomic species which can contaminate the powder, they can be

  16. First-principles-based Landau-Devonshire potential for BiFeO.sub.3./sub.

    Czech Academy of Sciences Publication Activity Database

    Márton, Pavel; Klíč, Antonín; Pasciak, Marek; Hlinka, Jiří

    2017-01-01

    Roč. 96, č. 17 (2017), s. 1-5, č. článku 174110. ISSN 2469-9950 R&D Projects: GA ČR GA15-04121S Grant - others:GA MŠk(CZ) LM2015042 Institutional support: RVO:68378271 Keywords : Landau-Devonshire potential * first-principles calculations * BiFeO3 * Energy-sampling technique Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.836, year: 2016

  17. Thermomechanical behavior of an Fe-based shape memory alloy: transformation conditions and hystereses

    International Nuclear Information System (INIS)

    Tanaka, K.; Nishimura, F.; Tobushi, H.; Oberaigner, E.R.; Fischer, F.D.

    1995-01-01

    Transformation/thermomechanical behavior in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy during thermomechanical loading is investigated. The transformation lines in the stress-temperature plane are strongly influenced by the parameters characterizing the thermomechanical loading. The transformation start condition, the martensite start stress and the austenite start temperature, is carefully measured to compare the results with the other experimental and theoretical observations. The stress-strain-temperature hysteresis loops, full and sub, are determined during cyclic loading. (orig.)

  18. Electrical and magnetic properties of Fe-based bulk metallic glass with minor Co and Ni addition

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H.Y. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); Stoica, M. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); POLITEHNICA University of Timisoara, P-ta Victoriei 2, Timisoara (Romania); Yi, S. [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, 702–701 Daegu (Korea, Republic of); Kim, D.H. [Center for Non-crystalline Materials, Department of Metallurgical Engineering, Yonsei University, 120–749 Seoul (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); University of Technology Dresden, Institute of Materials Science, D–01062 Dresden (Germany)

    2014-09-01

    The effect of minor Co and Ni alloying on soft magnetic properties and electrical resistivity of Fe{sub 75.5}C{sub 7.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} (at%) bulk metallic glass has been investigated. Within examined compositional range (Co and Ni up to 4 at%, respectively), the saturation magnetization and electrical resistivity of the alloys continuously decrease with increasing Co or Ni content, while the Curie temperature and initial permeability increase. Comparing the effect of Co and Ni additions, the alloys with Co addition have much higher Curie temperature and saturation magnetization than the alloy with Ni addition. Also, the Co-added alloys show smaller coercivity and larger permeability than the Ni-added alloys. The present results suggest that minor addition of Co can provide better effectiveness to enhance the magnetic softness of Fe-based BMGs than minor Ni addition. - Highlights: • Soft magnetic characteristics of CI-based BMGs can be enhanced with minor Co and Ni alloying. • Minor Co addition can provide better effectiveness to enhance the magnetic softness of CI-based BMG than Ni addition. • Optimum Co addition enlarges atomic packing density and randomness of amorphous structure.

  19. A comprehensive study of soft magnetic materials based on FeSi spheres and polymeric resin modified by silica nanorods

    International Nuclear Information System (INIS)

    Strečková, M.; Füzer, J.; Kobera, L.; Brus, J.; Fáberová, M.; Bureš, R.; Kollár, P.; Lauda, M.; Medvecký, Ĺ.; Girman, V.; Hadraba, H.; Bat'ková, M.; Bat'ko, I.

    2014-01-01

    A novel soft magnetic composite (SMC) based on spherical FeSi particles precisely covered by hybrid phenolic resin was designed. The hybrid resin including silica nano-rods chemically incorporated into the phenolic polymer matrix was prepared by the modified sol–gel method. A chemical bridge connecting silica nano-rods with the base polymeric net was verified by FTIR, 13 C and 29 Si NMR spectroscopy, whereas the shape and size of silica nano-rods were determined by TEM. It is shown that the modification of polymeric resin by silica nano-rods generally leads to the improved thermal and mechanical properties of the final samples. The hybrid resin serves as a perfect insulating coating deposited on FeSi particles and the core–shell particles can be further compacted by standard powder metallurgy methods in order to prepare final samples for mechanical, electric and magnetic testing. SEM images evidence negligible porosity, uniform distribution of the hybrid resin around FeSi particles, as well as, dimensional shape stability of the final samples after thermal treatment. The hardness, flexural strength and density of the final samples are comparable to the sintered SMCs, but they simultaneously exhibit much higher specific resistivity along with only slightly lower coercivity and permeability. - Highlights: • Soft magnetic composites are designed for electrotechnical applications. • Electroinsulating layer consists of phenolic resin modified with silica nano-rods. • NMR, FTIR and DSC analysis is used to characterize hybrid resin. • Spherical Fe–Si particles covered by hybrid resin form a core–shell composite. • Mechanical, electrical and magnetic properties are described in detail

  20. Structure and magnetism in Fe-Gd based dinuclear and chain systems: the interplay of weak exchange coupling and zero field splitting effects

    NARCIS (Netherlands)

    Ferbinteanu, M.; Cimpoesu, F.; Gîrtu, M. A.; Enachescu, C.; Tanase, S.

    2012-01-01

    The synthesis and characterization of two Fe-Gd systems based on bpca- (Hbpca = bis(2-pyridilcarbonyl)amine) as bridging ligand is presented, taking the systems as a case study for structure-property correlations. Compound 1, [FeLSII(μ-bpca)2Gd(NO3)2(H2O)]NO3·2CH3NO2, is a zigzag polymer,

  1. Preparation of FeS2 nanotube arrays based on layer-by-layer assembly and their photoelectrochemical properties

    International Nuclear Information System (INIS)

    Wang, Mudan; Xue, Dongpeng; Qin, Haiying; Zhang, Lei; Ling, Guoping; Liu, Jiabin; Fang, Youtong; Meng, Liang

    2016-01-01

    Graphical abstract: - Highlights: • Amorphous Fe 2 O 3 nanotube arrays are prepared via layer-by-layer assembly. • Pyrite FeS 2 nanotube arrays are obtained by sulfurizing Fe 2 O 3 nanotube arrays. • Various electrochemical properties are characterized. • A comparison between FeS 2 nanotube and nanoparticle films is conducted. • Nanotube arrays show enhanced corrosion resistance and photoresponse. - Abstract: Well-aligned one-dimensional iron pyrite FeS 2 nanotube arrays have been fabricated via layer-by-layer assembly technique on ZnO nanorod arrays in combination with subsequent sulfurization. The as-prepared products were confirmed to be pure phase pyrite FeS 2 with Fe/S ratio approaching 1/2. Typical nanotube structure was observed for the FeS 2 with average outer diameter of 150 ± 20 nm and wall thickness of 50 ± 5 nm. Comparisons of photoelectrochemical properties between FeS 2 nanotubes and FeS 2 nanoparticles were conducted. Tafel polarization curves and electrochemical impedance spectroscopy indicate that FeS 2 nanotubes possess high corrosion resistance and electrochemical stability. The J–V curves show that the photocurrent at 1.0 V for FeS 2 nanotubes is more than five times larger than that of FeS 2 nanoparticles, indicating enhanced photoresponse and rapid charge transfer performances of 1-D nanotube structure. The enhanced photoelectrochemical properties mainly benefit from the unique architecture features of nanotube array structure.

  2. FE Analysis of Rock with Hydraulic-Mechanical Coupling Based on Continuum Damage Evolution

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2016-01-01

    Full Text Available A numerical finite element (FE analysis technology is presented for efficient and reliable solutions of rock with hydraulic-mechanical (HM coupling, researching the seepage characteristics and simulating the damage evolution of rock. To be in accord with the actual situation, the rock is naturally viewed as heterogeneous material, in which Young’s modulus, permeability, and strength property obey the typical Weibull distribution function. The classic Biot constitutive relation for rock as porous medium is introduced to establish a set of equations coupling with elastic solid deformation and seepage flow. The rock is subsequently developed into a novel conceptual and practical model considering the damage evolution of Young’s modulus and permeability, in which comprehensive utilization of several other auxiliary technologies, for example, the Drucker-Prager strength criterion, the statistical strength theory, and the continuum damage evolution, yields the damage variable calculating technology. To this end, an effective and reliable numerical FE analysis strategy is established. Numerical examples are given to show that the proposed method can establish heterogeneous rock model and be suitable for different load conditions and furthermore to demonstrate the effectiveness and reliability in the seepage and damage characteristics analysis for rock.

  3. Interior Noise Prediction of the Automobile Based on Hybrid FE-SEA Method

    Directory of Open Access Journals (Sweden)

    S. M. Chen

    2011-01-01

    created using hybrid FE-SEA method. The modal density was calculated using analytical method and finite element method; the damping loss factors of the structural and acoustic cavity subsystems were also calculated with analytical method; the coupling loss factors between structure and structure, structure and acoustic cavity were both calculated. Four different kinds of excitations including road excitations, engine mount excitations, sound radiation excitations of the engine, and wind excitations are exerted on the body of automobile when the automobile is running on the road. All the excitations were calculated using virtual prototype technology, computational fluid dynamics (CFD, and experiments realized in the design and development stage. The interior noise of the automobile was predicted and verified at speed of 120 km/h. The predicted and tested overall SPLs of the interior noise were 73.79 and 74.44 dB(A respectively. The comparison results also show that the prediction precision is satisfied, and the effectiveness and reliability of the hybrid FE-SEA model of the automobile is verified.

  4. First principles analysis of lattice dynamics for Fe-based superconductors and entropically-stabilized phases

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Steven [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    Modern calculations are becoming an essential, complementary tool to inelastic x-ray scattering studies, where x-rays are scattered inelastically to resolve meV phonons. Calculations of the inelastic structure factor for any value of Q assist in both planning the experiment and analyzing the results. Moreover, differences between the measured data and theoretical calculations help identify important new physics driving the properties of novel correlated systems. We have used such calculations to better and more e ciently measure the phonon dispersion and elastic constants of several iron pnictide superconductors. This dissertation describes calculations and measurements at room temperature in the tetragonal phase of CaFe{sub 2}As{sub 2} and LaFeAsO. In both cases, spin-polarized calculations imposing the antiferromagnetic order present in the low-temperature orthorhombic phase dramatically improves the agreement between theory and experiment. This is discussed in terms of the strong antiferromagnetic correlations that are known to persist in the tetragonal phase. In addition, we discuss a relatively new approach called self-consistent ab initio lattice dynamics (SCAILD), which goes beyond the harmonic approximation to include phonon-phonon interactions and produce a temperature-dependent phonon dispersion. We used this technique to study the HCP to BCC transition in beryllium.

  5. Synthesis, characterization and gas sensing properties of undoped and Zn-doped γ-Fe2O3-based gas sensors

    International Nuclear Information System (INIS)

    Jing Zhihong

    2006-01-01

    In this study, undoped and Zn-doped γ-Fe 2 O 3 nanopowders have been prepared using Fe(NO 3 ) 3 .9H 2 O and Zn(NO 3 ) 2 .6H 2 O as starting materials and lauryl alcohol as anhydrous medium. Thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron micrograph (TEM) were employed to characterize the products. Sensitivity characteristics of the undoped and Zn-doped γ-Fe 2 O 3 semiconductor gas sensors have been investigated. The results show that both of the undoped and 15 mol% Zn-doped γ-Fe 2 O 3 -based gas sensors present good sensitivity and selectivity to acetone and ethanol in presence of CH 4 , H 2 and CO at the operating temperatures of 240 and 270 deg. C, respectively. After being doped with 15 mol% Zn addition, the γ-Fe 2 O 3 -based gas element displays higher sensitivity and selectivity as well as shorter response-recovery time compared with the undoped, suggesting that the promoting effect of ZnO is excellent. So, it seems that the γ-Fe 2 O 3 -based gas sensor doped with 15 mol% Zn is expected to be a promising sensor for detecting acetone and ethanol

  6. Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 1. Structural, Hydrogen Storage, and Electrochemical Properties

    Directory of Open Access Journals (Sweden)

    Kwo-Hsiung Young

    2016-11-01

    Full Text Available The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA were studied. Addition of Fe increases the lattice constants and abundance of the main Ce2Ni7 phase, decreases the NdNi3 phase abundance, and increases the CaCu5 phase when the Fe content is above 2.3 at%. For the gaseous phase hydrogen storage (H-storage, Fe incorporation does not change the storage capacity or equilibrium pressure, but it does decrease the change in both entropy and enthalpy. With regard to electrochemistry, >2.3 at% Fe decreases both the full and high-rate discharge capacities due to the deterioration in both bulk transport (caused by decreased secondary phase abundance and consequent lower synergetic effect and surface electrochemical reaction (caused by the lower volume of the surface metallic Ni inclusions. In a low-temperature environment (−40 °C, although Fe increases the reactive surface area, it also severely hinders the ability of the surface catalytic, leading to a net increase in surface charge-transfer resistance. Even though Fe increases the abundance of the beneficial Ce2Ni7 phase with a trade-off for the relatively unfavorable NdNi3 phase, it also deteriorates the electrochemical performance due to a less active surface. Therefore, further surface treatment methods that are able to increase the surface catalytic ability in Fe-containing superlattice alloys and potentially reveal the positive contributions that Fe provides structurally are worth investigating in the future.

  7. Externally fired gas turbine cycles with high temperature heat exchangers utilising Fe-based ODS alloy tubing

    International Nuclear Information System (INIS)

    Olsson, F.; Svensson, S.-A.; Duncan, R.

    2001-01-01

    This work is part of the BRITE / EuRAM Project 'Development of Torsional Grain Structures to Improve Biaxial Creep Performance of Fe-based ODS Alloy Tubing for Biomass Power Plant'. The main goal of this project is to heat exchanger tubes working at 1100 o C and above. The paper deals with design implications of a biomass power plant, using an indirectly fired gas turbine with a high temperature heat exchanger containing Fe-based ODS alloy tubing. In the current heat exchanger design, ODS alloy tubing is used in a radiant section, using a bayonet type tube arrangement. This enables the use of straight sections of ODS tubing and reduces the amount of material required. In order to assess the potential of the power plant system, thermodynamic calculations have been conducted. Both co-generation and condensing applications are studied and results so far indicate that the electrical efficiency is high, compared to values reached by conventional steam cycle power plants of the same size (approx. 5 MW e ). (author)

  8. Ubbelohde viscometer measurement of water-based Fe{sub 3}O{sub 4} magnetic fluid prepared by coprecipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gu, H. [School of Physics and Electronic Engineering, Changshu Institute of Technology, Changshu 215500 (China); Tang, X. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); College of Chemistry and Chemical Engineering, Fuzhou University, Fuzhou 350002 (China); Feng, W.G. [Suzhou Nanocomp Inc., Suzhou New District, Suzhou 215011 (China); Xie, H.D.; Chen, D.X. [Suzhou YouNuo Plastic Industry Co., Ltd., Suzhou 215021 (China); Badami, D. [Department of Chemical Engineering, University of Waterloo, Waterloo, Canada ON N2L 3G1 (Canada)

    2013-12-15

    Fe{sub 3}O{sub 4} nanoparticles were prepared by co-precipitation and coated by sodium dodecyl benzene sulfonate (SDBS) to obtain water-based magnetic fluid. The viscosity of the magnetic fluid was measured using an Ubbelohde viscometer. The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity were studied. Experimental results showed that the magnetic fluid with low magnetic particle volume fraction behaved as a Newtonian fluid and the viscosity of the magnetic fluid increased with an increase of the suspended magnetic particles volume fraction. The experimental data was compared with the results of a theoretically derived equation. The viscosity of the magnetic fluid also increased with an increase in surfactant mass portion, while it decreased with increasing temperature. Moreover, the viscosity increased with increasing the magnetic field intensity. Increasing the temperature and the surfactant mass fraction weakened the influence of the magnetic field on the viscosity of the magnetic fluid. - Highlights: • Fe{sub 3}O{sub 4} nanoparticles were prepared using co-precipitation and coated by sodium dodecyl benzene sulfonate to obtain water-based magnetic fluid. • The viscosity of different magnetic fluids was measured using an Ubbelohde viscometer. • The effects of magnetic particles volume fraction, surfactant mass fraction and temperature on the viscosity of magnetic fluids were studied.

  9. Liquid crystal based optical platform for the detection of Pb2+ ions using NiFe2O4 nanoparticles

    Science.gov (United States)

    Zehra, Saman; Gul, Iftikhar Hussain; Hussain, Zakir

    2018-06-01

    A simple, sensitive, selective and real time detection protocol was developed for Pb2+ ions in water using liquid crystals (LCs). In this method, NiFe2O4 nanoparticles were synthesized using chemical co-precipitation method. Crystallite size, morphological, functional groups and magnetization studies were confirmed using X-ray diffraction, Scanning Electron Microscopy, and Fourier transform infrared spectroscopy techniques, respectively. The nanoparticles were mono dispersed with average particle size of 20 ± 2 nm. The surfactant stabilized magnetic nanoparticles were incubated in liquid crystal based sensor system for the detection of Pb+2 ions. The bright to dark transition of LC was observed through optical microscope. When this system was further immersed with a solution containing Pb2+ ions, it caused homeotropic to planar orientation of LC. This interaction is attributed to the presence of abundant hydroxyl groups in such as M-OH, Fe-OH on the surface of spinel ferrites nanoparticles. These groups interact with metal ions at aqueous interface, causing disruption in LCs orientation giving bright texture. This sensor showed higher selectivity towards Pb2+ ions. The detection limit was estimated to be 100 ppb. The cheap and effective protocol reported here should make promising development of LC based sensor for lead ion detection.

  10. Liquid crystal based optical platform for the detection of Pb2+ ions using NiFe2O4 nanoparticles

    Directory of Open Access Journals (Sweden)

    Saman Zehra

    2018-06-01

    Full Text Available A simple, sensitive, selective and real time detection protocol was developed for Pb2+ ions in water using liquid crystals (LCs. In this method, NiFe2O4 nanoparticles were synthesized using chemical co-precipitation method. Crystallite size, morphological, functional groups and magnetization studies were confirmed using X-ray diffraction, Scanning Electron Microscopy, and Fourier transform infrared spectroscopy techniques, respectively. The nanoparticles were mono dispersed with average particle size of 20 ± 2 nm. The surfactant stabilized magnetic nanoparticles were incubated in liquid crystal based sensor system for the detection of Pb+2 ions. The bright to dark transition of LC was observed through optical microscope. When this system was further immersed with a solution containing Pb2+ ions, it caused homeotropic to planar orientation of LC. This interaction is attributed to the presence of abundant hydroxyl groups in such as M-OH, Fe-OH on the surface of spinel ferrites nanoparticles. These groups interact with metal ions at aqueous interface, causing disruption in LCs orientation giving bright texture. This sensor showed higher selectivity towards Pb2+ ions. The detection limit was estimated to be 100 ppb. The cheap and effective protocol reported here should make promising development of LC based sensor for lead ion detection. Keywords: Chemical co-precipitation method, Fourier transform infrared spectroscopy, Liquid crystals, Nanoparticles, Sensor, X-ray diffraction

  11. Photo-catalytic hydrogen production over Fe{sub 2}O{sub 3} based catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Boudjemaa, A. [Technical and Scientific Research Centre of Physico-chemistry Analysis (CRAPC), BP 248, RP 16004, Algiers (Algeria); Laboratory of Chemistry of Natural Gas, Faculty of Chemistry (USTHB) BP 32, 16111 Algiers (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB) BP 32, 16111 Algiers (Algeria)

    2010-08-15

    The hydrogen photo-evolution was successfully achieved in aqueous (Fe{sub 1-x}Cr{sub x}){sub 2}O{sub 3} suspensions (0 {<=} x {<=} 1). The solid solution has been prepared by incipient wetness impregnation and characterized by X-ray diffraction, BET, transport properties and photo-electrochemistry. The oxides crystallize in the corundum structure, they exhibit n-type conductivity with activation energy of {proportional_to}0.1 eV and the conduction occurs via adiabatic polaron hops. The characterization of the band edges has been studied by the Mott Schottky plots. The onset potential of the photo-current is {proportional_to}0.2 V cathodic with respect to the flat band potential, implying a small existence of surface states within the gap region. The absorption of visible light promotes electrons into (Fe{sub 1-x}Cr{sub x}){sub 2}O{sub 3}-CB with a potential ({proportional_to}-0.5 V{sub SCE}) sufficient to reduce water into hydrogen. As expected, the quantum yield increases with decreasing the electro affinity through the substitution of iron by the more electropositive chromium which increases the band bending at the interface and favours the charge separation. The generated photo-voltage was sufficient to promote simultaneously H{sub 2}O reduction and SO{sub 3}{sup 2-} oxidation in the energetically downhill reaction (H{sub 2}O + SO{sub 3}{sup 2-} {yields} H{sub 2} + SO{sub 4}{sup 2-}, {delta}G = -17.68 kJ mol{sup -1}). The best activity occurs over Fe{sub 1.2}Cr{sub 0.8}O{sub 3} in SO{sub 3}{sup 2-} (0.1 M) solution with H{sub 2} liberation rate of 21.7 {mu}mol g{sup -1} min{sup -1} and a quantum yield 0.06% under polychromatic light. Over time, a pronounced deceleration occurs, due to the competitive reduction of the end product S{sub 2}O{sub 6}{sup 2-}. (author)

  12. Effects of chromium addition on microstructure and properties of TiC–VC reinforced Fe-based laser cladding coatings

    International Nuclear Information System (INIS)

    Zhang, Hui; Zou, Yong; Zou, Zengda; Shi, Chuanwei

    2014-01-01

    Highlights: • In situ TiC–VC reinforced Fe-based coatings with different Cr addition were obtained. • Some long strip Cr 3 C 2 synthesized while the Cr addition was 12.0% or more. • A moderate amount of Cr improved hardness and corrosion resistance significantly. • The cladding layer microhardness could reach as high as 1090HV 0.2 with 3.0% Cr. • The corrosion resistance could improve 4.5 times with 12.0% Cr. - Abstract: Effects of different addition of Cr on microstructure and properties (especially the corrosion resistance) of cladding layers were investigated by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that Fe–Ti–V–C alloy powders with different addition of Cr formed good cladding layers without defects such as cracking and porosity. Phases of the cladding layers were α-Fe, γ-Fe, TiC, VC and TiVC 2 . A certain amount of long strip Cr 3 C 2 synthesized while the addition of Cr was 12.0% or more. Microhardness and corrosion resistance of cladding layer both improved greatly with a moderate amount of Cr. The cladding layer with 3.0% Cr showed a highest microhardness 1090HV 0.2 , and the variation tendency of the hardness is not a linearly relationship with increasing the chromium addition. The cladding layer with 12.0% Cr addition showed the best corrosion resistance, which was about 4.5 times than that of the cladding layer without Cr. EIS spectrum of the cladding layer without Cr was composed of an inductive arc at low frequency and a capacitive arc at high frequency. However, the inductive arc at low frequency transformed into a capacitive arc gradually with the addition of Cr increasing

  13. Effects of chromium addition on microstructure and properties of TiC–VC reinforced Fe-based laser cladding coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hui; Zou, Yong, E-mail: yzou@sdu.edu.cn; Zou, Zengda; Shi, Chuanwei

    2014-11-25

    Highlights: • In situ TiC–VC reinforced Fe-based coatings with different Cr addition were obtained. • Some long strip Cr{sub 3}C{sub 2} synthesized while the Cr addition was 12.0% or more. • A moderate amount of Cr improved hardness and corrosion resistance significantly. • The cladding layer microhardness could reach as high as 1090HV{sub 0.2} with 3.0% Cr. • The corrosion resistance could improve 4.5 times with 12.0% Cr. - Abstract: Effects of different addition of Cr on microstructure and properties (especially the corrosion resistance) of cladding layers were investigated by means of X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), potentio-dynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that Fe–Ti–V–C alloy powders with different addition of Cr formed good cladding layers without defects such as cracking and porosity. Phases of the cladding layers were α-Fe, γ-Fe, TiC, VC and TiVC{sub 2}. A certain amount of long strip Cr{sub 3}C{sub 2} synthesized while the addition of Cr was 12.0% or more. Microhardness and corrosion resistance of cladding layer both improved greatly with a moderate amount of Cr. The cladding layer with 3.0% Cr showed a highest microhardness 1090HV{sub 0.2}, and the variation tendency of the hardness is not a linearly relationship with increasing the chromium addition. The cladding layer with 12.0% Cr addition showed the best corrosion resistance, which was about 4.5 times than that of the cladding layer without Cr. EIS spectrum of the cladding layer without Cr was composed of an inductive arc at low frequency and a capacitive arc at high frequency. However, the inductive arc at low frequency transformed into a capacitive arc gradually with the addition of Cr increasing.

  14. High-Tc superconductivity near the anion height instability in Fe-based superconductors: analysis of LaFeAsO(1-x)H(x).

    Science.gov (United States)

    Onari, Seiichiro; Yamakawa, Youichi; Kontani, Hiroshi

    2014-05-09

    The isostructural transition in the tetragonal phase with a sizable change in the anion height, is realized in heavily H-doped LaFeAsO and (La,P) codoped CaFe2As2. In these compounds, the superconductivity with higher Tc (40-50 K) is realized near the isostructural transition. To find the origin of the anion-height instability and the role in realizing the higher-Tc state, we develop the orbital-spin fluctuation theory by including the vertex correction. We analyze LaFeAsO(1-x)H(x) and find that the non-nematic orbital fluctuations, which induce the anion-height instability, are automatically obtained at x∼0.5, in addition to the conventional nematic orbital fluctuations at x∼0. The non-nematic orbital order triggers the isostructural transition, and its fluctuation would be a key ingredient to realize higher-Tc superconductivity of order 50 K.

  15. The gas-sensing properties of thick film sensors based on nano-ZnFe2O4 prepared by hydrothermal method

    International Nuclear Information System (INIS)

    Chu Xiangfeng; Jiang Dongli; Zheng Chenmou

    2006-01-01

    ZnFe 2 O 4 sensors were fabricated from nano-ZnFe 2 O 4 powders prepared by hydrothermal method and their gas-sensing properties were investigated. It was found that the phase composition of the product and the gas-sensing properties greatly depend on the reaction pH value and the reaction temperature. Nano-ZnFe 2 O 4 powders could be obtained at a pH of 8-10 and the sensor based on the nano-ZnFe 2 O 4 powder prepared at 220 deg. C exhibited the best performance, characterized by high sensitivity to low concentrations of C 2 H 5 OH at 180 deg. C, especially, the sensitivity to 100 ppm C 2 H 5 OH was as high as 76

  16. Isochronal and isothermal crystallization kinetics of amorphous Fe-based alloys

    International Nuclear Information System (INIS)

    Zhang, J.T.; Wang, W.M.; Ma, H.J.; Li, G.H.; Li, R.; Zhang, Z.H.

    2010-01-01

    Using the differential scanning calorimetry (DSC), the isochronal and isothermal crystallization kinetics of amorphous Fe 61 Co 9-x Zr 8 Mo 5 W x B 17 (x = 0 and 2) ribbons was investigated by the Kissinger equation and by the Kolmogorov-Johnson-Mehl-Avrami and Ranganathan-Heimendahl equations, respectively. The results show that tungsten can improve the activation energy E 1 K for the first crystallization in the isochronal annealing process and activation energy E n for the nucleation in the isothermal annealing process, which can be ascribed to the dissolution of tungsten in the amorphous phase. Meanwhile, tungsten can decrease the activation energy E 2 K for the second crystallization in the isochronal annealing process and growth activation energy E g in the isothermal annealing process, which is possibly associated with the formation of W-rich compound after the early nucleation process.

  17. Development of Fe-based superconducting wires for liquid-hydrogen level sensors

    Science.gov (United States)

    Ishida, S.; Tsuchiya, Y.; Mawatari, Y.; Eisaki, H.; Nakano, A.; Yoshida, Y.

    2017-07-01

    We developed liquid-hydrogen (LH2) level sensors with Ba(Fe1-x Co x )2As2 superconducting wires (Co-Ba122 wires) as their detection elements. We fabricated Co-Ba122 wires with different Co concentrations x by using the powder-in-tube method. The superconducting transition temperatures of the wires were successfully controlled in the range of 20-25 K by changing x from 0.06 to 0.10. The resistance-temperature curves of the wires exhibited sharp superconducting transitions with widths of 0.5-1.0 K. In addition, we performed an operation test of the Co-Ba122 level sensors with LH2. Close correspondence between the output resistance and the actual LH2 level was observed for a sensor equipped with x = 0.09 wire, demonstrating that this sensor can accurately measure LH2 levels.

  18. Influence of iridium on the reactivity of LaFeO3 base perovskites

    DEFF Research Database (Denmark)

    Kindermann, L.; Das, D.; Bahadur, D.

    1998-01-01

    The influence of iridium on the reactivity of powder mixtures made of perovskites and 8 mol% yttria stabilized zirconia (8 YSZ) is reported. Iridium is added to the perovskites of the composition (La0.6M0.4)(z)Fe0.8TM0.2O3-delta (M = Sr, Ca; TM = Mn, Co; z = 0.90, 1.00) via the gaseous phase....... Iridium is present in the perovskite lattice as Ir4+ replacing iron as is evident from XRD and TEM/EDX results. Compatibility studies carried out at 1000 degrees C demonstrate that iridium has considerable influence on the reactivity. The results are discussed with respect to the stability...... of the perovskites, thermodynamic activities, Ir(IV)-O bonding, tolerance factor and oxygen migration....

  19. Reentrant spin glass ordering in an Fe-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Qiang; Shen, Jun, E-mail: junshen@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China)

    2015-02-07

    We report the results of the complex susceptibility, temperature, and field dependence of DC magnetization and the nonequilibrium dynamics of a bulk metallic glass Fe{sub 40}Co{sub 8}Cr{sub 15}Mo{sub 14}C{sub 15}B{sub 6}Er{sub 2}. Solid indication of the coexistence of reentrant spin glass (SG) and ferromagnetic orderings is determined from both DC magnetization and AC susceptibility under different DC fields. Dynamics scaling of AC susceptibility indicates critical slowing down to a reentrant SG state with a static transition temperature T{sub s} = ∼17.8 K and a dynamic exponent zv = ∼7.3. The SG nature is further corroborated from chaos and memory effects, magnetic hysteresis, and aging behavior. We discuss the results in terms of the competition among random magnetic anisotropy and exchange interactions and compare them with simulation predictions.

  20. Gold Nanoparticle-based Surface-enhanced Raman Scattering Fe(III) Ion Sensor

    International Nuclear Information System (INIS)

    Ly, Nguyen Hoang; Joo, Sang-Woo; Cho, Kwang Hwi

    2015-01-01

    We performed density functional theory (DFT) calculations of 4-aminobenzo-15-crown-5 (4AB15C5) in conjugation with 4-mercaptobenzoic acid (4MCB) with the polarizable continuum model (PCM) while considering the aqueous media. After specific binding of the ferric ion onto the 4MCB.4AB15C5 compound, the Raman frequencies and intensities were estimated by DFT calculations with the PCM. It was predicted that the Raman intensities became significantly increased upon binding of the ferric ion. 4MCB.4AB15C5 could be assembled on gold nanoparticles (AuNPs) via the cleavage of the thiol bond. Colorimetric and UV.Vis absorption spectroscopy indicated that AuNPs became significantly aggregated in the presence of 1.10 mM of the ferric ion. Surface-enhanced Raman scattering (SERS) of 4MCB.4AB15C5 was used to identify the dissimilar spectral behaviors that yield a difference in intensity in the presence of the ferric ion. These changes were not observed in the other biological ions Zn 2+ , Mn 2+ , Fe 2+ , Na + , K + , Ca 2+ , Mg 2+ , NH 4+ , and Co 2+ . This study indicated that 4AB15C5 could be used to detect ferric ions in aqueous AuNP solutions by a combined method of colorimetric, UV.Vis absorption, and Raman spectroscopy. AuNPs.[4MCB. 4AB15C5] can thus be utilized as a selective turn-on sensor to Fe3 + in aqueous solutions above 1 mM.

  1. Performance Investigation of Automobile Radiator Operated with ZnFe2O4 Nano Fluid based Coolant

    Directory of Open Access Journals (Sweden)

    Tripathi Ajay

    2015-01-01

    Full Text Available The cooling system of an Automobile plays an important role in its performance, consists of two main parts, known as radiator and fan. Improving thermal efficiency of engine leads to increase the engine's performance, decline the fuel consumption and decrease the pollution emissions. Water and ethylene glycol as conventional coolants have been widely used in radiators of an automotive industry for many years. These heat transfer fluids offer low thermal conductivity. With the advancement of nanotechnology, the new generation of heat transfer fluids called, “nanofluids” have been developed and researchers found that these fluids offer higher thermal conductivity compared to that of conventional coolants. This study focused on the preparation of Zinc based nanofluids (ZnFe2O4 using chemical co-precipitation method and its application in an automotive cooling system along with mixture of ethylene glycol and water (50:50. Relevant input data, nanofluids properties and empirical correlations were obtained from literatures to investigate the heat transfer enhancement of an automotive car radiator operated with nano fluid-based coolants. It was observed that, overall heat transfer coefficient and heat transfer rate in engine cooling system increased with the usage of nanofluids (with ethylene glycol the base-fluid compared to ethylene glycol (i.e. base-fluid alone. It is observed that, about 78% of heat transfer enhancement could be achieved with the addition of 1% ZnFe2O4 particles in a base fluid at the Reynolds number of 84.4x103 and 39.5x103 for air and coolant respectively

  2. Synthesis of Hydrocarbons from H2-Deficient Syngas in Fischer-Tropsch Synthesis over Co-Based Catalyst Coupled with Fe-Based Catalyst as Water-Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2015-01-01

    Full Text Available The effects of metal species in an Fe-based catalyst on structural properties were investigated through the synthesis of Fe-based catalysts containing various metal species such, as Mn, Zr, and Ce. The addition of the metal species to the Fe-based catalyst resulted in high dispersions of the Fe species and high surface areas due to the formation of mesoporous voids about 2–4 nm surrounded by the catalyst particles. The metal-added Fe-based catalysts were employed together with Co-loaded beta zeolite for the synthesis of hydrocarbons from syngas with a lower H2/CO ratio of 1 than the stoichiometric H2/CO ratio of 2 for the Fischer-Tropsch synthesis (FTS. Among the catalysts, the Mn-added Fe-based catalyst exhibited a high activity for the water-gas shift (WGS reaction with a comparative durability, leading to the enhancement of the CO hydrogenation in the FTS in comparison with Co-loaded beta zeolite alone. Furthermore, the loading of Pd on the Mn-added Fe-based catalyst enhanced the catalytic durability due to the hydrogenation of carbonaceous species by the hydrogen activated over Pd.

  3. Metagenomic and PCR-Based Diversity Surveys of [FeFe]-Hydrogenases Combined with Isolation of Alkaliphilic Hydrogen-Producing Bacteria from the Serpentinite-Hosted Prony Hydrothermal Field, New Caledonia.

    Science.gov (United States)

    Mei, Nan; Postec, Anne; Monnin, Christophe; Pelletier, Bernard; Payri, Claude E; Ménez, Bénédicte; Frouin, Eléonore; Ollivier, Bernard; Erauso, Gaël; Quéméneur, Marianne

    2016-01-01

    High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia), where high-pH (~11), low-temperature (< 40°C), and low-salinity fluids are discharged in both intertidal and shallow submarine environments. In this study, we investigated the diversity and distribution of potentially hydrogen-producing bacteria in Prony hyperalkaline springs by using metagenomic analyses and different PCR-amplified DNA sequencing methods. The retrieved sequences of hydA genes, encoding the catalytic subunit of [FeFe]-hydrogenases and, used as a molecular marker of hydrogen-producing bacteria, were mainly related to those of Firmicutes and clustered into two distinct groups depending on sampling locations. Intertidal samples were dominated by new hydA sequences related to uncultured Firmicutes retrieved from paddy soils, while submarine samples were dominated by diverse hydA sequences affiliated with anaerobic and/or thermophilic submarine Firmicutes pertaining to the orders Thermoanaerobacterales or Clostridiales. The novelty and diversity of these [FeFe]-hydrogenases may reflect the unique environmental conditions prevailing in the PHF (i.e., high-pH, low-salt, mesothermic fluids). In addition, novel alkaliphilic hydrogen-producing Firmicutes (Clostridiales and Bacillales) were successfully isolated from both intertidal and submarine PHF chimney samples. Both molecular and cultivation-based data demonstrated the ability of Firmicutes originating from serpentinite-hosted environments to produce hydrogen by fermentation, potentially contributing to the molecular hydrogen balance in situ.

  4. Determination of the ground state of an Au-supported FePc film based on the interpretation of Fe K - and L -edge x-ray magnetic circular dichroism measurements

    Science.gov (United States)

    Natoli, Calogero R.; Krüger, Peter; Bartolomé, Juan; Bartolomé, Fernando

    2018-04-01

    We determine the magnetic ground state of the FePc molecule on Au-supported thin films based on the observed values of orbital anisotropy and spectroscopic x-ray magnetic circular dichroism (XMCD) measurements at the Fe K and L edges. Starting from ab initio molecular orbital multiplet calculations for the isolated molecule, we diagonalize the spin-orbit interaction in the subspace spanned by the three lowest spin triplet states of 3A2 g and 3Eg symmetry in the presence of a saturating magnetic field at a polar angle θ with respect to the normal to the plane of the film, plus an external perturbation representing the effect of the molecules in the stack on the FePc molecule under consideration. We find that the orbital moment of the ground state strongly depends on the magnetic field direction in agreement with the sum rule analysis of the L23-edge XMCD data. We calculate integrals over the XMCD spectra at the Fe K and L23 edges as used in the sum rules and explicitly show that they agree with the expectation values of the orbital moment and effective spin moment of the ground state. On the basis of this analysis, we can rule out alternative candidates proposed in the literature.

  5. Effects of eddy current and dispersion of magnetic anisotropy on the high-frequency permeability of Fe-based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Han, M., E-mail: mangui@gmail.com [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Rozanov, K.N.; Zezyulina, P.A. [Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, Moscow (Russian Federation); Wu, Yan-Hui [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China)

    2015-06-01

    Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe{sub 3}(Si) with D0{sub 3} superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9.

  6. Effects of eddy current and dispersion of magnetic anisotropy on the high-frequency permeability of Fe-based nanocomposites

    International Nuclear Information System (INIS)

    Han, M.; Rozanov, K.N.; Zezyulina, P.A.; Wu, Yan-Hui

    2015-01-01

    Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe 3 (Si) with D0 3 superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9

  7. Sequential Monte Carlo filter for state estimation of LiFePO4 batteries based on an online updated model

    Science.gov (United States)

    Li, Jiahao; Klee Barillas, Joaquin; Guenther, Clemens; Danzer, Michael A.

    2014-02-01

    Battery state monitoring is one of the key techniques in battery management systems e.g. in electric vehicles. An accurate estimation can help to improve the system performance and to prolong the battery remaining useful life. Main challenges for the state estimation for LiFePO4 batteries are the flat characteristic of open-circuit-voltage over battery state of charge (SOC) and the existence of hysteresis phenomena. Classical estimation approaches like Kalman filtering show limitations to handle nonlinear and non-Gaussian error distribution problems. In addition, uncertainties in the battery model parameters must be taken into account to describe the battery degradation. In this paper, a novel model-based method combining a Sequential Monte Carlo filter with adaptive control to determine the cell SOC and its electric impedance is presented. The applicability of this dual estimator is verified using measurement data acquired from a commercial LiFePO4 cell. Due to a better handling of the hysteresis problem, results show the benefits of the proposed method against the estimation with an Extended Kalman filter.

  8. Supramolecular Host-Guest System as Ratiometric Fe3+ Ion Sensor Based on Water-Soluble Pillar[5]arene.

    Science.gov (United States)

    Yao, Qianfang; Lü, Baozhong; Ji, Chendong; Cai, Yang; Yin, Meizhen

    2017-10-18

    Developing a specific, ratiometric, and reversible detection method for metal ions is significant to guard against the threat of metal-caused environmental pollution and organisms poisoning. Here a supramolecular host-guest system (WP5⊃G) based on water-soluble pillar[5]arene (WP5) and water-soluble quaternized perylene diimide derivative (G) was constructed. Morphological transformation was achieved during the process of adding WP5 into G aqueous solution, and a fluorescence "turn-off" phenomenon was observed which was caused by supramolecular photoinduced electron transfer (PET). Meanwhile, hydrophobic effect and electrostatic interaction played important roles in this supramolecular process, which was confirmed by isothermal titration calorimeter (ITC) and ζ potential experiments. Furthermore, the supramolecular host-guest system could be a "turn-on" fluorescent probe for Fe 3+ ion detection through the process of interdicting supramolecular PET. Moreover, the Fe 3+ ion detection showed specific, ratiometric, and reversible performances with a detection limit of 2.13 × 10 -7 M, which might have great potentials in biological and environmental monitoring.

  9. Modelling the Peak Elongation of Nylon6 and Fe Powder Based Composite Wire for FDM Feedstock Filament

    Science.gov (United States)

    Garg, Harish Kumar; Singh, Rupinder

    2017-10-01

    In the present work, to increase the application domain of fused deposition modelling (FDM) process, Nylon6-Fe powder based composite wire has been prepared as feed stock filament. Further for smooth functioning of feed stock filament without any change in the hardware and software of the commercial FDM setup, the mechanical properties of the newly prepared composite wire must be comparable/at par to the existing material i.e. ABS, P-430. So, keeping this in consideration; an effort has been made to model the peak elongation of in house developed feedstock filament comprising of Nylon6 and Fe powder (prepared on single screw extrusion process) for commercial FDM setup. The input parameters of single screw extruder (namely: barrel temperature, temperature of the die, speed of the screw, speed of the winding machine) and rheological property of material (melt flow index) has been modelled with peak elongation as the output by using response surface methodology. For validation of model the result of peak elongation obtained from the model equation the comparison was made with the results of actual experimentation which shows the variation of ±1 % only.

  10. Atomic force microscopy study of stacking modes of martensitic transformation in Fe-Mn-Si based shape memory alloys

    International Nuclear Information System (INIS)

    Liu, D.Z.; Kikuchi, T.; Kajiwara, S.; Shinya, N.

    2000-01-01

    Stacking modes of thermally induced and stress-induced martensitic transformation in Fe-28Mn-6Si-5Cr shape memory alloys have been studied using atomic force microscopy (AFM). It has been found that thermally induced martensite plates appear with the self-accommodated stacking form, in which all the three possible variants with different left angle 112 right angle shear directions in a {111} plane are activated and formed in parallel but at separate places; i.e. each plate corresponds to one variant. In addition, a plastic deformation band is always induced in austenite between two different variants. On the other hand, stress-induced martensite plates appear with the mono-partial stacking form, i.e. only single variant is activated in a {111} plane in a grain. The difference between stacking modes of thermally induced and stress-induced martensites makes them play a different role in contributing to shape memory effect in Fe-Mn-Si based shape memory alloys. (orig.)

  11. Defects in hyperpure Fe-based alloys created by 3 MeV e{sup -}-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Li, X H; Moser, P [CEA Centre d` Etudes de Grenoble, 38 (France). Dept. de Recherche Fondamentale sur la Matiere Condensee; Akamatsu, M; Van Duysen, C [Electricite de France (EDF), 77 - Ecuelles (France)

    1994-12-31

    Information about vacancy defects created in RPV (Reactor Pressure Vessels) steels after neutron irradiations are obtained via a simulation: the RPV steels are simulated by a series of high purity Fe-based alloys; the neutron irradiation is simulated by a 3 MeV electron irradiation; vacancy defects characteristics are obtained by positron lifetime techniques. Irradiations are made at 150 or 288 deg C, with a dose of 4*10{sup 19} e-/cm{sup 2}, and followed by isochronal annealing in the range 20-500 deg C. The observed vacancy defects are single trapped vacancies and small vacancy clusters, the size of which being lower than 10 empty atomic volumes (vacancy clusters containing more than 50 empty atomic volumes were never found). A large recovery step is observed between 200 and 400 deg C, after 150 deg C irradiation and attributed to vacancy-impurity detrapping, and also, vacancy cluster evaporation. The influence of C, Cu and Mo are presented. These results are in agreement with a model supposing, in pure Fe, single vacancy migration at -50 deg C and vacancy-impurity detrapping at 200 deg C. (authors). 4 figs., 15 refs.

  12. Effect of Soil Parameters on the Kinetics of the Displacement of Fe from FeEDDHA Chelates by Cu

    NARCIS (Netherlands)

    Schenkeveld, W.D.C.; Reichwein, A.M.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2012-01-01

    In soil application, o,o-FeEDDHA (iron (3+) ethylene diamine-N,N'-bis(2-hydroxy phenyl acetic acid) complex) is the active ingredient of FeEDDHA chelate-based Fe fertilizers. The effectiveness of o,o-FeEDDHA is potentially compromised by the displacement of Fe from FeEDDHA by Cu. The actual impact

  13. Static and dynamic magnetic properties of Co{sub 2}FeAl-based stripe arrays

    Energy Technology Data Exchange (ETDEWEB)

    Belmeguenai, M., E-mail: belmeguenai.mohamed@univ-paris13.fr [LSPM-CNRS, Université Paris XIII-Sorbonne Paris Cité, 93430 Villetaneuse (France); Gabor, M.S. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114, Cluj-Napoca (Romania); Zighem, F. [LSPM-CNRS, Université Paris XIII-Sorbonne Paris Cité, 93430 Villetaneuse (France); Berling, D. [IS2M, CNRS-LRC 7228, Université de Haute-Alsace, 68057 Mulhouse-Cedex (France); Roussigné, Y. [LSPM-CNRS, Université Paris XIII-Sorbonne Paris Cité, 93430 Villetaneuse (France); Petrisor, T. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114, Cluj-Napoca (Romania); Chérif, S.M. [LSPM-CNRS, Université Paris XIII-Sorbonne Paris Cité, 93430 Villetaneuse (France); Tiusan, C. [Center for Superconductivity, Spintronics and Surface Science, Technical University of Cluj-Napoca, Str. Memorandumului No. 28 RO-400114, Cluj-Napoca (Romania); Institut Jean Lamour, CNRS, Université de Nancy, BP 70239, F-54506 Vandoeuvre (France); Brinza, O.; Moch, P. [LSPM-CNRS, Université Paris XIII-Sorbonne Paris Cité, 93430 Villetaneuse (France)

    2016-02-01

    25 nm to 50 nm Co{sub 2}FeAl (CFA) thick wire arrays with varying widths and spacing have been patterned from continuous CFA films deposited on MgO(001) using e-beam lithography and Ar ion milling. Magneto-optical Kerr effect, transverse bias initial inverse susceptibility and torque measurements reveal that the in-plane magnetic anisotropy of the wires is dominantly monitored by a uniaxial term, in contrast with the continuous films where it is governed by the superposition of a fourfold term and of a smaller uniaxial term. The microstrip ferromagnetic resonance spectra performed using a magnetic field H, applied in the plane of the studied sample along various directions, or perpendicularly to this plane, gave us access to various quantized modes originating from the patterning. In addition, Brillouin light scattering also exhibits quantized modes. A large part of the experimental observations can be quantitatively interpreted as resulting from the demagnetizing terms induced by the geometrical patterning. However, the presented model, simply built on the effect of the demagnetizing field, is not able to give account of all the quantized modes present in the resonance spectra. When H is parallel to the wires, a more complete description is used: it considers the wave-vector quantization induced by the patterning. For the magnetic modes concerned by both approaches, the correspondence between the 2 models is easily established. When H is not parallel to the wires quantitative descriptions of the behavior of the field dependence of the observed modes still can often be performed. Finally, in all the studied patterned samples, the uniform magnetic mode, termed “film mode”, relative to the parent continuous film is observed by ferromagnetic resonance: such a behavior, which has been reported previously, remains to be completely interpreted. - Highlights: • The static and dynamic properties of Co{sub 2}FeAl wire arrays have been studied. • Microstrip

  14. Facile Synthesis of Magnetic Copolymer Microspheres Based on Poly(glycidyl methacrylate-co-N-isopropylacrylamide/Fe3O4 by Suspension Photopolymerization

    Directory of Open Access Journals (Sweden)

    Siti Zulaikha Mazlan

    2014-01-01

    Full Text Available Magnetic copolymer based on poly(glycidyl methacrylate-co-N-isopropylacrylamide microspheres was prepared by 2,2-dimethoxy-2-phenylacetophenone- (DMPP- photo initiated and poly(vinyl alcohol- (PVA- stabilized single step suspension photopolymerization. The effect of chemical interaction, morphology, and thermal properties by adding 0.1% w/v Fe3O4 in the copolymer was investigated. Infrared analysis (FTIR showed that (C=C band disappeared after copolymerization, indicating that the magnetic copolymer microspheres were successfully synthesized and two important bands at 908 cm−1 and 1550 cm−1 appear. These are associated with the epoxy group stretching of GMA and secondary amide (N–H/C–H deformation vibration of NIPAAm in magnetic microspheres. The X-ray diffraction (XRD result proved the incorporation of Fe3O4 nanoparticles with copolymer microspheres as peak of Fe3O4 was observed. Morphology study revealed that magnetic copolymer exhibited uniform spheres and smoother appearance when entrapped with Fe3O4 nanoparticles. The lowest percentage of Fe3O4 nanoparticles leached from the copolymer microspheres was obtained at pH 7. Finally, thermal property of the copolymer microspheres was improved by adding a small amount of Fe3O4 nanoparticles that has been shown from the thermogram.

  15. Cooperative redox-active additives of anthraquinone-2,7-disulphonate and K4Fe(CN)6 for enhanced performance of active carbon-based capacitors

    Science.gov (United States)

    Tian, Ying; Liu, Ming; Che, Ruxing; Xue, Rong; Huang, Liping

    2016-08-01

    Two redox additives of anthraquinone-2,7-disulphonate (AQDS) and K4Fe(CN)6 are introduced into the neutral medium of KNO3 for enhanced performance of active carbon-based (AC) capacitor. The Faradaic redox reactions of AQ/H2AQ and Fe(CN)63-/Fe(CN)64- are diffusion-controlled and occurred on the negative electrode and the positive electrode respectively and simultaneously, resulting in the enhancement of specific capacitance, power density and energy density of 240 F g-1, 527 W kg-1 and 26.3 Wh kg-1, respectively at a current density of 1.0 A g-1 for a symmetric AC capacitor in the electrolyte of 1 M KNO3-0.017 M K4Fe(CN)6-0.017 M AQDS. These values are much higher than those in the controls of either 1 M KNO3-0.017 M K4Fe(CN)6 or 1 M KNO3-0.017 M AQDS with only one pair of redox additives. These results demonstrate the cooperative K4Fe(CN)6 and AQDS for enhanced performance of AC capacitor, and thus provide an alternative approach for efficient capacitors.

  16. Detection of malachite green in fish based on magnetic fluorescent probe of CdTe QDs/nano-Fe3O4@MIPs

    Science.gov (United States)

    Wu, Le; Lin, Zheng-Zhong; Zeng, Jun; Zhong, Hui-Ping; Chen, Xiao-Mei; Huang, Zhi-Yong

    2018-05-01

    A magnetic fluorescent probe of CdTe QDs/nano-Fe3O4@MIPs was prepared using CdTe QDs and Fe3O4 nanoparticles as co-nucleus and molecularly imprinted polymers (MIPs) as specific recognition sites based on a reverse microemulsion method. With the specific enrichment and magnetic separation properties, the probe of CdTe QDs/nano-Fe3O4@MIPs was used to detect malachite green (MG) in fish samples. The TEM analysis showed that the particles of CdTe QDs/nano-Fe3O4@MIPs were spherical with average diameter around 53 nm, and a core-shell structure was well-shaped with several Fe3O4 nanoparticles and CdTe QDs embedded in each of the microsphere. Quick separation of the probes from solutions could be realized with a magnet, indicating the excellent magnetic property of CdTe QDs/nano-Fe3O4@MIPs. The probe exhibited high specific adsorption towards MG and excellent fluorescence emission at λem 598 nm. The fluorescence of CdTe QDs/nano-Fe3O4@MIPs could be linearly quenched by MG at the concentrations from 0.025 to 1.5 μmol L-1. The detection limit was 0.014 μmol L-1. The average recovery of spiked MG in fish samples was 105.2%. The result demonstrated that the as-prepared CdTe QDs/nano-Fe3O4@MIPs could be used as a probe to the detection of trace MG in fish samples.

  17. An electrochemical sensor for gallic acid based on Fe2O3/electro-reduced graphene oxide composite: Estimation for the antioxidant capacity index of wines

    International Nuclear Information System (INIS)

    Gao, Feng; Zheng, Delun; Tanaka, Hidekazu; Zhan, Fengping; Yuan, Xiaoning; Gao, Fei; Wang, Qingxiang

    2015-01-01

    A highly sensitive electrochemical sensor for gallic acid (GA), an important polyphenolic compound, was fabricated using the hybrid material of chitosan (CS), fishbone-shaped Fe 2 O 3 (fFe 2 O 3 ), and electrochemically reduced graphene oxide (ERGO) as the sensing matrix. The electrochemical characterization experiments showed that the CS–fFe 2 O 3 –ERGO modified glassy carbon electrode (CS–fFe 2 O 3 –ERGO/GCE) had large surface area, excellent electronic conductivity and high stability. The GA presented a superior electrochemical response on CS–fFe 2 O 3 –ERGO/GCE in comparison with the single-component modified electrode. The electrochemical mechanism and optimal test conditions of GA on the electrode surface were carefully investigated. Under the optimal conditions, the oxidation peak currents in differential pulse voltammetry (DPV) experiments exhibited a good linear relationship with the logarithmic values of GA concentration over the range from 1.0 × 10 −6 M to 1.0 × 10 −4 M. Based on signal-to-noise (S/N) characteristic of 3, the detection limit was estimated to be 1.5 × 10 −7 M. The proposed sensor has also been applied for estimating the antioxidant capacity index of real samples of red and white wines. - Highlights: • Fishbone-shaped Fe 2 O 3 (fFe 2 O 3 ) nanoparticles were synthesized by a simple template-free solvothermal method. • The nanocomposite of fFe 2 O 3 , graphene and chitosan was used as the sensing platform for gallic acid. • The sensor shows a wide linear range and low detection limit for gallic acid. • The antioxidant capacity index of wines was successfully evaluated by the sensor

  18. High frequency and magnetoelectrical properties of magnetoresistive memory element based on FeCoNi/TiN/FeCoNi film

    Directory of Open Access Journals (Sweden)

    Kurlyandskaya, G. V.

    2000-08-01

    Full Text Available A miniaturised memory device for information recording and readout processes have been designed on the basis of anisotropic magnetoresistive effect in Fe15Co20Ni65(160Å/ TiN(50Å/Fe15Co20Ni65(160Å three-layered film done by rf diode sputtering. Stable recording and readout processes were available for 32 rectangular element column, where each element had μm dimensions convenient to fabricate memory chip with 106 bits capacity. Rectangles of different sizes with removed corners were used in order to define the geometry of most of all stable recording and readout processes. Magnetoresistance and magnetoimpedance effects of a magnetic memory device have been comparatively analysed. We suggest that the decrease of the absolute value of the magnetoimpedance of the memory device comes from the reduction of the real part via the magnetoresistance.

    Se ha diseñado un dispositivo de memoria para la grabación y lectura de información basado en el efecto de la anisotropía magnetorresistiva de una multicapa fabricada por sputtering mediante diodo de rf. El elemento de memoria se compone de tres películas delgadas, de composición Fe15Co20Ni65(160Å/ TiN(50Å/Fe15Co20Ni65(160Å. El dispositivo permite procesos de grabación y lectura estables, y se compone de 32 elementos de memoria rectangulares por columna, donde cada elemento tiene dimensiones de μm lo que permite la fabricación de memorias integradas con capacidades del orden de 106 bits. Se han ensayado elementos de memoria rectangulares de diferentes tamaños, con las esquinas redondeadas con objeto de conseguir procesos de lectura-escritura lo más estable posible. Se han analizado comparativamente los efectos de magnetorresistencia y magnetoimpedancia de los elementos de memoria de diferentes dimensiones. Sugerimos que la disminución del valor absoluto de la magnetoimpedancia del elemento de memoria es consecuencia de la reducción de la parte real, de origen magnetorresistivo.

  19. Influence of voids in the hybrid layer based on self-etching adhesive systems: a 3-D FE analysis

    Directory of Open Access Journals (Sweden)

    Ana Paula Martini

    2009-01-01

    Full Text Available The presence of porosities at the dentin/adhesive interface has been observed with the use of new generation dentin bonding systems. These porosities tend to contradict the concept that etching and hybridization processes occur equally and simultaneously. Therefore, the aim of this study was to evaluate the micromechanical behavior of the hybrid layer (HL with voids based on a self-etching adhesive system using 3-D finite element (FE analysis. MATERIAL AND METHODS: Three FE models (Mr were built: Mr, dentin specimen (41x41x82 μm with a regular and perfect (i.e. pore-free HL based on a self-etching adhesive system, restored with composite resin; Mp, similar to M, but containing 25% (v/v voids in the HL; Mpp, similar to Mr, but containing 50% (v/v voids in the HL. A tensile load (0.03N was applied on top of the composite resin. The stress field was obtained by using Ansys Workbench 10.0. The nodes of the base of the specimen were constrained in the x, y and z axes. The maximum principal stress (σmax was obtained for all structures at the dentin/adhesive interface. RESULTS: The Mpp showed the highest peak of σmax in the HL (32.2 MPa, followed by Mp (30 MPa and Mr (28.4 MPa. The stress concentration in the peritubular dentin was high in all models (120 MPa. All other structures positioned far from voids showed similar increase of stress. CONCLUSION: Voids incorporated into the HL raised the σmax in this region by 13.5%. This behavior might be responsible for lower bond strengths of self-etching and single-bottle adhesives, as reported in the literature.

  20. Isochronal and isothermal crystallization kinetics of amorphous Fe-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.T. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Wang, W.M., E-mail: weiminw@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Key Lab of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Ma, H.J.; Li, G.H.; Li, R.; Zhang, Z.H. [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

    2010-06-10

    Using the differential scanning calorimetry (DSC), the isochronal and isothermal crystallization kinetics of amorphous Fe{sub 61}Co{sub 9-x}Zr{sub 8}Mo{sub 5}W{sub x}B{sub 17} (x = 0 and 2) ribbons was investigated by the Kissinger equation and by the Kolmogorov-Johnson-Mehl-Avrami and Ranganathan-Heimendahl equations, respectively. The results show that tungsten can improve the activation energy E{sub 1}{sup K} for the first crystallization in the isochronal annealing process and activation energy E{sub n} for the nucleation in the isothermal annealing process, which can be ascribed to the dissolution of tungsten in the amorphous phase. Meanwhile, tungsten can decrease the activation energy E{sub 2}{sup K} for the second crystallization in the isochronal annealing process and growth activation energy E{sub g} in the isothermal annealing process, which is possibly associated with the formation of W-rich compound after the early nucleation process.

  1. Optical properties of the iron-based superconductor LiFeAs single crystal

    International Nuclear Information System (INIS)

    Min, Byeong Hun; Kwon, Yong Seung; Hong, Jong Beom; Yun, Jae Hyun; Bang, Yunkyu; Iizuka, Takuya; Kimura, Shin-ichi

    2013-01-01

    We have measured the reflectivity spectra of the LiFeAs (T c = 17.6 K) single crystal in the temperature range from 4 to 300 K. In the superconducting (SC) state (T c ), the clean opening of the optical absorption gap was observed below 25 cm −1 , indicating an isotropic full gap formation. In the normal state (T > T c ), the optical conductivity spectra display typical metallic behavior with the Drude-type spectra at low frequencies, but we found that the introduction of the two Drude components best fits the data, indicating the multiband nature of this compound. A theoretical analysis of the low-temperature data (T = 4 K c ) also suggests that two SC gaps best fit the data and their values were estimated as Δ 1 = 3.3 meV and Δ 2 = 1.59 meV, respectively. Using the Ferrell–Glover–Tinkham sum rule and dielectric function ϵ 1 (ω), the plasma frequency of the SC condensate (ω ps ) is consistently estimated to be 6665 cm −1 , implying that about 65% of the free carriers of the normal state condense into the SC condensate. To investigate the various interband transition processes (for ω > 200 cm −1 ), we have also performed the local-density approximation band calculation and calculated the optical spectra of the interband transitions. This theoretical result provided qualitative agreement with the experimental data below 4000 cm −1 . (paper)

  2. IR thermographic observation and shear bands plasticity analysis in Fe-based metallic glass

    International Nuclear Information System (INIS)

    Bouzakher, B.; Benameur, T.; Sidhom, H.

    2009-01-01

    Infrared thermography observation and in situ atomic force microscopy characterization were carried out to investigate the mechanical damage processes at the edge-notch region of large ribbons of Fe 78 Si 10 B 12 metallic glass. An obvious thermoelastic and inelastic degradation phenomenon was observed ahead at the notched region of the specimens, which probably result from free volume accumulation process and shear band activity during plane stress solicitations. Moreover, AFM topographic and frictional analysis of changes in the crack path during stable crack propagation regime revealed a periodic morphology evolution, formation of nanoscale damage cavity in the range of 20-140 nm and a maximum temperature rise ahead of the pre-crack tip was found in the order of 1.5 deg. C. The nanometer scaled shear offset, discreteness and shear bands density were determined. While these key parameters play a role in observing a large plastic zone in front of the crack, however they are unable to explain the distinct intrinsic ductility of some monolithic metallic glasses. A general Mohr-Coulomb-type constitutive description was used to deduce analytic expressions for prediction of the variation of hydrostatic component of the applied stress to the shear stress ratio as function of Poisson's ratio.

  3. Formation and stability of aluminum-based metallic glasses in Al-Fe-Gd alloys

    International Nuclear Information System (INIS)

    He, Y.; Poon, S.J.; Shiflet, G.J.

    1988-01-01

    Metallic glasses, a class of amorphous alloys made by rapid solidification, have been studied quite extensively for almost thirty years. It has been recognized for a long time that metallic glasses are usually very strong and ductile, and exhibit high corrosion resistance relative to crystalline alloys with the same compositions. Recently, metallic glasses containing as much as 90 atomic percent aluminum have been discovered independently by two groups. This discovery has both scientific and technological implications. The formability of these new glasses have been found to be unusual. Studies of mechanical properties in these new metallic glasses show that many of them have tensile strengths over 800MPa, greatly exceeding the strongest commercial aluminum alloys. The high strengths of aluminum-rich metallic glasses can be of significant importance in obtaining high strength low density materials. Therefore, from both scientific and technological standpoints, it is important to understand the formation and thermal stability of these metallic glasses. Al-Fe-Gd alloys were chosen for a more detailed study since they exhibit high tensile strengths

  4. FeNi-based flat magnetoimpedance nanostructures with open magnetic flux: New topological approaches

    Energy Technology Data Exchange (ETDEWEB)

    Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Dpto. de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Mira 19, 620002 Ekaterinburg (Russian Federation); Chlenova, A.A. [Ural Federal University, Department of Magnetism and Magnetic Nanomaterials, Mira 19, 620002 Ekaterinburg (Russian Federation); Fernández, E. [Universidad del País Vasco, UPV/EHU, Dpto. de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Lodewijk, K.J. [Universidad del País Vasco, UPV/EHU, Dpto. de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Department of Material Sciences, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2015-06-01

    Classic flat MI multilayers consist of top and bottom ferromagnetic parts of equal thickness separated by a conductive lead. In previous studies symmetric MI structures were considered because they provide the highest sensitivity with respect to uniform external magnetic fields. There are a number of applications where non-uniform magnetic fields of complex configurations must be detected. Non-symmetric MI structures can be advantageous in this particular case. We describe our experience in design, fabrication and characterization of symmetric and non-symmetric MI multilayers with open magnetic flux. Non-symmetry of the structures was obtained by the deposition of top and bottom ferromagnetic parts of MI element of different thickness. MI responses of the structures with even or odd configurations of the FeNi layers were also considered. - Highlights: • Classic flat MI multilayer consists of ferromagnetic parts of equal thickness separated by a conductive lead. • In previous studies symmetric MI structures were considered. • Non-symmetric MI structures can be advantageous for applications where non-uniform magnetic fields are detected. • MI responses of the structures with even or odd configuration can be very different.

  5. FeNi-based flat magnetoimpedance nanostructures with open magnetic flux: New topological approaches

    International Nuclear Information System (INIS)

    Kurlyandskaya, G.V.; Chlenova, A.A.; Fernández, E.; Lodewijk, K.J.

    2015-01-01

    Classic flat MI multilayers consist of top and bottom ferromagnetic parts of equal thickness separated by a conductive lead. In previous studies symmetric MI structures were considered because they provide the highest sensitivity with respect to uniform external magnetic fields. There are a number of applications where non-uniform magnetic fields of complex configurations must be detected. Non-symmetric MI structures can be advantageous in this particular case. We describe our experience in design, fabrication and characterization of symmetric and non-symmetric MI multilayers with open magnetic flux. Non-symmetry of the structures was obtained by the deposition of top and bottom ferromagnetic parts of MI element of different thickness. MI responses of the structures with even or odd configurations of the FeNi layers were also considered. - Highlights: • Classic flat MI multilayer consists of ferromagnetic parts of equal thickness separated by a conductive lead. • In previous studies symmetric MI structures were considered. • Non-symmetric MI structures can be advantageous for applications where non-uniform magnetic fields are detected. • MI responses of the structures with even or odd configuration can be very different

  6. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

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

  7. Mechanical properties of hexaferite based magnet composite of SrFe12019 and BaFe12O19 with natural rubber bonding agent

    International Nuclear Information System (INIS)

    Waluyo, T.; Herman, Y.A.; Sudirman; Ridwan

    2000-01-01

    Research on mechanical properties at magnet composite of SrFe 12 0 19 (SrM) and BaFe 12 O 19 (BaM)magnet powder with natural rubber bonding agent have been done. The natural rubber used was rubber made of latex without vulcanization, The SrM powder having average particle size of 1.6 μm and flat shaped. and the BaM powder having particle size of 1.2 μm and nodular shaped. The production of composite carried out in Labo Plastomill at 100 o C and mixer speed of 30 rpm for 7 minutes. The result obtained from Labo Plastomill then made into sheets. Mechanical properties of the composite tested were strain, elongation break and hardness, The results showed that the highest strain of the SrM composite obtained at composition of 70% vol of powder that is 2,22 MPa, and 3,84 MPa for BaM composite at 50% vol. of powder The elongation break of SrM composite decreased by increasing of powder volume fraction, that is 90% at the composition or 70% vol. of powder, and 370% for BaM composite at 50% vol. fraction of powder. The highest hardness for SrM composite obtained at composition of of 70% vol. of powder, that is 95 SHA. and for the BaM composite at 50% vol. of powder. that is 52 SHA

  8. Thermoelectric performance of spin Seebeck effect in Fe3O4/Pt-based thin film heterostructures

    Directory of Open Access Journals (Sweden)

    R. Ramos

    2016-10-01

    Full Text Available We report a systematic study on the thermoelectric performance of spin Seebeck devices based on Fe3O4/Pt junction systems. We explore two types of device geometries: a spin Hall thermopile and spin Seebeck multilayer structures. The spin Hall thermopile increases the sensitivity of the spin Seebeck effect, while the increase in the sample internal resistance has a detrimental effect on the output power. We found that the spin Seebeck multilayers can overcome this limitation since the multilayers exhibit the enhancement of the thermoelectric voltage and the reduction of the internal resistance simultaneously, therefore resulting in significant power enhancement. This result demonstrates that the multilayer structures are useful for improving the thermoelectric performance of the spin Seebeck effect.

  9. Highly efficient growth of vertically aligned carbon nanotubes on Fe-Ni based metal alloy foils for supercapacitors

    Science.gov (United States)

    Amalina Raja Seman, Raja Noor; Asyadi Azam, Mohd; Ambri Mohamed, Mohd

    2016-12-01

    Supercapacitors are highly promising energy devices with superior charge storage performance and a long lifecycle. Construction of the supercapacitor cell, especially electrode fabrication, is critical to ensure good performance in applications. This work demonstrates direct growth of vertically aligned carbon nanotubes (CNTs) on Fe-Ni based metal alloy foils, namely SUS 310S, Inconel 600 and YEF 50, and their use in symmetric vertically aligned CNT supercapacitor electrodes. Alumina and cobalt thin film catalysts were deposited onto the foils, and then CNT growth was performed using alcohol catalytic chemical vapour deposition. By this method, vertically aligned CNTs were successfully grown and used directly as a binder-free supercapacitor electrode to deliver excellent electrochemical performance. The device showed relatively good specific capacitance, a superior rate capability and excellent cycle stability, maintaining about 96% capacitance up to 1000 cycles.

  10. Compact magnetic-field sensor based on optical microfiber Michelson interferometer and Fe3O4 nanofluid.

    Science.gov (United States)

    Deng, Ming; Sun, Xiaokang; Han, Meng; Li, Decai

    2013-02-01

    We report a magnetic-field sensor by merging the advantages of optical fiber Michelson interferometers with that of magnetic fluid. Compact and low-cost optical fiber Michelson interferometers were first fabricated by a high-frequency CO(2) laser, and then they were inserted into glass capillaries with water-based Fe(3)O(4) magnetic fluid as sensing elements. The sensing characteristics have been investigated and the experimental results show that the reflective spectrum of the fiber-magnetic sensor linearly shifted with the change of the magnetic-field strength that is perpendicular to the axial of the devices. The fiber-magnetic sensor with interference arm's diameter of 50 μm is most sensitive to the external magnetic field, and the sensitivity is up to 64.9 pm/mT, which is 20 times higher than that of 125 μm diameter.

  11. Indentation size effects in the nano- and micro-hardness of a Fe-based bulk metallic glass

    Energy Technology Data Exchange (ETDEWEB)

    Xu, F., E-mail: xufu@xtu.edu.cn; Ding, Y.H.; Deng, X.H.; Zhang, P.; Long, Z.L.

    2014-10-01

    Hardness of a Fe-based bulk metallic glass (BMG) was evaluated by both atomic force microscopy (AFM) nanoindentation (nano-hardness) and instrumented indentation with a traditional indenter setup (micro-hardness) under different maximum loads at room temperature. The nano-hardness and the micro-hardness were found to be comparable. For both of the indentation methods, indentation size effect (ISE) is detected as increase in hardness with decrease in indentation peak load. It is proposed that strain rate dependent softening, loading history and the lag between free volume creation and mechanical softening should be responsible for the ISE in this BMG. Furthermore, ISE is found to be more significant in AFM nanoindentation than in instrumented indentation. This can be explained by taking into account the effect of exerted peak load and the face angle of the indenter in a qualitative manner.

  12. Understanding self ion damage in FCC Ni-Cr-Fe based alloy using X-ray diffraction techniques

    Science.gov (United States)

    Halder Banerjee, R.; Sengupta, P.; Chatterjee, A.; Mishra, S. C.; Bhukta, A.; Satyam, P. V.; Samajdar, I.; Dey, G. K.

    2018-04-01

    Using X-ray diffraction line profile analysis (XRDLPA) approach the radiation response of FCC Ni-Cr-Fe based alloy 690 to 1.5 and 3 MeV Ni2+ ion damage was quantified in terms of its microstructural parameters. These microstructural parameters viz. average domain size, microstrain and dislocation density were found to vary anisotropically with fluence. The anisotropic behaviour is mainly attributable to presence of twins in pre-irradiated microstructure. After irradiation, surface roughness increases as a function of fluence attributable to change in surface and sub-surface morphology caused by displacement cascade, defects and sputtered atoms created by incident energetic ion. The radiation hardening in case of 1.5 MeV Ni2+ irradiated specimens too is a consequence of the increase in dislocation density formed by interaction of radiation induced defects with pre-existing dislocations. At highest fluence there is an initiation of saturation.

  13. Preliminary Results on the Surface of a New Fe-Based Metallic Material after “In Vivo” Maintaining

    Science.gov (United States)

    Săndulache, F.; Stanciu, S.; Cimpoeşu, N.; Stanciu, T.; Cimpoeșu, R.; Enache, A.; Baciu, R.

    2017-06-01

    Abstract A new Fe-based alloy was obtained using UltraCast melting equipment. The alloy, after mechanical processing, was implanted in five rabbit specimens (with respect for the “in-bone” procedure). After 30 days of implantation the samples were recovered and analyzed by weight and surface state meanings. Scanning electron microscopy technique was used to determine the new compounds morphology from the metallic surface and X-ray dispersive energy spectroscopy for chemical analyze results. A bond between the metallic material and biological material of the bone was observed through increasing of sample weight and by SEM images. After the first set of tests, as the samples were extracted and biologically cleaned, the samples were ultrasonically cleaned and re-analyzed in order to establish the stability of the chemical compounds.

  14. Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel - A macroscopic assessment

    Science.gov (United States)

    Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.; Camino, F.; Şavklıyıldız, İ.; Akdoğan, E. K.

    2017-06-01

    The study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ∼2 × 1018 n/cm2. At the higher neutron dose of ∼2 × 1019, macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe2B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

  15. Neutron irradiation and high temperature effects on amorphous Fe-based nano-coatings on steel – A macroscopic assessment

    International Nuclear Information System (INIS)

    Simos, N.; Zhong, Z.; Dooryhee, E.; Ghose, S.; Gill, S.

    2017-01-01

    Here, this study revealed that loss of ductility in an amorphous Fe-alloy coating on a steel substrate composite structure was essentially prevented from occurring, following radiation with modest neutron doses of ~2 x 10 18 n/cm 2 . At the higher neutron dose of ~2 x 10 19 , macroscopic stress-strain analysis showed that the amorphous Fe-alloy nanostructured coating, while still amorphous, experienced radiation-induced embrittlement, no longer offering protection against ductility loss in the coating-substrate composite structure. Neutron irradiation in a corrosive environment revealed exemplary oxidation/corrosion resistance of the amorphous Fe-alloy coating, which is attributed to the formation of the Fe 2 B phase in the coating. To establish the impact of elevated temperatures on the amorphous-to-crystalline transition in the amorphous Fe-alloy, electron microscopy was carried out which confirmed the radiation-induced suppression of crystallization in the amorphous Fe-alloy nanostructured coating.

  16. Fe-Ti-O based catalyst for large-chiral-angle single-walled carbon nanotube growth

    DEFF Research Database (Denmark)

    He, Maoshuai; Zhang, Lili; Jiang, Hua

    2016-01-01

    Catalyst selection is very crucial for controlled growth of single-walled carbon nanotubes (SWNTs). Here we introduce a well-designed Fe-Ti-O solid solution for SWNT growth with a high preference to large chiral angles. The Fe-Ti-O catalyst was prepared by combining Ti layer deposition onto premade...... Fe nanoparticles with subsequent high-temperature air calcination, which favours the formation of a homogeneous Fe-Ti-O solid solution. Using CO as the carbon feedstock, chemical vapour deposition growth of SWNTs at 800 °C was demonstrated on the Fe-Ti-O catalyst. Nanobeam electron diffraction...... characterization on a number of individual SWNTs revealed that more than 94% of SWNTs have chiral angles larger than 15°. In situ environmental transmission electron microscopy study was carried out to reveal the catalyst dynamics upon reduction. Our results identify that the phase segregation through reducing Fe...

  17. Microstructural stability and mechanical properties of a boron modified Ni–Fe based superalloy for steam boiler applications

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Changshuai, E-mail: cswang@imr.ac.cn; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang, E-mail: lzz@imr.ac.cn

    2015-07-15

    Ni–Fe based superalloys are being considered as boiler materials in 700 °C advanced ultra-supercritical (A-USC) coal fired power plants due to their excellent oxidation and hot corrosion resistance, outstanding workability and low cost. In this paper, the microstructural stability and mechanical properties of a boron (B) modified Ni–Fe based superalloy designed for 700 °C A-USC during thermal exposure at 650–750 °C for up to 5000 h were investigated. The results show that adding boron has no apparent influence on the major precipitates, including spherical γ′ and blocky MC. However, the amount of M{sub 23}C{sub 6} decreases markedly after standard heat treatment. During long-term thermal exposure, the addition of boron has no influence on γ′ coarsening, η phase precipitation and primary MC degeneration, but decreases the growth rate of M{sub 23}C{sub 6} along grain boundary. The stress rupture life and ductility are obviously improved after the addition of B. Meanwhile, the yield strength of B-doped alloy almost keeps the same level as that without boron addition. The fracture surface characterization exhibits that the dimples increase significantly after adding boron. During long-term thermal exposure, the elongation of the alloy with B addition increases slightly, but, for the alloy without B addition, the elongation obviously increases. The improvement of the stress rupture life and ductility can be attributed to the increase of grain boundary strength and the optimization of M{sub 23}C{sub 6} carbide distribution at grain boundary.

  18. Microstructural stability and mechanical properties of a boron modified Ni–Fe based superalloy for steam boiler applications

    International Nuclear Information System (INIS)

    Wang, Changshuai; Guo, YongAn; Guo, Jianting; Zhou, Lanzhang

    2015-01-01

    Ni–Fe based superalloys are being considered as boiler materials in 700 °C advanced ultra-supercritical (A-USC) coal fired power plants due to their excellent oxidation and hot corrosion resistance, outstanding workability and low cost. In this paper, the microstructural stability and mechanical properties of a boron (B) modified Ni–Fe based superalloy designed for 700 °C A-USC during thermal exposure at 650–750 °C for up to 5000 h were investigated. The results show that adding boron has no apparent influence on the major precipitates, including spherical γ′ and blocky MC. However, the amount of M 23 C 6 decreases markedly after standard heat treatment. During long-term thermal exposure, the addition of boron has no influence on γ′ coarsening, η phase precipitation and primary MC degeneration, but decreases the growth rate of M 23 C 6 along grain boundary. The stress rupture life and ductility are obviously improved after the addition of B. Meanwhile, the yield strength of B-doped alloy almost keeps the same level as that without boron addition. The fracture surface characterization exhibits that the dimples increase significantly after adding boron. During long-term thermal exposure, the elongation of the alloy with B addition increases slightly, but, for the alloy without B addition, the elongation obviously increases. The improvement of the stress rupture life and ductility can be attributed to the increase of grain boundary strength and the optimization of M 23 C 6 carbide distribution at grain boundary

  19. Development of Fe-Ni and Ni-base alloys without {gamma}' strengthening for advanced USC boilers

    Energy Technology Data Exchange (ETDEWEB)

    Semba, Hiroyuki; Okada, Hirokazu; Igarashi, Masaaki; Hirata, Hiroyuki [Sumitomo Metal Industries, Ltd., Amagasaki, Hyogo (Japan). Corporate Research and Development Labs.; Yoshizawa, Mitsuru [Sumitomo Metal Industries Ltd., Amagasaki, Hyogo (Japan). Steel Tube Works

    2010-07-01

    An Fe-Ni base alloy, 23Cr-45Ni-7W alloy (HR6W) strengthened by Fe{sub 2}W-type Laves phase is one of the candidate materials for the piping application. Stability of long-term creep strength and superior creep rupture ductility have been proved by creep rupture tests up to 60000h at 650-800 C. The 10{sup 5}h extrapolated creep rupture strength at 700 C approved by TUV is 85MPa. It has also been confirmed that HR6W has excellent microstructural stability by means of microstructural observations after term creep tests and aging. A thick wall pipe of HR6W, which is 457mm in diameter and 60mm in wall thickness, has successfully been manufactured by the Erhart Push Bench press method. This trial production has shown that hot workability of HR6W is sufficient for manufacturing thick wall piping for A-USC plants. A new Ni-base alloy, 30r-50Ni-4W alloy (HR35) has been proposed for piping application having comparable creep rupture strength with Alloy 617 at 700 C. This alloy is not strengthened by {gamma}' phase but mainly by {alpha}-Cr phase. The 10{sup 5}h extrapolated creep rupture strength is estimated to be 114 MPa at 700 C. It has sufficient creep rupture ductility compared with Alloy 617. A thick wall pipe of HR35 has also been successfully manufactured. Capability of HR6W and HR35 as structural materials for A-USC plants has been examined in detail. They have high resistance to relaxation cracking after welding. It is, therefore, concluded that both the alloys are promising candidates especially for thick wall piping in A-USC power plants. (orig.)

  20. Feasibility Study on Tension Estimation Technique for Hanger Cables Using the FE Model-Based System Identification Method

    Directory of Open Access Journals (Sweden)

    Kyu-Sik Park

    2015-01-01

    Full Text Available Hanger cables in suspension bridges are partly constrained by horizontal clamps. So, existing tension estimation methods based on a single cable model are prone to higher errors as the cable gets shorter, making it more sensitive to flexural rigidity. Therefore, inverse analysis and system identification methods based on finite element models are suggested recently. In this paper, the applicability of system identification methods is investigated using the hanger cables of Gwang-An bridge. The test results show that the inverse analysis and systemic identification methods based on finite element models are more reliable than the existing string theory and linear regression method for calculating the tension in terms of natural frequency errors. However, the estimation error of tension can be varied according to the accuracy of finite element model in model based methods. In particular, the boundary conditions affect the results more profoundly when the cable gets shorter. Therefore, it is important to identify the boundary conditions through experiment if it is possible. The FE model-based tension estimation method using system identification method can take various boundary conditions into account. Also, since it is not sensitive to the number of natural frequency inputs, the availability of this system is high.

  1. Non-enzymatic hydrogen peroxide biosensor based on rose-shaped FeMoO4 nanostructures produced by convenient microwave-hydrothermal method

    International Nuclear Information System (INIS)

    Liu, Hongying; Gu, Chunchuan; Li, Dujuan; Zhang, Mingzhen

    2015-01-01

    Graphical abstract: A non-enzymatic H 2 O 2 sensor with high selectivity and sensitivity based on rose-shaped FeMoO 4 synthesized by the convenient microwave-assisted hydrothermal method, was fabricated. - Highlights: • Rose-shaped FeMoO 4 is synthesized within 10 min via microwave-assisted hydrothermal approach. • Non-enzymatic hydrogen peroxide biosensor based on FeMoO 4 nanomaterials is fabricated. • The biosensor exhibits good performance. - Abstract: In this work, we demonstrated a simple, rapid and reliable microwave-assisted hydrothermal approach to synthesize the uniform rose-shaped FeMoO 4 within 10 min. The morphologies of the synthesized materials were characterized by X-ray powder diffraction and scanning electron microscopy. Moreover, a non-enzymatic amperometric sensor for the detection of hydrogen peroxide (H 2 O 2 ) was fabricated on the basis of the FeMoO 4 as electrocatalysis. The resulting FeMoO 4 exhibited high sensitivity and good stability for the detection of H 2 O 2 , which may be attributed to the rose-shaped structure of the material and the catalytic property of FeMoO 4 . Amperometric response showed that the modified electrode had a good response for H 2 O 2 with a linear range from 1 μM to 1.6 mM, a detection limit of 0.5 μM (S/N = 3), high selectivity and short response time. Additionally, good recoveries of analytes in real milk samples confirm the reliability of the prepared sensor in practical applications

  2. Non-enzymatic hydrogen peroxide biosensor based on rose-shaped FeMoO{sub 4} nanostructures produced by convenient microwave-hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongying, E-mail: liuhongying@hdu.edu.cn [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Zhejiang, Hangzhou 310018 (China); Gu, Chunchuan [Department of Clinical Laboratory, Hangzhou Cancer Hospital, Zhejiang, Hangzhou 310002 (China); Li, Dujuan; Zhang, Mingzhen [College of Life Information Science & Instrument Engineering, Hangzhou Dianzi University, Zhejiang, Hangzhou 310018 (China)

    2015-04-15

    Graphical abstract: A non-enzymatic H{sub 2}O{sub 2} sensor with high selectivity and sensitivity based on rose-shaped FeMoO{sub 4} synthesized by the convenient microwave-assisted hydrothermal method, was fabricated. - Highlights: • Rose-shaped FeMoO{sub 4} is synthesized within 10 min via microwave-assisted hydrothermal approach. • Non-enzymatic hydrogen peroxide biosensor based on FeMoO{sub 4} nanomaterials is fabricated. • The biosensor exhibits good performance. - Abstract: In this work, we demonstrated a simple, rapid and reliable microwave-assisted hydrothermal approach to synthesize the uniform rose-shaped FeMoO{sub 4} within 10 min. The morphologies of the synthesized materials were characterized by X-ray powder diffraction and scanning electron microscopy. Moreover, a non-enzymatic amperometric sensor for the detection of hydrogen peroxide (H{sub 2}O{sub 2}) was fabricated on the basis of the FeMoO{sub 4} as electrocatalysis. The resulting FeMoO{sub 4} exhibited high sensitivity and good stability for the detection of H{sub 2}O{sub 2}, which may be attributed to the rose-shaped structure of the material and the catalytic property of FeMoO{sub 4}. Amperometric response showed that the modified electrode had a good response for H{sub 2}O{sub 2} with a linear range from 1 μM to 1.6 mM, a detection limit of 0.5 μM (S/N = 3), high selectivity and short response time. Additionally, good recoveries of analytes in real milk samples confirm the reliability of the prepared sensor in practical applications.

  3. Complex permeability and core loss of soft magnetic Fe-based nanocrystalline powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Füzerová, Jana, E-mail: jana.fuzerova@tuke.sk [Faculty of Mechanical Engineering, Technical University, Letná 1, 042 00 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, P.J. Šafárik University, Park Angelinum 9, 040 23 Košice (Slovakia); Bureš, Radovan; Fáberová, Mária [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

    2013-11-15

    Rapidly quenched ribbons of Fe{sub 73}Cu{sub 1}Nb{sub 3}Si{sub 16}B{sub 7} were ball milled and cryomilled to get powder and warm consolidated to get bulk compacts. The data presented here are relative to different experimental procedures, one corresponding to milling at room temperature (sample R1) and the other corresponding to cryomilling at temperature of liquid nitrogen (sample L1). It was found that the properties of the initial powder influenced the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys. Permeability and core loss are structure sensitive and depend on factors such as powder size and shape, porosity, purity, and internal stress. Permeability spectra of sample R1 decreases with increasing the frequency and its values are larger than that for sample L1 at low frequencies. On the other hand the permeability of sample L1 remains steady up to 1 kHz and at certain frequency is larger than that for sample R1. Also there are different frequency dependences of the imaginary parts of permeability and loss factor, respectively. The cryomilling of the amorphous ribbon positively influences on the AC magnetic properties at higher frequencies (above 100 Hz) of resulting bulk sample. - Highlights: • We prepared two different amorphous powder vitroperm samples. • We have examined changes in the properties of the bulk samples prepared by compaction. • It was found that properties of the initial powder influence the density, the electrical resistivity and electromagnetic properties of the resulting bulk alloys.

  4. Amperometric glucose sensor based on enhanced catalytic reduction of oxygen using glucose oxidase adsorbed onto core-shell Fe3O4-silica-Au magnetic nanoparticles

    International Nuclear Information System (INIS)

    Wang Aijun; Li Yongfang; Li Zhonghua; Feng Jiuju; Sun Yanli; Chen Jianrong

    2012-01-01

    Monodisperse Fe 3 O 4 magnetic nanoparticles (NPs) were prepared under facile solvothermal conditions and successively functionalized with silica and Au to form core/shell Fe 3 O 4 -silica-Au NPs. Furthermore, the samples were used as matrix to construct a glucose sensor based on glucose oxidase (GOD). The immobilized GOD retained its bioactivity with high protein load of 3.92 × 10 −9 mol·cm −2 , and exhibited a surface-controlled quasi-reversible redox reaction, with a fast heterogeneous electron transfer rate of 7.98 ± 0.6 s −1 . The glucose biosensor showed a broad linear range up to 3.97 mM with high sensitivity of 62.45 μA·mM −1 cm −2 and fast response (less than 5 s). - Graphical abstract: Core-shell structured Fe 3 O 4 -silica-Au nanoparticles were prepared and used as matrix to construct an amperometric glucose sensor based on glucose oxidase, which showed broad linear range, high sensitivity, and fast response. Highlights: ► Synthesis of monodispersed Fe 3 O 4 nanoparticles. ► Fabrication of core/shell Fe 3 O 4 -silica-Au nanoparticles. ► Construction of a novel glucose sensor with wide linear range, high sensitivity and fast response.

  5. Graphene–palladium nanowires based electrochemical sensor using ZnFe{sub 2}O{sub 4}–graphene quantum dots as an effective peroxidase mimic

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Weiyan; Yang, Hongmei; Ma, Chao; Ding, Ya-nan [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Ge, Shenguang [Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan 250022 (China); Yu, Jinghua [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Yan, Mei, E-mail: chm_yanm@126.com [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2014-12-10

    Highlights: • The nanohybrid ZnFe{sub 2}O{sub 4}/GQDs was developed by assembling the GQDs on the ZnFe{sub 2}O{sub 4} through a photo-Fenton reaction. • The ZnFe{sub 2}O{sub 4}/GQDs exhibited higher peroxidase-like activity and better stability than each individual and HRP. • An electrochemical sensor was fabricated using ZnFe{sub 2}O{sub 4}/GQDs nanohybrid as a mimic enzymatic to detect DNA. • Graphene and Pd nanowires were modified on the glassy carbon electrode, which improved the electronic transfer rate. - Abstract: We proposed an electrochemical DNA sensor by using peroxidase-like magnetic ZnFe{sub 2}O{sub 4}–graphene quantum dots (ZnFe{sub 2}O{sub 4}/GQDs) nanohybrid as a mimic enzymatic label. Aminated graphene and Pd nanowires were successively modified on glassy carbon electrode, which improved the electronic transfer rate as well as increased the amount of immobilized capture ssDNA (S1). The nanohybrid ZnFe{sub 2}O{sub 4}/GQDs was prepared by assembling the GQDs on the surface of ZnFe{sub 2}O{sub 4} through a photo-Fenton reaction, which was not only used as a mimic enzyme but also as a carrier to label complementary ssDNA (S3). By synergistically integrating highly catalytically activity of nano-sized GQDs and ZnFe{sub 2}O{sub 4}, the nanohybrid possessed highly-efficient peroxidase-like catalytic activity which could produce a large current toward the reduction of H{sub 2}O{sub 2} for signal amplification. Thionine was used as an excellent electron mediator. Compared with traditional enzyme labels, the mimic enzyme ZnFe{sub 2}O{sub 4}/GQDs exhibited many advantages such as environment friendly and better stability. Under the optimal conditions, the approach provided a wide linear range from 10{sup −16} to 5 × 10{sup −9} M and low detection limit of 6.2 × 10{sup −17} M. The remarkable high catalytic capability could allow the nanohybrid to replace conventional peroxidase-based assay systems. The new, robust and convenient assay systems

  6. Graphene–palladium nanowires based electrochemical sensor using ZnFe2O4–graphene quantum dots as an effective peroxidase mimic

    International Nuclear Information System (INIS)

    Liu, Weiyan; Yang, Hongmei; Ma, Chao; Ding, Ya-nan; Ge, Shenguang; Yu, Jinghua; Yan, Mei

    2014-01-01

    Highlights: • The nanohybrid ZnFe 2 O 4 /GQDs was developed by assembling the GQDs on the ZnFe 2 O 4 through a photo-Fenton reaction. • The ZnFe 2 O 4 /GQDs exhibited higher peroxidase-like activity and better stability than each individual and HRP. • An electrochemical sensor was fabricated using ZnFe 2 O 4 /GQDs nanohybrid as a mimic enzymatic to detect DNA. • Graphene and Pd nanowires were modified on the glassy carbon electrode, which improved the electronic transfer rate. - Abstract: We proposed an electrochemical DNA sensor by using peroxidase-like magnetic ZnFe 2 O 4 –graphene quantum dots (ZnFe 2 O 4 /GQDs) nanohybrid as a mimic enzymatic label. Aminated graphene and Pd nanowires were successively modified on glassy carbon electrode, which improved the electronic transfer rate as well as increased the amount of immobilized capture ssDNA (S1). The nanohybrid ZnFe 2 O 4 /GQDs was prepared by assembling the GQDs on the surface of ZnFe 2 O 4 through a photo-Fenton reaction, which was not only used as a mimic enzyme but also as a carrier to label complementary ssDNA (S3). By synergistically integrating highly catalytically activity of nano-sized GQDs and ZnFe 2 O 4 , the nanohybrid possessed highly-efficient peroxidase-like catalytic activity which could produce a large current toward the reduction of H 2 O 2 for signal amplification. Thionine was used as an excellent electron mediator. Compared with traditional enzyme labels, the mimic enzyme ZnFe 2 O 4 /GQDs exhibited many advantages such as environment friendly and better stability. Under the optimal conditions, the approach provided a wide linear range from 10 −16 to 5 × 10 −9 M and low detection limit of 6.2 × 10 −17 M. The remarkable high catalytic capability could allow the nanohybrid to replace conventional peroxidase-based assay systems. The new, robust and convenient assay systems can be widely utilized for the identification of other target molecules

  7. Detection of CO{sub 2} using CNT-based sensors: Role of Fe catalyst on sensitivity and selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Tit, Nacir, E-mail: ntit@uaeu.ac.ae [Physics Department, UAE University, P.O. Box 15551, Al-Ain (United Arab Emirates); Ezzi, Mohammed M. Al; Abdullah, Hasan M. [Physics Department, King Fahd University of Petroleum and Minerals, P.O. Box 1690, Dhahran, 31261 (Saudi Arabia); Yusupov, Maksudbek [Research Group PLASMANT, Department of Chemistry, University of Antwerp, Universiteitsplein 1, BE-2610, Wilrijk-Antwerp (Belgium); Kouser, Summayya [Theoretical Sciences Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur, Bangalore (India); Bahlouli, Hocine [Physics Department, King Fahd University of Petroleum and Minerals, P.O. Box 1690, Dhahran, 31261 (Saudi Arabia); Yamani, Zain H. [Physics Department, King Fahd University of Petroleum and Minerals, P.O. Box 1690, Dhahran, 31261 (Saudi Arabia); Center for Research Excellence in Nanotechnology, KFUPM, P.O. Box 5040, Dhahran 31261 (Saudi Arabia)

    2017-01-15

    The adsorption of CO{sub 2} on surfaces of graphene and carbon nanotubes (CNTs), decorated with Fe atoms, are investigated using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method, neglecting the heat effects. Fe ad-atoms are more stable when they are dispersed on hollow sites. They introduce a large density of states at the Fermi level (N{sub F}); where keeping such density low would help in gas sensing. Furthermore, the Fe ad-atom can weaken the C=O double bonds of the chemisorbed CO{sub 2} molecule, paving the way for oxygen atoms to drain more charges from Fe. Consequently, chemisorption of CO{sub 2} molecules reduces both N{sub F} and the conductance while it enhances the sensitivity with the increasing gas dose. Conducting armchair CNTs (ac-CNTs) have higher sensitivity than graphene and semiconducting zigzag CNTs (zz-CNTs). Comparative study of sensitivity of ac-CNT-Fe composite towards various gases (e.g., O{sub 2}, N{sub 2}, H{sub 2}, H{sub 2}O, CO and CO{sub 2}) has shown high sensitivity and selectivity towards CO, CO{sub 2} and H{sub 2}O gases. - Highlights: • DFTB is used to study Adsorptions of CO{sub 2} molecule on pG and CNT, with Fe catalyst. • Armchair CNT-Fe has higher sensitivity to detect CO{sub 2} than zigzag CNT-Fe and pG-Fe. • Ac-CNT-Fe is highly sensitive and selective towards CO, CO{sub 2} and H{sub 2}O gases. • Keeping Fe ad-atoms dispersed and with low density enhances sensitivity. • Our theoretical results corroborate the experimental findings of Ref. .

  8. Ageing and Water-Based Processing of LiFeMnPO4 Secondary Agglomerates and Its Effects on Electrochemical Characteristics

    Directory of Open Access Journals (Sweden)

    Benjamin Starke

    2017-12-01

    Full Text Available LiFeMnPO4 secondary agglomerates have been aged under different temperature and moisture conditions. The aged and pristine powder samples were then processed to water- and solvent-based cathodes. Structural studies by means of neutron and X-ray diffraction revealed that neither ageing nor water-based processing significantly modified the crystal structure of LiFeMnPO4 secondary agglomerates. Electrochemical characterization was carried out with full-cells. It was found that long-term cycling is similar independent of the solvent used for slurry preparation. Full-cells assembled with water-based cathodes show a better C-rate capability due to a more homogeneous distribution of cathode constituents compared to solvent-based ones. In no case was any negative effect of initial active material ageing on the electrochemical performance found. During ageing and processing, LiFeMnPO4 is effectively protected by carbon coating and water can be completely removed by drying since it is only reversibly bound. This contribution shows that LiFeMnPO4 secondary agglomerates allow simplified active material handling and have a high potential for sustainable water-based electrode manufacturing.

  9. Spatially and size selective synthesis of Fe-based nanoparticles on ordered mesoporous supports as highly active and stable catalysts for ammonia decomposition.

    Science.gov (United States)

    Lu, An-Hui; Nitz, Joerg-Joachim; Comotti, Massimiliano; Weidenthaler, Claudia; Schlichte, Klaus; Lehmann, Christian W; Terasaki, Osamu; Schüth, Ferdi

    2010-10-13

    Uniform and highly dispersed γ-Fe(2)O(3) nanoparticles with a diameter of ∼6 nm supported on CMK-5 carbons and C/SBA-15 composites were prepared via simple impregnation and thermal treatment. The nanostructures of these materials were characterized by XRD, Mössbauer spectroscopy, XPS, SEM, TEM, and nitrogen sorption. Due to the confinement effect of the mesoporous ordered matrices, γ-Fe(2)O(3) nanoparticles were fully immobilized within the channels of the supports. Even at high Fe-loadings (up to about 12 wt %) on CMK-5 carbon no iron species were detected on the external surface of the carbon support by XPS analysis and electron microscopy. Fe(2)O(3)/CMK-5 showed the highest ammonia decomposition activity of all previously described Fe-based catalysts in this reaction. Complete ammonia decomposition was achieved at 700 °C and space velocities as high as 60,000 cm(3) g(cat)(-1) h(-1). At a space velocity of 7500 cm(3) g(cat)(-1) h(-1), complete ammonia conversion was maintained at 600 °C for 20 h. After the reaction, the immobilized γ-Fe(2)O(3) nanoparticles were found to be converted to much smaller nanoparticles (γ-Fe(2)O(3) and a small fraction of nitride), which were still embedded within the carbon matrix. The Fe(2)O(3)/CMK-5 catalyst is much more active than the benchmark NiO/Al(2)O(3) catalyst at high space velocity, due to its highly developed mesoporosity. γ-Fe(2)O(3) nanoparticles supported on carbon-silica composites are structurally much more stable over extended periods of time but less active than those supported on carbon. TEM observation reveals that iron-based nanoparticles penetrate through the carbon layer and then are anchored on the silica walls, thus preventing them from moving and sintering. In this way, the stability of the carbon-silica catalyst is improved. Comparison with the silica supported iron oxide catalyst reveals that the presence of a thin layer of carbon is essential for increased catalytic activity.

  10. Biogenic Fe(III) minerals lower the efficiency of iron-mineral based commercial filter systems for arsenic removal

    DEFF Research Database (Denmark)

    Kleinert, Susanne; Muehe, Eva M.; Posth, Nicole

    2011-01-01

    Millions of people worldwide are affected by As (arsenic) contaminated groundwater. Fe(III) (oxy)hydroxides sorb As efficiently and are therefore used in water purification filters. Commercial filters containing abiogenic Fe(III) (oxy)hydroxides (GEH) showed varying As removal, and it was unclear...

  11. Vertically aligned carbon nanotube field emitter arrays with Ohmic base contact to silicon by Fe-catalyzed chemical vapor deposition

    NARCIS (Netherlands)

    Morassutto, M.; Tiggelaar, Roald M.; Smithers, M.A.; Smithers, M.A.; Gardeniers, Johannes G.E.

    2016-01-01

    Abstract In this study, dense arrays of aligned carbon nanotubes are obtained by thermal catalytic chemical vapor deposition, using Fe catalyst dispersed on a thin Ta layer. Alignment of the carbon nanotubes depends on the original Fe layer thickness from which the catalyst dispersion is obtained by

  12. Preparation and characterization of new cathodic materials for Li-ion battery based polypyrrole-FePO4

    International Nuclear Information System (INIS)

    Fedorkova, A.; Kaniansky, D.; Orinakova, R.; Orinak, A.

    2009-01-01

    To investigate the electrochemical properties and stability of our samples, we used cyclic voltammetry and electrochemical impedance spectroscopy. We found that PEG-PPy layer on the particles FePO 4 considerably increased material conductivity in comparison with a layer of pure PPy. It also improved the incorporation of Li + ions into FePO 4 structure during charging and discharging. (Authors)

  13. Safety assessment of historical masonry churches based on pre-assigned kinematic limit analysis, FE limit and pushover analyses

    Energy Technology Data Exchange (ETDEWEB)

    Milani, Gabriele, E-mail: milani@stru.polimi.it; Valente, Marco, E-mail: milani@stru.polimi.it [Department of Architecture, Built Environment and Construction Engineering (ABC), Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy)

    2014-10-06

    This study presents some results of a comprehensive numerical analysis on three masonry churches damaged by the recent Emilia-Romagna (Italy) seismic events occurred in May 2012. The numerical study comprises: (a) pushover analyses conducted with a commercial code, standard nonlinear material models and two different horizontal load distributions; (b) FE kinematic limit analyses performed using a non-commercial software based on a preliminary homogenization of the masonry materials and a subsequent limit analysis with triangular elements and interfaces; (c) kinematic limit analyses conducted in agreement with the Italian code and based on the a-priori assumption of preassigned failure mechanisms, where the masonry material is considered unable to withstand tensile stresses. All models are capable of giving information on the active failure mechanism and the base shear at failure, which, if properly made non-dimensional with the weight of the structure, gives also an indication of the horizontal peak ground acceleration causing the collapse of the church. The results obtained from all three models indicate that the collapse is usually due to the activation of partial mechanisms (apse, façade, lateral walls, etc.). Moreover the horizontal peak ground acceleration associated to the collapse is largely lower than that required in that seismic zone by the Italian code for ordinary buildings. These outcomes highlight that structural upgrading interventions would be extremely beneficial for the considerable reduction of the seismic vulnerability of such kind of historical structures.

  14. Safety assessment of historical masonry churches based on pre-assigned kinematic limit analysis, FE limit and pushover analyses

    International Nuclear Information System (INIS)

    Milani, Gabriele; Valente, Marco

    2014-01-01

    This study presents some results of a comprehensive numerical analysis on three masonry churches damaged by the recent Emilia-Romagna (Italy) seismic events occurred in May 2012. The numerical study comprises: (a) pushover analyses conducted with a commercial code, standard nonlinear material models and two different horizontal load distributions; (b) FE kinematic limit analyses performed using a non-commercial software based on a preliminary homogenization of the masonry materials and a subsequent limit analysis with triangular elements and interfaces; (c) kinematic limit analyses conducted in agreement with the Italian code and based on the a-priori assumption of preassigned failure mechanisms, where the masonry material is considered unable to withstand tensile stresses. All models are capable of giving information on the active failure mechanism and the base shear at failure, which, if properly made non-dimensional with the weight of the structure, gives also an indication of the horizontal peak ground acceleration causing the collapse of the church. The results obtained from all three models indicate that the collapse is usually due to the activation of partial mechanisms (apse, façade, lateral walls, etc.). Moreover the horizontal peak ground acceleration associated to the collapse is largely lower than that required in that seismic zone by the Italian code for ordinary buildings. These outcomes highlight that structural upgrading interventions would be extremely beneficial for the considerable reduction of the seismic vulnerability of such kind of historical structures

  15. Mesoscopic modeling and parameter estimation of a lithium-ion battery based on LiFePO4/graphite

    Science.gov (United States)

    Jokar, Ali; Désilets, Martin; Lacroix, Marcel; Zaghib, Karim

    2018-03-01

    A novel numerical model for simulating the behavior of lithium-ion batteries based on LiFePO4(LFP)/graphite is presented. The model is based on the modified Single Particle Model (SPM) coupled to a mesoscopic approach for the LFP electrode. The model comprises one representative spherical particle as the graphite electrode, and N LFP units as the positive electrode. All the SPM equations are retained to model the negative electrode performance. The mesoscopic model rests on non-equilibrium thermodynamic conditions and uses a non-monotonic open circuit potential for each unit. A parameter estimation study is also carried out to identify all the parameters needed for the model. The unknown parameters are the solid diffusion coefficient of the negative electrode (Ds,n), reaction-rate constant of the negative electrode (Kn), negative and positive electrode porosity (εn&εn), initial State-Of-Charge of the negative electrode (SOCn,0), initial partial composition of the LFP units (yk,0), minimum and maximum resistance of the LFP units (Rmin&Rmax), and solution resistance (Rcell). The results show that the mesoscopic model can simulate successfully the electrochemical behavior of lithium-ion batteries at low and high charge/discharge rates. The model also describes adequately the lithiation/delithiation of the LFP particles, however, it is computationally expensive compared to macro-based models.

  16. Metagenomic and PCR-based diversity surveys of [FeFe]-hydrogenases combined with isolation of alkaliphilic hydrogen-producing bacteria from the serpentinite-hosted Prony hydrothermal field, New Caledonia

    Directory of Open Access Journals (Sweden)

    Nan Mei

    2016-08-01

    Full Text Available High amounts of hydrogen are emitted in the serpentinite-hosted hydrothermal field of the Prony Bay (PHF, New Caledonia, where high-pH (~11, low-temperature (<40°C and low-salinity fluids are discharged in both intertidal and shallow submarine environments. In this study, we investigated the diversity and distribution of potentially hydrogen-producing bacteria in Prony hyperalkaline springs by using metagenomic analyses and different PCR-amplified DNA sequencing methods. The retrieved sequences of hydA genes, encoding the catalytic subunit of [FeFe]-hydrogenases and, used as a molecular marker of hydrogen-producing bacteria, were mainly related to those of Firmicutes and clustered into two distinct groups depending on sampling locations. Intertidal samples were dominated by new hydA sequences related to uncultured Firmicutes retrieved from paddy soils, while submarine samples were dominated by diverse hydA sequences affiliated with anaerobic and/or thermophilic submarine Firmicutes pertaining to the orders Thermoanaerobacterales or Clostridiales. The novelty and diversity of these [FeFe]-hydrogenases may reflect the unique environmental conditions prevailing in the PHF (i.e. high-pH, low-salt, mesothermic fluids. In addition, novel alkaliphilic hydrogen-producing Firmicutes (Clostridiales and Bacillales were successfully isolated from both intertidal and submarine PHF chimney samples. Both molecular and cultivation-based data demonstrated the ability of Firmicutes originating from serpentinite-hosted environments to produce hydrogen by fermentation, potentially contributing to the molecular hydrogen balance in situ.

  17. Shape memory and associated properties in Fe-Mn-Si-based ribbons produced by melt-spinning

    International Nuclear Information System (INIS)

    Valeanu, Mihaela; Filoti, G.; Kuncser, V.; Tolea, Felicia; Popescu, B.; Galatanu, A.; Schinteie, G.; Jianu, A.D.; Mitelea, I.; Schinle, D.; Craciunescu, C.M.

    2008-01-01

    Four Fe-Mn-Si alloys, Fe 62 Mn 32 Si 6 , Fe 62 Mn 20 Si 5 Cr 8 Ni 5 , Fe 62 Mn 16 Si 5 Cr 12 Ni 5 and Fe 65 Mn 9 Si 7 Cr 10 Ni 9 , were obtained by the melt-spinning method. The samples were structurally, magnetic and shape memory effect (SME) investigated, both 'as quenched' and thermally treated. The Mn-rich compositions show different phase, magnetic behavior and SME in comparison with Mn-poor compositions. The thermal treatments generate transformation between the two existing majority phases (α and γ), related magnetization and SME behavior. The features are derived from the corroboration of structural, magnetic interaction and magnitude of SME data

  18. Pd-isatin Schiff base complex immobilized onγ-Fe2O3 as a magnetically recyclable catalyst for the Heck and Suzuki cross-coupling reactions

    Institute of Scientific and Technical Information of China (English)

    Sara Sobhani; Farzaneh Zarifi

    2015-01-01

    A Pd‐isatin Schiff base complex immobilized onγ‐Fe2O3 (Pd‐isatin Schiff base‐γ‐Fe2O3) was synthe‐sized and characterized by Fourier transform infrared, scanning electron microscopy, high resolu‐tion transmission electron microscopy, X‐ray diffraction, thermogravimetric gravimetric analysis, inductively‐coupled plasma, X‐ray photoelectron spectroscopy, and elemental analysis. It was used as a magnetically reusable Pd catalyst for the Heck and Suzuki cross‐coupling reactions.

  19. Photochemical Decoration of Silver Nanocrystals on Magnetic MnFe2O4 Nanoparticles and Their Applications in Antibacterial Agents and SERS-Based Detection

    Science.gov (United States)

    Huy, Le Thanh; Tam, Le Thi; Van Son, Tran; Cuong, Nguyen Duy; Nam, Man Hoai; Vinh, Le Khanh; Huy, Tran Quang; Ngo, Duc-The; Phan, Vu Ngoc; Le, Anh-Tuan

    2017-06-01

    In this study, multifunctional nanocomposites consisting of silver nanoparticles and manganese ferrite nanoparticles (Ag-MnFe2O4) were successfully synthesized using a two-step chemical process. The formation of Ag-MnFe2O4 nanocomposites were analyzed by transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy measurements. Noticeable antibacterial activity of the Ag-MnFe2O4 nanocomposites was demonstrated against two Gram-negative bacteria, Salmonella enteritidis and Klebsiella pneumoniae. A direct-drop diffusion method can be an effective way to investigate the antibacterial effects of nanocomposite samples. Interestingly, we also demonstrated the use of Ag-MnFe2O4 nanocomposites as a surface-enhanced Raman scattering (SERS) platform to detect and quantify trace amounts of organic dye in water solutions. The combination of Ag and MnFe2O4 nanoparticles opens opportunities for creating advantages such as targeted bactericidal delivery, recyclable capability, and sensitive SERS-based detection for advanced biomedicine and environmental monitoring applications.

  20. Reduced graphene oxide wrapped Fe3O4-Co3O4 yolk-shell nanostructures for advanced catalytic oxidation based on sulfate radicals

    Science.gov (United States)

    Zhang, Lishu; Yang, Xijia; Han, Erfen; Zhao, Lijun; Lian, Jianshe

    2017-02-01

    In this work, we designed and synthesized a high performance catalyst of reduced graphene oxide (RGO) wrapped Fe3O4-Co3O4 (RGO/Fe3O4-Co3O4) yolk-shell nanostructures for advanced catalytic oxidation based on sulfate radicals. The synergistic catalytic action of the RGO/Fe3O4-Co3O4 yolk-shell nanostructures activate the peroxymonosulfate (PMS) to produce sulfate radicals (SO4rad -) for organic dyes degradation, and the Orange II can be almost completely degradated in 5 min. Meanwhile the RGO wrapping prevents the loss of cobalt in the catalytic process, and the RGO/Fe3O4-Co3O4 can be recycled after catalyzed reaction due to the presence of magnetic iron core. What's more, it can maintain almost the same high catalytic activity even after 10 cycles through repeated NaBH4 reduction treatment. Hence, RGO/Fe3O4-Co3O4 yolk-shell nanostructures possess a great opportunity to become a promising candidate for waste water treatment in industry.

  1. Synthesized of PEG-6000 coated MgFe2O4 nanoparticles based on natural iron sand by co-precipitation method

    Science.gov (United States)

    Setiadi, E. A.; Simbolon, S.; Saputra, A. S. P.; Marlianto, E.; Djuhana; Kurniawan, C.; Yunus, M.; Sebayang, P.

    2018-02-01

    The polymer coated Magnesium Ferrite nanoparticles (MgFe2O4) based on natural iron sand, Mg(CH3COO)2.4H2O, and PEG-6000 have been successfully prepared by co-precipitation method. The mass variation of PEG-6000 content was from 0 to 12 gram. It was prepared at synthesize temperature of 70°C. The PEG coating reduced the effect of agglomeration, so the coercivity value can be closed to soft magnets. The nanoparticle of synthesized has MgFe2O4 single phase and cubic spinel structure. The bonding of MgFe2O4 and PEG-6000 as a coating material was confirmed by FTIR curve. The MgFe2O4 density decreased with the increasing of PEG 6000 content. On the other hand, the coercivity value was slightly reduced as the addition of PEG-6000, with the lowest value was obtained on 8 gram PEG content. The optimum condition is obtained at addition of 8 gram PEG 6000 to MgFe2O4, with coercivity, saturation, and remanence are 198.41 Oe, 52.53 emu/g, and 8.51 emu/g, respectively. So that, the sample is widely used as absorbance material of heavy metal.

  2. Microstructure and High Temperature Oxidation Property of Fe-Cr-B Based Metal/Ceramic Composite Manufactured by Powder Injection Molding Process

    Science.gov (United States)

    Joo, Yeun-Ah; Kim, Young-Kyun; Yoon, Tae-Sik; Lee, Kee-Ahn

    2018-03-01

    This study investigated the microstructure and high temperature oxidation property of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding process. Observations of initial microstructure showed a unique structure where α-Fe and (Cr, Fe)2B form a continuous three-dimensional network. High temperature oxidation tests were performed at 900, 1000 and 1100 °C, for 24 h, and the oxidation weight gain according to each temperature condition was 0.13, 0.84 and 6.4 mg/cm2, respectively. The oxidation results according to time at 900 and 1000 °C conditions represented parabolic curves, and at 1100 °C condition formed a rectilinear curve. Observation and phase analysis results of the oxides identified Cr2O3 and SiO2 at 900 and 1000 °C. In addition to Cr2O3 and SiO2, CrBO3 and FeCr2O4 formed due to phase decomposition of boride were identified at 1100 °C. Based on the findings above, this study suggested the high temperature oxidation mechanism of Fe-Cr-B metal/ceramic composite manufactured using powder injection molding, and the possibility of its application as a high temperature component material was also discussed.

  3. Thermal Annealing Effect on Structural, Morphological, and Sensor Performance of PANI-Ag-Fe Based Electrochemical E. coli Sensor for Environmental Monitoring

    Directory of Open Access Journals (Sweden)

    Norshafadzila Mohammad Naim

    2015-01-01

    Full Text Available PANI-Ag-Fe nanocomposite thin films based electrochemical E. coli sensor was developed with thermal annealing. PANI-Ag-Fe nanocomposite thin films were prepared by oxidative polymerization of aniline and the reduction process of Ag-Fe bimetallic compound with the presence of nitric acid and PVA. The films were deposited on glass substrate using spin-coating technique before they were annealed at 300°C. The films were characterized using XRD, UV-Vis spectroscopy, and FESEM to study the structural and morphological properties. The electrochemical sensor performance was conducted using I-V measurement electrochemical impedance spectroscopy (EIS. The sensitivity upon the presence of E. coli was measured in clean water and E. coli solution. From XRD analysis, the crystallite sizes were found to become larger for the samples after annealing. UV-Vis absorption bands for samples before and after annealing show maximum absorbance peaks at around 422 nm–424 nm and 426 nm–464 nm, respectively. FESEM images show the diameter size for nanospherical Ag-Fe alloy particles increases after annealing. The sensor performance of PANI-Ag-Fe nanocomposite thin films upon E. coli cells in liquid medium indicates the sensitivity increases after annealing.

  4. About the choice of Gibbs' potential for modelling of FCC ↔ HCP transformation in FeMnSi-based shape memory alloys

    Science.gov (United States)

    Evard, Margarita E.; Volkov, Aleksandr E.; Belyaev, Fedor S.; Ignatova, Anna D.

    2018-05-01

    The choice of Gibbs' potential for microstructural modeling of FCC ↔ HCP martensitic transformation in FeMn-based shape memory alloys is discussed. Threefold symmetry of the HCP phase is taken into account on specifying internal variables characterizing volume fractions of martensite variants. Constraints imposed on model constants by thermodynamic equilibrium conditions are formulated.

  5. Preparation and thermopower of new mischmetal-based partially filled skutterudites Mm yFe4-x(Co/Ni) xSb12

    International Nuclear Information System (INIS)

    Bourgoin, B.; Berardan, D.; Alleno, E.; Godart, C.; Rouleau, O.; Leroy, E.

    2005-01-01

    We report on sample preparation and electron probe microanalysis (EPMA) in the series Mm y Fe 4-x (Co/Ni) x Sb 12 with Mm being mischmetal. We show the possibility of preparing mischmetal-based partially filled skutterudites without any segregation of the rare-earths. Room temperature thermopower is similar in mischmetal-based skutterudites to cerium- or ytterbium-based partially filled skutterudites

  6. Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

    Science.gov (United States)

    Skulkina, N. A.; Ivanov, O. A.; Pavlova, I. O.; Minina, O. A.

    2011-12-01

    On the example of soft magnetic Fe81B13Si4C2 and Fe77Ni1Si9B13 amorphous alloys, the relation between the level of magnetic properties and duration of isothermal holding in the course of heat treatment in air has been studied. The optimum temperature-dependent time τ of isothermal holding has been shown to be related to the volume fraction of domains ( V orth) with orthogonal magnetization in the initial (quenched) ribbon by equation V orth = ττ1/3. A temperature dependence of the proportionality coefficient α, which determines the degree of diffusion-process activity, has been determined. The results obtained allow us to substantially simplify the choice of optimum conditions of atmospheric heat treatment of soft magnetic Fe-based amorphous ribbons.

  7. Tailoring of K0.8Al0.7Fe0.15Si2.25O6 Leucite Based Dental Ceramic Material

    Directory of Open Access Journals (Sweden)

    Aleksandar Kremenović

    2016-06-01

    Full Text Available Potassium based ceramic materials composed from leucite in which 5 % of Al is exchanged with Fe and 4 % of hematite was synthesized by mechanochemical homogenization and annealing of K2O-SiO2-Al2O3-Fe2O3 mixtures. Synthesized material was characterized by X-ray Powder Diffraction (XRPD and Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM/EDX. The two methods are in good agreement in regard to the specimen chemical composition suggesting that a leucite chemical formula is K0.8Al0.7Fe0.15Si2.25O6. Rietveld structure refinement results reveal that about 20 % of vacancies exist in the position of K atoms. This work is licensed under a Creative Commons Attribution 4.0 International License.

  8. A high performance hydrogen sulfide gas sensor based on porous α-Fe{sub 2}O{sub 3} operates at room-temperature

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanwu; Chen, Weimei; Zhang, Shouchao; Kuang, Zhong; Ao, Dongyi [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Alkurd, Nooraldeen Rafat; Zhou, Weilie [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Liu, Wei [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China); Shen, Wenzhong [Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, 030001 (China); Li, Zhijie, E-mail: zhijieli@uestc.edu.cn [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu, 610054 (China)

    2015-10-01

    Highlights: • Novel porous α-Fe{sub 2}O{sub 3} nanoparticles were prepared by a facile hydrothermal method. • The sensor based on porous α-Fe{sub 2}O{sub 3} exhibits high sensitivity towards H{sub 2}S gas. • The detection limit towards H{sub 2}S gas was as low as 50 ppb at room temperature. • The sensor exhibits excellent selectivity against other toxic and noxious gases. - Abstract: Porous α-Fe{sub 2}O{sub 3} nanoparticles were synthesized by simple annealing of β-FeOOH precursor derived from a facile hydrothermal route, the structures and morphologies of the as-prepared product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the average crystallite size of the obtained porous α-Fe{sub 2}O{sub 3} was 34 nm and exits numerous irregularly distributed pores with a diameter varying from 2 nm to 10 nm on the particle surface. The gas-sensing properties of the sensor based on porous α-Fe{sub 2}O{sub 3} nanoparticles were investigated, and the result showed that the sensor exhibited a high performance in hydrogen sulfide (H{sub 2}S) detection at room temperature. The highest sensitivity reached 38.4 for 100 ppm H{sub 2}S, and the detection limit was as low as 50 ppb. In addition, the response of the sensor towards other gases including C{sub 2}H{sub 5}OH, CO, H{sub 2} and NH{sub 3} indicates the sensor has an excellent selectivity to detection H{sub 2}S gas. Finally, the sensing mechanism of the sensor towards H{sub 2}S was also discussed.

  9. Microstructures and properties of low-chromium high corrosion-resistant TiC-VC reinforced Fe-based laser cladding layer

    International Nuclear Information System (INIS)

    Zhang, Hui; Zou, Yong; Zou, Zengda; Wu, Dongting

    2015-01-01

    Highlights: • The cladding layer with 3.0%Cr and 0.25%CeO 2 showed a good corrosion resistance. • Passive film formed on the cladding layer without Cr and CeO 2 was Fe 3 O 4 . • Fe 3 O 4 displayed p type semiconductivity. • Passive film formed on the cladding layer with Cr and CeO 2 was Fe(OH) 3 and Cr(OH) 3 . • Fe(OH) 3 displayed n type while Cr(OH) 3 displayed p type semiconductivity. - Abstract: Effects of 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on microstructures and properties of TiC-VC reinforced Fe-based cladding layer were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Passive films formed on cladding layers surface were investigated by using X-ray photoelectron spectroscopy (XPS) and Mott-Schottky analysis. Results showed that phases of cladding layers were α-Fe, γ-Fe, TiC, VC and TiVC 2 . There were no obvious effects of adding 3.0 wt.%Cr and/or 0.25 wt.%CeO 2 on cladding layers phases. The microstructure of the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was lath martensite and retained austenite. Microhardness of the cladding layer with 0.25 wt.%CeO 2 decreased slightly. Microhardness and corrosion resistance of the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 both increased, the corrosion resistance increased 7.33 times while the EIS Nyquist spectrum transformed into a capacitive arc. The passive film formed on the cladding layer without Cr and CeO 2 was Fe 3 O 4 which displayed p type semiconductivity. The passive film formed on the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO 2 was composed of Fe(OH) 3 and Cr(OH) 3 , which displayed n and p type semiconductivity respectively

  10. Microstructures and properties of low-chromium high corrosion-resistant TiC-VC reinforced Fe-based laser cladding layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hui; Zou, Yong, E-mail: yzou@sdu.edu.cn; Zou, Zengda; Wu, Dongting

    2015-02-15

    Highlights: • The cladding layer with 3.0%Cr and 0.25%CeO{sub 2} showed a good corrosion resistance. • Passive film formed on the cladding layer without Cr and CeO{sub 2} was Fe{sub 3}O{sub 4}. • Fe{sub 3}O{sub 4} displayed p type semiconductivity. • Passive film formed on the cladding layer with Cr and CeO{sub 2} was Fe(OH){sub 3} and Cr(OH){sub 3}. • Fe(OH){sub 3} displayed n type while Cr(OH){sub 3} displayed p type semiconductivity. - Abstract: Effects of 3.0 wt.%Cr and/or 0.25 wt.%CeO{sub 2} on microstructures and properties of TiC-VC reinforced Fe-based cladding layer were investigated by using X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). Passive films formed on cladding layers surface were investigated by using X-ray photoelectron spectroscopy (XPS) and Mott-Schottky analysis. Results showed that phases of cladding layers were α-Fe, γ-Fe, TiC, VC and TiVC{sub 2}. There were no obvious effects of adding 3.0 wt.%Cr and/or 0.25 wt.%CeO{sub 2} on cladding layers phases. The microstructure of the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO{sub 2} was lath martensite and retained austenite. Microhardness of the cladding layer with 0.25 wt.%CeO{sub 2} decreased slightly. Microhardness and corrosion resistance of the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO{sub 2} both increased, the corrosion resistance increased 7.33 times while the EIS Nyquist spectrum transformed into a capacitive arc. The passive film formed on the cladding layer without Cr and CeO{sub 2} was Fe{sub 3}O{sub 4} which displayed p type semiconductivity. The passive film formed on the cladding layer with 3.0 wt.%Cr and 0.25 wt.%CeO{sub 2} was composed of Fe(OH){sub 3} and Cr(OH){sub 3}, which displayed n and p type semiconductivity respectively.

  11. A comparison of EBSD based strain indicators for the study of Fe-3Si steel subjected to cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Schayes, Claire [Université Lille 1 sciences et technologies, UMET – UMR CNRS 8207/ENSCL/Université de Lille, team Métallurgie Physique et Génie des Matériaux, Bâtiment C6, 59655 Villeneuve d' Ascq (France); Valeo Engine Electrical Systems, 2 Rue André Boulle, 94046 Créteil (France); Bouquerel, Jérémie, E-mail: jeremie.bouquerel@univ-lille1.fr [Université Lille 1 sciences et technologies, UMET – UMR CNRS 8207/ENSCL/Université de Lille, team Métallurgie Physique et Génie des Matériaux, Bâtiment C6, 59655 Villeneuve d' Ascq (France); Vogt, Jean-Bernard [Université Lille 1 sciences et technologies, UMET – UMR CNRS 8207/ENSCL/Université de Lille, team Métallurgie Physique et Génie des Matériaux, Bâtiment C6, 59655 Villeneuve d' Ascq (France); Palleschi, Frédéric [Valeo Engine Electrical Systems, 2 Rue André Boulle, 94046 Créteil (France); Zaefferer, Stefan [Max-Planck-Institut für Eisenforschung, Abteilung Mikrostrukturphysik und Umformtechnik, Max-Planck-Strasse 1, 40237 Düsseldorf (Germany)

    2016-05-15

    The current work aims at proposing an EBSD-based indicator for fatigue damage of a Fe-3Si steel. At the same time direct observation of dislocation structures is provided by electron channelling contrast imaging (ECCI). The investigation consisted in processing the EBSD data from patterns collected on specimen subjected to low cycle fatigue. It revealed two different regimes depending on the applied total strain variation which is explained by the identification of the dislocations structures and their evolution. At low strain variation, strain accommodation occurs by planar glide of dislocations uniformly distributed throughout the grains. No misorientation evolution is observed. At higher strain variation, the vein-channel structure is observed within the grain and the wall-channel structure in the vicinity of grain boundaries. The misorientation between these two dislocation structures is evaluated at about 0.7° which is detected by the EBSD analyses and explains the increase of the different misorientation based criteria. The EBSD study enables also the prediction of crack initiation mode. Finally, this study points out the limits of the EBSD technique as no misorientation evolution is detected at small strain variation. Indeed, the lattice distortion is too weak to be detected by conventional EBSD. - Highlights: • Microstructure investigation of the fatigue behaviour of an iron-silicon steel • Use of cECCI to investigate the fatigue dislocations structures • Characterisation of local plastic accommodation through EBSD misorientation criteria.

  12. Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

    2015-05-07

    Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-06-01

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

  14. X-ray studies of interface Fe-oxide in annealed MgO based magnetic tunneling junctions

    Energy Technology Data Exchange (ETDEWEB)

    Telesca, D., E-mail: donaldtelesca@gmail.com [Department of Physics, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269 (United States); Space Vehicles Directorate, Air Force Research Lab (AFRL), Kirtland AFB, NM 87117 (United States); Sinkovic, B. [Space Vehicles Directorate, Air Force Research Lab (AFRL), Kirtland AFB, NM 87117 (United States); Yang, See-Hun; Parkin, S.S.P. [IBM Amaden Research Center, 650 Harry Road, San Jose, CA 95120 (United States)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer This work concludes the presence of oxide in MgO/transition-metal bi-layers. Black-Right-Pointing-Pointer Thermal annealing causes a possible structural transformation of the oxide. Black-Right-Pointing-Pointer This is first evidence for a possible structural change of the oxide. Black-Right-Pointing-Pointer First use of the O K-edge XAS signature of TM oxides to confirm presence of oxide. Black-Right-Pointing-Pointer We see a diffusion of oxygen and a decrease in interface roughness. -- Abstract: X-ray absorption spectroscopy and X-ray scattering have been used to determine the oxidation reactions at the buried MgO/Fe interface as a result of the deposition of MgO. We confirm that Fe-oxide is present at the MgO/Fe and MgO/CoFe interfaces and amounts to less than 1 mL in thickness. The Fe-oxide is a mixture of different iron oxide phases within the ultra-thin layer which can be reduced following annealing. We observe the transformation of the interfacial oxide from a more Fe{sub 2}O{sub 3}-like phase to a more FeO-like phase following annealing, and that this process is most noticeable between the 200 and 350 Degree-Sign C annealing steps. In addition, the formation of a more bulk like MgO electronic structure following annealing was observed.

  15. Synthesis of fatty monoester lubricant base oil catalyzed by Fe-Zn ...

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 126, No. 4, July 2014, pp. 997–1003. c Indian Academy of Sciences. Synthesis of fatty ... environmental pollution which the conventional min- eral oil-based ... fication of a fatty acid or transesterification of veg- etable oil with a ...

  16. An experimental study of the magnetic ordering in Pd-based Fe and Mn alloys

    International Nuclear Information System (INIS)

    Verbeek, B.H.

    1979-01-01

    This thesis presents the results of an investigation on the magnetic ordering phenomena in some Pd based alloys with small concentrations of magnetic impurities. It has been the object to explore the ordering mechanisms in these alloys which lead to various types of magnetism at low temperature. The experimental techniques used are described. (Auth.)

  17. Preliminary Analysis of the General Performance and Mechanical Behavior of Irradiated FeCrAl Base Alloys and Weldments

    Energy Technology Data Exchange (ETDEWEB)

    Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Briggs, Samuel A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-09-30

    The iron-based, iron-chromium-aluminum (FeCrAl) alloys are promising, robust materials for deployment in current and future nuclear power plants. This class of alloys demonstrates excellent performance in a range of environments and conditions, including high-temperature steam (>1000°C). Furthermore, these alloys have the potential to have prolonged survival under loss-of-coolant accident (LOCA) conditions compared to the more traditional cladding materials that are either Zr-based alloys or austenitic steels. However, one of the issues associated with FeCrAl alloys is cracking during welding. The present project investigates the possibility of mitigating welding-induced cracking via alloying and precise structure control of the weldments; in the frame work of the project, several advanced alloys were developed and are being investigated prior to and after neutron irradiation to provide insight into the radiation tolerance and mechanical performance of the weldments. The present report provides preliminary results on the post-irradiation characterization and mechanical tests performed during United States Fiscal Year (FY) 2016. Chapter 1 provides a general introduction, and Chapter 2 describes the alloy compositions, welding procedure, specimen geometry and manufacturing parameters. Also, a brief discussion of the irradiation at the High Flux Isotope Reactor (HFIR) is provided. Chapter 3 is devoted to the analysis of mechanical tests performed at the hot cell facility; tensile curves and mechanical properties are discussed in detail focusing on the irradiation temperature. Limited fractography results are also presented and analyzed. The discussion highlights the limitations of the testing within a hot cell. Chapter 4 underlines the advantages of in-situ testing and discusses the preliminary results obtained with newly developed miniature specimens. Specimens were moved to the Low Activation Materials Development and Analysis (LAMDA) laboratory and prepared for

  18. Surface structure of MgO underlayer with Ti diffusion for (002 oriented L10 FePt-based heat assisted magnetic recording media

    Directory of Open Access Journals (Sweden)

    Sintaro Hinata

    2018-05-01

    Full Text Available Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm/Cr80Mn20 (0-30 nm/Cr50Ti50 (0-50 nm/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

  19. Surface structure of MgO underlayer with Ti diffusion for (002) oriented L10 FePt-based heat assisted magnetic recording media

    Science.gov (United States)

    Hinata, Sintaro; Jo, Shin; Saito, Shin

    2018-05-01

    Surface morphology of the MgO layer and magnetic properties of FePt-C layer deposited on the MgO were investigated for the FePt-based heat assisted magnetic recording media. Stacking structure of the underlayer for the FePt-C layer was MgO (0-5 nm)/Cr80Mn20 (0-30 nm)/Cr50Ti50 (0-50 nm)/glass sub.. Surface observation result for the MgO film by using an atomic force microscope revealed the existence of nodules with a height of about 2 nm and a network-like convex structure with a height difference of about sub nm (boundary wall, BW) on the MgO crystal grain boundary. Density of the nodules largely depends on the surface roughness of the CrTi layer, RaCrTi and it is suppressed from 10 to 2/0.5 μm2 by reducing RaCrTi from 420 to 260 pm. Height of the BW depends on thickness of the MgO layer, tMgO and it can be suppressed by reducing tMgO to less than 4 nm. From the cross-sectional energy dispersive x-ray mapping, it is clarified that the BW is formed by atomic diffusion of Ti atoms from CrTi layer due to the substrate heating process, and a compound consists of Mg, Ti and O atoms. This BW can be used as a template to magnetically isolate the FePt column in the FePt-based granular film, such as FePt-SiO2, if the size of the BW is reduced to less than 10 nm. M-H loop of the FePt-C granular film deposited on the underlayer showed that the nodule and BW induce oxidation of the FePt grains, and reduction of intergranular exchange coupling.

  20. Synthesis of monodisperse MFe{sub 2}O{sub 4} (M = Fe and Zn) nanoparticles for polydiethylsiloxane-based ferrofluid with a solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Zhuang, Lin, E-mail: stszhl@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Zhang, Yong [Laboratory of Nanophotonic Functional Materials and Devices, Institute of Optoelectronic Materials and Technology, South China Normal University, Guangzhou 510631 (China); Shen, Hui [State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Provincial Key Laboratory of Photovoltaics Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2015-09-15

    Highlights: • MFe{sub 2}O{sub 4} nanoparticles were synthesized through a facile solvothermal method. • The relationship between viscosity and temperature of the polydiethylsiloxane-based ferrofluid is discussed. • Fe{sub 3}O{sub 4} nanoparticles have a saturation magnetization of 73.06 emu/g at room temperature. - Abstract: Monodisperse MFe{sub 2}O{sub 4} (M = Fe, Zn) nanoparticles were successfully synthesized for the application of polydiethylsiloxane-based (PDES) ferrofluids (FFs) via a novel solvothermal method, with which 1-octanol and 1-octanamine act as binary solvent, oleic acid (OA) as the surfactant and metal acetylacetonate [M(acac){sub 3}](M = Fe and Zn) as the metal source. X-ray diffractometer confirms that the resultant nanoparticles are pure MFe{sub 2}O{sub 4} with a spinel structure. Infrared spectroscopy indicates that oleic acid is bound to the surface of MFe{sub 2}O{sub 4} through a covalent bond between carboxylate (COO{sup −}) and metal cations. The ratio of 1-octanol and 1-octanamine plays a key role in the formation of the sphere-shaped morphology. Transmission electron microscopy (TEM) images confirm that the Fe{sub 3}O{sub 4} particles are of 4–11 nm with good monodispersity and a narrow size distribution. The saturation magnetization of Fe{sub 3}O{sub 4} nanoparticles with sizes of 7 nm can reach up to 73.06 emu/g. Polydiethylsiloxane-based (PDES) FFs show relatively smaller changes of the viscosity with low temperatures (from −7 to 20 °C) than the polydimethylsiloxane-based (PDMS) FFs. For FFs applications, the relationship between viscosity and temperature is also discussed.

  1. Graphene-palladium nanowires based electrochemical sensor using ZnFe2O4-graphene quantum dots as an effective peroxidase mimic.

    Science.gov (United States)

    Liu, Weiyan; Yang, Hongmei; Ma, Chao; Ding, Ya-nan; Ge, Shenguang; Yu, Jinghua; Yan, Mei

    2014-12-10

    We proposed an electrochemical DNA sensor by using peroxidase-like magnetic ZnFe2O4-graphene quantum dots (ZnFe2O4/GQDs) nanohybrid as a mimic enzymatic label. Aminated graphene and Pd nanowires were successively modified on glassy carbon electrode, which improved the electronic transfer rate as well as increased the amount of immobilized capture ssDNA (S1). The nanohybrid ZnFe2O4/GQDs was prepared by assembling the GQDs on the surface of ZnFe2O4 through a photo-Fenton reaction, which was not only used as a mimic enzyme but also as a carrier to label complementary ssDNA (S3). By synergistically integrating highly catalytically activity of nano-sized GQDs and ZnFe2O4, the nanohybrid possessed highly-efficient peroxidase-like catalytic activity which could produce a large current toward the reduction of H2O2 for signal amplification. Thionine was used as an excellent electron mediator. Compared with traditional enzyme labels, the mimic enzyme ZnFe2O4/GQDs exhibited many advantages such as environment friendly and better stability. Under the optimal conditions, the approach provided a wide linear range from 10(-16) to 5×10(-9) M and low detection limit of 6.2×10(-17) M. The remarkable high catalytic capability could allow the nanohybrid to replace conventional peroxidase-based assay systems. The new, robust and convenient assay systems can be widely utilized for the identification of other target molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Gh. Nabiyouni

    2013-06-01

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

  3. Multiscale phase mapping of LiFePO4-based electrodes by transmission electron microscopy and electron forward scattering diffraction.

    Science.gov (United States)

    Robert, Donatien; Douillard, Thierry; Boulineau, Adrien; Brunetti, Guillaume; Nowakowski, Pawel; Venet, Denis; Bayle-Guillemaud, Pascale; Cayron, Cyril

    2013-12-23

    LiFePO4 and FePO4 phase distributions of entire cross-sectioned electrodes with various Li content are investigated from nanoscale to mesoscale, by transmission electron microscopy and by the new electron forward scattering diffraction technique. The distributions of the fully delithiated (FePO4) or lithiated particles (LiFePO4) are mapped on large fields of view (>100 × 100 μm(2)). Heterogeneities in thin and thick electrodes are highlighted at different scales. At the nanoscale, the statistical analysis of 64 000 particles unambiguously shows that the small particles delithiate first. At the mesoscale, the phase maps reveal a core-shell mechanism at the scale of the agglomerates with a preferential pathway along the electrode porosities. At larger scale, lithiation occurs in thick electrodes "stratum by stratum" from the surface in contact with electrolyte toward the current collector.

  4. Carbon-Based Fe3O4 Nanocomposites Derived from Waste Pomelo Peels for Magnetic Solid-Phase Extraction of 11 Triazole Fungicides in Fruit Samples

    Science.gov (United States)

    Ren, Keyu; Zhang, Wenlin; Cao, Shurui; Wang, Guomin; Zhou, Zhiqin

    2018-01-01

    Carbon-based Fe3O4 nanocomposites (C/Fe3O4 NCs) were synthesized by a simple one-step hydrothermal method using waste pomelo peels as the carbon precursors. The characterization results showed that they had good structures and physicochemical properties. The prepared C/Fe3O4 NCs could be applied as excellent and recyclable adsorbents for magnetic solid phase extraction (MSPE) of 11 triazole fungicides in fruit samples. In the MSPE procedure, several parameters including the amount of adsorbents, extraction time, the type and volume of desorption solvent, and desorption time were optimized in detail. Under the optimized conditions, the good linearity (R2 > 0.9916), the limits of detection (LOD), and quantification (LOQ) were obtained in the range of 1–100, 0.12–0.55, and 0.39–1.85 μg/kg for 11 pesticides, respectively. Lastly, the proposed MSPE method was successfully applied to analyze triazole fungicides in real apple, pear, orange, peach, and banana samples with recoveries in the range of 82.1% to 109.9% and relative standard deviations (RSDs) below 8.4%. Therefore, the C/Fe3O4 NCs based MSPE method has a great potential for isolating and pre-concentrating trace levels of triazole fungicides in fruits. PMID:29734765

  5. Synthesis of Acylated Xylan-Based Magnetic Fe3O4 Hydrogels and Their Application for H2O2 Detection

    Directory of Open Access Journals (Sweden)

    Qing-Qing Dai

    2016-08-01

    Full Text Available Acylated xylan-based magnetic Fe3O4 nanocomposite hydrogels (ACX-MNP-gels were prepared by fabricating Fe3O4 nanoctahedra in situ within a hydrogel matrix which was synthesized by the copolymerization of acylated xylan (ACX with acrylamide and N-isopropylacrylamide under ultraviolet irradiation. The size of the Fe3O4 fabricated within the hydrogel matrix could be adjusted through controlling the crosslinking concentrations (C. The magnetic hydrogels showed desirable magnetic and mechanical properties, which were confirmed by XRD, Raman spectroscopy, physical property measurement system, SEM, TGA, and compression test. Moreover, the catalytic performance of the magnetic hydrogels was explored. The magnetic hydrogels (C = 7.5 wt % presented excellent catalytic activity and provided a sensitive response to H2O2 detection even at a concentration level of 5 × 10−6 mol·L−1. This approach to preparing magnetic hydrogels loaded with Fe3O4 nanoparticles endows xylan-based hydrogels with new promising applications in biotechnology and environmental chemistry.

  6. Development and operation of a Pr_{2}Fe_{14}B based cryogenic permanent magnet undulator for a high spatial resolution x-ray beam line

    Directory of Open Access Journals (Sweden)

    C. Benabderrahmane

    2017-03-01

    Full Text Available Short period, high field undulators are used to produce hard x-rays on synchrotron radiation based storage ring facilities of intermediate energy and enable short wavelength free electron laser. Cryogenic permanent magnet undulators take benefit from improved magnetic properties of RE_{2}Fe_{14}B (Rare Earth based magnets at low temperatures for achieving short period, high magnetic field and high coercivity. Using Pr_{2}Fe_{14}B instead of Nd_{2}Fe_{14}B, which is generally employed for undulators, avoids the limitation caused by the spin reorientation transition phenomenon, and simplifies the cooling system by allowing the working temperature of the undulator to be directly at the liquid nitrogen one (77 K. We describe here the development of a full scale (2 m, 18 mm period Pr_{2}Fe_{14}B cryogenic permanent magnet undulator (U18. The design, construction and optimization, as well as magnetic measurements and shimming at low temperature are presented. The commissioning and operation of the undulator with the electron beam and spectrum measurement using the Nanoscopmium beamline at SOLEIL are also reported.

  7. Evaluation of surface energy state distribution and bulk defect concentration in DSSC photoanodes based on Sn, Fe, and Cu doped TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ako, Rajour Tanyi [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Ekanayake, Piyaisiri, E-mail: piyasiri.ekanayake@ubd.edu.bn [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Young, David James [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research -A*STAR, 3 Research Link, 117602 (Singapore); Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Locked Bag 4, Maroochydore DC, Queensland, 4558 (Australia); Hobley, Jonathan [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Chellappan, Vijila [Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, 3 Research Link, 117602 (Singapore); Tan, Ai Ling [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam); Gorelik, Sergey; Subramanian, Gomathy Sandhya [Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, 3 Research Link, 117602 (Singapore); Lim, Chee Ming [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara (Brunei Darussalam)

    2015-10-01

    Graphical abstract: - Highlights: • The structural, optical and optoelectronic properties of 1 mol.% Fe, Sn and Cu doped TiO{sub 2} have been compared. • Transient lifetimes for pure TiO{sub 2} and Sn doped TiO{sub 2} were considerably shorter than Fe and Cu doped TiO{sub 2}. • A good correlation between the bulk defects and transient decay for the doped TiO{sub 2} powders was observed. • Photon to current conversion efficiency of DSSC based on the metal doped TiO{sub 2} were in order Sn-TiO{sub 2} > Cu-TiO{sub 2} > Pure >> Fe-TiO{sub 2}. • DSSC based on Fe doped photoanodes is limited by a high concentration of surface free holes observed at 433 nm. - Abstract: Electron transfer dynamics in the oxide layers of the working electrodes in both dye-sensitized solar cells and photocatalysts greatly influences their performance. A proper understanding of the distribution of surface and bulk energy states on/in these oxide layers can provide insights into the associated electron transfer processes. Metal ions like Iron (Fe), Copper (Cu) and Tin (Sn) doped onto TiO{sub 2} have shown enhanced photoactivity in these processes. In this work, the structural, optical and transient properties of Fe, Cu and Sn doped TiO{sub 2} nanocrystalline powders have been investigated and compared using EDX, Raman spectroscopy, X-ray Photoelectron spectroscopy (XPS), and Transient Absorption spectroscopy (TAS). Surface free energy states distributions were probed using Electrochemical Impedance spectroscopy (EIS) on Dye Sensitized Solar Cells (DSSC) based on the doped TiO{sub 2} photoanodes. Raman and XPS Ti2p{sub 3/2} peak shifts and broadening showed that the concentration of defects were in the order: Cu doped TiO{sub 2} > Fe doped TiO{sub 2} > Sn doped TiO{sub 2} > pure TiO{sub 2}. Nanosecond laser flash photolysis of Fe and Cu doped TiO{sub 2} indicated slower transient decay kinetics than that of Sn doped TiO{sub 2} or pure TiO{sub 2}. A broad absorption peak and fast

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

    International Nuclear Information System (INIS)

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

    2016-01-01

    Magnetic Fe 3 O 4 @CuO nanocomposite with a core/shell structure was successfully synthesized via direct calcinations of magnetic Fe 3 O 4 @HKUST-1 in air atmosphere. The morphology, structure, magnetic and porous properties of the as-synthesized nano composites were characterized by using scanning electron microscope (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and vibration sample magnetometer (VSM). The results showed that the nanocomposite material included a Fe 3 O 4 core and a CuO shell. The Fe 3 O 4 @CuO core-shell can be separated easily from the medium by a small magnet. The antibacterial activity of Fe 3 O 4 -CuO core-shell was investigated against gram-positive and gram-negative bacteria. A new mechanism was proposed for inactivation of bacteria over the prepared sample. It was demonstrated that the core-shell exhibit recyclable antibacterial activity, acting as an ideal long-acting antibacterial agent. - Graphical abstract: Fe 3 O 4 @CuO core-shell release of copper ions. These Cu 2+ ions were responsible for the exhibited antibacterial activity. - Highlights: • The Fe 3 O 4 @CuO core-shell was prepared by MOF method. • This is the first study of antibacterial activity of core-shell consist of CuO and Fe 3 O 4 . • The core-shell can be reused effectively. • Core-shell was separated from the reaction solution by external magnetic field.

  9. Uncertainties and correlations for the 56Fe damage cross sections and spectra averaged quantities based on TENDL-TMC

    International Nuclear Information System (INIS)

    Simakov, S.P.; Konobeyev, A.Yu.; Koning, A.

    2016-01-01

    The goal of this work is a calculation of the covariance matrices for the physical quantities used to characterize the neutron induced radiation damage in the materials. Such quantities usually encompass: the charged particles kinetic energy deposition KERMA (locally deposited nuclear heating), damage energy (to calculate then the number of displaced atoms) and gas production cross sections [(n,xα), (n,xt), (n,xp) … to calculate then transmuting of target nuclei to gases]. The uncertainties and energy-energy or reaction-reaction correlations for such quantities were not assessed so far, whereas the covariances for many underlying cross sections are often presented in the evaluated data libraries. Due to the dependence of damage quantities on many reactions channels, on both total and differential cross sections, and in particular on the energy distribution of reaction recoils, the evaluation of uncertainty is not straightforward. To reach a goal, we used the method based on idea of Total Monte Carlo application to the Nuclear Data. This report summarises the current results for evaluation, validation and representation in the ENDF-6 format of the radiation damage covariances for n + 56 Fe from thermal energy up to 20 MeV. This study was motivated by the IAEA Coordinated Research Project ''Primary Radiation Damage Cross Sections'' and by present dedicated Technical Meeting “Nuclear Reaction Data and Uncertainties for Radiation Damage”

  10. A multiscale MD-FE model of diffusion in composite media with internal surface interaction based on numerical homogenization procedure.

    Science.gov (United States)

    Kojic, M; Milosevic, M; Kojic, N; Kim, K; Ferrari, M; Ziemys, A

    2014-02-01

    Mass transport by diffusion within composite materials may depend not only on internal microstructural geometry, but also on the chemical interactions between the transported substance and the material of the microstructure. Retrospectively, there is a gap in methods and theory to connect material microstructure properties with macroscale continuum diffusion characteristics. Here we present a new hierarchical multiscale model for diffusion within composite materials that couples material microstructural geometry and interactions between diffusing particles and the material matrix. This model, which bridges molecular dynamics (MD) and the finite element (FE) method, is employed to construct a continuum diffusion model based on a novel numerical homogenization procedure. The procedure is general and robust for evaluating constitutive material parameters of the continuum model. These parameters include the traditional bulk diffusion coefficients and, additionally, the distances from the solid surface accounting for surface interaction effects. We implemented our models to glucose diffusion through the following two geometrical/material configurations: tightly packed silica nanospheres, and a complex fibrous structure surrounding nanospheres. Then, rhodamine 6G diffusion analysis through an aga-rose gel network was performed, followed by a model validation using our experimental results. The microstructural model, numerical homogenization and continuum model offer a new platform for modeling and predicting mass diffusion through complex biological environment and within composite materials that are used in a wide range of applications, like drug delivery and nanoporous catalysts.

  11. A high selective methanol gas sensor based on molecular imprinted Ag-LaFeO3 fibers.

    Science.gov (United States)

    Rong, Qian; Zhang, Yumin; Wang, Chao; Zhu, Zhongqi; Zhang, Jin; Liu, Qingju

    2017-09-21

    Ag-LaFeO 3 molecularly imprinted polymers (ALMIPs) were fabricated, which provided special recognition sites to methanol. Then ALMIPs fiber 1, fiber 2 and fiber 3 were prepared using filter paper, silk and carbon fibers template, respectively. Based on the observation of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Nitrogen adsorption surface area analyzer (BET), the structure, morphology and surface area of the fibers were characterized. The ALMIPs fibers (fiber 1, fiber 2 and fiber 3) show excellent selectivity and good response to methanol. The responses to 5 ppm methanol and the optimal operating temperature of ALMIPs fibers are 23.5 and 175 °C (fiber 1), 19.67 and 125 °C (fiber 2), 17.59 and 125 °C (fiber 3), and a lower response (≤10, 3, 2) to other test gases including formaldehyde, acetone, ethanol, ammonia, gasoline and benzene was measured, respectively.

  12. Carrageenan-based semi-IPN nanocomposite hydrogels: Swelling kinetic and slow release of sequestrene Fe 138 fertilizer

    Directory of Open Access Journals (Sweden)

    Mohammad Kazem Bahrami

    2016-09-01

    Full Text Available Nanocomposite hydrogels based on kappa-carrageenan were synthesized by incorporating natural sodium montmorillonite (Cloisite nanoclay. Acrylamide (AAm and methylenebisacrylamide (MBA were used as a monomer and a crosslinker, respectively. Effects of reaction variables on the swelling kinetics were studied. The results revealed that the rate of swelling for nanocomposites with high content of MBA was higher than those of nanocomposites consisting of low content of MBA. Similar to the effect of MBA, the rate of swelling enhanced as the carrageenan content was decreased. The influence of clay content on swelling rate was not remarkable. The experimental swelling data were evaluated by pseudo-first-order and pseudo-second-order kinetic models. The swelling data described well by pseudo-second-order kinetic model. Sequestrene Fe 138 (Sq as an agrochemical was loaded into nanocomposites and releasing of this active agent from nanocomposites was studied. The clay-free hydrogel released the whole loaded Sq; whereas the presence of clay restricted the release of Sq.

  13. A multiscale MD–FE model of diffusion in composite media with internal surface interaction based on numerical homogenization procedure

    Science.gov (United States)

    Kojic, M.; Milosevic, M.; Kojic, N.; Kim, K.; Ferrari, M.; Ziemys, A.

    2014-01-01

    Mass transport by diffusion within composite materials may depend not only on internal microstructural geometry, but also on the chemical interactions between the transported substance and the material of the microstructure. Retrospectively, there is a gap in methods and theory to connect material microstructure properties with macroscale continuum diffusion characteristics. Here we present a new hierarchical multiscale model for diffusion within composite materials that couples material microstructural geometry and interactions between diffusing particles and the material matrix. This model, which bridges molecular dynamics (MD) and the finite element (FE) method, is employed to construct a continuum diffusion model based on a novel numerical homogenization procedure. The procedure is general and robust for evaluating constitutive material parameters of the continuum model. These parameters include the traditional bulk diffusion coefficients and, additionally, the distances from the solid surface accounting for surface interaction effects. We implemented our models to glucose diffusion through the following two geometrical/material configurations: tightly packed silica nanospheres, and a complex fibrous structure surrounding nanospheres. Then, rhodamine 6G diffusion analysis through an aga-rose gel network was performed, followed by a model validation using our experimental results. The microstructural model, numerical homogenization and continuum model offer a new platform for modeling and predicting mass diffusion through complex biological environment and within composite materials that are used in a wide range of applications, like drug delivery and nanoporous catalysts. PMID:24578582

  14. Effects of electrodes on the properties of sol-gel PZT based capacitors in FeRAM

    Science.gov (United States)

    Zhang, Ming-Ming; Jia, Ze; Ren, Tian-Ling

    2009-05-01

    The effects of electrodes on the properties of capacitors applied in ferroelectric random access memories (FeRAM) are investigated in this work. Pt and Ir are used as bottom and top electrodes (BE and TE), respectively, in sol-gel Pb(Zr xTi 1-x)O 3 (PZT) based capacitors. Bottom electrodes are found to play a dominant role in the properties of PZT films and capacitors. Capacitors using Pt as bottom electrode have larger remnant polarization (2Pr) than those using Ir which may result from the different orientations of PZT films. The higher Schottky barrier, more dense film and smaller roughness are believed to be the reasons for the better leakage performance of capacitors using Pt as bottom electrodes. Different vacancies types and interface conditions are believed to be the main reasons for the better fatigue (less than 10% initial 2Pr loss after 10 11 fatigue cycles) and better imprint properties of TE/PZT/Ir capacitors. Top electrodes are found to have smaller impact on the properties of capacitors compared with bottom electrodes. A decrease in 2Pr is found when Ir is used as top electrode instead of Pt for PZT/Pt, which is believed to be caused by the stress resulting from lattice mismatch. The different thermal processes that top and bottom electrodes suffered are believed to be the reason for the different impacts they have on capacitors.

  15. Experimental Studies on the Hydrotreatment of Kraft Lignin to Aromatics and Alkylphenolics Using Economically Viable Fe-Based Catalysts

    Science.gov (United States)

    2017-01-01

    Limonite, a low-cost iron ore, was investigated as a potential hydrotreatment catalyst for kraft lignin without the use of an external solvent (batch reactor, initial H2 pressure of 100 bar, 4 h). The best results were obtained at 450 °C resulting in 34 wt % of liquefied kraft lignin (lignin oil) on lignin intake. The composition of the lignin oil was determined in detail (elemental composition, GC-MS, GC×GC-FID, and GPC). The total GC-detectable monomeric species amounts up to 31 wt % on lignin intake, indicating that 92 wt % of the products in the lignin oil are volatile and thus of low molecular weight. The lignin oil was rich in low-molecular-weight alkylphenolics (17 wt % on lignin) and aromatics (8 wt % on lignin). Performance of the limonite catalyst was compared to other Fe-based catalysts (goethite and iron disulfide) and limonite was shown to give the highest yields of alkylphenolics and aromatics. The limonite catalyst before and after reaction was characterized using XRD, TEM, and nitrogen physisorption to determine changes in structure during reaction. Catalyst recycling tests were performed and show that the catalyst is active after reuse, despite the fact that the morphology changed and that the surface area of the catalyst particles was decreased. Our results clearly reveal that cheap limonite catalysts have the potential to be used for the depolymerization/hydrodeoxygenation of kraft lignin for the production of valuable biobased phenolics and aromatics. PMID:28413733

  16. Arc-Sprayed Fe-Based Coatings from Cored Wires for Wear and Corrosion Protection in Power Engineering

    Directory of Open Access Journals (Sweden)

    Korobov Yury

    2018-02-01

    Full Text Available High wear and corrosion of parts lead to an increase in operating costs at thermal power plants. The present paper shows a possible solution to this problem through the arc spraying of protective coatings. Cored wires of the base alloying system Fe-Cr-C were used as a feedstock. Rise of wear- and heat-resistance of the coatings was achieved by additional alloying with Al, B, Ti, and Y. The wear and heat resistance of the coatings were tested via a two-body wear test accompanied by microhardness measurement and the gravimetric method, respectively. A high-temperature corrosion test was performed at 550 °C under KCl salt deposition. The porosity and adhesion strengths of the coatings were also evaluated. The microstructure was investigated with a scanning electron microscope (SEM unit equipped with an energy dispersive X-ray (EDX microanalyzer, and the phase composition was assessed by X-ray diffractometry. The test results showed the positive influence of additional alloying with Y on the coating properties. A comparison with commercial boiler materials showed that the coatings have the same level of heat resistance as austenite steels and are an order of magnitude higher than that of pearlite and martensite-ferrite steels. The coatings can be applied to wear- and heat-resistant applications at 20–700 °C.

  17. NANOBIOCATALYTIC SYSTEMS BASED ON LIPASE-Fe3O4 AND CONVENTIONAL SYSTEMS FOR ISONIAZID SYNTHESIS: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    V. M. Costa

    Full Text Available Abstract Superparamagnetic nanomaterials have attracted interest in many areas due to the high saturation magnetization and surface area. For enzyme immobilization, these properties favor the enzyme-support contact during the immobilization reaction and easy separation from the reaction mixture by use of low-cost magnetic processes. Iron oxide magnetic nanoparticles (Fe3O4, MNPs, produced by the co-precipitation method, functionalized with 3-aminopropyltriethoxysilane (APTES and glutaraldehyde (GLU, were evaluated as a solid support for Candida antarctica lipase B (CALB immobilization. The nanomagnetic derivative (11nm obtained after CALB immobilization (MNPs/APTES/GLU/CALB was evaluated as biocatalyst in isoniazide (INH synthesis using ethyl isonicotinate (INE and hydrazine hydrate (HID as substrates, in 1,4-dioxane. The results showed that MNPs/APTES/CALB had a similar performance when compared to a commercial enzyme Novozym 435, showing significant advantages over other biocatalysts, such as Rhizhomucor miehei lipase (RML and CALB immobilized on non-conventional, low-cost, chitosan-based supports.

  18. Size dependence of spin-torque induced magnetic switching in CoFeB-based perpendicular magnetization tunnel junctions (invited)

    Science.gov (United States)

    Sun, J. Z.; Trouilloud, P. L.; Gajek, M. J.; Nowak, J.; Robertazzi, R. P.; Hu, G.; Abraham, D. W.; Gaidis, M. C.; Brown, S. L.; O'Sullivan, E. J.; Gallagher, W. J.; Worledge, D. C.

    2012-04-01

    CoFeB-based magnetic tunnel junctions with perpendicular magnetic anisotropy are used as a model system for studies of size dependence in spin-torque-induced magnetic switching. For integrated solid-state memory applications, it is important to understand the magnetic and electrical characteristics of these magnetic tunnel junctions as they scale with tunnel junction size. Size-dependent magnetic anisotropy energy, switching voltage, apparent damping, and anisotropy field are systematically compared for devices with different materials and fabrication treatments. Results reveal the presence of sub-volume thermal fluctuation and reversal, with a characteristic length-scale of the order of approximately 40 nm, depending on the strength of the perpendicular magnetic anisotropy and exchange stiffness. To have the best spin-torque switching efficiency and best stability against thermal activation, it is desirable to optimize the perpendicular anisotropy strength with the junction size for intended use. It also is important to ensure strong exchange-stiffness across the magnetic thin film. These combine to give an exchange length that is comparable or larger than the lateral device size for efficient spin-torque switching.

  19. Spin injection and magnetoresistance in MoS2-based tunnel junctions using Fe3Si Heusler alloy electrodes.

    Science.gov (United States)

    Rotjanapittayakul, Worasak; Pijitrojana, Wanchai; Archer, Thomas; Sanvito, Stefano; Prasongkit, Jariyanee

    2018-03-19

    Recently magnetic tunnel junctions using two-dimensional MoS 2 as nonmagnetic spacer have been fabricated, although their magnetoresistance has been reported to be quite low. This may be attributed to the use of permalloy electrodes, injecting current with a relatively small spin polarization. Here we evaluate the performance of MoS 2 -based tunnel junctions using Fe 3 Si Heusler alloy electrodes. Density functional theory and the non-equilibrium Green's function method are used to investigate the spin injection efficiency (SIE) and the magnetoresistance (MR) ratio as a function of the MoS 2 thickness. We find a maximum MR of ~300% with a SIE of about 80% for spacers comprising between 3 and 5 MoS 2 monolayers. Most importantly, both the SIE and the MR remain robust at finite bias, namely MR > 100% and SIE > 50% at 0.7 V. Our proposed materials stack thus demonstrates the possibility of developing a new generation of performing magnetic tunnel junctions with layered two-dimensional compounds as spacers.

  20. High-force NdFeB-based magnetic tweezers device optimized for microrheology experiments.

    Science.gov (United States)

    Lin, Jun; Valentine, Megan T

    2012-05-01

    We present the design, calibration, and testing of a magnetic tweezers device that employs two pairs of permanent neodymium iron boron magnets surrounded by low-carbon steel focusing tips to apply large forces to soft materials for microrheology experiments. Our design enables the application of forces in the range of 1-1800 pN to ∼4.5 μm paramagnetic beads using magnet-bead separations in the range of 0.3-20 mm. This allows the use of standard coverslips and sample geometries. A high speed camera, custom LED-based illumination scheme, and mechanically stabilized measurement platform are employed to enable the measurement of materials with viscoelastic moduli as high as ∼1 kPa.

  1. High-force NdFeB-based magnetic tweezers device optimized for microrheology experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lin Jun [Department of Mechanical Engineering, University of California, Santa Barbara, California 93106 (United States); Biomolecular Science and Engineering Program, University of California, Santa Barbara, California 93106 (United States); Valentine, Megan T. [Department of Mechanical Engineering, University of California, Santa Barbara, California 93106 (United States)

    2012-05-15

    We present the design, calibration, and testing of a magnetic tweezers device that employs two pairs of permanent neodymium iron boron magnets surrounded by low-carbon steel focusing tips to apply large forces to soft materials for microrheology experiments. Our design enables the application of forces in the range of 1-1800 pN to {approx}4.5 {mu}m paramagnetic beads using magnet-bead separations in the range of 0.3-20 mm. This allows the use of standard coverslips and sample geometries. A high speed camera, custom LED-based illumination scheme, and mechanically stabilized measurement platform are employed to enable the measurement of materials with viscoelastic moduli as high as {approx}1 kPa.

  2. Visual and quantitative determination of dopamine based on CoxFe3−xO4 magnetic nanoparticles as peroxidase mimetics

    International Nuclear Information System (INIS)

    Niu, Xiaoying; Xu, Yinyin; Dong, Yalei; Qi, Liye; Qi, Shengda; Chen, Hongli; Chen, Xingguo

    2014-01-01

    Graphical abstract: Co x Fe 3−x O 4 was proved to possess higher peroxidase-like activity comparing with Fe 3 O 4 MNPs. It could effectively catalyze the reaction between 3,3,5,5-tetramethylbenzidine (TMB) and H 2 O 2 under 40 °C within 15 min. So this proposed method was used for measuring dopamine. The color variation was very obvious on visual observation, which offered a convenient approach to detect DA by naked eye. -- Highlights: • The Co x Fe 3−x O 4 MNPs were firstly prepared by a simple coprecipitation method. • Co x Fe 3−x O 4 MNPs could effectively catalyze the reaction between TMB and H 2 O 2 . • This colorimetric analytical method was convenient, economic and speedy. • The method had been applied to detection of DA in Shan Yao and human serum sample. -- Abstract: In this study, cobalt doped magnetic composite nanoparticles (Co x Fe 3−x O 4 MNPs) were firstly prepared through a simple and convenient coprecipitation approach. The characterization results from EDX, ICP-AES, TEM, XRD and XPS showed that the cobalt atoms might be located in the lattice position instead of the part of iron atoms. Co x Fe 3−x O 4 MNPs possessed higher peroxidase-like activity comparing with Fe 3 O 4 MNPs, although they were similar in crystal structure, size distribution and morphology. The as-prepared nanomaterials could effectively catalyze the reaction between 3,3,5,5-tetramethylbenzidine (TMB) and H 2 O 2 under 40 °C within 15 min. Dopamine (DA) has some reducibility due to the existence of phenol hydroxyl group, which results in it can consume H 2 O 2 and cause the blue shallowing of the reaction solution between H 2 O 2 and TMB. A visual, sensitive and simple colorimetric method based on Co x Fe 3−x O 4 MNPs as peroxidase mimetics was developed for detecting DA. Good linear relationship and recoveries for DA were obtained from 0.6 to 8.0 μM and 98.7 to 101.0%, respectively. The limit of detection (LOD) of the proposed method was calculated as 0

  3. Structure and soft magnetic properties of the bulk samples prepared by compaction of the mixtures of Co-based and Fe-based powders

    International Nuclear Information System (INIS)

    Fuezer, J.; Bednarcik, J.; Kollar, P.; Roth, S.

    2007-01-01

    Ball milling of CoFeZrB ribbons and subsequent compaction of the resulting powders were used to prepare bulk amorphous samples. Further, two sets of powder samples were prepared by cryomilling of FeCuNbMoSiB alloy in amorphous and nanocrystalline state. Amorphous and nanocrystalline FeCuNbMoSiB powders were blended with CoFeZrB powder at different concentrations. Such powder mixtures were consolidated and several bulk nanocomposites have been synthesized. An addition of nanocrystalline or amorphous FeCuNbMoSiB powder to amorphous CoFeZrB powder caused a decrease of the magnetostriction of the resultant bulk samples, while the coercivity shows an opposite behavior. Our results show that the powder consolidation by hot pressing is an alternative method for the preparation of bulk metallic glasses, which are difficult to prepare by casting methods

  4. Structural and morphological study of