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Sample records for method rankinsosuho ni

  1. Ni nanoparticles prepared by simple chemical method for the synthesis of Ni/NiO-multi-layered graphene by chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ali, Mokhtar; Remalli, Nagarjuna; Gedela, Venkataramana; Padya, Balaji; Jain, Pawan Kumar; Al-Fatesh, Ahmed; Rana, Usman Ali; Srikanth, Vadali V. S. S.

    2017-02-01

    A new chemical method was used to obtain a high yield of nickel nanoparticles (Ni-NPs). The effect of solvent (distilled water, ethylene glycol, and ethanol) and surfactant (oleic acid and polyvinyl pyrrolidinone) on the morphology and crystallinity of the synthesized Ni-NPs has been investigated. The experimental results revealed that among the solvents mentioned above, ethanol gives the best results in terms of complete reduction, controlled morphology and size distribution of Ni-NPs. The surfactants played an important role in impeding the agglomeration and surface oxidation of Ni-NPs. The surfactants also affected the morphology of the Ni-NPs. The synthesized Ni-NPs are found to be quite stable in air. The best of the synthesized Ni-NPs were effectively used as catalysts for the synthesis of Ni/NiO-multi-layered graphene using catalytic chemical vapor deposition technique.

  2. Embedded Atom Method Potential for Ni-Cu Alloys and Its Applications for Ni, Cu growth on Cu(111)

    NASA Astrophysics Data System (ADS)

    Onat, Berk; Durukanoglu, Sondan

    2012-02-01

    We developed a semi-empirical, many-body type model potential to investigate static and dynamic properties of Ni-Cu alloys. The formalism is based on the embedded atom method with improved optimization techniques. The Ni-Cu alloy potential was determined by fitting to data on lattice parameters, cohesive energies for L10, L11, L12, and L13 phases, together with vacancy formation energies, bulk modulus and elastic properties for L12, L13 phases. Our preliminary calculations for energy barriers for the diffusing Ni and Cu atoms on Cu(111) based on the nudged elastic band method are found to be consistent with the available experimental and other theoretical results. Our ultimate goal is to describe the varying characteristics in growing islands of pure Cu, Ni atoms and mixed Ni-Cu combinations on Cu(111) [S. Pons et al., Surf. Sci., 511, 449, (2002)].

  3. A novel method for improving the adhesion strength of the electrodeposited Ni films in MEMS

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Liu, Rui; Jiang, Wei Qiao; Zhu, Jun; Feng, Jian Zhi; Ding, Gui Fu; Zhao, Xiaolin

    2011-01-01

    Adhesion performance of MEMS materials is increasingly important with the widely use of miniaturized devices. This paper proposed a novel method for improving adhesion performance between electrodeposited Ni multi-layers. The new method is to treat the Ni substrate in nickel chloride plating solution by pulse reverse current technique before electrodeposition. The dense oxide film of Ni substrate can be removed effectively by this electrochemical method, meanwhile, the proper roughness of Ni substrate is in favor of epitaxial growth during electrodeposition. Moreover, the Ni film is electrodeposited by the new method with low stress and coarse crystal grain. Consequently, the adhesion performance of Ni films is improved dramatically. The experimental results show that the adhesion performance of Ni film electrodeposited by the new method is about 3 times that of by traditional method.

  4. Ni-Co oxide formation with Cu assisted method on Ni foam: Unexpected higher areal capacitance of inner layer with naturally formed nanotubes

    NASA Astrophysics Data System (ADS)

    Shi, Diwen; Zhang, Liuyang; Gong, Hao

    2017-09-01

    Ni Foam substrate directly serves as the Ni source for the final Ni-Co oxide product with a Cu assisted chemical method. Especially, after shaking off top layer of Ni-Co oxide grown on Ni Foam, the sample unexpectedly exhibits a greatly enhanced areal capacitance from 4.17 to 11.44 F cm-2 (1 mA cm-2). Finer structures including oxide nanotubes are interestingly found underneath the top layer, which may account for this extraordinary phenomenon.

  5. Determination of the mean neutron energy using the Zr/Nb and the Ni method

    NASA Astrophysics Data System (ADS)

    Agrawal, H. M.; Pepelnik, R.

    1995-12-01

    The cross-section ratios for the 90Zr(n, 2n) 89g-mZr and 93Nb(n, 2n) 92mNb reactions as well as for the 58Ni(n, p) 58g+mCo and 58Ni(n, 2n) 57Ni reactions have been measured by the activation method for the purpose of neutron spectrometry around 14 MeV in a neutron tube having a cylindrical acceleration structure (KORONA). The results are compared with the theoretically calculated values. The superiority of the "Zr/Nb ratio" method over the "Ni-ratio" method is discussed.

  6. Fabrication of ultrathin Ni-Zn ferrite films using electron cyclotron resonance sputtering method

    SciTech Connect

    Tanaka, Terumitsu; Kurisu, Hiroki; Matsuura, Mitsuru; Shimosato, Yoshihiro; Okada, Shigenobu; Oshiro, Kazunori; Fujimori, Hirotaka; Yamamoto, Setsuo

    2006-04-15

    Well-crystallized Ni-Zn ferrite (Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4}) highly oriented ultrathin films were obtained at a substrate temperature of 200 deg. C by a reactive sputtering method utilizing electron cyclotron resonance microwave plasma, which is very effective to crystallize oxide or nitride materials without heat treatment. Thin films of Ni-Zn ferrite deposited on a MgO (100) underlayer showed an intense X-ray-diffraction peak of (400) from the Ni-Zn ferrite as compared to similar films deposited directly onto thermally oxidized Si substrates. A 1.5-nm-thick Ni-Zn ferrite film, which corresponds to twice the lattice constant for bulk Ni-Zn ferrite, crystallized on a MgO (100) underlayer.

  7. Novel combustion method to prepare octahedral NiO nanoparticles and its photocatalytic activity

    SciTech Connect

    Jegatha Christy, A.; Umadevi, M.

    2013-10-15

    Graphical abstract: - Highlights: • NiO nanoparticles were synthesized by solution combustion method. • Prepared NiO nanoparticles are fcc structure. • Synthesized NiO nanoparticles are octahedral shape. • Shows good photocatalytic activity. - Abstract: Nickel oxide nanoparticles (NiO NPs) were synthesized by solution combustion method using glycine and citric acid as fuels. The X-ray diffraction (XRD) result confirms the face centered cubic (fcc) structure of NiO. The octahedral shape of NiO NPs was confirmed by field emission scanning electron microscope (FESEM) and high resolution transmission electron microscopy (HRTEM). It is possible to suggest that the organic fuel (citric acid/glycine) is responsible for the formation of the octahedral shape due to the easier complex formation. Photocatalytic activity of NiO NPs also evaluated and found that the prepared NiO NPs have high photocatalytic degradation. In the present study, the crystalline nature and shape of the NiO nanoparticles plays a vital role in determining the photocatalytic activity.

  8. Method For Making Electronic Circuits Having Nial And Ni3al Substrates

    DOEpatents

    Deevi, Seetharama C.; Sikka, Vinod K.

    2001-01-30

    A method for making electronic circuit component having improved mechanical properties and thermal conductivity comprises steps of providing NiAl and/or Ni.sub.3 Al, and forming an alumina layer thereupon prior to applying the conductive elements. Additional layers of copper-aluminum alloy or copper further improve mechanical strength and thermal conductivity.

  9. Tribological performance of Cu-Ni alloy nanoparticles synthesized using a pulsed-wire evaporation method

    NASA Astrophysics Data System (ADS)

    Oh, Jeongseok; Rhee, Changkyu

    2008-08-01

    Cu-Ni alloy nanoparticles were produced using a pulsed-wire evaporation method in Ar gas. The synthesized Cu-Ni alloy nanoparticles had an average size of 150 nm, were spherical in shape and agglomerated. We investigated the tribological propeties of dispersion-stabilized Cu-Ni alloy nanoparticles when used as a solid lubricant in oil at ambient temperature. The sedimentation behavior of Cu-Ni alloy nanoparticles in oil was examined using Turbiscan LAb. The particles were clearly quantified using delta backscattering profiles and peak thickness kinetics as functions of time. The rubbing surfaces were characterized after a friction test using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). We found that dispersed Cu-Ni nanoparticles as a solid lubricant in oil had superior dispersion stability properties for over 48 h. Dispersed Cu nanoparticles in oil showed a low friction coefficient and good wear rate compared to oil only. Dispersed Cu-Ni alloy nanoparticles had superior friction reduction and antiwear properties compared to Cu nanoparticles, and these effects increased with the Ni content in the alloy. However, non-dispersed Cu-Ni alloy nanoparticles had poor antiwear properties. Dispersion-stabilized Cu-Ni alloy nanoparticles in oil enhanced the rolling effect of spherical nanoparticles between rubbing surfaces during friction processes.

  10. Characterization of pure Ni ultrafine/nanoparticles synthesized by electromagnetic levitational gas condensation method

    SciTech Connect

    Khodaei, Azin Hasannasab, Malihe; Amousoltani, Narges; Kermanpur, Ahmad

    2016-02-15

    Highlights: • Ni ultrafine/nanoparticles were produced using the single-step ELGC method. • Ar and He–20%Ar gas mixtures were used as the condensing gas under 1 atm. • Effects of gas type and flow rate on particle size distribution were investigated. • The nanoparticles showed both high saturation magnetization and low coercivity. - Abstract: In this work, Ni ultrafine/nanoparticles were directly produced using the one-step, relatively large-scale electromagnetic levitational gas condensation method. In this process, Ni vapors ascending from the levitated droplet were condensed by Ar and He–20%Ar gas mixtures under atmospheric pressure. Effects of type and flow rate of the condensing gas on the size, size distribution and crystallinity of Ni particles were investigated. The particles were characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer (VSM). The process parameters for the synthesis of the crystalline Ni ultrafine/nanoparticles were determined.

  11. Semiconducting p-type MgNiO:Li epitaxial films fabricated by cosputtering method

    SciTech Connect

    Kwon, Yong Hun; Chun, Sung Hyun; Cho, Hyung Koun

    2013-07-15

    Li-doped ternary Mg{sub x}Ni{sub 1-x}O thin films were deposited on (0001) Al{sub 2}O{sub 3} substrates by a radio frequency (RF) magnetron cosputtering method with MgO and NiO:Li targets. The Mg mole fraction and Li content were relatively controlled by changing RF power for the MgO target over a range of 0-300 W, while the NiO:Li target was kept at 150 W. As a result, all films were epitaxially grown on (0001) Al{sub 2}O{sub 3} substrates with the relationship of [110]{sub NiO}||[1110]{sub Al2O3}, [112]{sub NiO}||[2110]{sub Al2O3} (in-plane), and [111]{sub NiO}||[0001]{sub Al2O3} (out-of-plane), and showed p-type semiconducting properties. Furthermore, from x-ray diffraction patterns, the authors found that MgO was effectively mixed with NiO:Li without structural deformation due to low lattice mismatch (0.8%) between NiO and MgO. However, the excess Li contents degraded the crystallinity of the MgNiO films. The band-gap of films was continuously shifted from 3.66 eV (339 nm) to 4.15 eV (299 nm) by the RF power of the MgO target. A visible transmittance of more than 80% was exhibited at RF powers higher than 200 W. Ultimately, the electrical resistivity of p-type MgNiO films was improved from 7.5 to 673.5 {Omega}cm, indicating that the Li-doped MgNiO films are good candidates for transparent p-type semiconductors.

  12. Method for measurement of diffusivity: Calorimetric studies of Fe/Ni multilayer thin films

    SciTech Connect

    Liu, JX; Barmak, K

    2015-07-15

    A calorimetric method for the measurement of diffusivity in thin film multilayers is introduced and applied to the Fe Ni system. Using this method, the diffusivity in [Fe (25 nm)/Ni (25 nm)](20) multilayer thin films is measured as 4 x 10(-3)exp(-1.6 +/- 0.1 eV/ k(B)T) cm(2)/s, respectively. The diffusion mechanism in the multilayers and its relevance to laboratory synthesis of L1(0) ordered FeNi are discussed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  13. Characterization of nano-sized SiC@Ni composite fabricated by electroless plating method.

    PubMed

    Xu, Zhan; Chen, Yigang

    2013-02-01

    A nano-sized SiC@Ni composite was prepared by simple electroless plating method. Nickel can be reduced by Na2H2PO2 under the catalysis of Pd to despite onto the surface of SiC nanoparticles. The composite structure was characterized by means of TEM images, XRD and the components were analyzed using EDS. The coating layer on the SiC particles was several nanometers thick and mainly in a form of fine Ni crystalline grain and amorphous Ni-P alloy. By increasing the concentration of Na2H2PO2 in the plating bath, the uniformity of the coating layer can be improved obviously. Both of the magnetism and crystallinity of Ni coatings depends on the P content in the coating which can be decreased by increasing the pH values of plating solutions. The SiC@Ni particles exhibited soft magnetic characteristics.

  14. WC/Ni bronze composite material formation by combined methods of laser cladding and cold spraying

    NASA Astrophysics Data System (ADS)

    Ryashin, N. S.; Malikov, A. G.; Gulyaev, I. P.; Klinkov, S. V.; Kosarev, V. F.; Orishich, A. M.

    2016-10-01

    Formation of composite material containing anti-friction bronze CuAl8.5Fe4Ni5Mn1.5 and reinforced by inner bulk profiled frame of WC/Ni was considered. Combined methods of laser cladding and cold spraying were used. Reinforced cold spraying copper-bronze blend deposits on profiled frames of WC/Ni produced by laser cladding were obtained. Dependence of bronze weight concentration in cold spraying copper-bronze deposit on bronze weight part in powder blend was analyzed. Results of non-contact profiling of reinforcing WC/Ni frame, EDS analysis and microhardness tests of obtained reinforced copper-bronze-WC/Ni composites were presented.

  15. Influence of PVP in magnetic properties of NiSn nanoparticles prepared by polyol method

    NASA Astrophysics Data System (ADS)

    Bobadilla, L. F.; García, C.; Delgado, J. J.; Sanz, O.; Romero-Sarria, F.; Centeno, M. A.; Odriozola, J. A.

    2012-11-01

    The influence of PVP on the magnetic properties of NiSn nanoparticles prepared by polyol method has been studied. NiSn nanoparticles exhibit superparamagnetic behavior although there is a ferromagnetic contribution due to particles agglomerated below the blocking temperature. The particle size is controlled by the addiction of PVP in varying amounts. The addition of PVP also favours the particles isolation, narrow the particle size distribution and decrease the interparticle interaction strength increasing the superparamagnetic contribution.

  16. Defect Structure of Beta NiAl Using the BFS Method for Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Amador, Carlos; Ferrante, John; Noebe, Ronald D.

    1996-01-01

    The semiempirical BFS method for alloys is generalized by replacing experimental input with first-principles results thus allowing for the study of complex systems. In order to examine trends and behavior of a system in the vicinity of a given point of the phase diagram a search procedure based on a sampling of selected configurations is employed. This new approach is applied to the study of the beta phase of the Ni-Al system, which exists over a range of composition from 45-60 at.% Ni. This methodology results in a straightforward and economical way of reproducing and understanding the basic features of this system. At the stoichiometric composition, NiAl should exist in a perfectly ordered B2 structure. Ni-rich alloys are characterized by antisite point defects (with Ni atoms in the Al sites) with a decrease in lattice parameters. On the Al-rich side of stoichiometry there is a steep decrease in lattice parameter and density with increasing Al content. The presence of vacancies in Ni sites would explain such behavior. Recent X-ray diffraction experiments suggest a richer structure: the evidence, while strongly favoring the presence of vacancies in Ni sites, also suggests the possibility of some vacancies in Al sites in a 3:1 ratio. Moreover, local ordering of vacant sites may be preferred over a random distribution of individual point defects.

  17. Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

    PubMed

    Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

    2013-10-01

    In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles.

  18. An Introduction to the BFS Method and Its Use to Model Binary NiAl Alloys

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante, J.; Amador, C.

    1998-01-01

    We introduce the Bozzolo-Ferrante-Smith (BFS) method for alloys as a computationally efficient tool for aiding in the process of alloy design. An intuitive description of the BFS method is provided, followed by a formal discussion of its implementation. The method is applied to the study of the defect structure of NiAl binary alloys. The groundwork is laid for a detailed progression to higher order NiAl-based alloys linking theoretical calculations and computer simulations based on the BFS method and experimental work validating each step of the alloy design process.

  19. Stable cube texture in an advanced Ni alloy composite substrate prepared by powder metallurgic method

    NASA Astrophysics Data System (ADS)

    Gao, M. M.; Suo, H. L.; Gao, P. K.; Zhao, Y.; Ma, L.; Wang, J. H.; Liu, M.; Qiu, H. Q.; Ji, Y.

    2010-06-01

    Thin, reinforced and biaxially textured Ni5W/Ni12W/Ni5W composite substrate for coated conductor applications has been fabricated by traditional powder metallurgy method using the sparking plasma sintering (SPS) technology, followed by cold rolling and annealing. In-situ EBSD strain-stress analysis shows that the yield stress (δ0.2) can reach 240MPa. The high quality of cubic texture and boundaries of low misorientation angle were stable until elongations as high as 2%. Meanwhile, the cubic grain fractions on surfaces of top Ni5W layer of the composite tapes are 98.3%, 99.5% and 99.8%, respectively, corresponding to be annealed at 1250°C for 60min, 120min and 180min, indicating the cube texture can successfully sustain after severe treatment condition.

  20. Preliminary Study on Synthesis of Composite rGO/Ni by Microwave Assisted Method

    NASA Astrophysics Data System (ADS)

    Fakhri, Hafizh A.; Husnah, Miftahul; Hasdi Aimon, Akfiny; Ferry, Iskandar

    2017-07-01

    Composite reduced graphene oxide-nickel (rGO/Ni) was successfully synthesized by wet chemical process via microwave assisted method. The nickel fraction was varied 0%, 5% and 20%. Crystallinity, morphology, chemical composition, chemical bonding, and conductivity were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), elemental dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), 4 point probes and electrochemical impedance spectroscopy (EIS). Based on the XRD patterns, the crystal sizes were 1.62 nm for 5% rGO/Ni and 1.64 nm for 20% rGO/Ni respectively. Furthermore, vibration of C=C aromatic stretching was detected in the FTIR spectra, which corresponds to rGO fingerprint. These results give a new perspective on synthesis of composite rGO/Ni.

  1. Study on preparation of NiOOH by a new catalytic electrolysis method

    SciTech Connect

    Sun Yanzhi; Pan Junqing Wan Pingyu; Liu Xiaoguang

    2009-04-02

    The present paper reports a new catalytic electrolysis method to prepare NiOOH. KMnO{sub 4} is proposed as a catalyst to play the role of electron-transfer medium in the electrolysis preparation of NiOOH for the first time. Through the self-redox reaction of KMnO{sub 4}, the highly efficient electron-transfer process between the electrolyte and the electrode of the spherical Ni(OH){sub 2} is realized, thus resulting in a high electrolytic efficiency and short electrolysis time. The mechanism of catalytic electrolysis is preliminarily discussed. The experimental results show that the electrode prepared with the NiOOH powders by catalytic electrolysis offers a discharge capacity of 267 mAh g{sup -1} at a current density of 120 mA g{sup -1} and exhibits good cycling performance.

  2. Progress in the Modeling of NiAl-Based Alloys Using the BFS Method

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Ferrante, John; Garg, Anita

    1997-01-01

    The BFS method has been applied to the study of NiAl-based materials to assess the effect of alloying additions on structure. Ternary, quaternary and even pent-alloys based on Ni-rich NiAl with additions of Ti, Cr and Cu were studied. Two approaches were used, Monte Carlo simulations to determine ground state structures and analytical calculations of high symmetry configurations which give physical insight into preferred bonding. Site occupancy energetics for ternary and the more complicated case of quaternary additions were determined, and solubility limits and precipitate formation with corresponding information concerning structure and lattice parameter were also 'observed' computationally. The method was also applied to determine the composition of alloy surfaces and interfaces. Overall, the results demonstrate that the BFS method for alloys is a powerful tool for alloy design and with its simplicity and obvious advantages can be used to complement any experimental alloy design program.

  3. Structure of Bergman-type W-TiZrNi approximants to quasicrystal, analyzed by lattice inversion method

    NASA Astrophysics Data System (ADS)

    Huang, H.; Meng, D. Q.; Lai, X. C.; Liu, T. W.; Long, Y.; Hu, Q. M.

    2014-08-01

    The combined interatomic pair potentials of TiZrNi, including Morse and Inversion Gaussian, are successfully built by the lattice inversion method. Some experimental controversies on atomic occupancies of sites 6-8 in W-TiZrNi are analyzed and settled with these inverted potentials. According to the characteristics of composition and site preference occupancy of W-TiZrNi, two stable structural models of W-TiZrNi are proposed and the possibilities are partly confirmed by experimental data. The stabilities of W-TiZrNi mostly result from the contribution of Zr atoms to the phonon densities of states in lower frequencies.

  4. Pre-concentration of Pb, Cd, and Ni in river water using back extraction method

    NASA Astrophysics Data System (ADS)

    Koesmawati, T. A.; Moelyo, M.; Rizqiani, A.; Tanuwidjaja, S.

    2017-03-01

    Dissolved heavy metals such as Pb, Cd and Ni in natural water can be the source of harmful contaminant for human health and aquatic life in aquatic systems. Particular treatment is needed for low concentration of metals in water samples using Flame Atomic Absorption Spectrophotometer (FAAS) measurement. The sample was collected from Cikapundung River in Siliwangi and Dayeuhkolot, Bandung. Back-extraction procedure was used as an alternative method for pre-concentration in trace metal analysis. Ammonium Pyrrolidine Dithiocarbamate (APDC) and Diethylammonium Diethyldithiocarbamate (DDDC) in Methyl Isobuthyl Ketone (MIBK) were used as chelating agent. In this study, the application of back-extraction procedure using APDC/DDDC chelating agent in MIBK resulted the detection limit of 2.2 μg/L for Pb; 1.6 μg/L for Cd; and 1.0 μg/L for Ni. The result showed that sensitivity was increased 4 times for Pb, 6 times for Ni, and none for Cd. The highest concentration of Pb in Cikapundung River was found 8.0 μg/L. All Ni concentration in water samples were under limit of detection. Method validation was conducted in this study and found that the value of correlation coefficient (r) for Pb, Cd and Ni was 0.9995, 0.9960 and 0.9994, respectively. The recovery value for Pb, Cd and Ni were 112.0, 81.5 and 85.9%, respectively in Cikapundung River, and 119.0, 83.5 and 85.9 %, respectively, in groundwater samples. The value of Relative Standard Deviation (RSD) for Pb, Cd and Ni in Cikapundung River were 2.01, 2.15 and 6.40%, respectively. On the other hand, the value of RSD of Pb, Cd and Ni in groundwater were 2.70, 3.30 and 7.69%, respectively. In conclusion, back-extraction method can be applied as pre-concentration for low concentration of Pb and Ni in river water samples.

  5. Properties of nano-structured Ni/YSZ anodes fabricated from plasma sprayable NiO/YSZ powder prepared by single step solution combustion method

    NASA Astrophysics Data System (ADS)

    Prakash, B. Shri; Balaji, N.; Kumar, S. Senthil; Aruna, S. T.

    2016-12-01

    NiO/YSZ anode coatings are fabricated by atmospheric plasma spraying at different plasma powers from plasma grade NiO/YSZ powders that are prepared in a single step by solution combustion method. The process adopted is devoid of multi-steps that are generally involved in conventional spray drying or fusing and crushing methods. Density of the coating increased and porosity decreased with increase in the plasma power of deposition. An ideal nano-structured Ni/YSZ anode encompassing nano YSZ particles, nano Ni particles and nano pores is achieved on reducing the coating deposited at lower plasma powers. The coating exhibit porosities in the range of 27%, sufficient for anode functional layers. Electronic conductivity of the coatings is in the range of 600 S/cm at 800 °C.

  6. Structural and Conductivity Studies on Lanthanum Doped LiNiPO4 Prepared by Polyol Method

    NASA Astrophysics Data System (ADS)

    Karthickprabhu, S.; Hirankumar, G.; Maheswaran, A.; Bella, R. S. Daries; Sanjeeviraja, C.

    2013-07-01

    Pure and Lanthanum doped LiNiPO4 (with different Molar concentrations) have been prepared by polyol method using 1,2 propanediol as a polyol medium. XRD analysis reveal that sample calcined at 650°C for 6 hrs shows good crystalline nature with orthorhombic structure and this result is consistent with TG/DTA result. It is found that the conductivity enhances upon doping of Lanthanum while backhoprate decreases compared with pure LiNiPO4. Dielectric studies have also been discussed.

  7. Effects of Ni content on nanocrystalline Fe-Co-Ni ternary alloys synthesized by a chemical reduction method

    NASA Astrophysics Data System (ADS)

    Chokprasombat, Komkrich; Pinitsoontorn, Supree; Maensiri, Santi

    2016-05-01

    Magnetic properties of Fe-Co-Ni ternary alloys could be altered by changing of the particle size, elemental compositions, and crystalline structures. In this work, Fe50Co50-xNix nanoparticles (x=10, 20, 40, and 50) were prepared by the novel chemical reduction process. Hydrazine monohydrate was used as a reducing agent under the concentrated basic condition with the presence of poly(vinylpyrrolidone). We found that the nanoparticles were composed of Fe, Co and Ni with compositions according to the molar ratio of the metal sources. Interestingly, the particles were well-crystalline at the as-prepared state without post-annealing at high temperature. Increasing Ni content resulted in phase transformation from body centered cubic (bcc) to face centered cubic (fcc). For the fcc phase, the average particle size decreased when increased the Ni content; the Fe50Ni50 nanoparticles had the smallest average size with the narrowest size distribution. In additions, the particles exhibited ferromagnetic properties at room temperature with the coercivities higher than 300 Oe, and the saturation magnetiation decreased with increasing Ni content. These results suggest that the structural and magnetic properties of Fe-Co-Ni alloys could be adjusted by varying the Ni content.

  8. Uncertainties in 63Ni and 55Fe determinations using liquid scintillation counting methods.

    PubMed

    Herranz, M; Idoeta, R; Abelairas, A; Legarda, F

    2012-09-01

    The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory implies their validation. In this process, the uncertainties related to these methods should be analysed. In this work, the expression of the uncertainty of the results obtained using separation methods followed by liquid scintillation counting is presented. This analysis includes the consideration of uncertainties coming from the different alternatives which these methods use as well as those which are specific to the individual laboratory and the competency of its operators in applying the standard ORISE (Oak Ridge Institute for Science and Education) methods. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Formation of three-dimensional arrays of magnetic clusters NiO, Co3O4, and NiCo2O4 by the matrix method

    NASA Astrophysics Data System (ADS)

    Kurdyukov, D. A.; Pevtsov, A. B.; Smirnov, A. N.; Yagovkina, M. A.; Grigorev, V. Yu.; Romanov, V. V.; Bagraev, N. T.; Golubev, V. G.

    2016-06-01

    A method has been proposed for the formation of three-dimensional arrays of isolated magnetic clusters NiO, Co3O4, and NiCo2O4 in the sublattice of pores in the matrix of bulk synthetic opals through a single impregnation of the pores with melts of nickel and cobalt nitrate crystal hydrates and their thermal degradation. The method makes it possible to controllably vary the degree of filling of pores in the matrix with oxides within 10-70 vol %. The composition and structure of the synthesized materials, as well as the dependences of their static magnetic susceptibility on the magnetic field strength, have been investigated.

  10. The optical properties of NiAs phase ZnO under pressure calculated by GGA+U method

    NASA Astrophysics Data System (ADS)

    Wang, Qing-Bo; Zhou, Cui; Chen, Ling; Wang, Xi-Cheng; He, Kai-Hua

    2014-02-01

    To comprehend the optical properties of the recent-predicted NiAs phase ZnO under pressure, we used the generalized gradient approximation plus U (GGA+U) method to calculate the properties. The GGA+U method is more suited for the strong correlated NiAs phase. The direct band gap increases with increasing pressure. The calculated band gap shows that NiAs phase is an insulator, while the real part ε1(ω) shows the NiAs phase expresses metallic behavior around 18.6 (22.5 GPa) and 26.0 eV (215 GPa). The relation between the imaginary part ε2(ω) and PDOS was also discussed. The calculated optical constants show the NiAs phase is transparent and can be used in the vacuum ultraviolet region. We also compared the optical constants of NiAs with wurtzite and CsCl phases ZnO at according transition pressure. And the new-appeared peaks of optical constants can be used to identify the phase transition. The blue-shift optical constants of NiAs phase ZnO can be used to measure pressure after carefully calibrated. Our research provides a reference for identifying and using the NiAs phase ZnO under pressure.

  11. Preparation of Ni-Sn alloys by an electroless-deposition method

    SciTech Connect

    Shimauchi, Hidenori; Ozawa, Susumu; Tamura, Keiu; Osaka, Tetsuya . Dept. of Applied Chemistry)

    1994-06-01

    Ni-Sn alloy is expected for as a functional material, because of its excellent corrosion resistance, wear resistance, and solderability. Electroless-deposited Ni-Sn alloy films were investigated to increase tin content in the deposit. The maximum tin contents of electroless Ni-Sn-P and Ni-Sn-B were ca. 30 atom percent (a/o) and 42 a/o, respectively. The maximum tin contents in the case of Ni-Sn-B was nearly equal to that of electrodeposited Ni-Sn alloy already reported. The crystallinity of Ni-Sn-P and Ni-Sn-B alloys was raised up with an increase in tin content. The corrosion resistance of Ni-Sn-P and Ni-Sn-B alloys was between that of amorphous and crystalline electroless-deposited Ni-P. Codeposition of tin into Ni-P films improved solderability, but into the Ni-B films, the solderability of Ni-Sn-B films situated in the region between those of Ni-P and NiB, because the solderability of NiB is higher.

  12. Hydrogen Gas Sensing Characteristics of Nanostructured NiO Thin Films Synthesized by SILAR Method

    NASA Astrophysics Data System (ADS)

    Karaduman, Irmak; Çorlu, Tugba; Yıldırım, M. Ali; Ateş, Aytunç; Acar, Selim

    2017-03-01

    Nanostructured NiO thin films have been synthesized by a facile, low-cost successive ionic layer adsorption and reaction (SILAR) method, and the effects of the film thickness on their hydrogen gas sensing properties investigated. The samples were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD) analysis, and energy-dispersive x-ray analysis. The XRD results revealed that the crystallinity improved with increasing thickness, exhibiting polycrystalline structure. SEM studies showed that all the films covered the glass substrate well. According to optical absorption measurements, the optical bandgap decreased with increasing film thickness. The gas sensing properties of the nanostructured NiO thin films were studied as a function of operating temperature and gas concentration. The samples showed good sensing performance of H2 gas with high response. The maximum response was 75% at operating temperature of 200°C for hydrogen gas concentration of 40 ppm. These results demonstrate that nanostructured NiO thin films synthesized by the SILAR method have potential for application in hydrogen detection.

  13. Structural, electrical and magnetic properties of Ni2+ substituted cobalt nanoferrite using sol-gel method

    NASA Astrophysics Data System (ADS)

    Blessington Selvadurai, A. Paul; Gazzali, P. M. Md.; Murugasen, C.; Pazhanivelu, V.; Murugaraj, R.; Chandrasekaran, G.

    2013-02-01

    Ni doped cobalt ferrite of chemical formula Ni(1-x)CoxFe2O4 with x values = 1, 0.5, 0 were prepared by using Poly Vinyl Alcohol (PVA) sol-gel method. The prepared samples were heat treated at 450°C for an hour and grounded to form fine powder. XRD of the powder sample confirms the formation of spinel ferrite phase. SEM and EDAX spectrum reveals the surface and chemical composition of the sample. FTIR spectra of the samples show the stretching vibration of the tetrahedral (ν1) and octahedral (ν2) bands of Fe-O bonds appearing at 600cm-1 and 424cm-1 respectively. Room temperature magnetic and electrical studies were done using VSM and LCZ meter to analyze their property respectively.

  14. NiO nanowall array prepared by a hydrothermal synthesis method and its enhanced electrochemical performance for lithium ion batteries

    SciTech Connect

    Cao, F.; Pan, G.X.; Tang, P.S.; Chen, H.F.

    2013-03-15

    Graphical abstract: Self-supported NiO nanowall array is fabricated by a facile hydrothermal synthesis method and exhibits noticeable Li ion battery performance with good cycle life and high capacity. Highlights: ► NiO nanowall array is prepared by a hydrothermal synthesis method. ► NiO nanowall array with high capacity as anode material for Li ion battery. ► Nanowall array structure is favorable for fast ion/electron transfer. - Abstract: Free-standing quasi-single-crystalline NiO nanowall array is successfully fabricated via a simple hydrothermal synthesis method. The as-prepared NiO film exhibits a highly porous nanowall structure composed of many interconnected nanoflakes with thicknesses of ∼20 nm. The NiO nanowalls arrange vertically to the substrate resulting in the formation of extended porous net-like structure with pores of 30–300 nm. As anode material for lithium ion batteries, the quasi-single-crystalline NiO nanowall array exhibits pretty good electrochemical performances with high capacity, weaker polarization, higher coulombic efficiency and better cycling performance as compared to the dense polycrystalline NiO film. The quasi-single-crystalline NiO nanowall array presents an initial coulombic efficiency of 76% and good cycling life with a capacity of 564 mAh g{sup −1} at 0.5 A g{sup −1} after 50 cycles, higher than that of the dense polycrystalline NiO film (358 mAh g{sup −1}). The enhanced performance is due to the unique nanowall array structure providing faster ion/electron transport and better morphological stability.

  15. Investigation of the properties of nanostructured Li-doped NiO films using the modified spray pyrolysis method

    PubMed Central

    2013-01-01

    The lithium-doped nickel oxide (L-NiO) films were synthetized using the modified spray pyrolysis method with a two-step grown process. By observing the spectra of X-ray photoemission spectroscopy of L-NiO films, the intensity of Ni 2p3/2 peak of Ni3+ bonding state increases with increasing Li concentration that causes the decrease of transparency and resistivity. The L-NiO films with optimum characteristics were obtained at Li = 8 at%, where a p-type resistivity of 4.1 × 10−1 Ω cm and optical transparency above 76% in the visible region are achieved. PMID:23331663

  16. Hydrogen effects on Ni-Ti fatigue performance by self -heating method

    NASA Astrophysics Data System (ADS)

    Rokbani, M.; Saint-Sulpice, L.; Arbab Chirani, S.; Bouraoui, T.

    2017-10-01

    Ni-Ti superelastic alloys are extensively used in manufacturing biomedical devices because of their high mechanical performance, good fatigue durability and biocompatibility compared to traditional metallic materials. During clinical use, most of these devices are intended to work under cyclic or repetitive loadings and may be in contact with corrosive environments leading to unexpected failures. It is however recognized that the fatigue–environment interaction, especially fatigue–hydrogen absorption, can be the main cause of these failures. The aim of this work is to investigate the fatigue behavior of superelastic Ni-Ti intended for manufacturing medical devices at high number of cycles (HCF) with a particular emphasis to the effect of hydrogen on fatigue properties. Fatigue tests were analyzed using self-heating measurements based on observing thermal effects during cyclic loadings. The results obtained with self-heating approach showed a trend of a decrease in the fatigue life of Ni-Ti alloys after hydrogen absorption and the fatigue limit extrapolated will be compared with the results obtained with the classical S-N curves method.

  17. Metal Temperature Evaluation Method Based on Microstructure Change of Ni Based Superalloy

    NASA Astrophysics Data System (ADS)

    Okada, Ikuo; Taneike, Masaki; Oguma, Hidetaka

    It is known that among numerous factors, industrial turbine Inlet gas Temperature (TIT, hereafter) has greatest influence on thermal efficiency of industrial gas turbine. In order to achieve higher thermal efficiency, TIT has already reached as high as 1500°C, which has been realized owing to improvement and development of cooling configuration and materials for hot parts. On the other hand, to operate gas turbines soundly, it is necessary to evaluate metal temperature of hot parts precisely. So, metal temperature evaluation methods of Ni base superalloy were investigated and developed based on coarsening phenomenon of γ' phase and carbide particles.

  18. Lifetime measurement of the 41+ state of 58Ni with the recoil distance method

    NASA Astrophysics Data System (ADS)

    Loelius, C.; Iwasaki, H.; Brown, B. A.; Honma, M.; Bader, V. M.; Baugher, T.; Bazin, D.; Berryman, J. S.; Braunroth, T.; Campbell, C. M.; Dewald, A.; Gade, A.; Kobayashi, N.; Langer, C.; Lee, I. Y.; Lemasson, A.; Lunderberg, E.; Morse, C.; Recchia, F.; Smalley, D.; Stroberg, S. R.; Wadsworth, R.; Walz, C.; Weisshaar, D.; Westerberg, A.; Whitmore, K.; Wimmer, K.

    2016-08-01

    The quadrupole transition rate for the 41+→21+ transition of 58Ni was determined from an application of the recoil distance method with the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA). The present result of the B (E 2 ;41+→21+) was found to be 50-6+11e2fm4 , which is about three times smaller than the literature value, indicating substantially less collectivity than previously believed. Shell model calculations performed with the GXPF1A effective interaction agree with the present data and the validity of the standard effective charges in understanding collectivity in the nickel isotopes is discussed.

  19. Ni, Fe Co-doped ZnO nanoparticles synthesized by solution combustion method

    SciTech Connect

    Dhiman, Pooja Chand, Jagdish Verma, S. Sarveena, Singh, M.

    2014-04-24

    This paper outlines the synthesis and characterization of Ni-Fe co-doped ZnO nanoparticles by facile solution combustion method. The structural characterization by XRD confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed cubic type shape of grains. EDS analysis conformed the elemental composition. Higher value of DC electrical conductivity and less band gap for co-doped ZnO from UV-Vis studies confirmed the change in defect chemistry of ZnO Matrix.

  20. Ni, Fe Co-doped ZnO nanoparticles synthesized by solution combustion method

    NASA Astrophysics Data System (ADS)

    Dhiman, Pooja; Chand, Jagdish; Verma, S.; Sarveena, Singh, M.

    2014-04-01

    This paper outlines the synthesis and characterization of Ni-Fe co-doped ZnO nanoparticles by facile solution combustion method. The structural characterization by XRD confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed cubic type shape of grains. EDS analysis conformed the elemental composition. Higher value of DC electrical conductivity and less band gap for co-doped ZnO from UV-Vis studies confirmed the change in defect chemistry of ZnO Matrix.

  1. Structural, Optical and Magnetic Properties of Ni-Zn Ferrite Nanoparticles Prepared by a Microwave Assisted Combustion Method.

    PubMed

    Vijaya, J Judith; Bououdina, M

    2016-01-01

    Ni-doped ZnFe₂O₄(Ni(x)Zn₁₋xFe₂O₄; x = 0.0 to 0.5) nanoparticles were synthesized by a simple microwave combustion method. The X-ray diffraction confirms the presence of cubic spinel ZnFe₂O₄for all compositions. The lattice parameter decreases with an increase in Ni content resulting in the reduction of lattice strain. High resolution scanning electron microscope images revealed that the as-prepared samples are crystalline with particle size distribution in 40-50 nm range. Optical properties were determined by UV-Visible diffuse reflectance and photoluminescence spectroscopy respectively. The saturation magnetization (Ms) shows the super paramagnetic nature of the sample for x = 0.0-0.2, whereas for x = 0.3-0.5, it shows ferromagnetic nature. The Ms value is 1.638 emu/g for pure ZnFe₂O₄ sample and it increases with increase in Ni content.

  2. Room temperature ferromagnetism and luminescent behavior of Ni doped ZnO nanoparticles prepared by coprecipitation method

    SciTech Connect

    Arora, Deepawali; Mahajan, Aman; Kaur, Parvinder; Singh, Gurinder Pal; Kumar, Sunil; Singh, D. P.; Ashokan, K.

    2016-05-23

    The samples of Zn{sub 1-x}Ni{sub x}O (x= 0.00 and 0.05) were prepared using coprecipitation method and annealed at different temperatures. The effect of Ni ion substitution on the structural and optical properties has been studied using X-ray Diffraction, UV-Visible, Photoluminescence and Magnetic measurements. XRD measurements demonstrate that all the prepared samples are wurtzite polycrystalline single phase in nature, ruling out the presence of any secondary phase formation. Ultraviolet visible measurements showed a decrease in band gap with the increase in annealing temperature and doping concentration. The PL data shows the red shift in all the samples and luminescence quenching with Ni doping. Compared to undoped ZnO, Ni doped ZnO showed room temperature ferromagnetism.

  3. Electrical characterization of ZnO/NiO p-n junction prepared by the sol-gel method

    NASA Astrophysics Data System (ADS)

    Merih Akyuzlu, A.; Dagdelen, Fethi; Gultek, Ahmet; Hendi, A. A.; Yakuphanoglu, Fahrettin

    2017-04-01

    ZnO and NiO films were synthesized on fluourine-doped tin oxide (FTO) glass substrate by the sol-gel method. The surface morphology of the films was investigated by atomic force microscopy. The optical band gaps of the ZnO and NiO films were found to be 3.198 and 3.827eV, respectively. A ZnO/NiO p-n junction diode was prepared and electrical charge transport mechanism of the diode was analyzed using thermionic emission and Norde functions. The ideality factor, barrier height and series resistance of the diode were determined to be 6.46, 1.036eV and 39.1 M {Ω} , respectively. The obtained results indicate that ZnO/NiO p-n junction can be used as transparent diode for optic communications.

  4. The effect of precipitants on Ni-Al2O3 catalysts prepared by a co-precipitation method for internal reforming in molten carbonate fuel cells

    PubMed Central

    Jung, You-Shick; Yoon, Wang-Lai; Seo, Yong-Seog; Rhee, Young-Woo

    2012-01-01

    Ni-Al2O3 catalysts are prepared via the co-precipitation method using various precipitants: urea, Na2CO3, NaOH, K2CO3, KOH and NH4OH. The effects of the precipitants on the physicochemical properties and catalytic activities of the Ni-Al2O3 catalysts are investigated. The Ni50-urea catalyst displays the largest specific surface area and the highest pore volume. This catalyst also exhibits the highest Ni dispersion and the largest Ni surface area. Ni50-urea catalyst prepared with urea as precipitant and Ni50-K2CO3 catalyst prepared with K2CO3 as precipitant exhibit high pore volumes and good catalytic activities for methane steam reforming. The Ni50-urea catalyst exhibits the best physicochemical properties and shows good catalytic activity and a strong resistance to electrolyte contamination. PMID:22962548

  5. Deposition of Ni-CGO composite anodes by electrostatic assisted ultrasonic spray pyrolysis method

    SciTech Connect

    Chen, J.-C.; Chang, C.-L.; Hsu, C.-S.; Hwang, B.-H. . E-mail: zorro@mail.nsysu.edu.tw

    2007-09-04

    Deposition of composite films of Ni and Gd-doped ceria was carried out using the electrostatic assisted ultrasonic spray pyrolysis method for the first time. The composite films were highly homogeneous, as revealed by element mapping via energy-dispersive spectrometry. Scanning electron microscope examinations revealed that deposition temperature and electric field strength had profound influence on resultant microstructure, while composition of the precursor solution had little effect. A highly porous cauliflower structure ideal for solid oxide fuel cell anode performance was obtained with a deposition temperature of 450 deg. C under an electric field introduced by an applied voltage of 12 kV. Films obtained with a lower deposition temperature of 250 deg. C or a higher applied voltage of 15 kV resulted in denser films with low porosity, while lower applied voltages of 7 or 5 kV resulted in thinner or discontinuous films due to the insufficient electrostatic attraction on the aerosol droplets. As revealed by AC impedance measurement, the area specific resistances of the Ni-CGO anode with porous cauliflower structure were rather low and a value of 0.09 {omega} cm{sup 2} at 550 deg. C was obtained.

  6. Process optimization for Ni(II) removal from wastewater by calcined oyster shell powders using Taguchi method.

    PubMed

    Yen, Hsing Yuan; Li, Jun Yan

    2015-09-15

    Waste oyster shells cause great environmental concerns and nickel is a harmful heavy metal. Therefore, we applied the Taguchi method to take care of both issues by optimizing the controllable factors for Ni(II) removal by calcined oyster shell powders (OSP), including the pH (P), OSP calcined temperature (T), Ni(II) concentration (C), OSP dose (D), and contact time (t). The results show that their percentage contribution in descending order is P (64.3%) > T (18.9%) > C (8.8%) > D (5.1%) > t (1.7%). The optimum condition is pH of 10 and OSP calcined temperature of 900 °C. Under the optimum condition, the Ni(II) can be removed almost completely; the higher the pH, the more the precipitation; the higher the calcined temperature, the more the adsorption. The latter is due to the large number of porosities created at the calcination temperature of 900 °C. The porosities generate a large amount of cavities which significantly increase the surface area for adsorption. A multiple linear regression equation obtained to correlate Ni(II) removal with the controllable factors is: Ni(II) removal(%) = 10.35 × P + 0.045 × T - 1.29 × C + 19.33 × D + 0.09 × t - 59.83. This equation predicts Ni(II) removal well and can be used for estimating Ni(II) removal during the design stage of Ni(II) removal by calcined OSP. Thus, OSP can be used to remove nickel effectively and the formula for removal prediction is developed for practical applications.

  7. Effect of Ni doping on structural and optical properties of Zn{sub 1−x}Ni{sub x}O nanopowder synthesized via low cost sono-chemical method

    SciTech Connect

    Singh, Budhendra; Kaushal, Ajay; Bdikin, Igor; Venkata Saravanan, K.; Ferreira, J.M.F.

    2015-10-15

    Highlights: • Pure and Ni doped ZnO nanopowders were synthesized by low cost sonochemical method. • The optical properties of Zn{sub 1−x}Ni{sub x}O nanopowders can be tuned by varying Ni content. • The results reveal the solubility limit of Ni into ZnO matrix as below 8%. - Abstract: Zn{sub 1−x}Ni{sub x}O nanopowders with different Ni contents of x = 0.0, 0.04 and 0.08 were synthesized via cost effective sonochemical reaction method. X-ray diffraction (XRD) pattern reveals pure wurtzite phase of prepared nanostructures with no additional impurity peaks. The morphology and dimensions of nanoparticles were investigated using scanning electron microscope (SEM). A sharp and strong peak for first order optical mode for wurtzite zinc oxide (ZnO) structure was observed at ∼438 cm{sup −1} in Raman spectra. The calculated optical band gap (E{sub g}) from UV–vis transmission data was found to decrease with increase in Ni content. The observed red shift in E{sub g} with increasing Ni content in ZnO nanopowders were in agreement with band gap behaviours found in their photoluminescence (PL) spectra. The synthesised ZnO nanopowders with controlled band gap on Ni doping reveals their potential for use in various electronic and optical device applications. The results were discussed in detail.

  8. Bonding and Microstructural Stability in Ni55Ti45 Studied by Experimental and Theoretical Methods

    NASA Technical Reports Server (NTRS)

    Stott, Amanda C.; Brauer, Jonathan I.; Garg, Anita; Pepper, Stephen V.; Abel, Phillip B.; DellaCorte, Christopher; Noebe, Ronald D.; Glennon, Glenn; Bylaska, Eric; Dixon, David A.

    2010-01-01

    Spiral orbit tribometry friction tests performed on Ni-rich Ni55Ti45 titanium ball bearings indicate that this alloy is a promising candidate for future aerospace bearing applications. Microstructural characterization of the bearing specimens was performed using transmission electron microscopy and energy dispersive spectroscopy, with NiTi, Ni4Ti3, Ni3Ti, and Ni2Ti4Ox phases identified within the microstructure of the alloy. Density functional theory was applied to predict the electronic structure of the NixTiy phases, including the band structure and site projected density of states. Ultraviolet photoemission spectroscopy was used to verify the density of states results from the density functional theory calculations, with good agreement observed between experiment and theory.

  9. Bonding and Microstructural Stability in Ni55Ti45 Studied by Experimental and Theoretical Methods

    NASA Technical Reports Server (NTRS)

    Stott, Amanda C.; Brauer, Jonathan I.; Garg, Anita; Pepper, Stephen V.; Abel, Phillip B.; DellaCorte, Christopher; Noebe, Ronald D.; Glennon, Glenn; Bylaska, Eric; Dixon, David A.

    2010-01-01

    Spiral orbit tribometry friction tests performed on Ni-rich Ni55Ti45 titanium ball bearings indicate that this alloy is a promising candidate for future aerospace bearing applications. Microstructural characterization of the bearing specimens was performed using transmission electron microscopy and energy dispersive spectroscopy, with NiTi, Ni4Ti3, Ni3Ti, and Ni2Ti4Ox phases identified within the microstructure of the alloy. Density functional theory was applied to predict the electronic structure of the NixTiy phases, including the band structure and site projected density of states. Ultraviolet photoemission spectroscopy was used to verify the density of states results from the density functional theory calculations, with good agreement observed between experiment and theory.

  10. Bonding and microstructural stability in Ni55Ti45 studied by experimental and theoretical methods

    SciTech Connect

    Stott, Amanda C.; Brauer, Jonathann I.; Garg, Anita; Pepper, Stephen V.; Abel, Phillip B.; DellaCorte, Christopher; Noebe, Ronald D.; Glennon, Glenn; Bylaska, Eric J.; Dixon, David A.

    2010-11-25

    Spiral orbit tribometry friction tests performed on Ni-rich Ni55Ti45 titanium ball bearings indicate that this alloy is a promising candidate for future aerospace bearing applications. Microstructural characterization of the bearing specimens was performed using transmission electron microscopy and energy dispersive spectroscopy, with NiTi, Ni4Ti3, Ni3Ti, and Ni2Ti4Ox phases identified within the microstructure of the alloy. Density functional theory was applied to predict the electronic structure of the NixTiy phases, including the band structure and site projected density of states. Ultraviolet photoemission spectroscopy was used to verify the density of states results from the density functional theory calculations, with good agreement observed between experiment and theory.

  11. Electronic properties of Co and Ni silicides: a theoretical approach using extended Huckel method

    NASA Astrophysics Data System (ADS)

    Galvan, D. H.; Posada Amarillas, A.; Samaniego Reyna, J. C.; García-Méndez, M.; Farías, M. H.

    2004-11-01

    Calculations of electronic structure, total and projected density of states (DOS), crystal orbital overlap population (COOP), and average net charge, and also Mulliken population analysis, were performed to study electronic properties of Co and Ni silicides. Analysis of the energy bands depicts metallic behavior for both silicides.The projected DOS yields an indication that hybridization occurs for Co and Ni silicides. The hybridized band in CoSi2 is composed of Co d and p orbitals and Si p and s orbitals, while in NiSi2 the hybridized band is formed by Ni d and p orbitals with Si p orbitals. The fact that the Fermi energy crosses a small part of the DOS, as is the case of CoSi2, yields an indication of the different electronic properties of CoSi2 when compared to NiSi2. The hybridization is stronger in CoSi2 than in NiSi2. Mulliken population analysis provides an indication that a smaller charge distribution exists in NiSi2 when compared to CoSi2. This difference in charge distribution accounts for the different electronic behavior, in agreement with the DOS analysis. Moreover, COOP analysis provides an indication of the existence of covalent bonding between M and Si (M = Ni, Co), this being stronger in Co than in Ni silicides. Furthermore, the average net charge in both compounds yields an indication that there is a charge transfer from M towards Si.

  12. Phonon dispersion and local density of states in NiPd alloy using modified embedded atom method potential

    SciTech Connect

    Joshi, Subodh Chand, Manesh Dabral, Krishna Semalty, P. D.

    2016-05-06

    A modified embedded atom method (MEAM) potential model up to second neighbours has been used to calculate the phonon dispersions for Ni{sub 0.55}Pd{sub 0.45} alloy in which Pd is introduced as substitutional impurity. Using the force-constants obtained from MEAM potential, the local vibrational density of states in host Ni and substitutional Pd atoms using Green’s function method has been calculated. The calculation of phonon dispersions of NiPd alloy shows a good agreement with the experimental results. Condition of resonance mode has also been investigated and resonance mode in the frequency spectrum of impurity atom at low frequency is observed.

  13. Effects of loading methods on microstructure of diffusion welded joint of AZ31B/Cu with Ni interlayer

    NASA Astrophysics Data System (ADS)

    Du, S. M.; Zhang, Y. Q.; Du, C.; Hu, J.

    2017-02-01

    Diffusion brazing was carried out to weld AZ31B magnesium alloy and copper with Ni foil interlayer under different loading methods that are divided into intermittent gradient pressure, gradient pressure and constant pressure. The microstructure and element diffusion of welded joint were analyzed by SEM and EDS. The results show that the AZ31B/Cu can achieve good bonded joint composed of brazing seam zone and magnesium substrate grain boundary penetration zone at 500 °C for 20 min. The loading methods have great influence on the thickness of brazing seam zone, microstructure and α-Mg grain size of the welded joint. At intermittent gradient pressure, the brazing seam zone reaches the biggest width of 0.18 mm, and the microstructure of brazing seam zone is composed of Cu11Mg10Ni9, (α-Mg+Mg2Cu+Mg2Ni)eutectic structure and α-Mg. Under gradient pressure, the width of brazing seam zone reduces, and the microstructure of brazing seam zone is mainly dominated by (α-Mg+Mg2Cu+Mg2Ni)eutectic structure and Cu11Mg10Ni9 compounds closed magnesium matrix. When using constant pressure, the microstructure of joint is similar to that under intermittent gradient pressure, the brazing seam zone reaches the smallest width of 0.11 mm, and the size of α-Mg grains reduces.

  14. A reddening-free method to estimate the 56Ni mass of Type Ia supernovae

    NASA Astrophysics Data System (ADS)

    Dhawan, S.; Leibundgut, B.; Spyromilio, J.; Blondin, S.

    2016-04-01

    The increase in the number of Type Ia supernovae (SNe Ia) has demonstrated that the population shows greater diversity than has been assumed in the past. The reasons (e.g. parent population, explosion mechanism) for this diversity remain largely unknown. We investigated a sample of SNe Ia near-infrared light curves and correlated the phase of the second maximum with the bolometric peak luminosity. The peak bolometric luminosity is related to the time of the second maximum (relative to the B light curve maximum) as follows: Lmax(1043 erg s-1) = (0.039 ± 0.004) × t2(J)(days) + (0.013 ± 0.106). 56Ni masses can be derived from the peak luminosity based on Arnett's rule, which states that the luminosity at maximum is equal to the instantaneous energy generated by the nickel decay. We checked this assumption against recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models and find this assumption is valid to within 10% in recent radiative-transfer calculations of Chandrasekhar-mass delayed detonation models. The Lmax vs. t2 relation is applied to a sample of 40 additional SNe Ia with significant reddening (E(B - V) > 0.1 mag), and a reddening-free bolometric luminosity function of SNe Ia is established. The method is tested with the 56Ni mass measurement from the direct observation of γ-rays in the heavily absorbed SN 2014J and found to be fully consistent. Super-Chandrasekhar-mass explosions, in particular SN 2007if, do not follow the relations between peak luminosity and second IR maximum. This may point to an additional energy source contributing at maximum light. The luminosity function of SNe Ia is constructed and is shown to be asymmetric with a tail of low-luminosity objects and a rather sharp high-luminosity cutoff, although it might be influenced by selection effects.

  15. Structural and room temperature ferromagnetic properties of Ni doped ZnO nanoparticles via low-temperature hydrothermal method

    NASA Astrophysics Data System (ADS)

    Xu, Kun; Liu, Changzhen; Chen, Rui; Fang, Xiaoxiang; Wu, Xiuling; Liu, Jie

    2016-12-01

    A series of Zn1-xNixO (x=0, 1%, 3%, 5%) nanoparticles have been synthesized via a low-temperature hydrothermal method. Influence of Ni doping concentration on the structure, morphology, optical properties and magnetism of the samples was investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV-vis spectrophotometer and vibrating sample magnetometer instruments. The results show that the undoped and doped ZnO nanoparticles are both hexagonal wurtzite structures. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The images of SEM reveal that the structure of pure ZnO and Ni doped samples are nanoparticles which intended to form flakes with thickness of few nanometers, being overlain with each one to develop the network with some pores and voids. Based on the ultraviolet-visible (UV-vis) spectroscopy analysis, it indicates that the band gap energy decreases with the increasing concentration of Ni. Furthermore, The Ni doped ZnO samples didn't exhibit higher ultraviolet-light-driven photocatalytic activity compared to the undoped ZnO sample. Vibrating sample magnetometer was used for the magnetic property investigations, and the result indicates that room temperature ferromagnetism property of 3% Ni doped sample is attributed to oxygen vacancy and interaction between doped ions.

  16. Structural and optical properties of Ni added ZnO thin films deposited by sol-gel method

    NASA Astrophysics Data System (ADS)

    Murugan, R.; Vijayaprasath, G.; Mahalingam, T.; Anandhan, N.; Ravi, G.

    2014-04-01

    Pure and Ni added zinc oxide thin films were prepared by sol-gel method using spin-coating technique on glass substrates. The influences of nickel on ZnO thin films are characterized by Powder X-ray diffraction study. Pure and Ni added thin films are hexagonal wurtzite structure without any secondary phase in c-axis orientation. The SEM images of thin films show uniform sphere like particles covered completely on glass substrates. All the films exhibit transmittance of 85-95% in the visible range up to 800nm and cut-off wavelength observed at 394 nm corresponding to the fundamental absorption of ZnO. The photoluminescence property for pure and Ni added ZnO thin films has been studied and results are presented in detail.

  17. Structural and optical properties of Ni added ZnO thin films deposited by sol-gel method

    SciTech Connect

    Murugan, R.; Vijayaprasath, G.; Anandhan, N. E-mail: gravicrc@gmail.com; Ravi, G. E-mail: gravicrc@gmail.com; Mahalingam, T.

    2014-04-24

    Pure and Ni added zinc oxide thin films were prepared by sol-gel method using spin-coating technique on glass substrates. The influences of nickel on ZnO thin films are characterized by Powder X-ray diffraction study. Pure and Ni added thin films are hexagonal wurtzite structure without any secondary phase in c-axis orientation. The SEM images of thin films show uniform sphere like particles covered completely on glass substrates. All the films exhibit transmittance of 85-95% in the visible range up to 800nm and cut-off wavelength observed at 394 nm corresponding to the fundamental absorption of ZnO. The photoluminescence property for pure and Ni added ZnO thin films has been studied and results are presented in detail.

  18. Effect of calcination time on NiAl-Al2O3 using gel combustion synthesis method

    NASA Astrophysics Data System (ADS)

    Afandi, N. F.; Manap, A.; Yusof, S. N. A.; Salim, M. A.; Azim, M. Al.; Othman, S. Z.; Pauzi, N. I. M.; Omar, Nooririnah; Misran, H.

    2015-07-01

    This study was conducted in order to investigate the effect of calcination time on phase and microstructural characteristics of intermetallic matric composite (IMC), NiAl-Al2O3 powder. This powder was synthesized using gel combustion method with octyl alcohol as fuel. Upon completion of the combustion process, the loose powder was calcined at 1050°C for 1, 2 and 4 hours and characterized using XRD, FESEM and TEM. The crystallite size was calculated to be in the range of 29-30 nm. It was found that NiAl-Al2O3 exhibits high crystalline structure after calcination for 4 hours. Furthermore, longer calcination time also cause growth of the particle size. Findings indicate that high crystalline nanostructured NiAl-Al2O3 powder consisting of submicron particles can be successfully produced using gel combustion synthesis with longer calcination time.

  19. Investigation of Thermal Properties of Ni-Coated Graphene Nanoribbons Based on Molecular Dynamics Methods

    NASA Astrophysics Data System (ADS)

    Zhu, Fulong; Kan, Yan; Tang, Kai; Liu, Sheng

    2017-08-01

    The thermal properties of graphene and Ni-coated graphene have been investigated using non-equilibrium molecular dynamics simulations. The results showed that the thermal conductivity of Ni-coated graphene was lower than that of graphene. More excited low-frequency phonons resulted in this decrease. The thermal conductivity of single-layer Ni-coated graphene was 70% of that of graphene, and the thermal conductivity of double-layer Ni-coated graphene was 56% of that of graphene at room temperature. The strong dependence of size on the thermal conductivity of graphene and Ni-coated graphene is discussed in this work. The thermal conductivity of Ni-coated graphene increased with length, but the trend was less pronounced than that of the thermal conductivity of graphene. Because of boundary scattering, the thermal conductivity of Ni-coated graphene increased with increasing width. The temperature effect indicated that the thermal conductivity decreased with increasing temperature from 200 K to 700 K.

  20. Crystal growth by Bridgman and Czochralski method of the ferromagnetic quantum critical material YbNi4P2

    NASA Astrophysics Data System (ADS)

    Kliemt, K.; Krellner, C.

    2016-09-01

    The tetragonal YbNi4P2 is one of the rare examples of compounds that allow the investigation of a ferromagnetic quantum critical point. We report in detail on two different methods which have been used to grow YbNi4P2 single crystals from a self-flux. The first, a modified Bridgman method, using a closed crucible system yields needle-shaped single crystals oriented along the [001]-direction. The second method, the Czochralski growth from a levitating melt, yields large single crystals which can be cut in any desired orientation. With this crucible-free method, samples without flux inclusions and a resistivity ratio at 1.8 K of RR1.8K = 17 have been grown.

  1. High Work Output Ni-Ti-Pt High Temperature Shape Memory Alloys and Associated Processing Methods

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D. (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Garg, Anita (Inventor)

    2009-01-01

    According to the invention, compositions of Ni-Ti-Pt high temperature, high force, shape memory alloys are disclosed that have transition temperatures above 100 C.; have narrow hysteresis; and produce a high specific work output.

  2. Electrochemical methods to detect susceptibility of Ni-Cr-Mo-W alloy 22 to intergranular corrosion

    NASA Astrophysics Data System (ADS)

    Gorhe, D. D.; Raja, K. S.; Namjoshi, S. A.; Radmilovic, Velimir; Tolly, Alfredo; Jones, D. A.

    2005-05-01

    Alloy 22 (UNS N06022), a Ni-Cr-Mo-W based alloy, is a candidate material for the outer wall of nuclear waste package (NWP) containers. Even though the alloy is highly stable at low temperatures, it could undergo microstructural changes during processing such as welding and stress relieving. Formation of topologically close-packed (TCP) phases such as μ, P, σ, etc. and Cr-rich carbides could make the material susceptible to localized corrosion. Hence, it is important to correlate the microstructural changes with the corrosion resistance of the alloy by nondestructive and rapid electrochemical tests. In this investigation, different electrochemical test solutions were used to quantify the microstructural changes associated with aging and welding of the wrought alloy 22. The results of double-loop (DL) electrochemical potentiodynamic reactivation (EPR) tests in 1 M H2SO4+0.5 M NaCl+0.01 M KSCN solution indicated Cr depletion during initial stages of aging of wrought alloy 22. Results of EPR tests in 2 M HCl+0.01 M KSCN solution at 60 °C correlated well with the Mo depletion that occurred near TCP phases formed during aging of both weld and wrought alloy 22 materials. The EPR test results were compared with standard chemical weight loss measurements specified by ASTM standard G-28 methods A and B.

  3. Method for Fabricating Miniaturized NiTi Self-Expandable Thin Film Devices with Increased Radiopacity

    NASA Astrophysics Data System (ADS)

    Bechtold, Christoph; Lima de Miranda, Rodrigo; Chluba, Christoph; Zamponi, Christiane; Quandt, Eckhard

    2016-12-01

    Nitinol is the material of choice for many medical applications, in particular for minimally invasive implants due to its superelasticity and biocompatibility. However, NiTi has limited radiopacity which complicates positioning in the body. A common strategy to increase the radiopacity of NiTi devices is the addition of radiopaque markers by micro-riveting or micro-welding. The recent trend of miniaturizing medical devices, however, reduces their radiopacity further, and makes the addition of radiopaque markers to these miniaturized devices difficult. NiTi thin film technology has great potential to overcome such limitations and to fabricate new generations of miniaturized, self-expandable NiTi medical devices with additional functionalities, such as structured multilayer devices with increased radiopacity. For this purpose, we have produced superelastic thin film NiTi samples covered locally with Tantalum structures of different thickness and different shape. These multilayer devices were characterized regarding their mechanical and corrosion properties as well as their X-ray visibility. The superelastic behavior of the underlying NiTi layer is impeded by the Ta layer, and shows therefore a dependence on the Tantalum patterning geometry and thickness. No delamination was observed after mechanical and corrosion tests. The multilayers reveal excellent corrosion resistance, as well as a significant increase in radiopacity.

  4. Study of the structure and interface of NiTi SMA/FC composite films prepared by the sol-gel method

    SciTech Connect

    Liu, Q.S. Liu, Y.F.; Ma, X.; Han, X.

    2008-02-15

    Ferroelectric ceramic (FC) films were prepared on a NiTi shape memory alloy (NiTi SMA) substrate by the sol-gel method. The effect of the heat treatment temperature on the crystallization of both the NiTi SMA and ferroelectric ceramic is discussed. The heterostructure of the interface was characterized by scanning electron microscopy and X-ray diffraction. The results indicate that aging reactions in the NiTi SMA substrate were restricted by the presence of the ceramic film. Also, the transitional TiO{sub 2} layer produced in-situ by the oxidation of the surface of the NiTi SMA substrate improves the adhesion between the ceramic film and NiTi SMA.

  5. A facile method to synthesize boron-doped Ni/Fe alloy nano-chains as electrocatalyst for water oxidation

    NASA Astrophysics Data System (ADS)

    Yang, Yisu; Zhuang, Linzhou; Lin, Rijia; Li, Mengran; Xu, Xiaoyong; Rufford, Thomas E.; Zhu, Zhonghua

    2017-05-01

    We report a novel magnetic field assisted chemical reduction method for the synthesis of boron-doped Ni/Fe nano-chains as promising catalysts for the oxygen evolution reaction (OER). The boron-doped Ni/Fe nano-chains were synthesised in a one step process at room temperature using NaBH4 as a reducing agent. The addition of boron reduced the magnetic moment of the intermediate synthesis products and produced nano-chains with a high specific surface area of 73.4 m2 g-1. The boron-doped Ni/Fe nano-chains exhibited catalytic performance superior to state-of-the-art Ba0.5Sr0.5Co0.8Fe0.2O3-δ perovskite and RuO2 noble metal oxide catalysts. The mass normalized activity of the boron-doped Ni/Fe nano-chains measured at an overpotential of 0.35 V was 64.0 A g-1, with a Tafel slope of only 40 mV dec-1. The excellent performance of the boron-doped Ni/Fe nano-chains can be attributed to the uniform elemental distribution and highly amorphous structure of the B-doped nano-chains. These results provide new insights into the effect of doping transition-metal based OER catalysts with non-metallic elements. The study demonstrates a facile approach to prepare transition metal nano-chains using magnetic field assisted chemical reduction method as cheap and highly active catalysts for electrochemical water oxidation.

  6. Influence of Sn on the magnetic ordering of Ni-Sn alloy synthesized using chemical reduction method

    NASA Astrophysics Data System (ADS)

    Dhanapal, K.; Narayanan, V.; Stephen, A.

    2016-05-01

    The Ni-Sn alloy was synthesized using borohydride assisted chemical reduction method. The composition of the synthesized alloy was determined using atomic absorption spectroscopy which revealed that the observed composition of Sn is high when compared to the initial composition. The ultrafine particles are clearly observed from field emission scanning electron microscope for all the sample. The X-ray diffraction measurement confirmed that the as-synthesized samples are of amorphous like nature while the samples annealed at 773 K showed crystalline nature. The Fourier transform infrared spectroscopy confirmed metallic bond stretching in the alloy samples. The crystallization and phase transition temperature was observed from differential scanning calorimetry. The shift in the crystallization temperature of Ni with increasing percentage of Sn was observed. The vibrating sample magnetometer was employed to understand the magnetic behavior of the Ni-Sn alloy. As-synthesized alloy samples showed paramagnetic nature while the annealed ones exhibit the soft ferromagnetic, antiferromagnetic and paramagnetic nature. The saturation magnetization value and magnetic ordering in the Ni-Sn alloys depend on the percentage of Sn present in the alloy.

  7. Exploring possible reaction pathways for the o-atom transfer reactions to unsaturated substrates catalyzed by a [Ni-NO2 ] ↔ [Ni-NO] redox couple using DFT methods.

    PubMed

    Tsipis, Athanassios C

    2017-07-15

    The (nitro)(N-methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO2 )(S2 CNHMe)(PMe3 )] complex catalyses efficiently the O-atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO2 )(S2 CNHMe)(PMe3 )] ↔ Ni(NO2 )(S2 CNHMe)(PMe3 ) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five-member metallacycle intermediate, via a [3 + 2] cyclo-addition reaction of HC≡CH to the Ni-N = O moiety of the Ni(NO2 )(S2 CNHMe)(PMe3 )] complex, followed by a β H-atom migration toward the Cα carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( κN1-NO2 )(S2 CNHMe)(PMe3 )] ⇌ [Ni( κO,O2-ONO)(S2 CNHMe)(PMe3 )] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Ni(2+) doped glass ceramic fiber fabricated by melt-in-tube method and successive heat treatment.

    PubMed

    Fang, Zaijin; Zheng, Shupei; Peng, Wencai; Zhang, Hang; Ma, Zhijun; Dong, Guoping; Zhou, Shifeng; Chen, Danping; Qiu, Jianrong

    2015-11-02

    Glass ceramic fibers containing Ni(2+) doped LiGa(5)O(8) nanocrystals were fabricated by a melt-in-tube method and successive heat treatment. Fiber precursors were prepared by drawing at high temperature where fiber core glass was melted while fiber clad glass was softened. After heat treatment, LiGa(5)O(8) nanocrystals were precipitated in the fiber core. Excited by 980 nm laser, efficient broadband near-infrared emission was observed in the glass ceramic fiber compared to that of precursor fiber. The melt-in-tube method can realize controllable crystallization and is suitable for fabrication of novel glass ceramic fibers. The Ni(2+)-doped glass ceramic fiber is promising for broadband optical amplification.

  9. The halogen effect for Ni-base alloys - A new method for increasing the oxidation protection at high temperatures

    NASA Astrophysics Data System (ADS)

    Zschau, Hans-Eberhard; Renusch, Daniel; Masset, Patrick J.; Schütze, Michael

    2009-05-01

    A new method for oxidation protection of Ni-base alloys is presented. The method is based on the halogen effect. Thermodynamic calculations show the preferred formation of gaseous Al-halogenides within a certain region of fluorine partial pressures. Ion implantation has been chosen for fluorine treatment. The implantation parameters are defined by using the T-DYN simulation software. Based on these results fluorine implantations of the Ni-base alloy IN 738 are performed to meet the required fluorine content near the surface. The fluorine depth profiles are analyzed by using the PIGE-technique. After oxidation at 1050 °C a dense protecting external alumina scale is formed on the surface.

  10. Iron and Fe-Ni alloy coatings containing ɛ-Fe produced by non-stationary deposition method

    NASA Astrophysics Data System (ADS)

    Smirnova, Natalya; Zhikhareva, Irina; Schmidt, Vadim; Vorobyev, Oleg

    2016-09-01

    A novel material, an electrolytic coating of iron and Fe-Ni alloy containing ɛ-Fe hexagonal close-packed phase (HCP) was obtained using the method of high-frequency alternating current at atmospheric pressure. This transition occurs according to the orientational mechanism by removing weak extreme iron atoms in the crystal lattice of α-Fe due to anodic dissolution and action of the electromagnetic waves loosening the valence bonds.

  11. Yield Strengths of Biaxially Textured Metallic Substrates (Ni and Its Alloys) Determined Using a Simplified Test Method (Postprint)

    DTIC Science & Technology

    2007-09-14

    confirm the chemical compositions. A retired test method for tensile strength and Youngs modulus for high -modulus single-filament materials (ASTM D3379... strengths . Testing very high YS substrates may require reducing the sample width so that the load required for the deformation will be reduced. As such, 2...AFRL-RZ-WP-TP-2012-0139 YIELD STRENGTHS OF BIAXIALLY TEXTURED METALLIC SUBSTRATES (Ni AND ITS ALLOYS) DETERMINED USING A SIMPLIFIED TEST

  12. NiS/ZnS multilayer thinfilm prepared by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Yuvaloshini, J.; Ravi, G.; Shanmugavadivu, Ra.

    2013-06-01

    NiS/ZnS multilayer thin films were prepared by Chemical Bath Deposition (CBD) technique by successive coatings of nickel, zinc and sulphur. The X-ray diffraction was used to obtain structural characterization for the multilayer thinfilms, the crystalline size of 50 nm. The Scanning Electron Microscope techniques were employed to study the internal structure and indentified as of hexagonal structure. An EDAX spectrum confirms the compositional analysis of nickel, zinc and sulphur in nominal composition. The photoluminescence behaviour of NiS/ZnS multilayered system consists in the superposition independent photoluminescence emission in blue shift.

  13. Size dependence of the magnetic properties of Ni nanoparticles prepared by thermal decomposition method

    PubMed Central

    2013-01-01

    By means of thermal decomposition, we prepared single-phase spherical Ni nanoparticles (23 to 114 nm in diameter) that are face-centered cubic in structure. The magnetic properties of the Ni nanoparticles were experimentally as well as theoretically investigated as a function of particle size. By means of thermogravimetric/differential thermal analysis, the Curie temperature TC of the 23-, 45-, 80-, and 114-nm Ni particles was found to be 335°C, 346°C, 351°C, and 354°C, respectively. Based on the size-and-shape dependence model of cohesive energy, a theoretical model is proposed to explain the size dependence of TC. The measurement of magnetic hysteresis loop reveals that the saturation magnetization MS and remanent magnetization increase and the coercivity decreases monotonously with increasing particle size, indicating a distinct size effect. By adopting a simplified theoretical model, we obtained MS values that are in good agreement with the experimental ones. Furthermore, with increase of surface-to-volume ratio of Ni nanoparticles due to decrease of particle size, there is increase of the percentage of magnetically inactive layer. PMID:24164907

  14. Influences of synthesis methods and modifier addition on the properties of Ni-based catalysts supported on reticulated ceramic foams

    NASA Astrophysics Data System (ADS)

    Nikolić, Vesna; Kamberović, Željko; Anđić, Zoran; Korać, Marija; Sokić, Miroslav; Maksimović, Vesna

    2014-08-01

    A method of synthesizing Ni-based catalysts supported on α-Al2O3-based foams was developed. The foams were impregnated with aqueous solutions of metal chlorides under an air atmosphere using an aerosol route. Separate procedures involved calcination to form oxides and drying to obtain chlorides on the foam surface. The synthesized samples were subsequently reduced with hydrogen. With respect to the Ni/Al2O3 catalysts, the chloride reduction route enabled the formation of a Ni coating without agglomerates or cracks. Further research included catalyst modification by the addition of Pd, Cu, and Fe. The influences of the additives on the degree of reduction and on the low-temperature reduction effectiveness (533 and 633 K) were examined and compared for the catalysts obtained from oxides and chlorides. Greater degrees of reduction were achieved with chlorides, whereas Pd was the most effective modifier among those investigated. The reduction process was nearly complete at 533 K in the sample that contained 0.1wt% Pd. A lower reduction temperature was utilized, and the calcination step was avoided, which may enhance the economical and technological aspects of the developed catalyst production method.

  15. Fe-based soft magnetic composites coated with NiZn ferrite prepared by a co-precipitation method

    NASA Astrophysics Data System (ADS)

    Peng, Yuandong; Yi, Yi; Li, Liya; Ai, Hengyu; Wang, Xiaoxu; Chen, Lulu

    2017-04-01

    Fe powder was coated with NiZn ferrite by a co-precipitation method using chlorate as the raw material. Soft magnetic composites were manufactured via compaction and heat treatment of the coated powder. The coated powder and heat treated powder were analysed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy. Their magnetic properties were determined using a Quantum Design-Vibrating Sample Magnetometer (QD-VSM). The composites were analysed with SEM and EDS. The permeability and magnetic loss of the composites were measured with a B-H curve analyzer. The results show that, using the co-precipitation method, the raw precipitate was successfully prepared and coated the pure Fe powder and turned into spinel NiZn ferrite treated at 600 ℃ for 1 h. After heat treatment at 500 ℃ under air, the insulation coating layer of soft magnetic composite (SMC) was not destroyed and containing Fe, Ni, Zn and oxygen. The permeabilities of the SMC are stable at edge of the 2-200 kHz frequency range and the total loss was lower.

  16. Quantitative Characterization of the Toxicities of Cd-Ni and Cd-Cr Binary Mixtures Using Combination Index Method

    PubMed Central

    Zheng, Minyi; Qin, Meng; Zhang, Xin; Zeng, Honghu; Liang, Yanpeng

    2016-01-01

    Direct equipartition ray design was used to construct Cd-Ni and Cd-Cr binary mixtures. Microplate toxicity analysis was used to evaluate the toxicity of individual substance and the Cd-Ni and Cd-Cr mixtures on Chlorella pyrenoidosa and Selenastrum capricornutum. The interacting toxicity of the mixture was analyzed with concentration addition (CA) model. In addition, combination index method (CI) was proposed and used to quantitatively characterize the toxicity of the binary mixtures of Cd-Ni and Cd-Cr observed in experiment and find the degree of deviation from the predicted outcome of the CA model, that is, the intensity of interacting toxicity. Results indicate that most of the 20 binary mixtures exhibit enhancing and synergistic effect, and only Cd-Cr-R4 and Cd-Cr-R5 mixtures have relatively high antagonistic effects against C. pyrenoidosa. Based on confidence interval, CI can compare the intensities of interaction of the mixtures under varying levels of effect. The characterization methods are applicable for analyzing binary mixture with complex interaction. PMID:28044127

  17. Quantitative Characterization of the Toxicities of Cd-Ni and Cd-Cr Binary Mixtures Using Combination Index Method.

    PubMed

    Mo, Lingyun; Zheng, Minyi; Qin, Meng; Zhang, Xin; Liu, Jie; Qin, Litang; Zeng, Honghu; Liang, Yanpeng

    2016-01-01

    Direct equipartition ray design was used to construct Cd-Ni and Cd-Cr binary mixtures. Microplate toxicity analysis was used to evaluate the toxicity of individual substance and the Cd-Ni and Cd-Cr mixtures on Chlorella pyrenoidosa and Selenastrum capricornutum. The interacting toxicity of the mixture was analyzed with concentration addition (CA) model. In addition, combination index method (CI) was proposed and used to quantitatively characterize the toxicity of the binary mixtures of Cd-Ni and Cd-Cr observed in experiment and find the degree of deviation from the predicted outcome of the CA model, that is, the intensity of interacting toxicity. Results indicate that most of the 20 binary mixtures exhibit enhancing and synergistic effect, and only Cd-Cr-R4 and Cd-Cr-R5 mixtures have relatively high antagonistic effects against C. pyrenoidosa. Based on confidence interval, CI can compare the intensities of interaction of the mixtures under varying levels of effect. The characterization methods are applicable for analyzing binary mixture with complex interaction.

  18. A method to detect low-level 63Ni activity for estimating fast neutron fluence from the Hiroshima atomic bomb.

    PubMed

    Ito, Y; Shibata, T; Imamura, M; Shibata, S; Nogawa, N; Uwamino, Y; Shizuma, K

    1999-06-01

    The Hiroshima and Nagasaki atomic bombs resulted in the worst reported exposure of radiation to the human body. The data of survivors have provided the basis for the risk estimation for ionizing radiation, and thus are widely used as the basis of radiation safety. In this report we have studied a new method to detect the low-level 63Ni activity in copper samples in order to estimate the fast neutron fluence from the Hiroshima atomic bomb. Only 0.8 x 10(-3) Bq g(-1) of 63Ni is expected to be produced by the atomic bomb in a copper sample with the 63Cu(n, p)63Ni reaction at a distance of 500 m from the hypocenter. Our method has the required level of sensitivity for determination of the fast neutron fluence out to distances of at least 500 m, and perhaps as far as 1,000 m. We have already investigated and collected some bomb-irradiated copper samples for further study.

  19. Exchange bias effect in CoCr2O4/NiO system prepared by two-step method

    NASA Astrophysics Data System (ADS)

    Wang, L. G.; Zhu, C. M.; Chen, L.; Yuan, S. L.

    2017-02-01

    CoCr2O4/NiO has been successfully synthesized through two-step method. X-ray diffraction results present the coexistence of CoCr2O4 and NiO with pure formation. Micrographs measured with scanning electron microscope and transmission electron microscope display the homogeneous and dense morphology with two kinds of nanoparticles. Exchange bias effect is observed in the sample. The exchange bias field is about 872 Oe at 10 K. As measuring temperature increases, exchange bias effect is weakened with decreasing coercive field. In addition, exchange bias field and the shift of magnetization show the linear relationship with increasing cooling field. The exchange bias behavior can be attributed to the exchange coupling at the disordered interfaces in the sample.

  20. Preparation of nanocrystalline NiZnCu ferrite particles by sol-gel method and their magnetic properties

    NASA Astrophysics Data System (ADS)

    Yan, Shifeng; Geng, Jianxin; Yin, Li; Zhou, Enle

    2004-06-01

    Polyvinyl alcohol (PVA) was first used as chelating agent and metal nitrates as precursor of ferrite in the fabrication of nanocrystalline Ni 0.65Zn 0.35Cu 0.1Fe 1.9O 4 particles by the sol-gel method. The thermal decomposition process of dried gel was studied by thermogravimetry (TG), differential thermal analysis (DTA) and infrared spectra (IR). The structural and magnetic properties of resultant particles were investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and Mössbauer spectroscopy. The dependence of the decomposition of dried gel, the formation of spinel structured NiZnCu ferrite, the sizes of annealed particles, the saturation magnetization and coercivity of annealed particles on annealing temperature is presented.

  1. Hydrogen production via CO2 reforming of methane over ZrO2-Doped Ni/ZSM-5 nanostructured catalyst prepared by ultrasound assisted sequential impregnation method

    NASA Astrophysics Data System (ADS)

    Rahmani, Farhad; Haghighi, Mohammad; Vafaeian, Yaser; Estifaee, Pooya

    2014-12-01

    In our continuing effort to find the proper catalyst for CO2 reforming of methane, Ni(8%)/ZSM-5-ZrO2 with various zirconium loadings (0-15%) are synthesized via sonochemical method. All samples are characterized by XRD, FESEM, TEM, EDX, BET, FTIR and TPR-H2 techniques. The XRD results confirm existence of NiO, ZrO2 and ZSM-5 as crystalline phase in catalyst structure. FESEM images reveal small particle size of active metals and low numbers of agglomerations for Ni(8%)/ZrO2(5%)-ZSM-5. BET analysis shows that addition of ZrO2 to Ni/ZSM-5 decreases the surface area but Ni/ZrO2(5%)-ZSM-5 has the highest surface area. TEM analysis demonstrates high dispersion of Ni nano particles over the support. EDX depicts the best active metal dispersion for the catalyst with 5% zirconia loading. The TPR results prove that the metal-support interaction is enhanced by zirconia addition, indicating the better Ni dispersion. Apart from characterization, activity tests are performed and parameters such as effect of temperature, CO and H2 yields and H2/CO ratio are investigated. The results show that Ni(8%)/ZrO2(5%)-ZSM-5 has the best structural properties and the highest activity and stability in comparison with the other catalysts.

  2. Single crystal growth of Ga3Ni2 by the Czochralski method

    NASA Astrophysics Data System (ADS)

    Wencka, Magdalena; Pillaca, Mirtha; Gille, Peter

    2016-09-01

    Intermetallic compounds have proved to be interesting alternatives to heterogeneous catalysts prepared from pure noble metals or their alloys. As to study their intrinsic properties, to determine the crystalline structures of specific surfaces and finally to understand elementary processes of heterogeneous catalysis, single crystals of these intermetallics are needed. Inspired by the recent discovery of Ga-Ni catalysts for carbon dioxide reduction to methanol, we have grown for the first time cm3-size single crystals of trigonal Ga3Ni2. We report in detail on the synthesis and Czochralski growth from high-temperature solution using Ga as native solvent. Inclusion formation of Ga-rich fluid proved to be the most severe problem that was minimized by using an extremely low pulling rate down to 25 μm/h.

  3. A Zn-Ni coating with both high electrical conductivity and infrared emissivity prepared by hydrogen evolution method

    NASA Astrophysics Data System (ADS)

    Guo, Jiacheng; Guo, Xingwu; Xu, Wenbin; Zhang, Zhicheng; Dong, Jie; Peng, Liming; Ding, Wenjiang

    2017-04-01

    A Zn-Ni coating with both high electrical conductivity and infrared emissivity was prepared by hydrogen evolution method in order to satisfy the demand of thermal control in space. The maximum infrared emissivity of 0.91 was obtained, meanwhile the electrical resistivity is lower than 0.01 mΩ/cm. The infrared emissivity of the coating obtained from the experimental result is proportional to the projected area of pores per unit area in the coating. The addition of NH4SCN in the bath can obviously increase the projected area of pores per unit area in the coating and lead to the formation of NiO and ZnO compounds, which further increase the infrared emissivity of the coating. The porous hierarchical structure of Zn-Ni coating can further improve the infrared emissivity, and the infrared emissivity can be tuned by changing the projected area of pores in the coating. Based on the experimental results, a mathematical relationship between infrared emissivity and the projected area of pores per unit area is established. The bond strength and the mass of volatiles of the design of coatings satisfy the technical standard demanded by the satellites in space.

  4. Anomalous dielectric and AC conductivity behavior of the nanocrystalline Ni-Cu ferrite synthesized via combustion method

    SciTech Connect

    Madhu, B. J.; Rashmi, B. N.; Banu, Arshiya; Seema, G. A.; Shruthi, B.; Jayanna, H. S.

    2013-02-05

    Nanocrystalline Ni-Cu ferrites (Ni{sub 0.5}Cu{sub 0.5}Fe{sub 2}O{sub 4}) were prepared using solution combustion method. The structure of the samples were studied with the X-ray diffraction (XRD) using Cu-K{sub {alpha}} radiation. Frequency and temperature dependence of dielectric and a.c. conductivity studies have been undertaken on the Ni-Cu nanoferrites in the frequency region 100Hz-5MHz. The dielectric constant ({epsilon} Prime ) is found to decrease initially with the frequency and finally reaching a constant value at higher frequencies. Observed trends in the dielectric constant are ascribed to the Maxwell-Wagner type interfacial polarization, which is in agreement with the Koop'fs phenomenological theory. The a.c. conductivity ({sigma}{sub ac}) is found to increase with an increase in the frequency from room temperature up to 300 Degree-Sign C. However, at a temperature of 400 Degree-Sign C, the a.c. conductivity is found to decrease with an increase in the frequency exhibiting an abnormal behavior. The electrical conduction mechanism in the present nano nickel-copper ferrite is found to be in accordance with the electron hopping model.

  5. Structural and electrical properties of Cu doped NiFe2O4 nanoparticles prepared through modified citrate gel method

    NASA Astrophysics Data System (ADS)

    Batoo, Khalid Mujasam

    2011-12-01

    Nanoparticles of polycrystalline NiFe2-xCuxO4 (0.0≤x≤0.05) ferrites were prepared through the modified citrate-gel method. The samples were obtained as dried gel after the successful chemical reaction of their respective metal nitrate solutions in the midst of citric acid as catalyst. X-ray diffraction (XRD) and selective area electron diffraction (SAED) confirmed the single phase nature of all the samples with an average particle size of 19.8 (±1). Fourier transformation infrared spectroscopy (FTIR) shows the presence of two broad vibrational bands between 400 and 1000 cm-1 corresponding to the tetrahedral and the octahedral sites. The variation of dielectric properties (ɛ‧, ɛ″, tan δ) and ac conductivity (σac), with frequency reveals that the dispersion is due to the Maxwell-Wagner type of interfacial polarization in general and due to hopping of charges between Fe+2 and Fe+3 as well as between Ni+2 and Ni+3 ions at B-sites. The complex impedance spectroscopy has been used to study the effect of grain and grain boundary on the electrical properties of all the ferrite nanoparticles.

  6. Two-Solvent Method Synthesis of NiO/ZnO Nanoparticles Embedded in Mesoporous SBA-15: Photocatalytic Properties Study

    NASA Astrophysics Data System (ADS)

    Dai, Peng; Yan, Tao-tao; Yu, Xin-xin; Bai, Zhi-man; Wu, Ming-zai

    2016-04-01

    Different loadings of NiO/ZnO nanoparticles embedded in mesoporous silica (SBA-15) were prepared via a two-solvent method with the ordered hexagonal mesoporous structure of SBA-15 kept. X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, diffusive reflective UV-vis spectroscopy, and N2 adsorption porosimetry were employed to characterize the nanocomposites. The results indicate that the ordered hexagonal mesoporous structure of SBA-15 is kept and the absorption band edges of the nanocomposites shift into the ultraviolet light regime. The photocatalytic activity of our samples for degradation of methylene orange was investigated under UV light irradiation, and the results show that the nanocomposites have higher photodegradation ability toward methylene orange than commercial pure P-25. The photocatalytic activity of the nanocomposites was found to be dependent on both the adsorption ability of the SBA-15 and the photocatalytic activity of NiO-ZnO nanoparticles encapsulated in SBA-15. In addition, there is an optimal loading of NiO-ZnO nanoparticles. Too high or low loading will lower the photodegradation ability of the nanocomposites.

  7. Anomalous dielectric and AC conductivity behavior of the nanocrystalline Ni-Cu ferrite synthesized via combustion method

    NASA Astrophysics Data System (ADS)

    Madhu, B. J.; Rashmi, B. N.; Banu, Arshiya; Seema, G. A.; Shruthi, B.; Jayanna, H. S.

    2013-02-01

    Nanocrystalline Ni-Cu ferrites (Ni0.5Cu0.5Fe2O4) were prepared using solution combustion method. The structure of the samples were studied with the X-ray diffraction (XRD) using Cu-Kα radiation. Frequency and temperature dependence of dielectric and a.c. conductivity studies have been undertaken on the Ni-Cu nanoferrites in the frequency region 100Hz-5MHz. The dielectric constant (ɛ') is found to decrease initially with the frequency and finally reaching a constant value at higher frequencies. Observed trends in the dielectric constant are ascribed to the Maxwell-Wagner type interfacial polarization, which is in agreement with the Koop'fs phenomenological theory. The a.c. conductivity (σac) is found to increase with an increase in the frequency from room temperature up to 300 °C. However, at a temperature of 400 °C, the a.c. conductivity is found to decrease with an increase in the frequency exhibiting an abnormal behavior. The electrical conduction mechanism in the present nano nickel-copper ferrite is found to be in accordance with the electron hopping model.

  8. Magnetic configurations of Ni-Cu alloy nanowires obtained by the template method

    NASA Astrophysics Data System (ADS)

    Matei, Elena; Enculescu, Ionut; Toimil-Molares, Maria Eugenia; Leca, Aurel; Ghica, Corneliu; Kuncser, Victor

    2013-08-01

    High aspect ratio nanowires of Ni-Cu alloys have been synthesized by potentiostatic electrochemical deposition in etched ion-track membranes. The nickel-to-copper ratio in the nanowires was controlled via the deposition potential and electrochemical bath composition. We present a detailed study of nanowire properties including morphology, composition, and magnetic behavior. We report the magnetic configurations measured as function of the nanowire composition and discuss domain formation, anisotropy aspects, and local easy axis distributions.

  9. Potentiodynamic studies of Ni-P-TiO2 nano-composited coating on the mild steel deposited by electroless plating method

    NASA Astrophysics Data System (ADS)

    Uttam, Vibha; Duchaniya, R. K.

    2016-05-01

    Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO2 on mild steel are deposited by varying volume of TiO2 nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent, lactic acid as a complexing agents and TiO2 nano powder. Electroless Ni-P-TiO2 coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO2 nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO2 nanocomposited coating.

  10. Potentiodynamic studies of Ni-P-TiO{sub 2} nano-composited coating on the mild steel deposited by electroless plating method

    SciTech Connect

    Uttam, Vibha Duchaniya, R. K.

    2016-05-06

    Now a days, corrosion studies are important for reducing the wastage of metals. The importance of corrosion studies is two folds i.e. first is economic, including the reduction of material losses resulting from the wasting away or sudden failure of materials and second is conservation Electroless process is an autocatalytic reduction method in which metallic ions are reduced in the solution. Nanocomposite coatings of Ni-P-TiO{sub 2} on mild steel are deposited by varying volume of TiO{sub 2} nano-powder by electroless method from Ni-P plating bath containing Nickel Sulphate as a source of nickel ions, sodium hypophosphite as the reducing agent, lactic acid as a complexing agents and TiO{sub 2} nano powder. Electroless Ni-P-TiO{sub 2} coating have been widely used in the chemical process industries, mechanical industries, electronic industries and chloroalkali industries due to their excellent corrosion with mechanical properties. In the present work, deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coatings were done on the mild steel and corrosion properties were studied with Potentio-dynamic polarization measurements method in 3.5 wt% sodium chloride solution. It showed in the experiments that Ni-P-TiO{sub 2} nanocomposited coating has better corrosion resistance as comparedthan Ni-P alloy coating. Morphological studies were done by field emission scanning electron microscopy (FESEM), energy–dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). These studies confirmed the deposition of Ni-P alloy coating and Ni-P-TiO{sub 2} nanocomposited coating.

  11. Characterization of YbNi4(P1-xAsx)2, x = 0, 0.2 single crystals grown by Czochralski method

    NASA Astrophysics Data System (ADS)

    Kliemt, K.; Krellner, C.

    2017-04-01

    We have investigated large single crystals of YbNi4P2 that were grown from a levitating melt by the Czochralski method. The new samples facilitate the determination of the absolute values of the electrical resistivity. Phase pure polycrystalline samples of the non-magnetic reference LuNi4P2 were prepared and the electrical resistivity was measured. Furthermore we have grown a single crystal of the As substituted compound YbNi4(P1-xAsx)2, x = 0.2 and investigated the homogenity of the As distribution.

  12. Comparative study of embedded-atom methods applied to the reactivity in the Ni-Al system

    NASA Astrophysics Data System (ADS)

    Turlo, V.; Baras, F.; Politano, O.

    2017-09-01

    Structural, thermodynamic, atomic and thermal transport properties of solid and liquid phases of the Ni-Al system were studied by means of MD simulations using three embedded-atom method (EAM) potentials developed by Mishin and colleagues (Mishin et al 2002 Phys. Rev. B 65 224114; Mishin 2004 Acta Mater. 52 145167; Purja Pun and Mishin 2009 Phil. Mag. 89 32453267). The extracted properties (lattice parameter, enthalpy, heat capacity, mass diffusivity and thermal conductivity) were compared with experimental data. The limitations of EAM potentials for studying different aspects of reactivity were assessed for each potential separately.

  13. A new method for fracture toughness determination of graded (Pt,Ni)Al bond coats by microbeam bend tests

    NASA Astrophysics Data System (ADS)

    Jaya B, Nagamani; Jayaram, Vikram; Biswas, Sanjay Kumar

    2012-09-01

    A novel method is proposed for fracture toughness determination of graded microstructurally complex (Pt,Ni)Al bond coats using edge-notched doubly clamped beams subjected to bending. Micron-scale beams are machined using the focused ion beam and loaded in bending under a nanoindenter. Failure loads gathered from the pop-ins in the load-displacement curves combined with XFEM analysis are used to calculate K c at individual zones, free from substrate effects. The testing technique and sources of errors in measurement are described and possible micromechanisms of fracture in such heterogeneous coatings discussed.

  14. Synthesis of NiO nanoparticles by a simple chemical method

    SciTech Connect

    Chatterjee, Soumi; Maiti, R. P.; Chakravorty, Dipankar; Saha, S. K.

    2016-05-23

    NiO nanoparticles with diameters in the range 15-30 nm have been synthesized using the surfactant P123 in a liquid medium. The particles were characterized by X-ray diffraction and transmission electron microscope. The particle exhibit photoluminescence in the UV range with maximum intensity at 315 nm. due to optical band gap of the material. DC electrical resistivity was found to have an activation energy 0.23 eV. These materials are expected to find applications as electrodes in lithium ion batteries as also in fabrication of solar cells.

  15. Magnetic properties of Ni and Cu-Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Ganga, B. G.; Santhosh, P. N.; Thomas, P. John

    2012-06-01

    Ni and Cu-Ni nanoparticles were prepared by solution phase method and crystal phase was identified by XRD. SEM and EDX were used to analyze morphology and elemental composition of nanoparticles. Magnetic measurements indicate that Ni nanoparticles are superparamagnetic at room temperature and blocking temperature is around 103 K. Ferromagnetism is observed in the case of Cu-Ni nanoparticles with decrease in magnetization compared to Ni nanoparticles.

  16. SmBa2Cu3O7-δ superconducting layer prepared on NiO buffer layer through fluorine-free chemical method

    NASA Astrophysics Data System (ADS)

    Zhang, Hong; Zhao, Yong; Zhang, Yong; Pan, Min; Lei, Ming

    2015-09-01

    With energy shortage becoming increasingly severe, the application of high-temperature superconducting material is a considerable prospects, where economic, efficient and energy-saving preparation technology becoming the key factors for the large-scale applications of REBa2Cu3O7-δ (REBCO) superconducting coated conductors. Currently, non-vacuum chemical solution deposition technique is an important way to reduce the cost of preparation of coated conductors. However, a randomly oriented NiO growth is an important problem for the non-vacuum chemical preparation of superconducting coated conductor. A simple and valid method is to prepare textured NiO film on the bare nickel (Ni) tape. In this paper, NiO films with c-axis texture were prepared in air and in argon respectively by the surface oxidation epitaxial method. We obtained the smooth and densification NiO films. The layer of SmBa2Cu3O7-δ was fabricated on the NiO film via a fluorine-free chemistry method. The purpose of this paper is to provide a potential value of non-vacuum chemical solution deposition technique for preparation of REBCO superconducting coated conductors.

  17. Simultaneous determination of Ca, Cu, Ni, Zn and Cd binding strengths with fulvic acid fractions by Schubert's method

    USGS Publications Warehouse

    Brown, G.K.; MacCarthy, P.; Leenheer, J.A.

    1999-01-01

    The equilibrium binding of Ca2+, Ni2+, Cd2+, Cu2+ and Zn2+ with unfractionated Suwannee river fulvic acid (SRFA) and an enhanced metal binding subfraction of SRFA was measured using Schubert's ion-exchange method at pH 6.0 and at an ionic strength (??) of 0.1 (NaNO3). The fractionation and subfractionation were directed towards obtaining an isolate with an elevated metal binding capacity or binding strength as estimated by Cu2+ potentiometry (ISE). Fractions were obtained by stepwise eluting an XAD-8 column loaded with SRFA with water eluents of pH 1.0 to pH 12.0. Subfractions were obtained by loading the fraction eluted from XAD-8 at pH 5.0 onto a silica gel column and eluting with solvents of increasing polarity. Schuberts ion exchange method was rigorously tested by measuring simultaneously the conditional stability constants (K) of citric acid complexed with the five metals at pH 3.5 and 6.0. The logK of SRFA with Ca2+, Ni2+, Cd2+, Cu2+ and Zn2+ determined simultaneously at pH 6.0 follow the sequence of Cu2+>Cd2+>Ni2+>Zn2+>Ca2+ while all logK values increased for the enhanced metal binding subfraction and followed a different sequence of Cu2+>Cd2+>Ca2+>Ni2+>Zn2+. Both fulvic acid samples and citric acid exhibited a 1:1 metal to ligand stochiometry under the relatively low metal loading conditions used here. Quantitative 13C nuclear magnetic resonance spectroscopy showed increases in aromaticity and ketone content and decreases in aliphatic carbon for the elevated metal binding fraction while the carboxyl carbon, and elemental nitrogen, phosphorus, and sulfur content did not change. The more polar, elevated metal binding fraction did show a significant increase in molecular weight over the unfractionated SRFA. Copyright (C) 1999 Elsevier Science B.V.

  18. Clustering of metal atoms in organic media. 9. High-activity Ni/MgO catalysts prepared by metal vapor methods. Surface area and particle size effects

    SciTech Connect

    Matsuo, K.; Klabunde, K.J.

    1982-02-01

    A metal vapor method was employed to prepare highly dispersed Ni metal catalysts (solvated metal atom dispersed = SMAD catalyst) supported on MgO. Compared with conventional Ni/MgO compositions, the SMAD catalysts showed much greater activities for all reactions studied (hydrogenolysis of methylcyclopentane, MCP; hydrogenation/hydrogenolysis of toluene, TOL; methanation of carbon monoxide, CO; dehydration of isopropyl alcohol, IPA). These high activities for the SMAD catalysts are attributed to the high surface area of Ni on MgO and the high percentage of this Ni in a zero-valent state (reduction degree). Conventional methods for preparing Ni/MgO catalysts did not yield nearly such favorable surface areas or reduction degrees. Nickel particle size effects were observed during hydrogenolysis studies of MCP and hydrogenation studies of TOL. These phenomena are explained by assuming the size of an active Ni particle to be largest for hydrogenolysis of MCP > hydrogenation of TOL > methanation of CO approx. = dehydrogenation of IPA. 8 figures, 2 tables.

  19. A comparative study of alumina-supported Ni catalysts prepared by photodeposition and impregnation methods on the catalytic ozonation of 2,4-dichlorophenoxyacetic acid

    NASA Astrophysics Data System (ADS)

    Rodríguez, Julia L.; Valenzuela, Miguel A.; Tiznado, Hugo; Poznyak, Tatiana; Chairez, Isaac; Magallanes, Diana

    2017-02-01

    The heterogeneous catalytic ozonation on unsupported and supported oxides has been successfully tested for the removal of several refractory compounds in aqueous solution. In this work, alumina-supported nickel catalysts prepared by photodeposition and impregnation methods were compared in the catalytic ozonation of 2,4-dichlorophenoxyacetic acid (2,4-D). The catalysts were characterized by high-resolution electron microscopy and X-ray photoelectron spectroscopy. The photochemical decomposition of Ni acetylacetonate to produce Ni(OH)2, NiO, and traces of Ni° deposited on alumina was achieved in the presence of benzophenone as a sensitizer. A similar surface composition was found with the impregnated catalyst after its reduction with hydrogen at 500 °C and exposed to ambient air. Results indicated a higher initial activity and maleic acid (byproduct) concentration with the photodeposited catalyst (1 wt% Ni) compared to the impregnated catalyst (3 wt% Ni). These findings suggest the use of the photodeposition method as a simple and reliable procedure for the preparation of supported metal oxide/metal catalysts under mild operating conditions.

  20. Element specific electronic states and spin-flip-like behavior of Ce in (Ce0.2Gd0.8)Ni composed of heavy fermion CeNi and ferri-magnet GdNi through XMCD method

    NASA Astrophysics Data System (ADS)

    Yano, K.; Okane, T.; Takeda, Y.; Yamagami, H.; Fujimori, A.; Nishimura, K.; Sato, K.

    2017-06-01

    The electronic states of the three constituent elements in the crystal mixed system between CeNi and GdNi, Ce0.2Gd0.8Ni, were investigated by soft X-ray magnetic circular dichroism (XMCD) with the aid of sum rule analysis. Not only Gd 4f but also Ni 3d and Ce 4f electrons were magnetic and both magnetic moments of Ni and Ce were coupled anti-parallel to the direction of the Gd magnetic moment, which is in accordance with the general rule in rare earth (RE)-transition metal (TM) systems. After saturation, Ce magnetic moment decreased over 2 T and this behavior was explained by a spin-flip behavior of the Ce magnetic moment with keeping their electronic states unchanged. Furthermore, the magnetic field dependence on a part of the XAS at Ce M4,5 absorption edges, which had been observed in the Gd=0.5 disappeared in the present sample in Gd-rich content of 0.8 and this could be explained by the increase of molecular field from Gd on Ce 4f electrons. In addition, sum rule analysis has revealed that the magnetic moments of Gd 4 f and Ni 3d electrons could retain small values of angular (orbital) magnetic moments μL and this was explained consistently.

  1. Influence of the ARC patterning method and annealing on the contact adhesion of Ni/Cu-plated solar cells

    NASA Astrophysics Data System (ADS)

    Baik, Jong Wook; Lee, Sang Hee; Lee, Doo Won; Lee, Soo Hong

    2016-05-01

    Ni/Cu two-step plating is a promising metallization technique because low contact resistance and improved contact adhesion can be achieved after the Ni annealing process. Also, narrow fingers, which are required for high-efficiency solar cells, can be formed by plating. However, the reliability of contact adhesion is still considered one obstacle to industrializing solar cells with plated metal contacts. In this experiment, the influence of ARC opening methods on plated contact adhesion was investigated because the roughnesses of the Si surfaces produced by using pico-second laser ablation and photolithography may be different. Also, the annealing process was conducted before and after plating Cu/Ag metal stacks. The sequence of the annealing can be significant for efficient production because plating is a wet process while annealing is a dry process. The contact adhesion was measured by using a peel-off test. The test was conducted on a 1.5-mm-wide by a 60 ~ 70- mm-long bus bar area. A 3.2-N/mm adhesion force was recorded as a highest average value along the bus bar.

  2. Ni and Zn Substituted M-type Barium Hexaferrite Processed by Sol-Gel Auto Combustion Method

    NASA Astrophysics Data System (ADS)

    Widyastuti; Sasria, Nia; Marsha Alviani, A.; Dwi Febri R, M.; Vania Mitha, P.

    2017-07-01

    Barium hexaferrite (BaFe12O19) or BaM was synthesized by sol-gel auto combustion method with the new dopan elements, Ni and Zn, with mole fraction (0.2, 0.4, 0.6), pH (7, 9, 11) and sintering temperature (850, 950, 1050 °C) for 3 hours. Ni - Zn ions were substituted to Fe3+ ion of BaM in order to modify the magnetic properties such as magnetic saturation (Ms) and coercivity (Hc). Magnetic properties and microstructure were characterized by various instruments; XRD, SEM, FTIR, and VSM. It was obtained that the largest crystal size of BaM (588.049 nm) was found at X=0.6, pH 11 and sintering temperature of 850 °C. It was found that from the VSM graphs that magnetic saturation (Ms) has reached a maximum of 95 emu/g at X=0.6 pH 11, sintering temperature at 1050 °C and coercivity (Hc) at 0.13 T. Considering these properties, BaM was qualified as a candidate for stealth technology materials.

  3. Synthesis and characterization of ZnO and Ni doped ZnO nanorods by thermal decomposition method for spintronics application

    SciTech Connect

    Saravanan, R.; Santhi, Kalavathy; Sivakumar, N.; Narayanan, V.; Stephen, A.

    2012-05-15

    Zinc oxide nanorods and diluted magnetic semiconducting Ni doped ZnO nanorods were prepared by thermal decomposition method. This method is simple and cost effective. The decomposition temperature of acetate and formation of oxide were determined by TGA before the actual synthesis process. The X-ray diffraction result indicates the single phase hexagonal structure of zinc oxide. The transmission electron microscopy and scanning electron microscopy images show rod like structure of ZnO and Ni doped ZnO samples with the diameter {approx} 35 nm and the length in few micrometers. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The Ni doped ZnO exhibits room temperature ferromagnetism. This diluted magnetic semiconducting Ni doped ZnO nanorods finds its application in spintronics. - Highlights: Black-Right-Pointing-Pointer The method used is very simple and cost effective compared to all other methods for the preparation DMS materials. Black-Right-Pointing-Pointer ZnO and Ni doped ZnO nanorods Black-Right-Pointing-Pointer Ferromagnetism at room temperature.

  4. Improvement of the tool life of a micro-end mill using nano-sized SiC/Ni electroplating method.

    PubMed

    Park, Shinyoung; Kim, Kwang-Su; Roh, Ji Young; Jang, Gyu-Beom; Ahn, Sung-Hoon; Lee, Caroline Sunyong

    2012-04-01

    High mechanical properties of a tungsten carbide micro-end-mill tool was achieved by extending its tool life by electroplating nano-sized SiC particles (< 100 nm) that had a hardness similar to diamond in a nickel-based material. The co-electroplating method on the surface of the micro-end-mill tool was applied using SiC particles and Ni particles. Organic additives (saccharin and ammonium chloride) were added in a Watts bath to improve the nickel matrix density in the electroplating bath and to smooth the surface of the co-electroplating. The morphology of the coated nano-sized SiC particles and the composition were measured using Scanning Electron Microscope and Energy Dispersive Spectrometer. As the Ni/SiC co-electroplating layer was applied, the hardness and friction coefficient improved by 50%. Nano-sized SiC particles with 7 wt% were deposited on the surface of the micro-end mill while the Ni matrix was smoothed by adding organic additives. The tool life of the Ni/SiC co-electroplating coating on the micro-end mill was at least 25% longer than that of the existing micro-end mills without Ni/SiC co-electroplating. Thus, nano-sized SiC/Ni coating by electroplating significantly improves the mechanical properties of tungsten carbide micro-end mills.

  5. Deformation Heterogeneity and Texture Evolution of NiTiFe Shape Memory Alloy Under Uniaxial Compression Based on Crystal Plasticity Finite Element Method

    NASA Astrophysics Data System (ADS)

    Liang, Yulong; Jiang, Shuyong; Zhang, Yanqiu; Zhao, Yanan; Sun, Dong; Zhao, Chengzhi

    2017-04-01

    Crystal plastic finite element method (CPFEM) is used to simulate microstructural evolution, texture evolution and macroscopic stress-strain response of polycrystalline NiTiFe shape memory alloy (SMA) with B2 austenite phase during compression deformation. A novel two-dimensional polycrystalline finite element model based on electron back-scattered diffraction (EBSD) experiment data is developed to represent virtual grain structures of polycrystalline NiTiFe SMA. In the present study, CPFEM plays a significant role in predicting texture evolution and macroscopic stress-strain response of NiTiFe SMA during compression deformation. The simulated results are in good agreement with the experimental ones. It can be concluded that intragranular and intergranular strain heterogeneities are of great importance in guaranteeing plastic deformation compatibility of NiTiFe SMA. CPFEM is able to capture the evolution of grain boundaries with various misorientation angles for NiTiFe SMA subjected to the various compression deformation degrees. During uniaxial compression of NiTiFe SMA, the microstructure evolves into high-energy substructure and consequently the well-defined subgrains are formed. Furthermore, the grain boundaries and the subgrain boundaries are approximately aligned with the direction in which metal flows.

  6. A novel Ag catalyzation process using swelling impregnation method for electroless Ni deposition on Kevlar® fiber

    NASA Astrophysics Data System (ADS)

    Pang, Hongwei; Bai, Ruicheng; Shao, Qinsi; Gao, Yufang; Li, Aijun; Tang, Zhiyong

    2015-12-01

    A novel Ag catalyzation process using swelling impregnation pretreatment method was developed for electroless nickel (EN) deposition on Kevlar fiber. Firstly, the fiber was immersed into an aqueous dimethylsulfoxide (DMSO) solution of silver nitrate to impart silver nitrate into the inner part of the fiber near the surface. Subsequently silver nitrate was reduced to metal silver nanoparticles on the fiber surface by treatment with aqueous solution of sodium borohydride. After electroless plating, a dense and homogeneous nickel coating was obtained on the fiber surface. The silver nanoparticles formed at the fiber surface functioned as a catalyst for electroless deposition as well as an anchor for the plated layer. The study also revealed that the incorporation of surfactant sodium dodecyl sulfate (SDS) in electroless nickel plating bath can enhance the adhesion strength of EN layer with the fiber surface and minimize the surface roughness of the EN coating. The Ni plated Kevlar fiber possessed excellent corrosion resistance and high tensile strength.

  7. Intermetallic M--Sn.sub.5 (M=Fe, Cu, Co, Ni) compound and a method of synthesis thereof

    DOEpatents

    Wang, Xiao-Liang; Han, Weiqiang

    2017-09-05

    Novel intermetallic materials are provided that are composed of tin and one or more additional metal(s) having a formula M.sub.(1-x)-Sn.sub.5, where -0.1.ltoreq.x.ltoreq.0.5, with 0.01.ltoreq.x.ltoreq.0.4 being more preferred and the second metallic element (M) is selected from iron (Fe), copper (Cu), cobalt (Co), nickel (Ni), and a combination of two or more of those metals. Due to low concentration of the second metallic element, the intermetallic compound affords an enhanced capacity applicable for electrochemical cells and may serve as an intermediate phase between Sn and MSn.sub.2. A method of synthesizing these intermetallic materials is also disclosed.

  8. Investigation of structural and magnetic properties of Tb-Ni-doped bismuth ferrite nanoparticles by auto-combustion method

    NASA Astrophysics Data System (ADS)

    Sharma, Jyoti; Kumar, Arun; Kumar, Sachin; Srivastava, A. K.

    2017-08-01

    The current work reports the synthesis of Bi1- x Tb x Fe1- x Ni x O3 ( x = 0, 0.01, 0.03) using auto-combustion sol-gel method. XRD analysis reveals the formation of a rhombohedrally distorted perovskite structure to the R3c space group at room temperature. The crystallite size decreases from 46 to 15 nm with increasing dopants concentration. The presence of two strong peaks between 440 and 590 cm-1 attribute to bending and stretching of FeO bond, the characteristic of the octahedral FeO6 group in perovskite structure. The presence of irregular morphology is observed in the FE-SEM images. The occurrence of doublet in Mossbauer spectra of x = 0.03 sample indicates the superparamagnetic nature of the material. From VSM analysis, the coercivity of x = 0.03 sample is found to be zero, also supporting the superparamagnetic nature of this sample.

  9. Effect of Co(2+) and Ni(2+)-doped zinc borate nano crystalline powders by co-precipitation method.

    PubMed

    Shim, Jaesool; Venkata Reddy, Ch; Sarma, G V S S; Narayana Murthy, P; Ravikumar, R V S S N

    2015-05-05

    A simple co-precipitation method has been used for the synthesis of Co(2+) and Ni(2+)-doped zinc borate nanopowders. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), UV/Vis absorption, Scanning electron microscope (SEM) with EDS and photoluminescence (PL) spectroscopies techniques has been employed for their characterization. Powder X-ray diffraction data reveals that the crystal structure belongs to monoclinic for both as-prepared samples. SEM images showed surface morphology of the prepared samples. Optical absorption spectra showed the characteristic bands of doped ions in octahedral site symmetry. From the optical absorption data crystal field and inter-electronic repulsion parameters are evaluated. The FT-IR spectra showed the characteristic vibrational bands related to ZnO, BO3 and BO4 molecules. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions.

  10. Preparation method of Ni@Pt/C nanocatalyst affects the performance of direct borohydride-hydrogen peroxide fuel cell: Improved power density and increased catalytic oxidation of borohydride.

    PubMed

    Hosseini, Mir Ghasem; Mahmoodi, Raana

    2017-08-15

    The Ni@Pt/C electrocatalysts were synthesized using two different methods: with sodium dodecyl sulfate (SDS) and without SDS. The metal loading in synthesized nanocatalysts was 20wt% and the molar ratio of Ni: Pt was 1:1. The structural characterizations of Ni@Pt/C electrocatalysts were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). The electrocatalytic activity of Ni@Pt/C electrocatalysts toward BH4(-) oxidation in alkaline medium was studied by means of cyclic voltammetry (CV), chronopotentiometry (CP), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). The results showed that Ni@Pt/C electrocatalyst synthesized without SDS has superior catalytic activity toward borohydride oxidation (22016.92AgPt(-1)) in comparison with a catalyst prepared in the presence of SDS (17766.15AgPt(-1)) in NaBH4 0.1M at 25°C. The Membrane Electrode Assembly (MEA) used in fuel cell set-up was fabricated with catalyst-coated membrane (CCM) technique. The effect of Ni@Pt/C catalysts prepared with two methods as anode catalyst on the performance of direct borohydride-hydrogen peroxide fuel cell was studied. The maximum power density was obtained using Ni@Pt/C catalyst synthesized without SDS at 60°C, 1M NaBH4 and 2M H2O2 (133.38mWcm(-2)). Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Investigation of porous Ni-based metal-organic frameworks containing paddle-wheel type inorganic building units via high-throughput methods.

    PubMed

    Maniam, Palanikumar; Stock, Norbert

    2011-06-06

    In the search of Ni based metal-organic frameworks (MOFs) containing paddle-wheel type building units, three chemical systems Ni(2+)/H(n)L/base/solvent with H(n)L = H(3)BTC (1,3,5-benzenetricarboxylic acid), H(3)BTB (4,4',4'',-benzene-1,3,5-triyl-tris(benzoic acid)), and H(2)BDC (terephthalic acid) were investigated using high-throughput (HT) methods. In addition to the conventional heating, for the first time HT microwave assisted synthesis of MOFs was carried out. Six new compounds were discovered, and their fields of formation were established. In the first system, H(3)BTC was employed and a comprehensive HT-screening of compositional and process parameters was conducted. The synthesis condition for the Ni paddle-wheel unit was determined and two compounds [Ni(3)(BTC)(2)(Me(2)NH)(3)]·(DMF)(4)(H(2)O)(4) (1a) and [Ni(6)(BTC)(2)(DMF)(6)(HCOO)(6)] (1b) were discovered (Me(2)NH = dimethylamine, DMF = dimethylformamide). In the second system, the use of the extended tritopic linker H(3)BTB and the synthesis conditions for the paddle-wheel units led to the porous MOF, [Ni(3)(BTB)(2)(2-MeIm)(1.5)(H(2)O)(1.5)]·(DMF)(9)(H(2)O)(6.5) (2), (2-MeIm = 2-methylimidazole). This compound shows a selective adsorption of H(2)O and H(2) with a strong hysteresis. In the third system, H(2)BDC was used, and the base (DABCO) was incorporated as a bridging ligand into all structures. Thus, two pillared layered porous MOFs [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(1.5) (3a) and [Ni(2)(BDC)(2)(DABCO)]·(DMF)(4)(H(2)O)(4) (3b) as well as a layered compound [Ni(BDC)(DABCO)]·(DMF)(1.5)(H(2)O)(2) (3c) were isolated. The 3a and 3b polymorphs of the [Ni(2)(BDC)(2)(DABCO)] framework can be selectively synthesized. The combination of microwave assisted heating, low overall concentration, stirring of the reaction mixtures, and an excess of DABCO yields a highly crystalline pure phase of 3b. The fields of formation of all compounds were established, and scale-up was successfully performed for 1b, 2

  12. Effectiveness of silica-lasing method on the bond strength of composite resin repair to Ni-Cr alloy.

    PubMed

    Madani, Azam S; Astaneh, Pedram Ansari; Nakhaei, Mohammadreza; Bagheri, Hossein G; Moosavi, Horieh; Alavi, Samin; Najjaran, Niloufar Tayarani

    2015-04-01

    The aim of this study was to evaluate the effectiveness of silica-lasing method for improving the composite resin repair of metal ceramic restorations. Sixty Ni-Cr cylindrical specimens were fabricated. The bonding surface of all specimens was airborne-particle abraded using 50 μm aluminum oxide particles. Specimens were divided into six groups that received the following surface treatments: group 1-airborne-particle abrasion alone (AA); group 2-Nd:YAG laser irradiation (LA); group 3-silica coating (Si-CO); group 4-silica-lasing (metal surface was coated with slurry of opaque porcelain and irradiated by Nd:YAG laser) (Si-LA); group 5-silica-lasing plus etching with HF acid (Si-LA-HF); group 6-CoJet sand lased (CJ-LA). Composite resin was applied on metal surfaces. Specimens were thermocycled and tested in shear mode in a universal testing machine. The shear bond strength values were analyzed using ANOVA and Tukey's tests (α = 0.05). The mode of failure was determined, and two specimens in each group were examined by scanning electron microscopy and wavelength dispersive X-ray spectroscopy. Si-CO showed significantly higher shear bond strength in comparison to other groups (p < 0.001). The shear bond strength values of the LA group were significantly higher than those of the AA group (p < 0.05). No significant difference was found among lased groups (LA, Si-LA, Si-LA-HF, CJ-LA; p > 0.05). The failure mode was 100% adhesive for AA, Si-LA, Si-LA-HF, and CJ-LA. LA and Si-CO groups showed 37.5% and 87.5% cohesive failure, respectively. Silica coating of Ni-Cr alloy resulted in higher shear bond strength than those of other surface treatments. © 2014 by the American College of Prosthodontists.

  13. A study of NiZnCu-ferrite/SiO 2 nanocomposites with different ferrite contents synthesized by sol-gel method

    NASA Astrophysics Data System (ADS)

    Yan, Shifeng; Geng, Jianxin; Chen, Jianfeng; Yin, Li; Zhou, Yunchun; Liu, Leijing; Zhou, Enle

    2005-04-01

    Ni 0.65Zn 0.35Cu 0.1Fe 1.9O 4/SiO 2 nanocomposites with different weight percentages of NiZnCu-ferrite dispersed in silica matrix were successfully fabricated by the sol-gel method using tetraethylorthosilicate (TEOS) as a precursor of silica, and metal nitrates as precursors of NiZnCu ferrite. The thermal decomposition process of the dried gel was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The obtained Ni 0.65Zn 0.35Cu 0.1Fe 1.9O 4/SiO 2 nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), Mössbauer spectroscopy and vibrating sample magnetometry (VSM). The formation of stoichiometric NiZnCu-ferrite dispersed in silica matrix is confirmed when the weight percentage of ferrite is not more than 30%. Samples with higher ferrite content have small amount of α-Fe 2O 3. The transition from the paramagnetic to the ferromagnetic state is observed as the ferrite content increases from 20 to 90 wt%. The magnetic properties of the nanocomposites are closely related to the ferrite content. The saturation magnetization increases with the ferrite content, while the coercivity reaches a maximum when the ferrite is 80 wt% in the silica matrix.

  14. Synthesis of renewable diesel through hydrodeoxygenation reaction from nyamplung oil (Calophyllum Inophyllum oil) using NiMo/Z and NiMo/C catalysts with rapid heating and cooling method

    NASA Astrophysics Data System (ADS)

    Susanto, B. H.; Prakasa, M. B.; Shahab, M. H.

    2016-11-01

    The synthesis of metal nanocrystal was conducted by modification preparation from simple heating method which heating and cooling process run rapidly. The result of NiMo/Z 575 °C characterizations are 33.73 m2/gram surface area and 31.80 nm crystal size. By used NiMo/C 700 °C catalyst for 30 minutes which had surface area of 263.21 m2/gram, had 31.77 nm crystal size, and good morphology, obtained catalyst with high activity, selectivity, and stability. After catalyst activated, synthesis of renewable diesel performed in hydrogenation reactor at 375 °C, 12 bar, and 800 rpm. The result of conversion was 81.99%, yield was 68.08%, and selectivity was 84.54%.

  15. Electrical properties of La0.67Sr0.33Mn0.7Ni0.3O3 synthesized by sol gel method

    NASA Astrophysics Data System (ADS)

    Widyaiswari, U.; Kurniawan, B.; Andika, R.; Laksanawati, W. D.; Fauziyah, I.; Imaduddin, A.

    2017-07-01

    Our previous study showed that La0.67Sr0.33MnO3 (LSMO) compound has Curie temperature, TC, above room temperature. In order to shift TC of the compound near room temperature, Ni doped was introduced to the Mn site of LSMO. In this paper, 30% Mn site was doped by Ni. La0.67Sr0.33Mn0.7Ni0.3O3 compound synthesized by sol-gel method and characterized by using X-ray Diffraction (XRD). Then single phase compound's resistivity was measured to see the electrical properties of this compound. The XRD result showed that the samples have a single phase with rhombohedral structure and R-3c space group. The resistivity measurement as a function of temperature did not show resistivity peak and metal-insulator transition. Below 300 K, the resistivity increased with decreasing of temperature which indicated insulator behavior.

  16. Novel method for fabrication of integrated resistors on bilayer Ag/YBa2Cu3O7 films using Ni implantation

    NASA Astrophysics Data System (ADS)

    LaGraff, J. R.; Chan, H.; Murduck, J. M.; Hong, S. H.; Ma, Q. Y.

    1997-10-01

    A novel ion implantation method is described for fabricating low inductance integrated resistors on Ag/YBa2Cu3O7 (YBCO) bilayer thin films. Parallel high and low value resistors were simultaneously formed by patterning bilayer films into 10-μm-wide lines, then masking and implanting with Ni to selectively inhibit superconductivity in YBCO. Low value resistors (<1 Ω/sq) were formed at 77 K as the supercurrent bypassed the Ni-doped nonsuperconducting YBCO and was shunted through the overlying low resistivity Ag metal. High value resistors (20-140 Ω/sq) were formed by removing Ag from above the implanted YBCO forcing the current through the implanted YBCO region. The sheet resistance of both types of resistors was found to increase systematically with increasing Ni implant energy.

  17. Manufacturing methods of a composite cell case for a Ni-Cd battery

    NASA Technical Reports Server (NTRS)

    Bauer, J. L.

    1979-01-01

    Basic manufacturing method refinements for using graphite epoxy material for a nickel cadmium battery cell case were performed to demonstrate production feasibility. The various facets of production scale-up, i.e., process and tooling development, together with material and process control, were integrated into a comprehensive manufacturing process that assures production reproducibility and product uniformity. Test results substantiate that a battery cell case produced from graphite epoxy pre-impregnated material, utilizing the internal pressure bag fabrication method, is feasible.

  18. Manufacturing methods of a composite cell case for a Ni-Cd battery

    NASA Technical Reports Server (NTRS)

    Bauer, J. L.; Bogner, R. S.; Lowe, E. P.; Orlowski, E.

    1979-01-01

    Graphite epoxy material for a nickel cadmium battery cell case has been evaluated and determined to perform in the simulated environment of the battery. The basic manufacturing method requires refinement to demonstrate production feasibility. The various facets of production scale-up, i.e., process and tooling development together with material and process control, have been integrated into a comprehensive manufacturing process that assures production reproducibility and product uniformity. Test results substantiate that a battery cell case produced from graphite epoxy pre-impregnated material utilizing internal pressure bag fabrication method is feasible.

  19. The effects of fuel type in synthesis of NiFe2O4 nanoparticles by microwave assisted combustion method

    NASA Astrophysics Data System (ADS)

    Karcıoğlu Karakaş, Zeynep; Boncukçuoğlu, Recep; Karakaş, İbrahim H.

    2016-04-01

    In this study, it was investigated the effects of the used fuels on structural, morphological and magnetic properties of nanoparticles in nanoparticle synthesis with microwave assisted combustion method with an important method in quick, simple and low cost at synthesis of the nanoparticles. In this aim, glycine, urea and citric acid were used as fuel, respectively. The synthesised nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmet-Teller surface area (BET), and vibrating sample magnetometry (VSM) techniques. We observed that fuel type is quite effective on magnetic properties and surface properties of the nanoparticles. X-ray difractograms of the obtained nanoparticles were compared with standard powder diffraction cards of NiFe2O4 (JCPDS Card Number 54-0964). The results demonstrated that difractograms are fully compatible with standard reflection peaks. According to the results of the XRD analysis, the highest crystallinity was observed at nanoparticles synthesized with glycine. The results demonstrated that the nanoparticles prepared with urea has the highest surface area. The micrographs of SEM showed that all of the nanoparticles have nano-crystalline behaviour and particles indication cubic shape. VSM analysis demonstrated that the type of fuel used for synthesis is highly effective a parameter on magnetic properties of nanoparticles.

  20. A study of the electrochemical lithium intercalation behavior of porous LiNiO 2 electrodes prepared by solid-state reaction and sol-gel methods

    NASA Astrophysics Data System (ADS)

    Choi, Young-Min; Pyun, Su-Il; Moon, Seong-In; Hyung, Yoo-Eup

    The electrochemical lithium intercalation behavior of porous LiNiO 2 electrodes prepared by solid-state reaction and sol-gel methods is investigated by using X-ray diffractometry (XRD), a galvanostatic intermittent charge-discharge experiment, electrochemical impedance spectroscopy(EIS), and a charge-discharge cycling test. The ultrafine LiNiO 2 powder is prepared by the sol-gel method in order to overcome the disadvantage of the conventional solid-state reaction method. From the results of XRD, the layered LiNiO 2 phase proves to be stable above 400°C. The conventional oxide electrode suffers a larger capacity loss, a greater instantaneous IR drop during the first intermittent discharge, and a smaller chemical diffusivity than the gel-derived electrode. The results are discussed with respect to the marked cation mixing effect in the former electrode. Furthermore, the charge-discharge cycling test shows that the cell Li/organic electrolyte/gel-derived LiNiO 2 electrode displays improved performance, i.e., an initial specific capacity of 150 Ah kg -1 and a specific energy density above 500 Wh kg -1.

  1. Fabrication and Characterization of Ni-SiC Nanocomposite Coatings on Al Substrates by Ball Impact Deposition Method

    NASA Astrophysics Data System (ADS)

    Yazdani, Arash; Zakeri, Alireza

    2017-06-01

    Micron-size Ni and SiC powder mixtures were used to prepare Ni-SiC nanocomposite coatings on an Al substrate by employing a high-energy ball milling technique. Ni:SiC weight ratio was varied over a wide range to explore the effect of the charge composition on the microstructure, composition, microhardness, and wear properties of the depositions. It was observed that the composition of the produced coating was correlated to the charge composition in a complex manner, which suggests that deposition rates for Ni and SiC particles significantly vary depending on the charge composition; SiC deposition rate was higher than that of Ni when Ni:SiC weight ratio was greater than 3:1. Diffusion of Al from the substrate into the Ni matrix provided evidence for the metallurgical bonding at the interface. Both microstructural and mechanical properties of the produced coatings were found to be crucially dependent on the charge composition. By increasing the SiC content in the charge from about 5 to 33 wt pct, the mechanical properties enhanced due to the dispersion strengthening effect of the incorporated SiC particles in the coatings and the crystallite size of the Ni matrix decreasing to the nanometer range. However, a further increase resulted in the formation of a coating with a poor degree of compaction. It was found that the composite coating with about 15 vol pct SiC, produced from the charge with Ni:SiC weight ratio of 2:1, showed a microhardness as high as 830 HV0.05 along with excellent wear resistance. Despite the current sample size limitations for applying high-energy ball milling, the present findings demonstrate that the adopted technique holds good prospect for the synthesis of nanostructured metal matrix composite coatings with enhanced and tunable properties.

  2. Fabrication and Characterization of Ni-SiC Nanocomposite Coatings on Al Substrates by Ball Impact Deposition Method

    NASA Astrophysics Data System (ADS)

    Yazdani, Arash; Zakeri, Alireza

    2017-09-01

    Micron-size Ni and SiC powder mixtures were used to prepare Ni-SiC nanocomposite coatings on an Al substrate by employing a high-energy ball milling technique. Ni:SiC weight ratio was varied over a wide range to explore the effect of the charge composition on the microstructure, composition, microhardness, and wear properties of the depositions. It was observed that the composition of the produced coating was correlated to the charge composition in a complex manner, which suggests that deposition rates for Ni and SiC particles significantly vary depending on the charge composition; SiC deposition rate was higher than that of Ni when Ni:SiC weight ratio was greater than 3:1. Diffusion of Al from the substrate into the Ni matrix provided evidence for the metallurgical bonding at the interface. Both microstructural and mechanical properties of the produced coatings were found to be crucially dependent on the charge composition. By increasing the SiC content in the charge from about 5 to 33 wt pct, the mechanical properties enhanced due to the dispersion strengthening effect of the incorporated SiC particles in the coatings and the crystallite size of the Ni matrix decreasing to the nanometer range. However, a further increase resulted in the formation of a coating with a poor degree of compaction. It was found that the composite coating with about 15 vol pct SiC, produced from the charge with Ni:SiC weight ratio of 2:1, showed a microhardness as high as 830 HV0.05 along with excellent wear resistance. Despite the current sample size limitations for applying high-energy ball milling, the present findings demonstrate that the adopted technique holds good prospect for the synthesis of nanostructured metal matrix composite coatings with enhanced and tunable properties.

  3. Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

    SciTech Connect

    Gupta, Vinay Kawaguchi, Toshikazu; Miura, Norio

    2009-01-08

    Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co{sub 3}O{sub 4}, NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm{sup 2} current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides.

  4. Synthesis, structural and optical properties of ZnO and Ni-doped ZnO hexagonal nanorods by Co-precipitation method.

    PubMed

    Raja, K; Ramesh, P S; Geetha, D

    2014-01-01

    Ni doped ZnO (Zn1-xNixO, x=0.0, 0.03, 0.06 and 0.09) nanorods have been synthesized by Co-precipitation method. Zinc acetate dehydrate [Zn(CH3COO)2⋅2H2O], nickel nitrate [Ni(NO3)3⋅6H2O], sodium hydroxide and poly (vinyl pyrrolidone) (PVP) were mixed together. The morphology, optical and microstructure were determined by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive spectrum (EDS), atomic force microscopy (AFM), UV-DRS spectrum, photoluminescence spectra (PL) and Fourier transformer infrared spectroscopy (FT-IR). The presence of functional groups and chemical bonding is confirmed by FTIR. PL spectra of the Zn1-xNixO systems shows that the shift in near band edge (NBE) UV emission from 321 to 322 nm and a shift in red band (RB) emission from 620 to 631 nm which conforms the substitution of Ni into the ZnO lattice. The investigation conformed that the products were of the wurtzite structure of ZnO. The hexagonal nanorods have edge length 31 nm and thickness of 39 nm. EDS result showed that the amount of Ni in the product is about 9%, these Ni doped hexagonal nanorods exhibits a blue shifts and weak (UV) emission peak, compared with pure ZnO, which may be induced by the Ni-doping different concentrations 0.0, 0.3, 0.6 and 0.9 M. The growth mechanism of the doped hexagonal nanorods was also discussed.

  5. Preparation of Fe-Ni-Based Metal-Metalloid Amorphous Alloys by Mechanical Alloying and Mechanical Grinding Methods

    NASA Astrophysics Data System (ADS)

    Miura, Harumatsu; Isa, Shigeteru; Omuro, Keisuke

    1990-02-01

    Using a high energy ball mill, alloys of Fe40Ni40P14B6 and Fe40Ni40B20 were synthesized from crystalline, elemental iron and nickel metals and iron-metalloid alloys such as Fe-B and Fe-P by mechanical alloying (MA). Powders of the Fe40Ni40P14B6 alloy were also prepared from the cast ingot products by mechanical grinding (MG). Each of the MA and MG powder products showed a halo pattern typical of amorphous materials in the X-ray diffraction trace, and the crystallization enthalpy of the Fe40Ni40P14B6 MA powder, measured by differential scanning calorimetry, was almost the same as that of the melt-quenched sample of the same composition.

  6. A new method for the assessment of the surface topography of NiTi rotary instruments.

    PubMed

    Ferreira, F; Barbosa, I; Scelza, P; Russano, D; Neff, J; Montagnana, M; Zaccaro Scelza, M

    2017-09-01

    To describe a new method for the assessment of nanoscale alterations in the surface topography of nickel-titanium endodontic instruments using a high-resolution optical method and to verify the accuracy of the technique. Noncontact three-dimensional optical profilometry was used to evaluate defects on a size 25, .08 taper reciprocating instrument (WaveOne(®) ), which was subjected to a cyclic fatigue test in a simulated root canal in a clear resin block. For the investigation, an original procedure was established for the analysis of similar areas located 3 mm from the tip of the instrument before and after canal preparation to enable the repeatability and reproducibility of the measurements with precision. All observations and analysis were taken in areas measuring 210 × 210 μm provided by the software of the equipment. The three-dimensional high-resolution image analysis showed clear alterations in the surface topography of the examined cutting blade and flute of the instrument, before and after use, with the presence of surface irregularities such as deformations, debris, grooves, cracks, steps and microcavities. Optical profilometry provided accurate qualitative nanoscale evaluation of similar surfaces before and after the fatigue test. The stability and repeatability of the technique enables a more comprehensive understanding of the effects of wear on the surface of endodontic instruments. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  7. Benchmarking Density Functional Theory Based Methods To Model NiOOH Material Properties: Hubbard and van der Waals Corrections vs Hybrid Functionals.

    PubMed

    Zaffran, Jeremie; Caspary Toroker, Maytal

    2016-08-09

    NiOOH has recently been used to catalyze water oxidation by way of electrochemical water splitting. Few experimental data are available to rationalize the successful catalytic capability of NiOOH. Thus, theory has a distinctive role for studying its properties. However, the unique layered structure of NiOOH is associated with the presence of essential dispersion forces within the lattice. Hence, the choice of an appropriate exchange-correlation functional within Density Functional Theory (DFT) is not straightforward. In this work, we will show that standard DFT is sufficient to evaluate the geometry, but DFT+U and hybrid functionals are required to calculate the oxidation states. Notably, the benefit of DFT with van der Waals correction is marginal. Furthermore, only hybrid functionals succeed in opening a bandgap, and such methods are necessary to study NiOOH electronic structure. In this work, we expect to give guidelines to theoreticians dealing with this material and to present a rational approach in the choice of the DFT method of calculation.

  8. [The method of replacement of defects in impression fractures of calcaneus. Porous NiTi or autotransplant?].

    PubMed

    Plotkin, G L; Moskalev, V P; Domashenko, A A; Sinitsyn, S S; Plotkin, Ia G; Turbin, K O

    2012-01-01

    An experience with treatment of 149 patients with severe injuries of the ankle joint operated using constructions of titanium-nickelide and autotransplant from the iliac crest is presented. Porous NiTi being bio-inert to organism tissues, having high through porosity, the formation of consolidation of the fracture develops more rapidly. Application of porous NiTi allowed the period of disablement to be on an average 20 days shorter and long-term results to be reliably better.

  9. Synthesis and magnetic properties of (Eu-Ni) substituted Y-type hexaferrite by surfactant assisted co-precipitation method

    NASA Astrophysics Data System (ADS)

    Ali, Irshad; Islam, M. U.; sadiq, Imran; Karamat, Nazia; Iftikhar, Aisha; khan, M. Azhar; Shah, Afzal; Athar, Muhammad; Shakir, Imran; Ashiq, Muhammad Naeem

    2015-07-01

    A series of (Eu-Ni) substituted Y-type hexaferrite with composition Sr2Co(2-x)NixEuyFe(12-y)O22 (x=0.0-1, Y=0.0-0.1) were prepared by the surfactant assisted co-precipitation method. The present samples were sintered at 1050 °C for 8 h. The shape of the particles is plate-like which is very advantageous for various applications and the grain size varies from 73 to 269 nm. The values of saturation magnetization (Ms), remanent magnetization (Mr) and magnetic moment (nB) were found to decrease which are attributed to the weakening of super exchange interactions. The values of in-plane Squareness ratios (Mr/Ms) ranging from 0.41 to 0.65 whereas in case of out of plane measurement it varies from 0.30 to 0.62.The investigated samples can be used in perpendicular recording media (PRM) due to high value of coercivity 2300 Oe which is analogous to the those of M-type and W-type hard magnetic.

  10. Fabrication and magnetic properties of La-X (X = Co, Ni, and Fe) nanotube arrays prepared by electrodeposition methods

    NASA Astrophysics Data System (ADS)

    Chen, J. Y.; Shi, D. W.; Ahmad, N.; Liu, D. P.; Zhou, W. P.; Han, X. F.

    2013-08-01

    Well-ordered La-X (X = Co, Ni and Fe) nanotubes, with the average diameter of ˜200 nm, wall thicknesses of ˜40 nm, have been fabricated into anodized aluminum oxide template by potentiostatic electrodeposition method. Various composition of La-X nanotubes were obtained by tuning the applied deposition potential. Magnetization measurements reveal that doped La could enhance the coercivity (Hc) of La-X nanotubes and their easy axis is perpendicular to the nanotube axis. There is a transition from the curling to transverse mode with increase of angle. Temperature dependent magnetization indicates the existence of superparamagnetic nanoparticles and that the surface effect results in the increase of saturation magnetization (Ms) at low temperature. Abnormal behavior of temperature dependent Hc may result from thermal excitation, magnetoelastic anisotropy, as well as oxide layer of nanotube inner surface induced coupling. These one-dimensional rare-earth transition metal nanostructures could have potential applications in novel spintronics device, ultra-small magnetic media, drug delivery, or other nanodevice.

  11. Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications

    PubMed Central

    2012-01-01

    Ferrite nanoparticles of basic composition Ni0.7-xZnxCu0.3Fe2O4 (0.0 ≤ x ≤ 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands (v1 and v2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters (ε', ε″, tanδ, and σac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm. PMID:22316055

  12. Preparation and characterization of polyol assisted ultrafine Cu-Ni-Mg-Ca mixed ferrite via co-precipitation method

    NASA Astrophysics Data System (ADS)

    Boobalan, T.; Pavithradevi, S.; Suriyanarayanan, N.; Manivel Raja, M.; Ranjith Kumar, E.

    2017-04-01

    Nanocrystalline spinel ferrite of composition Cu0.2Ni0.2Mg0.2Ca0.4Fe2O4 is synthesized by wet hydroxyl co-precipitation method in ethylene glycol as chelating agent and sodium hydroxide as precipitator at pH 8. Ethylene glycol is utilized as the medium which serves as the dissolvable and in addition a complexing specialist. The synthesized particles are annealed at various temperatures. Thermogravimetric investigation affirms that at 280 °C ethylene glycol is dissipated totally and stable phase arrangement happens over 680 °C. FTIR spectra of as synthesized and annealed at 1050 °C recorded between 400 cm-1 and 4000 cm-1. Structural characterizations of all the samples are carried out by X-ray diffraction (XRD) technique. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) affirm that the particles are spherical and cubic shape with the crystallite size of 12 nm to 32 nm. Magnetic measurements are performed utilizing vibrating sample magnetometer at room temperature.

  13. Low temperature-fired Ni-Cu-Zn ferrite nanoparticles through auto-combustion method for multilayer chip inductor applications

    NASA Astrophysics Data System (ADS)

    Batoo, Khalid Mujasam; Ansari, Mohammad Shahnawaze

    2012-02-01

    Ferrite nanoparticles of basic composition Ni0.7- x Zn x Cu0.3Fe2O4 (0.0 ≤ x ≤ 0.2, x = 0.05) were synthesized through auto-combustion method and were characterized for structural properties using X-ray diffraction [XRD], scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy [FT-IR]. XRD analysis of the powder samples sintered at 600°C for 4 h showed the cubic spinel structure for ferrites with a narrow size distribution from 28 to 32 nm. FT-IR showed two absorption bands ( v 1 and v 2) that are attributed to the stretching vibration of tetrahedral and octahedral sites. The effect of Zn doping on the electrical properties was studied using dielectric and impedance spectroscopy at room temperature. The dielectric parameters ( ɛ', ɛ″, tan δ, and σ ac) show their maximum value for 10% Zn doping. The dielectric constant and loss tangent decrease with increasing frequency of the applied field. The results are explained in the light of dielectric polarization which is similar to the conduction phenomenon. The complex impedance shows that the conduction process in grown nanoparticles takes place predominantly through grain boundary volume. PACS: 75.50.Gg; 78.20; 77.22.Gm.

  14. Synthesis and charcterization of Nanocrystalline NiCuZn Ferrite prepared by Sol-gel auto combution method

    NASA Astrophysics Data System (ADS)

    Rathod, Sopan M.; Shinde, Ashok B.

    2012-11-01

    Promising future applications of ferrite nanoparticles in medicine, making many devices like permanent magnets, memory storage devices etc. Ferrite nanoparticles have been the emerging focus of the recent scientific research. Therefore nanostructured powders of ferrites having chemical compositions [Ni0.8-xCu0.2Znxfe2O4], where x=0.3, 0.5, synthesised through nitrate citrate by sol-gel autocombustion method from stoichiometric mixture of their respective metal nitrate. The prepared powders were sintered at 400 0C and 600 0C for 4 hours. The structural, morphology, ferrite formation of powder were determined by X-ray powder diffractometry (XRD), Scanning Electron Microscope (SEM) photograph of the samples and Infrared (IR) spectroscopy technique. The X-ray revealed the formation of nano-sized ferrite particles with cubic spinel structure and the cubic phase in the ferrite matrix. The IR shows the characteristic ferrite bonds were confirmed. The average crystalline particles sized were calculated by Scherrer formula. The average crystalline size obtained from XRD was found between 40 and 44nm. The lattice parameters, X-ray density and bond length are different parameters are calculated from XRD patterns. The UV-Visible Spectroscopy of prepared sample shows that the band gap energy in the range of semiconductor materials. The Coercivity was found to change in proportionally and sintering temperature with the particle sizes of the investigated ferrites.

  15. Preparation and Thermal Stability of Ultrafine Nickel Powders Containing hcp-Ni Nanocrystallites Using Liquid-Phase Reduction Method

    NASA Astrophysics Data System (ADS)

    Xia, Zhimei; Jin, Shengming; Liu, Kun

    2016-10-01

    Ultrafine nickel powders containing hexagonal close-packed nickel (hcp-Ni) nanocrystallites were prepared using liquid-phase reduction with NiC2O4, NaOH, polyvinylpyrrolidone (PVP), and ethylene glycol (EG). The nickel powders were characterized by XRD and SEM. TG analysis was used to determine the thermal stability of ultrafine nickel powders. The results showed that nickel powders with 45.1 pct of hcp-Ni nanocrystallites were synthesized under the following conditions: a reflux time of 3 hours, an NiC2O4-to-EG molar ratio of 0.01, 5 g/L PVP, and 85 g/L NaOH. SEM results illustrated that spherical particles of size 500 nm were obtained. The results of thermal stability showed that the antioxidant property at high temperature was improved with the increase of hcp-Ni content. The oxidation rate of nickel powders with 43.3 pct hcp-Ni was less than 50 pct even if the temperature was up to 873 K (600 °C).

  16. A Comparative Study on Ni-Based Coatings Prepared by HVAF, HVOF, and APS Methods for Corrosion Protection Applications

    NASA Astrophysics Data System (ADS)

    Sadeghimeresht, E.; Markocsan, N.; Nylén, P.

    2016-12-01

    Selection of the thermal spray process is the most important step toward a proper coating solution for a given application as important coating characteristics such as adhesion and microstructure are highly dependent on it. In the present work, a process-microstructure-properties-performance correlation study was performed in order to figure out the main characteristics and corrosion performance of the coatings produced by different thermal spray techniques such as high-velocity air fuel (HVAF), high-velocity oxy fuel (HVOF), and atmospheric plasma spraying (APS). Previously optimized HVOF and APS process parameters were used to deposit Ni, NiCr, and NiAl coatings and compare with HVAF-sprayed coatings with randomly selected process parameters. As the HVAF process presented the best coating characteristics and corrosion behavior, few process parameters such as feed rate and standoff distance (SoD) were investigated to systematically optimize the HVAF coatings in terms of low porosity and high corrosion resistance. The Ni and NiAl coatings with lower porosity and better corrosion behavior were obtained at an average SoD of 300 mm and feed rate of 150 g/min. The NiCr coating sprayed at a SoD of 250 mm and feed rate of 75 g/min showed the highest corrosion resistance among all investigated samples.

  17. Preparation and Characterization of Ni Spines Grown on the Surface of Cubic Boron Nitride Grains by Electroplating Method.

    PubMed

    Gui, Yanghai; Zhao, Jianbo; Chen, Jingbo; Jiang, Yuanli

    2016-03-04

    Cubic boron nitride (cBN) is widely applied in cutting and grinding tools. cBN grains plated by pure Ni and Ni/SiC composite were produced under the same conditions from an additive-free nickel Watts type bath. The processed electroplating products were characterized by the techniques of scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermoanalysis (TG-DTA). Due to the presence of SiC particles, there are some additional nodules on the surface of Ni/SiC plated cBN compared with the pure Ni plated cBN. The unique morphology of Ni/SiC plated cBN should attain greater retention force in resin bond. Moreover, the coating weight of cBN grains could be controlled by regulating the plating time. cBN grains with 60% coating weight possess the optimum grinding performance due to their roughest and spiniest surface. In addition, Ni spines plated cBN grains show good thermal stability when temperature is lower than 464 °C. Therefore, the plated cBN grains are more stable and suitable for making resin bond abrasive tools below 225 °C. Finally, the formation mechanism of electroplating products is also discussed.

  18. Preparation and Characterization of Ni Spines Grown on the Surface of Cubic Boron Nitride Grains by Electroplating Method

    PubMed Central

    Gui, Yanghai; Zhao, Jianbo; Chen, Jingbo; Jiang, Yuanli

    2016-01-01

    Cubic boron nitride (cBN) is widely applied in cutting and grinding tools. cBN grains plated by pure Ni and Ni/SiC composite were produced under the same conditions from an additive-free nickel Watts type bath. The processed electroplating products were characterized by the techniques of scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermoanalysis (TG-DTA). Due to the presence of SiC particles, there are some additional nodules on the surface of Ni/SiC plated cBN compared with the pure Ni plated cBN. The unique morphology of Ni/SiC plated cBN should attain greater retention force in resin bond. Moreover, the coating weight of cBN grains could be controlled by regulating the plating time. cBN grains with 60% coating weight possess the optimum grinding performance due to their roughest and spiniest surface. In addition, Ni spines plated cBN grains show good thermal stability when temperature is lower than 464 °C. Therefore, the plated cBN grains are more stable and suitable for making resin bond abrasive tools below 225 °C. Finally, the formation mechanism of electroplating products is also discussed. PMID:28773283

  19. Production of Al-Co-Ni Ternary Alloys by the SHS Method for Use in Nickel Based Superalloys Manufacturing

    NASA Astrophysics Data System (ADS)

    Alkan, Murat; Sonmez, M. Seref; Derin, Bora; Yücel, Onuralp; Andreev, Dmitrii E.; Sanin, Vladimir N.; Yukhvid, Vladimir I.

    2015-05-01

    In this study, Al-Co-Ni ternary alloys were synthesized, in order to obtain low-cost starting material for Ni-based superalloy production, by a self-propagating high temperature synthesis (SHS) both under normal gravity conditions (a = 9.81 m/s2) and under high gravity conditions (up to 1000 g-force) by using a centrifugal machine. The mixture of Co3O4-NiO powder were reduced by Al powder for the production of SHS alloys with the estimated compositions of 5-10 mass% Al, 20-65 mass% Co, 25-75 mass% Ni. The effect of green mixture compositions and centrifugal overload on combustion temperature, alloy/slag separations, chemical composition and microstructure of final alloys were investigated. The chemical analysis results showed that production of SHS alloys were achieved by having up to 86.12% of Co and 92.32% of Ni recoveries. The highest metal recovery value was obtained in SHS alloy with the estimated composition of 10%Al-65%Co-25%Ni by the addition of 20% Al2O3 into the green mixture. The metal/slag separation efficiency increased by increasing the centrifugal overload.

  20. Electrical Properties of La0.67Sr0.33Mn0.8Ni0.2O3 Synthesized by Sol Gel Method

    NASA Astrophysics Data System (ADS)

    Kurniawan, B.; Widyaiswari, U.; Fauziyah, I.; Imaduddin, A.

    2017-05-01

    The previous study of lanthanum manganites showed that physical properties of LaMnO3 compound has changed when Sr doped the La site. La0.67Sr0.33MnO3 compound give the highest TC = 370 K and showed metal insulator transition. It happens as a result of changed in Mn3+/Mn4+ ratio. Its indicated that Mn has the most important rule to the physical properties changed. In order to shift Tc of the compound to the near room temperature, Ni doped was given to Mn site of LSMO. In this paper, 20% Mn site was doped by Ni. La0.67Sr0.33Mn0.8Ni0.2O3 compound synthesized by sol gel method and characterized using XRD. Then, single phase compound resisitivity was measured to see the electrical properties this compound. The XRD result showed that sample have single phase with rhombohedral structure and R-3c space group. Resistivity as a temperature function graph does not show resistivity peak and metal insulator transition. The resistivity measurement showed that below 300 K, resistivity inscreased with decreased of temperature that indicates insulator behavior. It caused by decreased of double exchange interaction and increase of superexchange interaction. From this result, we can conclude that Ni doped decreased electrical properties of the sample.

  1. A new mechanical characterization method for thin film microactuators and its application to NiTiCi shape memory alloy

    SciTech Connect

    Seward, Kirk P.

    1999-06-01

    In an effort to develop a more full characterization tool of shape memory alloys, a new technique is presented for the mechanical characterization of microactuators and applied to SMA thin films. A test instrument was designed to utilize a spring-loaded transducer in measuring displacements with resolution of 1.5 pm and forces with resolution of 0.2 mN. Employing an out-of-plane loading method for freestanding SMA thin films, strain resolution of 30με and stress resolution of 2.5 MPa were achieved. This new testing method is presented against previous SMA characterization methods for purposes of comparison. Four mm long, 2 μm thick NiTiCu ligaments suspended across open windows were bulk micromachined for use in the out-of-plane stress and strain measurements. The fabrication process used to micromachine the ligaments is presented step-by-step, alongside methods of fabrication that failed to produce testable ligaments. Static analysis showed that 63% of the applied strain was recovered while ligaments were subjected to tensile stresses of 870 MPa. In terms of recoverable stress and recoverable strain, the ligaments achieved maximum recovery of 700 MPa and 3.0% strain. No permanent deformations were seen in any ligament during deflection measurements. Maximum actuation forces and displacements produced by the 4 mm ligaments situated on 1 cm square test chips were 56 mN and 300 μm, respectively. Fatigue analysis of the ligaments showed degradation in recoverable strain from 0.33% to 0.24% with 200,000 cycles, corresponding to deflections of 90 μm and forces of 25 mN. Cycling also produced a wavering shape memory effect late in ligament life, leading to broad inconsistencies of as much as 35% deviation from average. Unexpected phenomena like stress-induced martensitic twinning that leads to less recoverable stress and the shape memory behavior of long life devices are addressed. Finally, a model for design of microactuators using shape memory alloys is presented

  2. Measurement of 59Ni and 63Ni by accelerator mass spectrometry at CIAE

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; He, Ming; Ruan, Xiangdong; Xu, Yongning; Shen, Hongtao; Du, Liang; Xiao, Caijin; Dong, Kejun; Jiang, Shan; Yang, Xuran; Lan, Xiaoxi; Wu, Shaoyong; Zhao, Qingzhang; Cai, Li; Pang, Fangfang

    2015-10-01

    The long lived isotopes 59Ni and 63Ni can be used in many areas such as radioactive waste management, neutron dosimetry, cosmic radiation study, and so on. Based on the large accelerator and a big Q3D magnetic spectrometer, the measurement method for 59Ni and 63Ni is under development at the AMS facility at China Institute of Atomic Energy (CIAE). By using the ΔE-Q3D technique with the Q3D magnetic spectrometer, the isobaric interferences were greatly reduced in the measurements of 59Ni and 63Ni. A four anode gas ionization chamber was then used to further identify isobars. With these techniques, the abundance sensitivities of 59Ni and 63Ni measurements are determined as 59Ni/Ni = 1 × 10-13 and 63Ni/Ni = 2 × 10-12, respectively.

  3. Structural and optical properties of Ni-doped CdS thin films prepared by chemical bath deposition method

    SciTech Connect

    Premarani, R.; Saravanakumar, S. Chandramohan, R.; Mahalingam, T.

    2015-06-24

    The structural and optical behavior of undoped Cadmiun Sulphide (CdS) and Ni-doped CdS thinfilms prepared by Chemical Bath Deposition (CBD) technique is reported. The crystallite sizes of the thinfilms have been characterized by X-ray diffraction pattern (XRD). The particle sizes increase with the increase of Ni content in the CdS thinfilms. Scanning Electron Microscope (SEM) results indicated that CdS thinfilms is made up of aggregate of spherical-like particles. The composition was estimated by Energy Dispersive Analysis of X-ray (EDX) and reported. Spectroscopic studies revealed considerable improvement in transmission and the band gap of the films changes with addition of Ni dopant that is associated with variation in crystallite sizes in the nano regime.

  4. Structural and optical properties of Ni-doped CdS thin films prepared by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Premarani, R.; Saravanakumar, S.; Chandramohan, R.; Mahalingam, T.

    2015-06-01

    The structural and optical behavior of undoped Cadmiun Sulphide (CdS) and Ni-doped CdS thinfilms prepared by Chemical Bath Deposition (CBD) technique is reported. The crystallite sizes of the thinfilms have been characterized by X-ray diffraction pattern (XRD). The particle sizes increase with the increase of Ni content in the CdS thinfilms. Scanning Electron Microscope (SEM) results indicated that CdS thinfilms is made up of aggregate of spherical-like particles. The composition was estimated by Energy Dispersive Analysis of X-ray (EDX) and reported. Spectroscopic studies revealed considerable improvement in transmission and the band gap of the films changes with addition of Ni dopant that is associated with variation in crystallite sizes in the nano regime.

  5. A study on structure and tribological properties of the electroerosion coating Mo-Ni-Cu, formed by the mixed method on copper

    NASA Astrophysics Data System (ADS)

    Romanov, D. A.; Goncharova, E. N.; Gromov, V. E.; Ivanov, Yu F.

    2016-09-01

    Multi-layered coating from immiscible components based on the system Mo-Ni-Cu was formed by the combined method of electro-explosive sputtering and subsequent irradiation by high-intensity pulse electron beam of submillisecond duration of influence on the surface of electrical copper contact (M00 grade of copper). The structure and phase composition studies of the applied coating as well as its mechanical and tribological properties are carried out.

  6. Study on the properties of vacancies and phonon dispersions by the improved ones of the modified analytic embedded atom method potentials for Al, Ni, and Ir

    NASA Astrophysics Data System (ADS)

    Jin, Hak-Son; Pak, Jae-Yon; Jong, Yon-Song

    2017-04-01

    The properties of the mono- and bi-vacancies and the phonon dispersions are calculated by adopting the improved ones of the modified analytical embedded atom method potentials for facet-centered cubic metals Al, Ni, and Ir. The results mainly agree with the experimental data and the other calculation results. Therefore, the improved potentials are effective in the study on the physical properties of the metals.

  7. A Facile Method to In-Situ Synthesize Porous Ni2GeO4 Nano-Sheets on Nickel Foam as Advanced Anode Electrodes for Li-Ion Batteries

    PubMed Central

    Ma, Delong; Shi, Xiaomin; Hu, Anming

    2016-01-01

    A strategy for growth of porous Ni2GeO4 nanosheets on conductive nickel (Ni) foam with robust adhesion as a high-performance electrode for Li-ion batteries is proposed and realized, through a facile two-step method. It involves the low temperature hydro-thermal synthesis of bimetallic (Ni, Ge) hydroxide nanosheets precursor on Ni foam substrates and subsequent thermal transformation to porous Ni2GeO4 nanosheets. The as-prepared Ni2GeO4 nanosheets possess many interparticle mesopores with a size range from 5 to 15 nm. The hierarchical structure of porous Ni2GeO4 nanosheets supported by Ni foam promises fast electron and ion transport, large electroactive surface area, and excellent structural stability. The efficacy of the specially designed structure is demonstrated by the superior electrochemical performance of the generated Ni2GeO4 nanosheets including a high capacity of 1.8 mA·h·cm−2 at a current density of 50 μA·cm−2, good cycle stability, and high power capability at room temperature. Because of simple conditions, this fabrication strategy may be easily extended to other mixed metal oxides (MxGeOy). PMID:28335346

  8. Temperature behavior of exothermic reaction of Al/Ni multilayer powder materials based on cold-rolling and pulverizing method

    NASA Astrophysics Data System (ADS)

    Kametani, Nagamasa; Izumi, Taisei; Miyake, Shugo; Kanetsuki, Shunsuke; Namazu, Takahiro

    2017-06-01

    In this paper, the characteristics of self-propagating exothermic reactions of an Al/Ni multilayer powder materials fabricated by a cold-rolling and powdering procedure are reported as initial findings of the first trial on a heat source for various applications with the energy-saving feature. Experimental results showed that, following the reaction of the developed Al/Ni multilayer powder materials in air atmosphere, the maximum temperature increased from approximately 1450 °C to over 1768 °C with increasing number of passes from 20 to 40 in cold-rolling. Furthermore, observations by scanning electron microscopy and crystallographic identification by X-ray diffraction measurements showed that the multilayer structure of powdered Al/Ni after 40 passes of cold-rolling was deformed, became thinner with below sub-micrometer thickness, and almost completely reacted to NiAl intermetallic compounds. It is possible that optimizing cold-rolling conditions enables us to control exothermic heat, which will be useful for heat sources.

  9. Using complimentary microscopy methods to examine Ni-Mn-Si-precipitates in highly-irradiated reactor pressure vessel steels

    DOE PAGES

    Edmondson, P. D.; Parish, C. M.; Nanstad, R. K.

    2017-05-29

    Nano-scale Ni-Mn-Si-rich precipitates formed in a reactor pressure vessel steel under high neutron fluence have been characterized using highly complimentary atom probe tomography (APT) and scanning transmission electron microscopy with energy dispersive spectroscopy (STEM-EDS) combined with STEM-EDS modeling. Using these techniques in a synergistic manner to overcome the well-known trajectory aberrations in APT data, the average upper limit Fe concentration within the precipitates was found to be ~6 at.%. Using this knowledge, accurate compositions of the precipitates was determined and it was found that the spread of precipitate compositions was large, but mostly centered around the Γ2-and G-phases. The usemore » of STEM-EDS also allowed for larger areas to be examined, and segregation of minor solutes was observed to occur on grain boundaries, along with Ni-Mn-Si-rich precipitates that were smaller in size than those in the matrix. Solute segregation at the grain boundaries is proposed to occur through a radiation induced segregation or radiation enhanced diffusion mechanism due to the presence of a denuded zone about the grain boundary. It is also proposed that the reduced precipitate size at the grain boundaries is due to the structure of the grain boundary. The lack of Ni-Mn-Si precipitates observed in larger Mo-rich precipitates is also discussed, and the absence of the minor solutes required to form the Ni-Mn-Si precipitates results in the lack of nucleation. This is in contrast to cementite phases in which Ni-Mn-Si precipitates have been seen to be formed. It was also determined through this work that the exclusion of all the Fe ions during atom probe analysis is a reasonable approximation.« less

  10. Application of carrier element free coprecipitation (CEFC) method for determination of Co(II), Cu(II) and Ni(II) ions in food and water samples.

    PubMed

    Serencam, Huseyin; Duran, Celal; Ozdes, Duygu; Bektas, Hakan

    2013-01-01

    A simple and highly sensitive separation and preconcentration procedure, which has minimal impact on the environment, has been developed. The procedure is based on the carrier element free coprecipitation (CEFC) of Co(II), Cu(II), and Ni(II) ions by using 2-{4-[2-(1H-indol-3-yl)ethyl]-3-(4-methylbenzyl)-5-oxo-4,5-dihydro- 1H-1,2,4-triazol-l-yl}-N'-(pyridin-2-yl methylidene)acetohydrazide (IMOTPA), as an organic coprecipitant. The levels of analyte ions were determined by flame atomic absorption spectrometry (FAAS). The detection limits for Co(II), Cu(II) and Ni(II) ions were found to be 0.40, 0.16 and 0.17 microg L(-1), respectively, and the relative standard deviations for the analyte ions were lower than 3.0%. Spike tests and certified reference material analyses were performed to validate the method. The method was successfully applied for the determination of Co(II), Cu(II) and Ni(II) ions levels in sea and stream water as liquid samples and red pepper, black pepper, and peppermint as solid samples.

  11. Hydrogen storage and hydrolysis properties of core-shell structured Mg-MFx (M=V, Ni, La and Ce) nano-composites prepared by arc plasma method

    NASA Astrophysics Data System (ADS)

    Mao, Jianfeng; Zou, Jianxin; Lu, Chong; Zeng, Xiaoqin; Ding, Wenjiang

    2017-10-01

    In this work, core-shell structured Mg-MFx (M = V, Ni, La and Ce) nano-composites are prepared by using arc plasma method. The particle size distribution, phase components, microstructures, hydrogen sorption properties of these composites and hydrolysis properties of their corresponding hydrogenated powders are carefully investigated. It is shown that the addition of MFx through arc plasma method can improve both the hydrogen absorption kinetics of Mg and the hydrolysis properties of corresponding hydrogenated powders. Among them, the Mg-NiF2 composite shows the best hydrogen absorption properties at relatively low temperatures, which can absorb 3.26 wt% of H2 at 373 K in 2 h. Such rapid hydrogen absorption rate is mainly due to the formation of Mg2Ni and MgF2 on Mg particles during arc evaporation and condensation. In contrast, measurements also show that the hydrogenated Mg-VF3 composite has the lowest peak desorption temperature and the fastest hydrolysis rate among all the hydrogenated Mg-MFx composites. The less agglomeration tendency of Mg particles and VO2 covered on MgH2 particles account for the reduced hydrogen desorption temperature and enhanced hydrolysis rate.

  12. Microwave anneal effect on magnetic properties of Ni 0.6Zn 0.4Fe 2O 4 nano-particles prepared by conventional hydrothermal method

    NASA Astrophysics Data System (ADS)

    Wang, Zhongzhu; Xie, Yanyu; Wang, Peihong; Ma, Yongqing; Jin, Shaowei; Liu, Xiansong

    2011-12-01

    Ni0.6Zn0.4Fe2O4 ferrite nano-particles with a crystallite size of about 20 nm were prepared by the conventional hydrothermal method, followed by annealing in a microwave oven for 7.5-15 min. The microstructure and magnetic properties of the samples were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The microwave annealing process has slight effect on the morphology and size of Ni0.6Zn0.4Fe2O4 ferrite nano-particles. However it reduces the lattice parameter and enhances the densification of the particles, and then greatly increases the saturation magnetization (50-56 emu/g) and coercive force of the samples as compared to the non-annealing condition. The microwave annealing process is an effective way to rapidly synthesize high performance ferrite nano-particle.

  13. Structural, dielectric and magnetic properties of NiFe2O4 prepared via sol-gel auto-combustion method

    NASA Astrophysics Data System (ADS)

    Sun, Li; Zhang, Ru; Wang, Zhenduo; Ju, Lin; Cao, Ensi; Zhang, Yongjia

    2017-01-01

    Nickelferrite (NiFe2O4)powders were synthesized via sol-gel auto-combustion method and the corresponding temperature dependence of microstructure, dielectric and magnetic properties have been investigated. Results of XRD and SEM indicate that the NiFe2O4 samples exhibit a typical single phase spinel structure and a uniform particle distribution. The dielectric constant and dielectric loss measurements show strong frequency dependence of all the samples. The peak observed in frequency dependence of dielectric loss measurements shifts to higher frequency with the increasing sintering temperature, indicating a Debye-like dielectric relaxation. The remanent magnetization increases with the increasing grain size while the coercivity is just the opposite. The saturation magnetization can achieve 50 emu/g when the sintering temperature is more than 1000 °C, and the lowest coercivity (159.49 Oe) was observed in the NFO sample sintered at 1300 °C for 2 h.

  14. Synthesis and Characterization of Pure Ni and Ni-Sn Intermetallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Yakymovych, A.; Ipser, H.

    2017-02-01

    The present research focused on the synthesis of Ni and Ni-Sn nanoparticles via a chemical reduction method using hydrazine hydrate. The syntheses were performed applying highly purified water or diethylene glycol as solvent. The produced nanoparticles were characterized by scanning electron microscopy and powder X-ray diffraction. The as-synthesized Ni-Sn nanoparticles with nominal starting ratios Ni:Sn = 3:1, 3:2, and 3:4 consisted of different amounts of pure Ni and a low-temperature Ni3Sn2 phase. It was found that all synthesized nanopowders had a spherical shape with the largest average size for pure Ni and decreasing size for particles containing Sn. X-ray diffraction showed that all synthesized nanoparticles contained Ni and a low-temperature Ni3Sn2 phase independent of the initial molar ratio; while Ni3Sn and Ni3Sn4 could not be detected.

  15. Effects of Varied Cleaning Methods on Ni-5% W Substrate for Dip-Coating of Water-based Buffer Layers: An X-ray Photoelectron Spectroscopy Study

    PubMed Central

    Narayanan, Vyshnavi; Bruneel, Els; Hühne, Ruben; van Driessche, Isabel

    2012-01-01

    This work describes various combinations of cleaning methods involved in the preparation of Ni-5% W substrates for the deposition of buffer layers using water-based solvents. The substrate has been studied for its surface properties using X-ray photoelectron spectroscopy (XPS). The contaminants in the substrates have been quantified and the appropriate cleaning method was chosen in terms of contaminants level and showing good surface crystallinity to further consider them for depositing chemical solution-based buffer layers for Y1Ba2Cu3Oy (YBCO) coated conductors.

  16. Synthesis of nanocrystalline NiCuZn ferrite powders by sol-gel auto-combustion method

    NASA Astrophysics Data System (ADS)

    Yue, Zhenxing; Zhou, Ji; Li, Longtu; Zhang, Hongguo; Gui, Zhilun

    2000-01-01

    A nitrate-citrate gel was prepared from metal nitrates and citric acid by sol-gel process, in order to synthesize Ni 0.25Cu 0.25Zn 0.50Fe 2O 4 ferrite. The thermal decomposition process was investigated by DTA-TG, IR and XRD techniques. The results revealed that the nitrate-citrate gel exhibits self-propagating combustion behavior. After combustion, the gel directly transformed into single-phase, nano-sized NiCuZn ferrite particles with spinel crystal structure. The synthesized powder can be densified at a temperature lower than 900°C. The sintered body possesses fine-grained microstructure, good frequency stability and high-quality factor compared to the sample prepared by conventional ceramic route.

  17. Stability vs. reactivity: understanding the adsorption properties of Ni3(BTP)2 by experimental and computational methods.

    PubMed

    Shearer, Greig C; Colombo, Valentina; Chavan, Sachin; Albanese, Elisa; Civalleri, Bartolomeo; Maspero, Angelo; Bordiga, Silvia

    2013-05-14

    FTIR spectroscopy and ab initio molecular modelling have been employed to probe the interaction between CO and Ni3(BTP)2, a thermally and chemically stable MOF. A combination of low pressure adsorption isotherms and FTIR spectroscopy has been utilised to study the material for its interaction with CO2 and H2. The experimental results indicate that despite an abundance of Ni(2+) coordination vacancies in the activated sample, the molecular probes considered in this study do not interact with them. These findings are in alignment with the data obtained by molecular modelling, in which it is shown that the unreactive diamagnetic, low spin state is more stable. Due to the strong N-donor character of the pyrazolate ligands on this material, the electrostatic potential map of the optimized low spin structure does not show any evidence of a region of positive potential typical of open metal sites.

  18. Dry reforming of methane over Ni/MgO-Al2O3 catalysts prepared by two-step hydrothermal method

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Zhang, Qian; Liu, Yi; Zhang, Yi

    2016-12-01

    Carbon dioxide reforming of methane has been investigated on a series of Ni/MgO-Al2O3 catalysts prepared by a simple two-step hydrothermal method. The sheet-like Ni/MgO-Al2O3 (15%) catalyst afforded as high as 52% CH4 conversion, which is almost six times higher than that of original Ni/MgO catalyst, with excellent stability during reaction, at relatively higher space velocity (6 × 105 cm3•g cat -1rad H-1) and lower reaction temperature (923 K). The effects of different ratio of Mg and Al have been investigated to understand the catalytic activity and coke formation for the obtained catalysts. The characterization results show that the addition Al2O3 to MgO would contribute to forming MgAl2O4 phase, which is stable and could effectively increase the CO2 adsorption due to the increased basic sites on the surface of catalyst, contributing to higher catalytic activity and better stability of this kind of catalyst during the dry reforming reaction. The catalysts were characterized by different techniques, such as BET, H2-TPR, XRD, SEM, CO2-TPD, TG-DTA and TEM analysis.

  19. The role of nano-Ni catalyst in MgH2 obtained by reactive mechanical milling method for solid hydrogen storage application

    NASA Astrophysics Data System (ADS)

    Jalil, Zulkarnain; Rahwanto, Adi; Handoko, Erfan; Mustanir

    2017-03-01

    Magnesium (Mg) is regarded as one of the candidate material for absorbing hydrogen, because theoretically, has the ability to absorb hydrogen in the large quantities (7.6 wt%). However, Mg has shortage, namely its kinetic reaction is very slow, it takes time to absorb hydrogen at least 60 minutes with very high operating temperatures (300-400°C). The aim of this study is to improve the hydrogen desorption temperature of Mg-based hydrogen storage material. In this work, we used nano-nickel (Ni) as catalyst in MgH2 and obtained by reactive mechanical milling method. The duration of milling was done in 2 hours (soft milling) with the 2 mol% Ni catalyst and milled under hydrogen atmosphere (10 bar). As the results, small amount of 2 mol% Ni in nanometer scale acts as a suitable catalyst for improvement the kinetics of MgH2 which could absorp 5.5 wt% of hydrogen within 10 minutes at 300°C. It is obvious that small amount has much better as catalyst in nanoparticle size and at the same time allowed to reduce the milling process in short time.

  20. Modified section method for laser-welding of ill-fitting cp Ti and Ni-Cr alloy one-piece cast implant-supported frameworks.

    PubMed

    Tiossi, R; Falcão-Filho, H; Aguiar Júnior, F A; Rodrigues, R C; Mattos, M da G; Ribeiro, R F

    2010-05-01

    This study aimed to verify the effect of modified section method and laser-welding on the accuracy of fit of ill-fitting commercially pure titanium (cp Ti) and Ni-Cr alloy one-piece cast frameworks. Two sets of similar implant-supported frameworks were constructed. Both groups of six 3-unit implant-supported fixed partial dentures were cast as one-piece [I: Ni-Cr (control) and II: cp Ti] and evaluated for passive fitting in an optical microscope with both screws tightened and with only one screw tightened. All frameworks were then sectioned in the diagonal axis at the pontic region (III: Ni-Cr and IV: cp Ti). Sectioned frameworks were positioned in the matrix (10-Ncm torque) and laser-welded. Passive fitting was evaluated for the second time. Data were submitted to anova and Tukey-Kramer honestly significant difference tests (P < 0.05). With both screws tightened, one-piece cp Ti group II showed significantly higher misfit values (27.57 +/- 5.06 microm) than other groups (I: 11.19 +/- 2.54 microm, III: 12.88 +/- 2.93 microm, IV: 13.77 +/- 1.51 microm) (P < 0.05). In the single-screw-tightened test, with readings on the opposite side to the tightened side, Ni-Cr cast as one-piece (I: 58.66 +/- 14.30 microm) was significantly different from cp Ti group after diagonal section (IV: 27.51 +/- 8.28 microm) (P < 0.05). On the tightened side, no significant differences were found between groups (P > 0.05). Results showed that diagonally sectioning ill-fitting cp Ti frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves passivity levels of the same frameworks when compared to one-piece cast structures.

  1. Synthesis of highly ordered 30 nm NiFe2O4 particles by the microwave-combustion method

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. H.; Elshahawy, A. M.; Makhlouf, Salah A.; Hamdeh, H. H.

    2014-11-01

    NiFe2O4 of 30 nm average size was synthesized by microwave combustion and subsequent solid state reaction at 1273 K. The materials were characterized by X-ray diffraction, TEM, vibrating sample magnetometery and Mössbauer spectroscopy. The microwave combustion produced materials were comprised chemically of ferrites and a smaller amount of hematite. The NiFe2O4 particles have the cubic spinel structure with crystallites of sizes less than 10 nm, and were found to have low magnetization, and essentially no hysteresis loop; characteristics of superparamagnetism. Upon annealing at temperatures 973 K and below, crystallite growth was accompanied by increase in both coercive field and magnetization. The coercive field was a maximum for the sample annealed at 973 K. On the other hand, crystallite growth at higher annealing temperatures yielded mainly ferrites and improvement in soft magnetic properties. Mössbauer and magnetization measurements indicate that the fine NiFe2O4 particles produced at the annealing temperature of 1273 K are in good chemical and magnetic order, excluding the spins arrangement at the surface of the particles which show spin glass-like behavior.

  2. Preparation and property of duplex Ni-B-TiO2/Ni nano-composite coatings

    NASA Astrophysics Data System (ADS)

    Wang, Shu-Jen; Wang, Yuxin; Shu, Xin; Tay, Seeleng; Gao, Wei; Shakoor, R. A.; Kahraman, Ramazan

    2015-03-01

    The duplex Nickel-Boron-Titania/Nickel (Ni-B-TiO2/Ni) coatings were deposited on mild steel by using two baths with Ni as the inner layer. TiO2 nanoparticles were incorporated into the Ni-B coatings as the outer layer by using solid particle mixing method. The microstructure, morphology and corrosion resistance of the duplex Ni-B-TiO2/Ni nanocomposite coatings were systemically investigated. The results show that the duplex interface was uniform and the adhesion between two layers was very good. The microhardness of duplex Ni-B-TiO2/Ni coating was much higher than the Ni coating due to the outer layer of Ni-B-TiO2 coating. The corrosion resistance of the duplex Ni-B-TiO2/Ni coating was also significantly improved comparing with single Ni-B coating. The Ni-B-10 g/L TiO2/Ni coating was found to have the best corrosion resistance among these duplex coatings. This type of duplex Ni-B-TiO2/Ni coating, with high hardness and good corrosion resistance properties, should be able to find broad applications under adverse environmental conditions.

  3. HAp/Ti2Ni coatings of high bonding strength on Ti-6Al-4V prepared by the eutectic melting bonding method.

    PubMed

    Ye, Ya-Jing; Wang, Peng-Yan; Li, Ya-Peng; Yin, Da-Chuan

    2015-02-01

    Eutectic melting bonding (EMB) method is a useful technique for fabricating bioactive coatings with relatively high crystallinity and bonding strength with substrate on titanium substrates. Using the EMB method, hydroxyapatite/Ti2Ni coatings were prepared on the surface of Ti-6Al-4V at a relatively low temperature (1,050 °C) in a vacuum furnace. The coatings were then characterized in terms of phase components, microstructure, bonding strength and cytotoxicity. The results showed that the coatings were mainly composed of HAp and Ti2Ni, and the thickness of the coatings was approximately 300 μm. X-ray diffraction analysis showed that the coatings exhibited relatively high crystallinity. The tensile bonding strength between the coatings and the substrates was 69.68±5.15 MPa. The coatings had a porous and rough surface which is suitable for cell attachment and filopodia growth. The cell culture study showed that the number of MG-63 cells increased, and the cell morphology changed with the incubation time. This study showed that the EMB method can be utilized as a potentially powerful method to obtain high quality hydroxyapatite coatings with desired mechanical and biocompatibility properties on Ti-alloy substrates.

  4. Effects of preparation method on the performance of Ni/Al(2)O(3) catalysts for hydrogen production by bio-oil steam reforming.

    PubMed

    Li, Xinbao; Wang, Shurong; Cai, Qinjie; Zhu, Lingjun; Yin, Qianqian; Luo, Zhongyang

    2012-09-01

    Steam reforming of bio-oil derived from the fast pyrolysis of biomass is an economic and renewable process for hydrogen production. The main objective of the present work has been to investigate the effects of the preparation method of Ni/Al(2)O(3) catalysts on their performance in hydrogen production by bio-oil steam reforming. The Ni/Al(2)O(3) catalysts were prepared by impregnation, co-precipitation, and sol-gel methods. XRD, XPS, H(2)-TPR, SEM, TEM, TG, and N(2) physisorption measurements were performed to characterize the texture and structure of the catalysts obtained after calcination and after their subsequent use. Ethanol and bio-oil model compound were selected for steam reforming to evaluate the catalyst performance. The catalyst prepared by the co-precipitation method was found to display better performance than the other two. Under the optimized reaction conditions, an ethanol conversion of 99% and a H(2) yield of 88% were obtained.

  5. Controlled study of the frequency of anti-HSP 70 with the ELISA and the Western Blot methods in patients with Ménière Disease.

    PubMed

    Wiederkehr Baú, Anne-Rose L; Lavinsky, Luiz; Bonorino, Cristina; Munari, Leonardo; Lavinsky-Wolff, Michelle; Wolff, Fernando Herz

    2011-01-01

    To establish the frequency of auto-antibodies anti-HSP 70 using ELISA and Western Blot (WB) methods and to compare the results of each method among patients with the Ménière's Disease (MD) and internal ear diseases (IED) who do not fulfill criteria for MD. Sensibility, specificity and predictive values of anti-HSP70 test in diagnosis of MD were calculated. Prospective, case-control. Blood samples were collected from 31 patients with MD and 78 patients with non Ménière IED. Data regarding cochlear and vestibular symptoms were obtained and blood sample was tested. ELISA tests results were positive in 4(13%) patients and results of WB were positive in 8(26%) patients. Among patients with positive ELISA results, 1 patient presented active disease and in the remaining 3 patients the disease was inactive. Among the 8 WB positive patients, only 2 patients presented active disease. Statistical analyses did not establish any association between serologic findings and clinical factors of MD. The presence of anti-HSP70 using the ELISA and the WB methods did not demonstrate clinical value for the diagnosis of MD. We did not find association between idiopathic MD nor unspecific etiology MD and the presence of anti-HSP70 auto-antibodies.

  6. Density functional theory study of the interfacial properties of Ni/Ni3Si eutectic alloy

    NASA Astrophysics Data System (ADS)

    Zhao, Yuhong; Wen, Zhiqin; Hou, Hua; Guo, Wei; Han, Peide

    2014-06-01

    In order to clarify the heterogeneous nucleation potential of α-Ni grains on Ni3Si particles in Ni-Ni3Si eutectic alloy, the work of adhesion (Wad), fracture toughness (G), interfacial energy (γi), and electronic structure of the index (0 0 1), (1 1 0) and (1 1 1) Ni/Ni3Si interfaces with two different cohesive manners are investigated using first-principles method based on density functional theory. Results indicate that the center site stacking sequence (OM) is preferable to continue the natural stacking sequence of bulk Ni and Ni3Si. Since OM stacking interfaces have larger Wad, G and γi than that of the top site stacking (OT) interfaces. The Ni/Ni3Si (1 1 0) interface with OM stacking has the best mechanical properties. Therefore, the formation of this interface can improve the stability, ductility and fracture toughness of Ni-Ni3Si eutectic alloy. The calculated interfacial energy of Ni/Ni3Si (0 0 1), (1 1 0) and (1 1 1) interfaces with OM stacking proves the excellent nucleation potency of Ni3Si particles for α-Ni phase from thermodynamic considerations. Besides, the electronic structure and chemical bonding of (1 1 0) interface with OM stacking are also discussed.

  7. Structural, magnetic and optical characterization of Ni0.8Zn0.2Fe2O4 nano particles prepared by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Kannan, Y. B.; Saravanan, R.; Srinivasan, N.; Praveena, K.; Sadhana, K.

    2016-12-01

    Bond strength values, between tetrahedral sites and octahedral sites atoms in the unit cell, are evaluated using maximum entropy method (MEM) for the Ni0.8Zn0.2Fe2O4 nano ferrite particles, prepared by co-precipitation method and sintered at 900 °C. The spinel structure is confirmed from the XRD analysis done using the Rietveld method. Substitution of zinc ion causes increase in lattice parameter value. Thermal behavior, morphology, magnetic properties and optical band gap energy values of the sample are determined by using thermogravimetric analysis and differential thermal analysis, scanning electron microscope, vibrating sample magnetometer and UV-VIS-NIR techniques respectively. Low value of saturation magnetization is attributed to the disorder in cation distribution.

  8. MgCoAl and NiCoAl LDHs synthesized by the hydrothermal urea hydrolysis method: Structural characterization and thermal decomposition

    SciTech Connect

    Chagas, L.H.; De Carvalho, G.S.G.; Do Carmo, W.R.; San Gil, R.A.S.; Chiaro, S.S.X.; Leitão, A.A.; Diniz, R.; De Sena, L.A.; Achete, C.A.

    2015-04-15

    Highlights: • We synthesized MgCoAl and NiCoAl LDHs by the urea hydrolysis method. • Aluminum rich and crystalline materials have been formed. • The calcination of the LDHs generated mixed oxides with high surface areas. - Abstract: Layered double hydroxides (LDHs) with Mg/Co/Al and Ni/Co/Al were synthesized for the first time by the urea hydrolysis method. The experimental conditions promoted aluminum rich and crystalline materials. The formation of LDHs was investigated by powder X-ray diffraction (XRD), chemical analysis, solid state nuclear magnetic resonance with magic angle spinning ({sup 27}Al-MAS-NMR), simultaneous thermogravimetric/differential thermal analysis (TGA/DTA), FTIR spectroscopy, scanning electron microscopy (SEM), and N{sub 2} adsorption–desorption experiments. A single phase corresponding to LDH could be obtained in all the investigated compositions. Thermal calcination of these LDHs at 500 °C resulted in the formation of solid solutions in which Al{sup 3+} was dissolved. All the calcined materials have rock-salt like structures and high surface areas.

  9. Synthesis and magnetic studies of Ni/NiO core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    Rinsha, C.; Anumol, C. N.; Chithra, M.; Sahu, B. N.; Sahoo, Subasa C.

    2015-06-01

    Ni/NiO core/shell nanoparticles were synthesized by chemical reduction method followed by oxidation by two different methods; (a) in air and (b) in microwave oven. Structural studies showed that the thickness of NiO shell on Ni core is less in air oxidized sample than the microwave oxidized samples which were supported by the magnetic studies. The samples prepared by air oxidation showed positive exchange biasing where as the samples prepared by microwave oxidation showed negative exchange biasing. Our study also showed that the thickness of the antiferromagnetic NiO is responsible for the different types of magnetic interactions at the interfaces between antiferromagnetic NiO and ferromagnetic Ni in Ni/NiO core/shell nanoparticles.

  10. Useful Method for the Preparation of Low-Coordinate Nickel(I) Complexes via Transformations of the Ni(I) Bis(amido) Complex K{Ni[N(SiMe3)(2,6- (i) Pr2-C6H3)]2}

    PubMed

    Lipschutz, Michael I; Tilley, T Don

    2014-10-13

    A convenient method of preparing two- and three-coordinate Ni(I) complexes of the form L-Ni(I)-X (L = P (t) Bu3, P (i) Pr3, DPPE, NHC; X = -N(SiMe3)(2,6- (i) Pr-C6H3), -O(2,6- (t) Bu2-4-Me-C6H2)) is reported. Protonation of the easily prepared anionic Ni(I) bis(amido) complex K{Ni[N(SiMe3)(2,6- (i) Pr-C6H3)]2} in the presence of an appropriate L-type ligand results in loss of HN(SiMe3)(2,6- (i) Pr-C6H3) and trapping of the resulting neutral Ni(I)-amido fragment to yield neutral, paramagnetic, two- and three-coordinate Ni(I) complexes. Protonation of these neutral amido complexes by the bulky phenol HO(2,6- (t) Bu2-4-Me-C6H2) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni(I)-O(2,6- (t) Bu2-4-Me-C6H2) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = P (t) Bu3, a poor π-acceptor, the phenoxide acts as a π-acceptor and adopts a η(5)-bonding mode through dearomatization of the phenyl ring. When L = NHC, a competent π-acceptor, the phenoxide acts as a π-donor, adopting a η(1)-bonding mode through the O atom. The modular nature of this synthetic strategy allows variation of both the L- and X-type ligands of the complex in a stepwise fashion and should be extendable to a wide variety of ligand types for new Ni(I) complexes.

  11. Synthesis and catalytic performance of SiO2@Ni and hollow Ni microspheres

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Liu, Yanhua; Shi, Xueting; Yu, Zhengyang; Feng, Libang

    2016-11-01

    Nickel (Ni) catalyst has been widely used in catalytic reducing reactions such as catalytic hydrogenation of organic compounds and catalytic reduction of organic dyes. However, the catalytic efficiency of pure Ni is low. In order to improve the catalytic performance, Ni nanoparticle-loaded microspheres can be developed. In this study, we have prepared Ni nanoparticle-loaded microspheres (SiO2@Ni) and hollow Ni microspheres using two-step method. SiO2@Ni microspheres with raspberry-like morphology and core-shell structure are synthesized successfully using SiO2 microsphere as a template and Ni2+ ions are adsorbed onto SiO2 surfaces via electrostatic interaction and then reduced and deposited on surfaces of SiO2 microspheres. Next, the SiO2 cores are removed by NaOH etching and the hollow Ni microspheres are prepared. The NaOH etching time does no have much influence on the crystal structure, shape, and surface morphology of SiO2@Ni; however, it can change the phase composition evidently. The hollow Ni microspheres are obtained when the NaOH etching time reaches 10 h and above. The as-synthesized SiO2@Ni microspheres exhibit much higher catalytic performance than the hollow Ni microspheres and pure Ni nanoparticles in the catalytic reduction of methylene blue. Meanwhile, the SiO2@Ni catalyst has high stability and hence it can be recycled for reuse.

  12. Characterization of thioether-linked protein adducts of DNA using a Raney-Ni-mediated desulfurization method and liquid chromatography-electrospray-tandem mass spectrometry.

    PubMed

    Chowdhury, Goutam; Guengerich, F Peter

    2015-03-09

    This unit contains a complete procedure for the detection and structural characterization of DNA protein crosslinks (DPCs). The procedure also describes an approach for the quantitation of the various structurally distinct DPCs. Although various methods have been described in the literature for labile DPCs, characterization of nonlabile adducts remain a challenge. Here we present a novel approach for characterization of both labile and non-labile adducts by the use of a combination of chemical, enzymatic, and mass spectrometric approaches. A Raney Ni-catalyzed reductive desulfurization method was used for removal of the bulky peptide adducts, enzymatic digestion was used to digest the protein to smaller peptides and DNA to nucleosides, and finally LC-ESI-tandem mass spectrometry (MS) was utilized for detection and characterization of nucleoside adducts. Copyright © 2015 John Wiley & Sons, Inc.

  13. Assessing the origin and fate of Cr, Ni, Cu, Zn, Pb, and V in industrial polluted soil by combined microspectroscopic techniques and bulk extraction methods.

    PubMed

    Terzano, Roberto; Spagnuolo, Matteo; Vekemans, Bart; De Nolf, Wout; Janssens, Koen; Falkenberg, Gerald; Fiore, Saverio; Ruggiero, Pacifico

    2007-10-01

    The major geochemical forms of Cr, Ni, Cu, Zn, Pb, and V in a soil from an industrial polluted site in the south of Italy were determined by means of synchrotron X-ray microanalytical techniques such as coupled micro-X-ray fluorescence/micro-X-ray diffraction and micro-X-ray absorption near edge structure spectroscopy in combination with bulk extraction methods (sequential extraction procedures, EDTA extractions, and toxicity leaching characteristic procedure tests). Cr, Ni, Zn, and Cu were found in spinel-type geochemical forms (chromite, trevorite, franklinite, zincochromite, and cuprospinel) and often in association with magnetite and hematite. Vwas mainly present as V(V) associated with iron-oxides or in the form of volborthite [Cu3(OH)2V2O7.2H2O]. Pb was speciated as minium (Pb3O4), lanarkite [Pb2O(SO4)], and, in association with Cr(VI), as crocoite (PbCrO4). In general, despite a high total concentration, metals appear to be speciated for the most part as rather insoluble geochemical forms. However, particular attention should be paid to Zn, Cu, V, and Pb that show non-negligible mobilizable fractions. On the basis of the geochemical forms identified, among others, two major former industrial activities were tentatively ascribed as being responsible for the observed major pollution: polyvinyl chloride and cement-asbestos productions.

  14. Structural and paramagnetic behavior of spinel NiCr2O4 nanoparticles synthesized by thermal treatment method: Effect of calcination temperature

    NASA Astrophysics Data System (ADS)

    Bakar, Syuhada Abu; Soltani, Nayereh; Yunus, W. Mahmood Mat; Saion, Elias; Bahrami, Afarin

    2014-08-01

    Spinel nickel chromite nanoparticles were synthesized using a simple thermal treatment method. The effect of calcination temperatures on the final properties of obtained materials was carefully examined using various characterization techniques.The infrared spectra of nickel chromite (NiCr2O4) revealed the characteristic bonds of metal-oxygen for Nisbnd O and Crsbnd O bands around 600 and 470 cm-1, respectively. The powder X-ray diffraction patterns exhibited the formation of normal spinel phase of NiCr2O4 in the calcination process at temperature between 550 and 850 °C. From transmission electron micrographs, nanosized particles with average size of ~7-64 nm were observed at calcination temperatures of 550-850 °C, respectively. The calcined samples at 750 and 850 °C exhibited paramagnetic behavior with g-factor values of 1.92 and 2.15, peak-to-peak line width of 25.59 and 117.02 Oe and resonance magnetic field of 342.04 and 306.49 Oe, respectively. Variation in the value of g-factor, peak-to-peak line width and resonance magnetic field can be attributed to the dipole-dipole and super exchange interactions.

  15. Structural and impedance studies of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} synthesized by sol-gel method

    SciTech Connect

    Lobo, Laurel Simon Rubankumar, A. Kalainathan, S.

    2016-05-23

    LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} is synthesized by sol-gel method by using succinic acid as chelating agent. X-ray diffraction pattern confirms the material is spinel cubic structure with Fd3m space group. Impedance spectroscopy analysis of spinel LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} was performed under a wide frequency and temperature range of 50 Hz to 5 MHz and 303 K to 783 K respectively. The hopping of the electrons, ionic conductivity and activation energy were analyzed from the relaxation frequency of the imaginary impedance (Z”). The activation energy E{sub a} is calculated from the Arrhenius plots and it is found to be 0.3713 eV, which indicates the existence of oxygen vacancy in the material. Nyquist plot indicates the presence of grain effect in the material and suppression in the grain effect is observed with increasing temperature.

  16. Restoration of Obliterated Numbers on 40NiCrMo4 Steel by Etching Method: Metallurgical and Statistical Approaches.

    PubMed

    Fortini, Annalisa; Merlin, Mattia; Soffritti, Chiara; Garagnani, Gian L

    2016-01-01

    The restoration of obliterated serial numbers is a problem of common occurrence in the forensic field. Among several restoration techniques, chemical etching is the most frequently used. The present research is aimed at studying the restoration of serial numbers, stamped on 40NiCrMo4 steel plates, by means of chemical etching. Microstructural characterization was firstly carried out to study the plastically deformed regions surrounding the marks. The obliteration was performed by controlled removals of material at increasing depths of erasure, and five etching reagents were considered to analyze their sensitivity and effectiveness. Experimental results revealed that Fry's reagent was the most sensitive, able to restore erased marks up to 60 μm under the depth of the imprint. The reagent comprising 25 mL HNO3 and 75 mL H2O provided good results, recovering the major numbers of characters. A descriptive statistical analysis was conducted to study the operator's influence on the recovered marks' identification. © 2015 American Academy of Forensic Sciences.

  17. Inter particle interaction in Ni0.5Zn0.5Fe2O4 prepared by self combustion method

    NASA Astrophysics Data System (ADS)

    Sudheesh, V. D.; Vinesh, A.; Lakshmi, N.; Venugopalan, K.

    2012-06-01

    Ni0.5Zn0.5Fe2O4 has been prepared by self combustion method and studied using X-ray diffraction, Mössbauer spectroscopy and DC magnetization techniques. X-ray diffractogram shows highly crystalline nano sized sample with no impurity phases. The room temperature Mössbauer and magnetization measurements show the co-existence of superparamagnetic and ferrimagnetic particles in the sample. The presence of inter particle interaction is confirmed from the δM(H) curve at 20K. The dependence of magnetic moment below blocking temperature in the field cooling curve indicates that the inter particle interaction is weak in the as prepared sample.

  18. Structural and magnetic properties of nano-sized NiCuZn ferrites synthesized by co-precipitation method with ultrasound irradiation

    NASA Astrophysics Data System (ADS)

    Harzali, Hassen; Saida, Fairouz; Marzouki, Arij; Megriche, Adel; Baillon, Fabien; Espitalier, Fabienne; Mgaidi, Arbi

    2016-12-01

    Sonochemically assisted co-precipitation has been used to prepare nano-sized Ni-Cu-Zn-ferrite powders. A suspension of constituent hydroxides was ultrasonically irradiated for various times at different temperatures with high intensity ultrasound radiation using a direct immersion titanium horn. Structural and magnetic properties were investigated using X-diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), Nitrogen adsorption at 77 K (BET) and Vibrating sample magnetometer (VSM). Preliminary experimental results relative to optimal parameters showed that reaction time t=2 h, temperature θ=90 °C and dissipated Power Pdiss=46.27 W. At these conditions, this work shows the formation of nanocrystalline single-phase structure with particle size 10-25 nm. Also, ours magnetic measurements proved that the sonochemistry method has a great influence on enhancing the magnetic properties of the ferrite.

  19. Improved electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode material synthesized by citric acid assisted sol-gel method for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Lee, Suk-Woo; Kim, Hyungsub; Kim, Myeong-Seong; Youn, Hee-Chang; Kang, Kisuk; Cho, Byung-Won; Roh, Kwang Chul; Kim, Kwang-Bum

    2016-05-01

    A citric acid assisted sol-gel method is employed for synthesizing LiNi0.6Co0.2Mn0.2O2 for use as a cathode material in lithium-ion batteries. The effects of heat-treatment temperature and oxygen atmosphere on the structural and electrochemical properties of LiNi0.6Co0.2Mn0.2O2 are investigated, in order to determine optimal conditions for the synthesis of LiNi0.6Co0.2Mn0.2O2 via the citric acid assisted sol-gel method. In particular, the presence of oxygen in the atmosphere effectively leads to a decrease in the degree of cation mixing and the formation of LiOH and Li2CO3 on the surface of LiNi0.6Co0.2Mn0.2O2. Furthermore, heat-treatment in an oxygen atmosphere improves the uniformity of oxidation state of Ni ions between the surface and bulk. LiNi0.6Co0.2Mn0.2O2 synthesized by heat-treatment at 850 °C under an oxygen atmosphere shows a discharge capacity of 174 mA h g-1 and 89% capacity retention after 100 cycles. In addition, it shows high rate capability (i.e., 41% capacity retention at 10 C), which is an improved rate performance over a previous report. The results of this study should provide useful information for the synthesis of Ni-rich layered oxides for lithium ion batteries.

  20. Effect of modification methods on the surface properties and n-butane isomerization performance of La/Ni-promoted SO42-/ZrO2-Al2O3

    NASA Astrophysics Data System (ADS)

    Wang, Pengzhao; Zhang, Jiaoyu; Han, Chaoyi; Yang, Chaohe; Li, Chunyi

    2016-08-01

    The La and/or Ni was introduced into alumina-promoted sulfated zirconia by impregnation and co-precipitation to improve the catalytic property of n-butane isomerization. Catalysts characterization shows that the addition of La/Ni has a remarkable influence on the surface and textual properties depending on the modification method. The impregnation of La/Ni facilitates the transformation of a small amount of tetragonal zirconia into monoclinic phase, while the co-precipitation improves the stability of tetragonal ZrO2. H2-TPR indicates that the addition of La/Ni changes the interaction between SO42- and supports, which affects the acidity on the surface. Specifically, the Lewis acidity is significantly enhanced by either modification method. The co-precipitation reserves almost all of the Brønsted acid sites, while the impregnation causes a remarkable decrease of Brønsted acid sites. Reaction results demonstrate that the co-precipitation exhibits a significant advantage over impregnation that the higher conversion of n-butane and selectivity to isobutane are obtained on the catalyst prepared by co-precipitation. The increase of catalytic activity is ascribed to the accelerated activation rate of n-butane molecules by hydride subtraction on the Lewis acid sites at higher reaction temperature. Furthermore, the addition of La/Ni improves the selectivity to isobutane by inhibiting the bimolecular reaction.

  1. Comparison of benzene adsorption on Ni(111) and Ni(100)

    SciTech Connect

    Myers, A.K.; Schoofs, G.R.; Benziger, J.B.

    1987-04-23

    The adsorption of benzene on the Ni(100) and the Ni(111) crystal faces was compared in order to investigate the effect of crystallographic orientation on the interaction of benzene with nickel. Temperature programmed reaction (TPR) was used to characterize adsorption bond strengths and determine product distributions. Benzene was found to adsorb 44 kJ/mol less strongly on the Ni(111) plane than on the Ni(100) surface. Di-hydrogen evolution formed after decomposition of benzene was similar for both surfaces. Benzene chemisorption was modeled by using extended Hueckel theory (EHT), a semiempirical molecular orbital method. The calculations predict bonding of benzene over a threefold hollow site on Ni(111). Multicenter bonding of the benzene carbon atoms with the nickel atoms is indicated by the calculations. The binding strength of benzene is controlled by the degree of overlap of the carbon ..pi.. orbitals with the nickel atom orbitals. Benzene binds more strongly to the Ni(100) surface because the carbon ..pi.. orbitals can overlap with four nickel atoms on the fourfold hollow site, whereas on Ni(111) the carbon atoms are closely associated with only three nickel atoms on the threefold hollow site.

  2. Effects of annealing temperature variation on the evolution of structural and magnetic properties of NiFe2O4 nanoparticles synthesized by starch-assisted sol-gel auto-combustion method

    NASA Astrophysics Data System (ADS)

    Singh Yadav, Raghvendra; Havlica, Jaromir; Masilko, Jiri; Kalina, Lukas; Wasserbauer, Jaromir; Hajdúchová, Miroslava; Enev, Vojtěch; Kuřitka, Ivo; Kožáková, Zuzana

    2015-11-01

    Evolution of the structural and magnetic properties of NiFe2O4 nanoparticles synthesized by starch-assisted sol-gel auto-combustion method, and exposed to further annealing at 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C, was evaluated in detail and correlation of these properties explored. The ferrite nanoparticles were characterized by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy and Vibrating Sample Magnetometer. The X-ray diffraction patterns demonstrated single phase formation of NiFe2O4 spinel ferrite nanoparticles at different annealing temperature 200 °C, 400 °C, 600 °C, 800 °C and 1000 °C. The change in crystallite size with increase of annealing temperature is observed. The FE-SEM analysis also indicated an increase of particle size with increase of higher annealing temperature. The change in Raman modes and infrared absorption bands were noticed with change of particle size. The X-ray photoelectron spectroscopy revealed the presence of Ni2+ and Fe3+ at octahedral and tetrahedral sites in NiFe2O4 nanoparticles. The representative sample NiFe2O4 nanoparticles annealed at 400 °C, have mixed cation distribution (Ni0.23+2 Fe0.52+3)[ Ni0.77+2 Fe1.48+3 ]O4. The highest value of coercivity 62.35 Oe and saturation magnetization 34.10 erg/g were obtained at annealing temperature 600 °C and 1000 °C, respectively.

  3. A simple mechanical mixing method for preparation of visible-light-sensitive NiO-CaO composite photocatalysts with high photocatalytic activity.

    PubMed

    Song, Limin; Zhang, Shujuan

    2010-02-15

    Composite photocatalysts composed of NiO and CaO have been prepared via mechanically mixing of the two powders. The as-synthesized NiO-CaO products were characterized by X-ray diffraction (XRD) and UV-vis spectrometry. The experimental results showed that the absorption wavelength range of the mixed NiO-CaO sample was notably extended towards the visible-light region (400-450 nm). Photocatalytic activity of the NiO-CaO composite was evaluated based on the decomposition of methylene blue under visible-light irradiation. The effects of CaO doping and the duration of heat treatment on the durability of the NiO-CaO products have been investigated in detail. Factors influencing photocatalytic activity and the mechanism of photocatalysis were also addressed.

  4. Fabrication of free-standing NiCo{sub 2}O{sub 4} nanoarrays via a facile modified hydrothermal synthesis method and their applications for lithium ion batteries and high-rate alkaline batteries

    SciTech Connect

    Zheng, Qingyun Zhang, Xiangyang; Shen, Youming

    2015-03-15

    Graphical abstract: Hydrothermal-synthesized NiCo{sub 2}O{sub 4} nanoflake arrays exhibit porous structure and high capacity as well as good cycling life for lithium ion batteries and alkaline batteries. - Highlights: • Self-supported NiCo{sub 2}O{sub 4} nanoflake arrays are prepared by a hydrothermal method. • NiCo{sub 2}O{sub 4} nanoflake arrays show high capacity and good cycling life. • Porous nanoflake arrays structure is favorable for fast ion/electron transfer. - Abstract: Self-supported NiCo{sub 2}O{sub 4} nanoflake arrays on nickel foam are prepared by a facile hydrothermal method. The obtained NiCo{sub 2}O{sub 4} nanoflakes with thicknesses of ∼25 nm grow vertically to the nickel foam substrate and form an interconnected porous network with pore diameters of 50–500 nm. As anode material of LIBs, the NiCo{sub 2}O{sub 4} nanoflake arrays show a high initial coulombic efficiency of 76%, as well as good cycling stability with a capacity of 880 mAh g{sup −1} at 0.5 A g{sup −1}, and 523 mAh g{sup −1} at 1.5 A g{sup −1} after 50 cycles. As the cathode of alkaline batteries, a high capacity of 95 mAh g{sup −1} is achieved at 2 A g{sup −1} and 94% retention is maintained after 10,000 cycles. The superior electrochemical performance is mainly due to the unique nanoflake arrays structure with large surface area and shorter diffusion length for mass and charge transport.

  5. Primary combination of phase-field and discrete dislocation dynamics methods for investigating athermal plastic deformation in various realistic Ni-base single crystal superalloy microstructures

    NASA Astrophysics Data System (ADS)

    Gao, Siwen; Rajendran, Mohan Kumar; Fivel, Marc; Ma, Anxin; Shchyglo, Oleg; Hartmaier, Alexander; Steinbach, Ingo

    2015-10-01

    Three-dimensional discrete dislocation dynamics (DDD) simulations in combination with the phase-field method are performed to investigate the influence of different realistic Ni-base single crystal superalloy microstructures with the same volume fraction of {γ\\prime} precipitates on plastic deformation at room temperature. The phase-field method is used to generate realistic microstructures as the boundary conditions for DDD simulations in which a constant high uniaxial tensile load is applied along different crystallographic directions. In addition, the lattice mismatch between the γ and {γ\\prime} phases is taken into account as a source of internal stresses. Due to the high antiphase boundary energy and the rare formation of superdislocations, precipitate cutting is not observed in the present simulations. Therefore, the plastic deformation is mainly caused by dislocation motion in γ matrix channels. From a comparison of the macroscopic mechanical response and the dislocation evolution for different microstructures in each loading direction, we found that, for a given {γ\\prime} phase volume fraction, the optimal microstructure should possess narrow and homogeneous γ matrix channels.

  6. Surface modification of 30CrNiMo8 low-alloy steel by active screen setup and conventional plasma nitriding methods

    NASA Astrophysics Data System (ADS)

    Ahangarani, Sh.; Sabour, A. R.; Mahboubi, F.

    2007-12-01

    In this paper, we report on a comparative study of active screen plasma nitriding (ASPN) and conventional dc plasma nitriding (CPN) behavior of 30CrNiMo8 low-alloy steel that has been examined under various process conditions. The process variables included active screen setup parameters (screen and iron plate top lids placed on the screen setup with 8 mm of hole size), treatment temperature (550 and 580 °C), gas mixture (75/25 and 25/75 of N 2/H 2) and treatment time (5 and 10 h) in 500 Pa pressure. The structure and phases composition of the diffusion zone and compound layer were studied by X-ray diffraction (XRD), microhardness tests, light optical microscopy and scanning electron microscopy (SEM). It was observed that treated sample surfaces in both CPN and ASPN methods consist of γ' and ɛ phases, and while the nitriding time and/or temperature increases, the intensity of ɛ phase in the compound layer will increase for ASPN and decrease for CPN method. Results show that the amount of nitrogen transferred from holes of screen toward the sample surface via sputtering and re-condensation mechanism can be affected due to the hardness and thickness of the layer.

  7. Useful Method for the Preparation of Low-Coordinate Nickel(I) Complexes via Transformations of the Ni(I) Bis(amido) Complex K{Ni[N(SiMe3)(2,6-iPr2-C6H3)]2}

    PubMed Central

    2015-01-01

    A convenient method of preparing two- and three-coordinate Ni(I) complexes of the form L–NiI–X (L = PtBu3, PiPr3, DPPE, NHC; X = −N(SiMe3)(2,6-iPr-C6H3), −O(2,6-tBu2-4-Me-C6H2)) is reported. Protonation of the easily prepared anionic Ni(I) bis(amido) complex K{Ni[N(SiMe3)(2,6-iPr-C6H3)]2} in the presence of an appropriate L-type ligand results in loss of HN(SiMe3)(2,6-iPr-C6H3) and trapping of the resulting neutral Ni(I)-amido fragment to yield neutral, paramagnetic, two- and three-coordinate Ni(I) complexes. Protonation of these neutral amido complexes by the bulky phenol HO(2,6-tBu2-4-Me-C6H2) results in loss of the second amido moiety and trapping by the resulting phenoxide to yield Ni(I)-O(2,6-tBu2-4-Me-C6H2) complexes. The hapticity of the phenoxide ligand is influenced by the π-accepting ability of the L-type ligand. Where L = PtBu3, a poor π-acceptor, the phenoxide acts as a π-acceptor and adopts a η5-bonding mode through dearomatization of the phenyl ring. When L = NHC, a competent π-acceptor, the phenoxide acts as a π-donor, adopting a η1-bonding mode through the O atom. The modular nature of this synthetic strategy allows variation of both the L- and X-type ligands of the complex in a stepwise fashion and should be extendable to a wide variety of ligand types for new Ni(I) complexes. PMID:25328273

  8. Preparation of alumina-iron oxide compounds by gel evaporation method and its simultaneous uptake properties for Ni2+, NH4+ and H2PO4-.

    PubMed

    Gulshan, Fahmida; Kameshima, Yoshikazu; Nakajima, Akira; Okada, Kiyoshi

    2009-09-30

    Fe(2)O(3)/Al(2)O(3) powders with a range of Fe/Al compositions were prepared by a gel evaporation method to investigate the effect of alumina on the product phases, magnetic properties and simultaneous adsorption of Ni(2+) (a model heavy metal cation), NH(4)(+) (a model eutrophication-related cation) and H(2)PO(4)(-) (a model harmful anion). Precursor gels were prepared by dissolving Fe(NO(3))(3).9H(2)O and Al(NO(3))(3).9H(2)O in ethylene glycol, evaporating to dryness, grinding and heating at 300-1000 degrees C for 5h. The crystalline products were gamma-Fe(2)O(3) (maghemite), formed at 300-600 degrees C, or alpha-Fe(2)O(3) (hematite) and AlFeO(3), formed >600 degrees C. The temperatures of the phase change from gamma-Fe(2)O(3) to alpha-Fe(2)O(3) increased with increasing alumina additions. The resulting lattice parameters suggest that Al(3+) is incorporated into these phases up to about 15 mol.% at 300 degrees C, falling to 11 mol.% in the gamma-Fe(2)O(3) formed at 600 degrees C. The alpha-Fe(2)O(3) formed at 700 degrees C contained 6 mol.% Al, increasing to 14 mol.% at 1000 degrees C. The magnetic properties of the samples were measured using a vibrating sample magnetometer. The saturation magnetization values of the gamma-Fe(2)O(3)-containing samples increased with the addition of alumina to a maximum value of 61emu/g in the sample containing 95 mol.% Fe(2)O(3) heated at 400 degrees C. The simultaneous adsorption of Ni(2+), NH(4)(+) and H(2)PO(4)(-) from water was investigated by a batch method. The highest adsorption values were found for the sample containing 80 mol.% Fe(2)O(3) heated at 600 degrees C, which contained both gamma-Fe(2)O(3) and alpha-Fe(2)O(3). It was therefore concluded that the addition of alumina to iron oxide affects the crystalline phases and phase changes, and enhances the simultaneous cation and anion uptake ability of the materials.

  9. Study of microstructural and dielectric properties of Ni substituted BaCo2 hexaferrite prepared by a heat treatment method

    NASA Astrophysics Data System (ADS)

    Chauhan, Chetna; Jotania, Rajshree

    2017-05-01

    Nickel doped barium cobalt hexaferrite samples were prepared using simple heat treatment method. The precursor was calcinated at 650°C for 3 hours and cooled at room temperature in order to obtain barium cobalt hexaferrite. The prepared hexaferrites were characterized by various experimental techniques like Fourier Transform Infrared Spectroscopy (FTIR) and Dielectric measurements. The FTIR spectra was recorded at room temperature using KBr pallet method. The FTIR result confirms the formation of ferrite phase. The dielectric measurements were carried out at room temperature between the frequency ranges of 100 Hz to 2 MHz. The dispersion of real dielectric constant is more at lower frequencies compared to that at higher frequencies, which can very well be explained on the basis of Maxwell Wagner model. The dielectric loss peak is observed at higher frequencies with increase in the cobalt content.

  10. Performance of Simulated El Niño-Southern Oscillation Climate Reconstructions over the Last Millennium: Comparison of Methods

    NASA Astrophysics Data System (ADS)

    Wahl, Eugene R.; Amrhein, Dan E.; Smerdon, Jason E.; Ammann, Caspar M.

    2010-05-01

    A key question in late-Holocene climate dynamics is the role of dominant modes in influencing climates in teleconnected regions of the world. For example, it has recently been proposed that ENSO had a key role in influencing the extended period of largely positive-phase NAO during ~1100-1400 CE (Trouet et al., 2009, Science, 324, 78). Fundamental to understanding the global and regional climatological roles of dominant modes are primary data on the variations of the modes themselves, in particular paleoclimate data that greatly extend instrumental-period information. Establishing records of ENSO indices that span the past millennium has proven difficult, and well-verified reconstructions produced to date have non-trivial differences (cf., e.g., Braganza et al., 2009, Journal of Geophysical Research, 114, D05106). This presentation examines important general questions regarding reconstructions of modal indices, including ENSO: is it best (1) to focus on proxy evidence from the most strongly influenced (or most strongly teleconnected) areas, (2) to combine proxy data from a large regional network encompassing the primary area of modal activity and teleconnections (e.g., around the Pacific Rim in the case of ENSO), or (3) to use climate field reconstruction (CFR) methods that assimilate up-to-global-scale proxy information? A systematic suite of reconstruction simulation experiments (RSEs), derived from NCAR CSM 1.4 millennium transient model output, is explored to test the various strengths and weaknesses of these three approaches for reconstructing the NINO3 index. By doing this, NINO3 reconstruction fidelity can be gauged over the entire simulated millennium via comparison to the known model target; such comparisons are restricted to brief "validation" periods in real-world reconstructions due to the length of the instrumental record. For strategies (1) and (2), pseudoproxies are formed by adding white noise to the model output (seasonally-appropriate precipitation

  11. Phase and structural states in the NiTi-based alloy surface layer formed by electron-ion-plasma methods using tantalum

    SciTech Connect

    Neiman, Aleksei A. Lotkov, Aleksandr I.; Gudimova, Ekaterina Y.; Meisner, Ludmila L. Semin, Viktor O.

    2015-10-27

    The paper reports on a study of regularities of formation gradient nano-, submicron and microstructural conditions in the surface layers of the samples after pulsed electron-beam melting of tantalum coating on the substrate NiTi alloy. Experimentally revealed the presence of submicron columnar structure in the upper layers of the tantalum coating. After irradiation modified NiTi surface takes on a layered structure in which each layer differs in phase composition and structural phase state.

  12. Phase and structural states in the NiTi-based alloy surface layer formed by electron-ion-plasma methods using tantalum

    NASA Astrophysics Data System (ADS)

    Neiman, Aleksei A.; Meisner, Ludmila L.; Lotkov, Aleksandr I.; Gudimova, Ekaterina Y.; Semin, Viktor O.

    2015-10-01

    The paper reports on a study of regularities of formation gradient nano-, submicron and microstructural conditions in the surface layers of the samples after pulsed electron-beam melting of tantalum coating on the substrate NiTi alloy. Experimentally revealed the presence of submicron columnar structure in the upper layers of the tantalum coating. After irradiation modified NiTi surface takes on a layered structure in which each layer differs in phase composition and structural phase state.

  13. Synthesis and characterization of magnetic of Ni/ABS nanocomposites by electrical explosion of wire in liquid and solution blending methods

    NASA Astrophysics Data System (ADS)

    Thuyet-Nguyen, Minh; Hai-Nguyen, Hong; Kim, Won Joo; Kim, Ho Yoon; Kim, Jin-Chun

    2017-03-01

    Nanomaterials have attracted great attention from chemists, physicists and materials scientists because of their application benefits and special properties. Thermoplastics have been used in many applications such as molding of non-electrical components, conducting, magnetic field and 3D printing. Nanocomposites are known as a material which blends the best properties of components, a high performance material exhibits unusual property combinations and unique design possibilities. In this research, we focused to investigate and report primary results in the synthesis of magnetic nanocomposites based on acrylonitrile butadiene styrene (ABS), which are useful and important thermoplastics. Nickel nanopowder was prepared by electrical explosion of wire in a liquid were used as magnetic component. The composites were prepared by following steps, first the obtained Ni nanopowders were incorporated into the ABS matrix via a solution blending method (drop-casting), and then the solvent was evaporated. The characterizations of obtaining composites were analyzed by field emission scanning electron microscopy, X-Ray Diffraction analysis and vibrating sample magnetometer.

  14. Homogeneous Ni catalysts for H2 Oxidation and Production: An Assessment of Theoretical Methods, from Density Functional Theory to Post Hartree-Fock Correlated Wave-Function Theory

    SciTech Connect

    Chen, Shentan; Raugei, Simone; Rousseau, Roger J.; Dupuis, Michel; Bullock, R. Morris

    2010-12-09

    A systematic assessment of theoretical methods applicable to the accurate characterization of catalytic cycles of homogeneous catalysts for H2 oxidation and evolution is reported. For these catalysts, H2 bond breaking or formation involve di-hydrogen, di-hydride, hydride-proton, and di-proton complexes. The key elementary steps have heterolytic character. In the context of Density Functional Theory (DFT) we investigated the use of functionals in the generalized gradient approximation (GGA) as well as hybrid functionals. We compared the results with wavefunction theories based on perturbation theory (MP2 and MP4) and on coupled-cluster expansions (CCSD and CCSD(T)). Our findings suggest that DFT results based on Perdew functionals are in semi-quantitative agreement with the CCSD(T) results, with deviations of a few kcal/mol only. On the other hand, the B3LYP functional is not even in qualitative agreement with CCSD[T]. Surprisingly the MP2 results are found to be extremely poor, a finding that we attribute to the limited treatment in MP2 theory of dynamic electron correlation effects in Ni(0) oxidation state. This material is based upon work supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

  15. Microstructure and magnetic properties of MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

    SciTech Connect

    Wang, Wei Ding, Zui; Zhao, Xiruo; Wu, Sizhu; Li, Feng; Yue, Ming; Liu, J. Ping

    2015-05-07

    Three kinds of spinel ferrite nanocrystals, MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH{sub 4}) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (M{sub s}). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.

  16. Template method to controllable synthesis 3D porous NiCo2O4 with enhanced capacitance and stability for supercapacitors.

    PubMed

    Bai, Yang; Wang, Ranran; Lu, Xiaoyu; Sun, Jing; Gao, Lian

    2016-04-15

    We present a facile template method to fabricate NiCo2O4 (NCO) composites with 3D porous structure as electrodes for supercapacitors. SiO2 sol is used as the template to prevent the aggregation of NCO and construct the porous structure with high specific surface area. Meanwhile, the binary metal oxides not only inherit the merits of single nickel oxides or cobalt oxides, but also show superior properties to promote the capacitance. The uniform structure of NCO12 (SiO2/NCO=1:2) is obtained through controlling the mass ratio of SiO2 and NCO. Owing to the dual advantages of porous structure and binary system, NCO12 composites exhibit highly enhanced electrochemical performance compared with those of directly prepared NCO, NCO21 (SiO2/NCO=1:0.5) and NCO14 (SiO2/NCO=1:4). The specific capacitance of NCO12 composite is about 1389 Fg(-1) at 1 Ag(-1). At 4 Ag(-1), the capacitance is still as high as 1090 Fg(-1) together with capacitance retention of 80% over 2500 cycles. The capacitance and stability are higher than those of most previously reported pure NCO composites, which make it a very promising electrode material for energy storage.

  17. Surface Tension and Viscosity of the Ni-Based Superalloys LEK94 and CMSX-10 Measured by the Oscillating Drop Method on Board a Parabolic Flight

    NASA Astrophysics Data System (ADS)

    Wunderlich, Rainer K.; Fecht, Hans-Jörg; Lohöfer, Georg

    2017-02-01

    The surface tension and viscosity of the Ni-based superalloys LEK94 and CMSX-10 were measured by the oscillating drop method in a containerless electromagnetic processing device on board a parabolic flight airplane. Surface oscillations were recorded by 150 and 200 Hz frame rate digital cameras positioned in two perpendicular directions and by the inductive coupling between the oscillating sample surface and the oscillating circuit of the radio frequency heating and positioning generator. The surface tension as a function of temperature of LEK94 and CMSX-10 was obtained as σ( T) = 1.73 - 4.51 × 10-4 [ T—1656 K (1383 °C)] Nm-1 and σ( T) = 1.71 - 5.80 × 10-4 [( T—1683 K (1410 °C)] Nm-1, respectively. The viscosity at the liquidus temperatures as 9.8 and 7.8 mPa.s, respectively. In addition, some basic thermophysical properties such as solidus and liquidus temperatures, densities at room temperature, and thermal expansion in the solid phase are reported.

  18. New methods for the preparation and dielectric properties of La{sub 2−x}Sr{sub x}NiO{sub 4} (x = 1/8) ceramic

    SciTech Connect

    Chupakhina, T.I.; Kadyrova, N.I.; Melnikova, N.V.; Gyrdasova, O.I.; Yakovleva, E.A.; Zainulin, Yu.G.

    2016-05-15

    Highlights: • A new fuel in solution combustion synthesis of fine powder La{sub 15/8}Sr{sub 1/8}NiO{sub 4}. • Changes in the morphology of the ceramic La{sub 15/8}Sr{sub 1/8}NiO{sub 4} after thermobaric treatment. • Changes in structural parameters of the La{sub 15/8}Sr{sub 1/8}NiO{sub 4} after thermobaric treatment. • Increase of the dielectric constant of the thermobaric treated ceramic La{sub 15/8}Sr{sub 1/8}NiO{sub 4}. • Using of dielectric modulus and impedance formalisms, of equivalent circuits method. - Abstract: The perovskite-type oxide La{sub 2−x}Sr{sub x}NiO{sub 4} (x = 1/8) was prepared by a new precursor route. The reaction proceeds in the self-ignition mode. Single-phase powder and gas-tight ceramic samples can be produced by single annealing of decomposition products. It was shown that as a result of thermobaric treatment of La{sub 2−x}Sr{sub x}NiO{sub 4} (x = 1/8) the solid solution La{sub 2−x}Sr{sub x}NiO{sub 4} with a higher concentration of strontium and the second phase La{sub 3}Ni{sub 2}O{sub 7} are formed. Short-term (5 min) thermobaric treatment (P = 2.5 GPa) at t° = 900 °C changes the unit cell parameters, but is not accompanied by structural transitions. At the same time, morphological restructuring of the sample occurs—the agglomerates delaminate into thin plates crystals. It was established that the permittivity of the material exposed to thermobaric treatment is much higher compared to that of the sample annealed at atmospheric pressure and virtually does not depend on frequency in a wide temperature range.

  19. Effect of SiO 2-ZrO 2 supports prepared by a grafting method on hydrogen production by steam reforming of liquefied natural gas over Ni/SiO 2-ZrO 2 catalysts

    NASA Astrophysics Data System (ADS)

    Seo, Jeong Gil; Youn, Min Hye; Song, In Kyu

    SiO 2-ZrO 2 supports with various zirconium contents are prepared by grafting a zirconium precursor onto the surface of commercial Carbosil silica. Ni(20 wt.%)/SiO 2-ZrO 2 catalysts are then prepared by an impregnation method, and are applied to hydrogen production by steam reforming of liquefied natural gas (LNG). The effect of SiO 2-ZrO 2 supports on the performance of the Ni(20 wt.%)/SiO 2-ZrO 2 catalysts is investigated. SiO 2-ZrO 2 prepared by a grafting method serves as an efficient support for the nickel catalyst in the steam reforming of LNG. Zirconia enhances the resistance of silica to steam significantly and increases the interaction between nickel and the support, and furthermore, prevents the growth of nickel oxide species during the calcination process through the formation of a ZrO 2-SiO 2 composite structure. The crystalline structures and catalytic activities of the Ni(20 wt.%)/SiO 2-ZrO 2 catalysts are strongly influenced by the amount of zirconium grafted. The conversion of LNG and the yield of hydrogen show volcano-shaped curves with respect to zirconium content. Among the catalysts tested, the Ni(20 wt.%)/SiO 2-ZrO 2 (Zr/Si = 0.54) sample shows the best catalytic performance in terms of both LNG conversion and hydrogen yield. The well-developed and pure tetragonal phase of ZrO 2-SiO 2 (Zr/Si = 0.54) appears to play an important role in the adsorption of steam and subsequent spillover of steam from the support to the active nickel. The small particle size of the metallic nickel in the Ni(20 wt.%)/SiO 2-ZrO 2 (Zr/Si = 0.54) catalyst is also responsible for its high performance.

  20. Synthesis and characterizations of Ni-NiO nanoparticles on PDDA-modified graphene for oxygen reduction reaction

    PubMed Central

    2014-01-01

    We are presenting our recent research results about the Ni-NiO nanoparticles on poly-(diallyldimethylammonium chloride)-modified graphene sheet (Ni-NiO/PDDA-G) nanocomposites prepared by the hydrothermal method at 90°C for 24 h. The Ni-NiO nanoparticles on PDDA-modified graphene sheets are measured by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) pattern for exploring the structural evidence to apply in the electrochemical catalysts. The size of Ni-NiO nanoparticles is around 5 nm based on TEM observations. The X-ray diffraction (XRD) results show the Ni in the (012), (110), (110), (200), and (220) crystalline orientations, respectively. Moreover, the crystalline peaks of NiO are found in (111) and (220). The thermal gravimetric analysis (TGA) result represents the loading content of the Ni metal which is about 34.82 wt%. The electron spectroscopy for chemical analysis/X-ray photoelectron spectroscopy (ESCA/XPS) reveals the Ni0 to NiII ratio in metal phase. The electrochemical studies with Ni-NiO/PDDA-G in 0.5 M aqueous H2SO4 were studied for oxygen reduction reaction (ORR). PMID:25246863

  1. Structural and magnetic properties of pristine and Fe-doped NiO nanoparticles synthesized by the co-precipitation method

    SciTech Connect

    Mishra, A.K.; Das, D.

    2012-09-15

    Highlights: ► The prepared samples were characterized by XRD, TEM, HR-TEM techniques. ► Magnetic properties of the samples were compared. ► Surface spins frozen at lower temperatures resulted a spin glass. ► The samples show enhancement of coercivity with decreased temperature. -- Abstract: Ni{sub 1−x}Fe{sub x}O (x = 0 and 0.03) nanoparticles are synthesized by a chemical route. XRD and TEM measurements confirm phase purity and crystallinity of the nanoparticles. Fe substitution in NiO reduces considerably the average particle size of the nanoparticles. The pristine NiO sample with size 14 nm and Fe-substituted sample having size 7 nm show room temperature ferromagnetism. The pristine NiO having 31 nm size and Fe-substituted sample with size 25 nm are found to be antiferromagnetic. The M–H and M–T behavior of the pristine and Fe-doped samples are explained with a core–shell model with an antiferromagnetic core and a ferromagnetic shell. The disordered spins at the shell give rise to a spin-glass like frozen state below 10 K. The obtained room temperature ferromagnetism in the pristine and Fe-doped NiO has been attributed to particle size effect.

  2. Water dissociation on Ni(100) and Ni(111): Effect of surface temperature on reactivity

    SciTech Connect

    Seenivasan, H.; Tiwari, Ashwani K.

    2013-11-07

    Water adsorption and dissociation on Ni(100) and Ni(111) surfaces are studied using density functional theory calculations. Water adsorbs on top site on both the surfaces, while H and OH adsorb on four fold hollow and three fold hollow (fcc) sites on Ni(100) and Ni(111), respectively. Transition states (TS) on both surfaces are identified using climbing image-nudged elastic band method. It is found that the barrier to dissociation on Ni(100) surface is slightly lower than that on Ni(111) surface. Dissociation on both the surfaces is exothermic, while the exothermicity on Ni(100) is large. To study the effect of lattice motion on the energy barrier, TS calculations are performed for various values of Q (lattice atom coordinate along the surface normal) and the change in the barrier height and position is determined. Calculations show that the energy barrier to reaction decreases with increasing Q and increases with decreasing Q on both the surfaces. Dissociation probability values at different surface temperatures are computed using semi-classical approximation. Results show that the influence of surface temperature on dissociation probability on the Ni(100) is significantly larger compared to that of Ni(111). Moreover, on Ni(100), a dramatic shift in energy barrier to lower incident energy values is observed with increasing surface temperature, while the shift is smaller in the case of Ni(111)

  3. Water dissociation on Ni(100) and Ni(111): effect of surface temperature on reactivity.

    PubMed

    Seenivasan, H; Tiwari, Ashwani K

    2013-11-07

    Water adsorption and dissociation on Ni(100) and Ni(111) surfaces are studied using density functional theory calculations. Water adsorbs on top site on both the surfaces, while H and OH adsorb on four fold hollow and three fold hollow (fcc) sites on Ni(100) and Ni(111), respectively. Transition states (TS) on both surfaces are identified using climbing image-nudged elastic band method. It is found that the barrier to dissociation on Ni(100) surface is slightly lower than that on Ni(111) surface. Dissociation on both the surfaces is exothermic, while the exothermicity on Ni(100) is large. To study the effect of lattice motion on the energy barrier, TS calculations are performed for various values of Q (lattice atom coordinate along the surface normal) and the change in the barrier height and position is determined. Calculations show that the energy barrier to reaction decreases with increasing Q and increases with decreasing Q on both the surfaces. Dissociation probability values at different surface temperatures are computed using semi-classical approximation. Results show that the influence of surface temperature on dissociation probability on the Ni(100) is significantly larger compared to that of Ni(111). Moreover, on Ni(100), a dramatic shift in energy barrier to lower incident energy values is observed with increasing surface temperature, while the shift is smaller in the case of Ni(111).

  4. Thermodynamic Assessment of the Bi-Ni and Bi-Ni-X (X = Ag, Cu) Systems

    NASA Astrophysics Data System (ADS)

    Liu, Yuling; Liu, Shuhong; Zhang, Cong; Lu, Xingxu; Chen, Chong; Du, Yong; Živković, Dragana

    2016-02-01

    The Bi-Ni system was reassessed by means of the calculation of phase diagrams (CALPHAD) method by considering the latest published experimental data. To maintain the compatibility in higher-order systems, the excess Gibbs energy of the solution phases was modeled with the Redlich-Kister polynomials, and a three-sublattice model, (Bi)0.3334(Ni,Va)0.3333(Va,Ni)0.3333, was used to describe the intermetallic compound BiNi with NiAs-type crystal structure. Compared with the previous thermodynamic description for the Bi-Ni system, noticeable improvements are achieved in the present work. The current thermodynamic parameters can well reproduce the newly published experimental data on thermodynamic properties. Based on the newly obtained parameters for the Bi-Ni system, as well as the thermodynamic descriptions for the Bi-Ag, Ni-Ag, Bi-Cu, and Ni-Cu systems in literature, a thermodynamic database of the Bi-Ni-Ag and Bi-Ni-Cu ternary systems was established by considering the available experimental data. The calculated phase equilibria in these ternary systems are in satisfactory agreement with experimental observations.

  5. One-pot synthesis of LaFeO3-NiFe2O4 nanocomposite ceramic by egg-white method and its magnetic and dielectric properties

    NASA Astrophysics Data System (ADS)

    Muthu, K. Sudalai; Lakshminarasimhan, N.; Perumal, P.

    2017-10-01

    A facile, one-pot synthesis of nanocomposite of LaFeO3-NiFe2O4 was demonstrated by using egg-white method. The same method was adopted to synthesize the individual component oxide nanoparticles of LaFeO3 (LFO) and NiFe2O4 (NFO). The phase formation of individual components and the nanocomposite was confirmed using powder X-Ray diffraction (XRD) technique. The measured room temperature magnetic properties of LFO, NFO and LFO-NFO nanoparticles revealed an enhancement in the properties of the nanocomposite. The dielectric behaviours of LFO, NFO and LFO-NFO pellets sintered at different temperatures such as 800, 900 and 1000 °C were investigated and correlated with the microstructures.

  6. Synthesis of dimorphic MR fluid containing NiCo nanoflowers by the polymer assisted polyol method and study of its magnetorheological properties

    NASA Astrophysics Data System (ADS)

    Arief, Injamamul; Mukhopadhyay, P. K.

    2014-09-01

    Flower-like nanostructures of NiCo (1:1) in the presence of Jeffamine was synthesized by homogeneous nucleation in 1, 2-propanediol for 3 h. Morphological characterizations performed by scanning and transmission electron microscopy (FESEM and TEM) revealed the average size distribution of 700 nm containing 2D nanosheets of 30 nm thickness. The nanoflowers crystallize exclusively in face-centered cubic structures and were confirmed by x-ray diffraction studies. Various factors, including nature of polyol, concentrations of base and metal salts in precursor proved to affect the geometry of nanoflowers. Magnetic studies revealed the ferromagnetic nature of NiCo nanoflowers with high saturation magnetization and low coercivity (108.6 emu/g and 78.4 Oe). The enhanced shear properties and yield stress of dimorphic MR fluid containing nanoflowers of NiCo in ferrofluids can be attributed to stronger microstructure formation in the presence of magnetic field.

  7. A Threonine Stabilizes the NiC and NiR Catalytic Intermediates of [NiFe]-hydrogenase*

    PubMed Central

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L.; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-01-01

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production. PMID:25666617

  8. A threonine stabilizes the NiC and NiR catalytic intermediates of [NiFe]-hydrogenase.

    PubMed

    Abou-Hamdan, Abbas; Ceccaldi, Pierre; Lebrette, Hugo; Gutiérrez-Sanz, Oscar; Richaud, Pierre; Cournac, Laurent; Guigliarelli, Bruno; De Lacey, Antonio L; Léger, Christophe; Volbeda, Anne; Burlat, Bénédicte; Dementin, Sébastien

    2015-03-27

    The heterodimeric [NiFe] hydrogenase from Desulfovibrio fructosovorans catalyzes the reversible oxidation of H2 into protons and electrons. The catalytic intermediates have been attributed to forms of the active site (NiSI, NiR, and NiC) detected using spectroscopic methods under potentiometric but non-catalytic conditions. Here, we produced variants by replacing the conserved Thr-18 residue in the small subunit with Ser, Val, Gln, Gly, or Asp, and we analyzed the effects of these mutations on the kinetic (H2 oxidation, H2 production, and H/D exchange), spectroscopic (IR, EPR), and structural properties of the enzyme. The mutations disrupt the H-bond network in the crystals and have a strong effect on H2 oxidation and H2 production turnover rates. However, the absence of correlation between activity and rate of H/D exchange in the series of variants suggests that the alcoholic group of Thr-18 is not necessarily a proton relay. Instead, the correlation between H2 oxidation and production activity and the detection of the NiC species in reduced samples confirms that NiC is a catalytic intermediate and suggests that Thr-18 is important to stabilize the local protein structure of the active site ensuring fast NiSI-NiC-NiR interconversions during H2 oxidation/production.

  9. Structure and magnetic properties evolution of rod-like Co0.5Ni0.25Zn0.25DyxFe2-xO4 synthesized by solvothermal method

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Liu, Dongsheng; Wu, Wenwei; Zhang, Huaxin; Wu, Juan

    2017-01-01

    A series of Dy3+ doped Co-Ni-Zn ferrites with the formula Co0.5Ni0.25Zn0.25DyxFe2-xO4 0≤x≤0.24) have been successfully synthesized using the solvothermal method. X-ray diffraction and scanning electron microscope examinations indicate that a highly-crystallized cubic Co0.5Ni0.25Zn0.25DyxFe2-xO4 with rod-like morphology is obtained when the precursor is calcined at 1000 °C in air for 3 h. Single phase Co0.5Ni0.25Zn0.25Fe2O4 is obtained at 650 °C, but all samples consist of the main spinel phase in combination of a small amount of a foreign Dy2O3 phase after doping Dy. When the precursor is calcined at 1000 °C, the lattice parameter of the ferrites initially increase after doping Dy, but then become smaller with increasing Dy content. The addition of Dy content results in a reduction of crystallite size, attributed that the binding energy of Dy3+-O2- is larger than that of Fe3+-O2-. Dy3+ substitution can decrease the remanence (Mr) and coercivity (Hc) of Co0.5Ni0.25Zn0.25DyxFe2-xO4 samples, which are very desirable characteristics for high density data storage devices.

  10. Enhanced hydrogen evolution from water splitting using Fe-Ni codoped and Ag deposited anatase TiO2 synthesized by solvothermal method

    NASA Astrophysics Data System (ADS)

    Sun, Tao; Liu, Enzhou; Liang, Xuhua; Hu, Xiaoyun; Fan, Jun

    2015-08-01

    In this paper, the Fe-Ni co-doped and Ag deposited anatase TiO2 (Fe-Ni/Ag/TiO2) nanocomposites were successfully prepared by a simple one-pot solvothermal approach. The investigations indicated that all as-prepared TiO2 samples were single anatase phase, and the impurity level was generated due to the Fe3+ or Ni2+ being located in the intrinsic band gap of TiO2, while the Ag+ ions could be transformed into metallic silver due to the reduction reaction and then loaded onto the surface of TiO2. Compared with pure TiO2, Fe-Ni/Ag/TiO2 composites with the sizes of Ag nanoparticles from 1.0 to 3.0 nm displayed the well optical property including higher visible light absorption activity and lower electron-hole pair recombination rate, and its absorption wavelength edge moved remarkably with a red shift to 700 nm. The photocatalytic water splitting was performed to produce H2 over the samples, and the experimental results indicate that Fe-Ni/Ag/TiO2 composites presented the highest H2 evolution rate, it can reach up to 793.86 μmol h-1 gcat-1 (λ > 400 nm for 6 h, energy efficiency is 0.25%), which was much higher than that of pure TiO2 for 9.57 μmol h-1 gcat-1. In addition, a tentative photocatalytic mechanism is proposed to understand the enhancement mechanism over Fe-Ni codoped and Ag deposited anatase TiO2.

  11. Effect of the method of introduction of Y2O3 into NiAl-based powder alloys on their structure: I. Agitation in a ball mill

    NASA Astrophysics Data System (ADS)

    Povarova, K. B.; Vershinina, T. N.; Skachkov, O. A.; Drozdov, A. A.; Morozov, A. E.; Pozharov, S. V.

    2012-09-01

    The effect of the sintering temperature (1100-1400°C) of NiAl alloy samples with oxide Y2O3 produced by hydrostatic pressing on their structure and phase composition and the distribution of oxide particles in a NiAl-based intermetallic matrix alloyed with ˜0.5 at % Fe is considered. It is found that dispersed oxide particles in the compact material prepared from a mixture of oxide Y2O3 powder and a NiAl alloy (produced by calcium hydride reduction of a mixture of nickel and aluminum oxides) powder in a standard ball mill are nonuniformly distributed in the volume. The morphology of oxides changes during sintering: sintered samples contain rounded particles, which differ strongly from the clearly faceted angular particles of oxide Y2O3 added to a mixture (they represent conglomerates of single crystals). In the sintered samples, large aggregates of oxides are revealed along grain boundaries. Mass transfer is possible at the NiAl/Y2O3 interface in the system: it leads to partial substitution of aluminum and/or iron atoms for yttrium atoms in the Y2O3 lattice and to the formation of submicroscopic particles of (Fe,Al)5Y3O12-type oxides.

  12. Synthesis and characterizations of (In{sub 0.90}Sn{sub 0.05}Ni{sub 0.05}){sub 2}O{sub 3} nanoparticles using solid state reaction method

    SciTech Connect

    Babu, S. Harinath; Krishna, N. Sai; Kaleemulla, S. Rao, N. Madhusudhana; Kuppan, M.; Krishnamoorthi, C.; Joshi, Girish M.; Basheed, G. A.

    2016-05-23

    ITO (In{sub 0.95}Sn{sub 0.05}){sub 2}O{sub 3} and Ni doped ITO (In{sub 0.90}Sn{sub 0.05}Ni{sub 0.05}){sub 2}O{sub 3} nanoparticles (NPs) were synthesized by solid state reaction method and subjected to study their structural, optical and magnetic properties. The NPs had a size distribution in the range of 40 nm and were identified as the bcc cubic In{sub 2}O{sub 3} by X-ray diffraction (XRD). Optical properties of the samples were studies using UV-Vis-NIR spectrophotometer. Magnetic measurements were carried out at room temperature and at 100 K using vibrating sample magnetometer and found that the ITO nanoparticles were ferromagnetic in nature at room temperature. The strength of the magnetization decreased in ITO nanoparticles when the magnetic measurements carried out at 100 K.

  13. Perpendicularly magnetized spin filtering Cu/Ni multilayers

    SciTech Connect

    Shirahata, Yasuhiro; Wada, Eiji; Itoh, Mitsuru; Taniyama, Tomoyasu

    2014-01-20

    Spin filtering at perpendicular magnetized Cu/Ni multilayer/GaAs(001) interfaces is demonstrated at remanence using optical spin orientation method. [Cu(9 nm)/Ni(t{sub Ni} nm)]{sub n} multilayers are found to show a crossover from the in-plane to out-of-plane magnetic anisotropy at the Cu/Ni bilayer repetition n = 4 and the Ni layer thickness t{sub Ni} = 3. For a perpendicularly magnetized Cu/Ni multilayer/n-GaAs(001) interface, circular polarization dependent photocurrent shows a clear hysteretic behavior under optical spin orientation conditions as a function of magnetic field out-of-plane while the bias dependence exhibits a substantial peak at a forward bias, verifying that Cu/Ni multilayers work as an efficient spin filter in the remanent state.

  14. Structural study of radiolytic catalysts Ni-Ce/Al2O3 and Ni-Pt/Al2O3

    NASA Astrophysics Data System (ADS)

    Seridi, F.; Chettibi, S.; Keghouche, N.; Beaunier, P.; Belloni, J.

    2017-01-01

    Ni-Ce and Ni-Pt bimetallic catalysts supported over α-Al2O3 are synthesized by using co-impregnation method, and then reduced, each via radiolytic process or thermal H2-treatment. For Ni-Ce/Al2O3, the structural study reveals that Ce is alloyed with Ni as Ce2Ni7 nanoparticles in the radiation-reduced catalysts, while it segregates to the surface in the form of CeO2 in the H2-reduced catalysts. For Ni-Pt/Al2O3 radiolytic catalysts, Ni, Pt, NiPt and Ni3Pt nanoparticles, which size is 3.5 nm, are observed. When the radiation-reduced samples are tested in the benzene hydrogenation, they both display high conversion rate. However, the Ni-Pt/Al2O3 is more efficient than Ni-Ce/Al2O3. The performance of the catalysts is correlated with the high dispersion of the metal and the presence of intermetallic Ni-Pt and Ni-Ce phases. It is compared to that of other radiolytic monometallic/oxide catalysts of the literature.

  15. Using a first-derivative spectrophotometric method for simultaneous determination of Fe(II) and Ni(II) in mineral vitamins by interaction with 2,4-diamino-5-(2-hydroxy-5-nitrophenylazo)benzenesulfonic acid sodium salt in the presence of Tween 20.

    PubMed

    Hashem, Elham Y; Seleim, Mohamed M; El-Zohry, Ahmed M

    2010-01-01

    A highly selective and sensitive derivative spectrophotometric method has been developed for the determination of Fe(II) and Ni(II) in different mineral vitamins. The method is based on the formation of binary complexes of Fe(II) and Ni(II) with 2,4-diamino-5-(2-hydroxy-5-nitrophenylazo) benzenesulfonic acid sodium salt (Mordant Brown 33) at pH 5.6 with Tween 20. At lambda(max) 512 and 493 nm, the molar absorbtivity was 2.09 x 10(4) and 0.58 x 10(4) L/mol cm for Fe(II) and Ni(II), respectively. Fe(II) can be determined in the range 0.55-2.79 microg/mL in the presence of 2.92 microg/mL Ni, and Ni(II) can be determined in the range 1.17-3.5 microg/mL in the presence of 2.79 microg/mL Fe(II) in the presence of Tween 20 (4%). The detection limits were 9.0 and 15.0 ng/mL for Fe(II) and Ni(II), respectively. The effect of foreign ions was elucidated. The RSD values were, in all instances, less than 1.3%. The proposed method was successfully applied for the simultaneous determination of Fe(II) and Ni(II) in different mineral vitamins.

  16. Synthesis cathode material LiNi0.80Co0.15Al0.05O2 with two step solid-state method under air stream

    NASA Astrophysics Data System (ADS)

    Xia, Shubiao; Zhang, Yingjie; Dong, Peng; Zhang, Yannan

    2014-01-01

    A facile generic strategy of solid-state reaction under air atmosphere is employed to prepare LiNi0.8Co0.15Al0.05O2 layer structure micro-sphere as cathodes for Li-ion batteries. The impurity phase has been eliminated wholly without changing the R-3m space group of LiNi0.8Co0.15Al0.05O2. The electrochemical performance of LiNi0.8Co0.15Al0.05O2 cathodes depend on the sintering step, temperature, particle size and uniformity. The sample pre-sintered at 540 °C for 12 h and then sintered at 720 °C for 28 h exhibits the best electrochemical performance, which delivers a reversible capacity of 180.4, 165.8, 154.7 and 135.6 mAhg-1 at 0.2 C, 1 C, 2 C and 5 C, respectively. The capacity retention keeps over 87% after 76 cycles at 1 C. This method is simple, cheap and mass-productive, and thus suitable to large scale production of NCA cathodes directly used for lithium ion batteries.

  17. Homogeneous Ni Catalysts for H2 Oxidation and Production: An Assessment of Theoretical Methods, from Density Functional Theory to Post Hartree-Fock Correlated Wave-Function Theory

    SciTech Connect

    Chen, Shentan; Raugei, Simone; Rousseau, Roger; Dupuis, Michel; Bullock, R. Morris

    2010-12-09

    A systematic assessment of theoretical methods applicable to the accurate characterization of catalytic cycles of homogeneous catalysts for H2 oxidation and evolution is reported. The key elementary steps involve heterolytic cleavage of the H-H bond and formation/cleavage of Ni-H and N-H bonds. In the context of density functional theory (DFT), we investigated the use of functionals in the generalized gradient approximation (GGA) as well as hybrid functionals. We compared the results with wave-function theories based on perturbation theory (MP2 and MP4) and on coupled-cluster expansions [CCD, CCSD, and CCSD(T)]. Our findings indicate that DFT results based on Perdew correlation functionals are in semiquantitative agreement with the CCSD(T) results, with deviations of only a few kilocalories/mole. On the other hand, the B3LYP functional is not even in qualitative agreement with CCSD(T). Surprisingly, the MP2 results are found to be extremely poor, in particular for the diproton Ni(0) and dihydride Ni(IV) species on the reaction potential energy surface. The Hartree-Fock reference wave function in MP2 theory gives a poor reference state description for these states that are electron rich on Ni, giving rise to erroneous MP2 energies. Finally, we present a detailed potential-energy diagram for the oxidation of H2 by these catalysts after accounting for the effects of solvation, as modeled by a polarizable continuum, and of free energy estimated at the harmonic level of theory.

  18. NiO(s) (Bunsenite) is not Available to Alyssum species

    USDA-ARS?s Scientific Manuscript database

    AIMS: To determine if the Ni-hyperaccumulator Alyssum corsicum can absorb Ni from the kinetically inert crystalline mineral NiO(s) (bunsenite). METHODS: A. corsicum and A. montanum plants were grown for 30 days in a serpentine Hoagland solution. NiO was provided at 0 or 0.1 g L-1 (1.34 mmol L-1) ...

  19. Investigation of primary static recrystallization in a NiTiFe shape memory alloy subjected to cold canning compression using the coupling crystal plasticity finite element method with cellular automaton

    NASA Astrophysics Data System (ADS)

    Zhang, Yanqiu; Jiang, Shuyong; Hu, Li; Zhao, Yanan; Sun, Dong

    2017-10-01

    The behavior of primary static recrystallization (SRX) in a NiTiFe shape memory alloy (SMA) subjected to cold canning compression was investigated using the coupling crystal plasticity finite element method (CPFEM) with the cellular automaton (CA) method, where the distribution of the dislocation density and the deformed grain topology quantified by CPFEM were used as the input for the subsequent SRX simulation performed using the CA method. The simulation results were confirmed by the experimental ones in terms of microstructures, average grain size and recrystallization fraction, which indicates that the proposed coupling method is well able to describe the SRX behavior of the NiTiFe SMA. The results show that the dislocation density exhibits an inhomogeneous distribution in the deformed sample and the recrystallization nuclei mainly concentrate on zones where the dislocation density is relatively higher. An increase in the compressive deformation degree leads to an increase in nucleation rate and a decrease in grain boundary spaces in the compression direction, which reduces the growth spaces for the SRX nuclei and impedes their further growth. In addition, both the mechanisms of local grain refinement in the incomplete SRX and the influence of compressive deformation degree on the grain size of SRX were vividly illustrated by the corresponding physical models.

  20. In Situ XAS of Ni-W Hydrocracking Catalysts

    NASA Astrophysics Data System (ADS)

    Yang, N.; Mickelson, G. E.; Greenlay, N.; Kelly, S. D.; Bare, Simon R.

    2007-02-01

    Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS2 platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni (˜25%) and W (<10%) in the lower activity sample.

  1. A facile method to synthesize carbon coated Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} with improved performance

    SciTech Connect

    Liu, Yunjian; Gao, Yanyong; Lv, Jun; Chen, Long

    2013-11-15

    Graphical abstract: Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} powders are synthesized and then coated by decomposed carbon. The discharge capacity of carbon-coated cathode at 0.1 and 5 C are 246 and 125 mAhg{sup −1}, while those of ball-milled cathode are 222 and 49 mAhg{sup −1}. - Highlights: • A simple method was applied to synthesize carbon-coated Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2}. • The discharge capacities of carbon-coated sample at 0.1 and 5.0 C rates are 246 and 125 mAh/g. • Capacity retention of carbon-coated electrode after 50 cycles is 97.5%. - Abstract: Carbon-coated Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} powders have been synthesized with Bakelite and heat process in air. The effect of carbon coating on the physical and electrochemical properties have been discussed through the characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), discharge and rate tests. The carbon-coated cathode exhibits much improved first discharge capacity and rate capability than the pristine sample. The discharge capacity at 0.1 and 5.0 C rates are 246 and 125 mAhg{sup −1}, while that of pristine are only about 222 and 49 mAhg{sup −1}, respectively. The capacity retention of Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} electrode after 50 cycles is improved from 89.8 to 97.5% after carbon coating. EIS results indicate that R{sub ct} of Li{sub 1.2}Ni{sub 0.2}Mn{sub 0.6}O{sub 2} electrode is decreased from 62 to 37 Ω after carbon coating.

  2. Li3PO4 surface coating on Ni-rich LiNi0.6Co0.2Mn0.2O2 by a citric acid assisted sol-gel method: Improved thermal stability and high-voltage performance

    NASA Astrophysics Data System (ADS)

    Lee, Suk-Woo; Kim, Myeong-Seong; Jeong, Jun Hui; Kim, Dong-Hyun; Chung, Kyung Yoon; Roh, Kwang Chul; Kim, Kwang-Bum

    2017-08-01

    A surface coating of Li3PO4 was applied to a Ni-rich LiNi0.6Co0.2Mn0.2O2 (NCM) material to improve its thermal stability and electrochemical properties via a citric acid assisted sol-gel method. The addition of citric acid effectively suppressed the instant formation of Li3PO4 in solution, resulting in successful coating of the NCM surface. The improved thermal stability of NCM after Li3PO4 surface coating was demonstrated by differential scanning calorimetry (DSC) analysis and in situ time-resolved X-ray diffraction (TR-XRD). In particular, the TR-XRD results showed that the improved thermal stability after Li3PO4 surface coating originates from suppression of the phase transition of charged NCM at high temperatures. Furthermore, the charge-discharge tests demonstrated that Li3PO4-coated LiNi0.6Co0.2Mn0.2O2 (LP-NCM) has excellent electrochemical properties. LP-NCM exhibited a specific capacity of 192.7 mAh g-1, a capacity retention of 44.1% at 10 C, and a capacity retention of 79.7% after 100 cycles at a high cut-off voltage of 4.7 V; these values represent remarkably improved electrochemical properties compared with those of bare NCM. These improved thermal and electrochemical properties were mainly attributed to the improvement of the structural stability of the material and the suppression of the interface reaction between the cathode and the electrolyte owing to the Li3PO4 coating.

  3. Structural and magnetic properties of Ni1-xZnxFe2O4 synthesized through the sol-gel method

    NASA Astrophysics Data System (ADS)

    Guan, Beh Hoe; Zahari, Muhammad Hanif; Chuan, Lee Kean

    2016-11-01

    Modification of crystal structure by means of substitution would result in the modification of the overall physical properties of crystallite materials especially in ferrites. This study aims to investigate the effect of non-magnetic Zn substitution in spinel NiFe2O4 and its direct effect towards its microstructural and magnetic properties. Magnetic nanoparticles of Nickel-Zinc ferrite with the chemical formula, Ni1-xZnxFe2O4 (x=0.00, 0.25, 0.50, 0.75) were synthesized through the sol-gel route. Phase formation and structural properties of the synthesized ferrite were identified through X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). Magnetic properties such as the magnetic saturation, coercivity and remanence were measured by a vibrating sample magnetometer (VSM). XRD measurements reveals successful synthesis of single-phased Nickel ferrite and Nickel—Zinc ferrite. Both crystallite and grain size shows fluctuation with increasing Zn content. The ferrites were found to be ferrimagnetic in nature and show differing values with different x values.

  4. Coupling the Phase Field Method for diffusive transformations with dislocation density-based crystal plasticity: Application to Ni-based superalloys

    NASA Astrophysics Data System (ADS)

    Cottura, M.; Appolaire, B.; Finel, A.; Le Bouar, Y.

    2016-09-01

    A phase field model is coupled to strain gradient crystal plasticity based on dislocation densities. The resulting model includes anisotropic plasticity and the size-dependence of plastic activity, required when plasticity is confined in region below few microns in size. These two features are important for handling microstructure evolutions during diffusive phase transformations that involve plastic deformation occurring in confined areas such as Ni-based superalloys undergoing rafting. The model also uses a storage-recovery law for the evolution of the dislocation density of each glide system and a hardening matrix to account for the short-range interactions between dislocations. First, it is shown that the unstable modes during the morphological destabilization of a growing misfitting circular precipitate are selected by the anisotropy of plasticity. Then, the rafting of γ‧ precipitates in a Ni-based superalloy is investigated during [100] creep loadings. Our model includes most of the important physical phenomena accounted for during the microstructure evolution, such as the presence of different crystallographic γ‧ variants, their misfit with the γ matrix, the elastic inhomogeneity and anisotropy, the hardening, anisotropy and viscosity of plasticity. In agreement with experiments, the model predicts that rafting proceeds perpendicularly to the tensile loading axis and it is shown that plasticity slows down significantly the evolution of the rafts.

  5. Corrosion behavior of Au and Ag modified Cu-Ni-Mn alloys.

    PubMed

    Wright, S R; Cocks, F H; Gettleman, L

    1980-04-01

    The linear electrochemical polarization method was used to provide quantitative in vitro measurements of corrosion rates as a function of exposure time for Cu-Ni-Mn, Cu-Ni-Mn-Au, Cu-Ni-Mn-Ag, and Cu-Ni-Mn-Au-Ag alloys in artificial saliva. Both Au and Ag additives to dental-cast Cu-Ni-Mn alloys lowered the corrosion rate significantly.

  6. Preparation of electrodeposited Mo-Ni coating and its spectral properties.

    PubMed

    Liu, Xiao-Zhen; Xiong, Li-Ping; Liu, Xiao-Zhou; Chen, Jie; Luo, Yi-Fan; Sun, Ying

    2014-04-01

    Mo-Ni coatings were prepared on Ni alloy by electrodeposition method. The properties of microhardness, wear weight loss and friction coefficients, and thermal expansion of the coatings were investigated, respectively. Mo-Ni coatings were characterized with inductively coupled plasma-atomic emission spectroscopy (ICP-AES), energy-dispersive analyses of X-ray (EDAX), scanning electron microcopy (SEM), and X-ray diffraction (XRD) techniques, respectively. Mo-Ni coating shows higher microhardness, lower wear weight loss and friction coefficient compared with those of Ni alloy. The microhardness of Mo-Ni coating is as high as 518 HV, which is 72.67% higher than that of the Ni alloy (300 HV). The wear weight losses of Mo-Ni coating is 1.94 times lower than that of Ni alloy. The friction coefficient of Ni alloy and Mo-Ni coating are 0.640 and 0.559 respectively. The physical thermal expansion curve of Ni alloy has two the peaks in the ranges of 100-120 and 570-640 degrees C respectively; and that of Ni alloy+Mo-Ni coating has one the peaks in the ranges of 570-640 degrees C. The peak of the physical thermal expansion curve of Ni alloy+Mo-Ni coating in the ranges of 570-640 degrees C is much smaller than that of the Ni alloy. Because the part of nickel was replaced by molybdenum in the Ni lattice, molybdenum decreases the lattices transformation of nickel (bcc --> fcc). The reason for the formation of the small peak of the physical thermal expansion curve of Ni alloy+Mo-Ni coating in the ranges of 595-625 degrees C is the changes of MoNi4 and MoNi from the semi-crystalline structure to the crystalline structure respectively.

  7. Fabrication and Characterization of Ni-P-CoNiCrAlY Composite Coatings

    NASA Astrophysics Data System (ADS)

    Heydari, H.; Monirvaghefi, S. M.; Hadipour, Ali

    2017-03-01

    In this study, Ni-P-CoNiCrAlY composite coatings were deposited on 310 stainless steel. The surface morphology and cross-sectional observations were carried out using scanning electron microscopy and optical microscopy. The high-temperature corrosion of all coatings was evaluated by cyclic oxidation method. According to the results, the amounts of CoNiCrAlY particles co-deposited in all samples coated at pH = 4.7 were higher than that of those produced at pH = 6.7. Also, the surface roughness of all composite coatings coated at pH = 6.7 is lower than the coatings produced at pH = 4.7. The Ni-P-(3 g/l) CoNiCrAlY deposit produced at pH = 6.7 had the best corrosion resistance among other coatings.

  8. Fabrication and Characterization of Ni-P-CoNiCrAlY Composite Coatings

    NASA Astrophysics Data System (ADS)

    Heydari, H.; Monirvaghefi, S. M.; Hadipour, Ali

    2017-02-01

    In this study, Ni-P-CoNiCrAlY composite coatings were deposited on 310 stainless steel. The surface morphology and cross-sectional observations were carried out using scanning electron microscopy and optical microscopy. The high-temperature corrosion of all coatings was evaluated by cyclic oxidation method. According to the results, the amounts of CoNiCrAlY particles co-deposited in all samples coated at pH = 4.7 were higher than that of those produced at pH = 6.7. Also, the surface roughness of all composite coatings coated at pH = 6.7 is lower than the coatings produced at pH = 4.7. The Ni-P-(3 g/l) CoNiCrAlY deposit produced at pH = 6.7 had the best corrosion resistance among other coatings.

  9. Nanostructure investigation of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} synthesized by sol-gel method

    SciTech Connect

    Pransisco, Prengki; Shafie, Afza Guan, Beh Hoe

    2015-07-22

    Magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} was successfully prepared by using sol-gel method. Heat treatment on material is always giving defect on properties of material. This paper investigates the effect of heat treatment on nanostructure of magnetic nanomaterial Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4}. According to thermo gravimetric analysis (TGA) that after 600°C there is no more weight loss detected and it was decided as minimum calcination temperature. Intensity, crystallite size, structure, lattice parameter and d-spacing of the material were investigated by using X-ray diffraction (XRD). High resolution transmission electron microscope (HRTEM) was used to examine nanostructure, nanosize, shape and distribution particle of magnetic material Ni{sub 0.5}Zn{sub 0.3}Cu{sub 0.2}Fe{sub 2}O{sub 4} and variable pressure field emission scanning electron microscope (VP-FESEM) was used to investigate the surface morphology and topography of the material. The XRD result shows single-phase cubic spinel structure with average crystallite size in the range of 25.6-95.9 nm, the value of the intensity of the material was increased with increasing temperature, and followed by lattice parameter was increased with increasing calcination temperature, value of d-spacing was relatively decreased with accompanied increasing temperature. From HRTEM result the distribution of particles was tend to be agglomerates with particle size of 7.8-17.68 nm. VP-FESEM result shows that grain size of the material increases with increasing calcination temperature and the surface morphology shows that the material is in hexagonal shape and it was also proved by mapping result which showing the presence each of constituents inside the compound.

  10. Structural, Magnetic, and Microwave Properties of SrFe12- x (Ni0.5Co0.5Sn) x/2O19 Particles Synthesized by Sol-Gel Combustion Method

    NASA Astrophysics Data System (ADS)

    Mousavinia, Mohammad; Ghasemi, Ali; Paimozd, Ebrahim

    2013-09-01

    This study is intended to evaluate the structural, magnetic, and microwave properties of Ni-Co-Sn-doped strontium hexaferrite SrFe12- x (Ni0.5Co0.5Sn) x/2 O19 particles with x = 0 to 2.5 synthesized by a sol-gel combustion method. These particles were evaluated to characterize the structural, magnetic, and reflection loss properties of prepared samples by use of x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared (FTIR) spectroscopy, vibrating-sample magnetometer (VSM), and vector network analyzer. The XRD results confirmed the presence of strontium ferrite phase with magnetoplumbite structure in all synthesized samples. The results of FTIR analysis indicated the formation of functional groups such as metal-oxygen (Sr-O and Fe-O) and carboxylic groups during the sol-gel process. In addition, FE-SEM micrographs indicated that submicron particles with different morphologies such as spherical, pyramidal, irregular, and hexagonal platelet shapes appeared in the structure. According to hysteresis loops, magnetization and coercivity decreased due to occupation of Ni-Co-Sn cations at low levels of substitutions. The microwave absorption characteristics of this ferrite were investigated in the 8 GHz to 12 GHz frequency range. The sample with 80 wt.% ferrite content showed a maximum reflection loss of -29 dB at 9.6 GHz with 4 GHz bandwidth through the entire frequency range of 8 GHz to 12 GHz for absorber thickness of 1.5 mm. Based on microwave measurements of reflectivity, this material with the expressed chemical composition could be proposed as a good choice for electromagnetic compatibility and other practical applications such as microwave absorption at high frequencies.

  11. Preparation and characterization of LaMnO3 and LaNiO3 perovskite type oxides by the hydrothermal synthesis method

    NASA Astrophysics Data System (ADS)

    Özbay, N.; Şahin, R. Z. Yarbay

    2017-02-01

    Perovskites which both naturally occurring and synthetically produced with important technological applications are a large class of minerals. Physical properties of interest to materials science through perovskites include superconductivity, magnetoresistance, ionic conductivity, and a multitude of dielectric properties, which are of great importance in microelectronics and telecommunication. Recently interest has arisen in perovskite-type oxides as catalysts due to high thermal and hydrothermal stability as well as high mechanical strength among other properties. In the present work, LaMnO3 and LaNiO3 perovskite type oxide catalysts are developed for the purpose of pyrolysis of biomass, and they are studied in terms of structure. The crystal structures of catalysts were determined via X-Ray Diffraction (XRD), morphology of the samples were analyzed by Scanning Electron Microscope (SEM), and the specific surface area of the samples were determined by N2 adsorption desorption isotherms (BET) measurements.

  12. Enhanced Electrocatalytic Activity for Water Splitting on NiO/Ni/Carbon Fiber Paper.

    PubMed

    Zhang, Ruoyu; Wei, Hehe; Si, Wenjie; Ou, Gang; Zhao, Chunsong; Song, Mingjun; Zhang, Cheng; Wu, Hui

    2016-12-28

    Large-scale growth of low-cost, efficient, and durable non-noble metal-based electrocatalysts for water splitting is crucial for future renewable energy systems. Atomic layer deposition (ALD) provides a promising route for depositing uniform thin coatings of electrocatalysts, which are useful in many technologies, including the splitting of water. In this communication, we report the growth of a NiO/Ni catalyst directly on carbon fiber paper by atomic layer deposition and report subsequent reduction and oxidation annealing treatments. The 10-20 nm NiO/Ni nanoparticle catalysts can reach a current density of 10 mA·cm(-2) at an overpotential of 189 mV for hydrogen evolution reactions and 257 mV for oxygen evolution reactions with high stability. We further successfully achieved a water splitting current density of 10 mA·cm(-2) at 1.78 V using a typical NiO/Ni coated carbon fiber paper two-electrode setup. The results suggest that nanoparticulate NiO/Ni is an active, stable, and noble-metal-free electrocatalyst, which facilitates a method for future water splitting applications.

  13. Effects of P/Ni ratio and Ni content on performance of γ-Al2O3-supported nickel phosphides for deoxygenation of methyl laurate to hydrocarbons

    NASA Astrophysics Data System (ADS)

    Zhang, Zhena; Tang, Mingxiao; Chen, Jixiang

    2016-01-01

    γ-Al2O3-supported nickel phosphides (mNi-Pn) were prepared by the TPR method and tested for the deoxygenation of methyl laurate to hydrocarbons. The effects of the P/Ni ratio (n = 1.0-2.5) and Ni content (m = 5-15 wt.%) in the precursors on their structure and performance were investigated. Ni/γ-Al2O3 was also studied for comparison. It was found that the formation of AlPO4 in the precursor inhibited the reduction of phosphate and so the formation of nickel phosphides. With increasing the P/Ni ratio and Ni content, the Ni, Ni3P, Ni12P5 and Ni2P phases orderly formed, accompanying with the increases of their particle size and the amount of weak acid sites (mainly due to P-OH group), while the CO uptake and the amount of medium strong acid sites (mainly related to Ni sites) reached maximum on 10%Ni-P1.5. In the deoxygenation reaction, compared with Ni/γ-Al2O3, the mNi-Pn catalysts showed much lower activities for decarbonylation, Csbnd C hydrogenolysis and methanation due to the ligand and ensemble effects of P. The conversion and the selectivity to n-C11 and n-C12 hydrocarbons achieved maximum on 10%Ni-P 2.0 for the 10%Ni-Pn catalysts and on 8%Ni-P2.0 for the mNi-P2.0 catalysts, while the turnover frequency (TOF) of methyl laurate mainly increased with the P/Ni ratio and Ni content. We propose that TOF was influenced by the nickel phosphide phases, the catalyst acidity and the particle size as well as the synergetic effect between the Ni site and acid site. Again, the hydrodeoxygenation pathway of methyl laurate was promoted with increasing P/Ni ratio and Ni content, ascribed to the phase change in the order of Ni, Ni3P, Ni12P5 and Ni2P in the prepared catalysts.

  14. Field emission properties of carbon nanotubes film grown on NiCr alloy films

    NASA Astrophysics Data System (ADS)

    Chen, T.; Wang, L. L.; Chen, Y. W.; Que, W. X.; Sun, Z.

    2007-06-01

    Carbon nanotubes (CNTs) are prepared on NiCr alloy films by low pressure thermal chemical vapor deposition at 600 °C. NiCr alloy films are deposited by magnetic co-sputtering method, and the various thickness and Ni/NiCr ratios are controlled by sputtering power. The diameter and length of CNTs, as well as the roughness of the CNTs films, mainly depend on the Ni/NiCr ratio. The field emission current density of the CNTs film increases with the increasing Ni/NiCr ratio from 65 wt% to 83 wt%, and decreases when the Ni/NiCr ratio is more than 87 wt% in the alloy film.

  15. Tuning the magnetic properties of multisegmented Ni/Cu electrodeposited nanowires with controllable Ni lengths.

    PubMed

    Susano, M; Proenca, M P; Moraes, S; Sousa, C T; Araújo, J P

    2016-08-19

    The fabrication of segmented Ni/Cu nanowires (NWs), with tunable structural and magnetic properties, is reported. A potentiostatic electrodeposition method with a single electrolytic bath has been used to fabricate multisegmented Ni/Cu NWs inside a highly hexagonally ordered anodic nanoporous alumina membrane, with diameters of 50 nm and Ni segment lengths (L Ni) tuned from 10 nm up to 140 nm. The x-ray diffraction results evidenced a strong dependence of the Ni NWs crystallographic face-centered-cubic (fcc) texture along the [220] direction on the aspect ratio of the NWs. The magnetic behavior of the multisegmented Ni/Cu NW arrays, as a function of the magnetic field and temperature, is also studied and correlated with their structural and morphological properties. Micromagnetic simulations, together with the experimental results, showed a dominant antiferromagnetic coupling between Ni segments along the wire length for small low aspect-ratio magnetic segments. When increasing the Ni segments' length, the magnetic interactions between these along the wire became stronger, favouring a ferromagnetic coupling. The Curie temperature of the NWs was also found to strongly depend on the Ni magnetic segment length. Particularly the Curie temperature was found to be reduced 75 K for the 20 nm Ni segments, following the finite-size scaling relation with ξ 0 = 8.1 Å and γ = 0.48. These results emphasize the advantages of using a template assisted method to electrodeposit multilayer NWs, as it allows an easy tailor of the respective morphological, chemical, structural and magnetic properties.

  16. The first principle study of Ni2ScGa and Ni2TiGa

    NASA Astrophysics Data System (ADS)

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; Iyigör, Ahmet; Candan, Abdullah

    2014-10-01

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni2TiGa and Ni2ScGa alloys in the cubic L21 structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C11, C12 and C44. We calculated elastic constants in L21 structure for Ni2TiGa and Ni2ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni2TiGa, Ni 3d states and Sc 3d states for Ni2ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni2TiGa, 0.76 states/eV Cell for Ni2ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L21 phase is unstable since the phonon calculations have imagine modes.

  17. Facile synthesis of self-supported Ni2P nanosheet@Ni sponge composite for high-rate battery

    NASA Astrophysics Data System (ADS)

    Shi, F.; Xie, D.; Zhong, Y.; Wang, D. H.; Xia, X. H.; Gu, C. D.; Wang, X. L.; Tu, J. P.

    2016-10-01

    To meet the requirements for high-rate battery with desirable performance, a self-supported Ni2P@Ni sponge electrode is synthesized via simple steps, in which the Ni sponge substrate is synthesized by a one-pot hydrothermal method and the Ni2P nanosheets grown on the novel substrate are converted from Ni(OH)2 via a phosphorization reaction. This hybrid composite combines the 3D porous structure of Ni sponge and high capacity of Ni2P nanosheets, which exhibits lightweight, flexible and highly-conductive properties, resulting in an excellent specific capacity of 430.3 mAh g-1 at a current density of 1 A g-1 and remaining as high as 77.0% capacity even at 40 A g-1. More importantly, the Ni2P@Ni sponge//C cell exhibits the maximum energy density of 182.1 W h kg-1 at a power density of 205 W kg-1 along with superior capacity retention of 85.2% after 3000 cycles. It is suggested that the Ni2P nanosheet@ Ni sponge composite is a promising electrode material for high-rate batteries.

  18. Template-Mediated Ni(II) Dispersion in Mesoporous SiO2 for Preparation of Highly Dispersed Ni Catalysts: Influence of Template Type.

    PubMed

    Ning, Xin; Lu, Yiyuan; Fu, Heyun; Wan, Haiqin; Xu, Zhaoyi; Zheng, Shourong

    2017-06-07

    Supported Ni catalysts on three mesoporous SiO2 supports (i.e., SBA-15, MCM-41, and HMS) were prepared using a solid-state reaction between Ni(NO3)2 and organic template-occluded mesoporous SiO2. For comparison, supported Ni catalysts on mesoporous SiO2 synthesized by the conventional impregnation method were also included. The catalysts were characterized by scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, N2 adsorption, X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, transmission electron microscopy, and transmission electron microscopy-energy-dispersive X-ray. The catalytic properties of the catalysts were evaluated using gas-phase catalytic hydrodechlorination of 1,2-dichloroethane. The results showed that upon grinding Ni(NO3)2 with template-occluded mesoporous SiO2, strong coordination between Ni(2+) and dodecylamine was identified in the Ni(NO3)2-HMS system. Additionally, the results of H2 temperature-programmed reduction revealed that NiO in calcined NiO/HMS was reduced at higher temperature than those in calcined NiO/SBA-15 and NiO/MCM-41, reflecting the presence of a strong interaction between NiO and mesoporous SiO2 in NiO/HMS. Consistently, the average particle sizes of metallic Ni were found to be 2.7, 3.4, and 9.6 nm in H2-reduced Ni/HMS, Ni/SBA-15, and Ni/MCM-41, respectively, indicative of a much higher Ni dispersion in Ni/HMS. For the catalytic hydrodechlorination of 1,2-dichloroethane, Ni/MCM-41 synthesized by the solid-state reaction method exhibited a catalytic activity similar to that prepared by the impregnation method, while higher catalytic activities were observed on Ni/HMS and Ni/SBA-15 than on their counterparts prepared by the impregnation method. Furthermore, a higher conversion was identified on Ni/HMS than on Ni/SBA-15 and Ni/MCM-41, highlighting the importance of template type for the preparation of highly dispersed metal catalysts on mesoporous SiO2.

  19. Determination of 63Ni and 59Ni in spent ion-exchange resin and activated charcoal from the IEA-R1 nuclear research reactor.

    PubMed

    Taddei, M H T; Macacini, J F; Vicente, R; Marumo, J T; Sakata, S K; Terremoto, L A A

    2013-07-01

    A radiochemical method has been adapted to determine (59)Ni and (63)Ni in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. The process includes extraction chromatographic resin with dimethylglyoxime (DMG) as a functional group. Activity concentrations of (59)Ni and (63)Ni were measured, respectively, by X-ray spectrometry and liquid scintillation counting, whereas the chemical yield was determined by ICP-OES. The average ratio of measured activity concentrations of (63)Ni and (59)Ni agree well with theory.

  20. Electrochemical Performance of LiNi0.5Mn1.5O4 by Sol-gel Self-combustion Reaction Method in Different Kinds of Electrolyte for High-voltage Rechargeable Lithium Cells

    NASA Astrophysics Data System (ADS)

    Liang, Xinghua; Shi, Lin; Liu, Yusi; Zeng, Shuaibo; Ye, Chaochao

    2015-07-01

    LiNi0.5Mn1.5O4 cathode material was synthesized through sol-gel self-combustion reaction method. LiNi0.5Mn1.5O4 powders were subsequently characterized as cathode materials in a Li-ion coin cell comprising a Li anode with electrolyte A or electrolyte B. 1.0 mol/L Lithium Hexafluorophosphate (LiPF6) dissolved in volume ration of ethylene carbonate (EC) to ethyl methyl carbonate (EMC) to diethyl carbonate (DEC) corresponded to 4:3:3as electrolyte A, 1.0 mol/L LiPF6 dissolved in volume ration of EC to EMC to DEC corresponded to 4:2:4 as electrolyte B. Electrochemical performance of lithium cells was evaluated. These tests showed that no matter the cells with electrolyte A or electrolyte B has good discharge platform in 4.7V range (3.5V-4.75V) at the rate of 0.1C, the initial discharge capacity of cell with electrolyte B was higher than that with electrolyte A.

  1. Facile one-step forming of NiO and yttrium-stabilized zirconia composite anodes with straight open pores for planar solid oxide fuel cell using phase-inversion tape casting method

    NASA Astrophysics Data System (ADS)

    Huang, Hua; Lin, Jie; Wang, Yunlong; Wang, Shaorong; Xia, Changrong; Chen, Chusheng

    2015-01-01

    The anode of NiO and yttria-stabilized zirconia (YSZ) with straight open pores is prepared by phase-inversion tape casting method. In the as-prepared green tape, its top and middle layers are derived from a slurry of NiO and YSZ, while the bottom layer from a slurry of graphite. The graphite layer is eliminated by calcination at elevated temperatures, leaving the finger-like porous layer exposed to the gas phase. A cell supported on the as-prepared anode substrate exhibits satisfactory electrochemical performances with a maximum power density of 780 mW cm-2 at 800 °C. The cell dose not show a convex-up curvature in I-V plots at high current density as often observed for most anode-supported cells, indicating the absence of concentration polarization which is in turn attributed to the open pore structure of the phase-inversion derived anode. The phase inversion tape casting technique explored in the present study involves almost the same equipments as and similar procedures to the conventional tape casting, and after further optimization it may become a simple and effective technique for mass production of anodes for SOFCs.

  2. Preparation of LiNi0.5Mn1.5O4 for Lithium Batteries Via Solid-State Redox Method using Nitrate and Acetate Based Reactants

    NASA Astrophysics Data System (ADS)

    Mat, A.; Sulaiman, K. S.; Sulaiman, M. A.; Hasim, M. F.

    2010-03-01

    LiNi0.5Mn1.5O4 is a potential cathode material for 5 V batteries. This material was prepared by the solid-state redox method using nitrate and acetate based reactants. The precursor material was obtained when the mixture reactants was heated at 500° C for 10 hours and calcined at different temperatures in the range between 650 and 950° C for 12 hours. The structures of the synthesized materials were verified with X- ray diffraction (XRD) measurement and Scanning Electron Microscope (SEM). The charge-discharge technique was determined using Solartron 1470. As calcination temperature increases, the well-ordered crystal growth oriented to [1 1 1] direction shows a clear octahedral morphology, which is the characteristic of the typical cubic spinel. The Li/LiNi0.5Mn1.5O4 prepared from acetate based reactants calcined at 750° C for 12 h delivered the discharge capacity of 140 mAh/g.

  3. Polarization of the angular momentum of electrons in calculations of the electronic structure of the NiO/sub 6//sup 10 -/ cluster by the X. cap alpha. -scattered-wave method

    SciTech Connect

    Gagarin, S.G.; Teterin, Yu.A.; Plekhanov, Yu.V.

    1986-05-01

    The x-ray photoelectron spectra of the core 2p/sub 1/2/, 2p/sub 3/2/, 3s/sub 1/2/, 3p/sub 1/2/, and 3/p/sub 3/2/ electrons of nickel in the oxide NiO and in an aluminum - nickel catalyst have been discussed on the basis of the results of a self-consistent calculation of the electronic states of the NiO/sub 6//sup 10 -/ cluster in the spin-polarized variation of the X..cap alpha..-scattered-wave method with complete consideration of the relativistic properties of the core electrons in the angular-momentum-polarized variant. Partial consideration of the relativistic properties of the valence-band electrons (consideration of the Darwin terms and the dependence of the mass on the velocity during the averaging of the wave functions and the density with respect to the angular momentum) does not alter the basic conclusions of the work.

  4. Enhanced Noble Gas Adsorption in Ag@MOF-74Ni

    SciTech Connect

    Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.

    2014-01-14

    Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) with an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles.

  5. Enhanced noble gas adsorption in Ag@MOF-74Ni.

    PubMed

    Liu, Jian; Strachan, Denis M; Thallapally, Praveen K

    2014-01-14

    Various amounts of Ag nanoparticles were successfully deposited in porous MOF-74Ni (or Ni/DOBDC) by an auto-reduction method. An optimized silver-loaded MOF-74Ni was shown to have an improved Xe adsorption capacity (15% more) at STP compared to the MOF without silver nanoparticles. The silver-loaded sample also has a higher Xe/Kr selectivity. These results are explained by the stronger interactions between polarizable Xe molecules and the well-dispersed Ag nanoparticles.

  6. NiCoO2 flowers grown on the aligned-flakes coated Ni foam for application in hybrid energy storage

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyang; Zhao, Huilin; Zhou, JingKuo; Xue, Ruinan; Gao, Jianping

    2016-10-01

    Many NiCoO2 flowers with an average diameter of about 4 μm were grown on the NiCoO2 flakes coated Ni foam (denoted as NiCoO2/Ni foam) through a simple hydrothermal method and confirmed by scanning and transmission electron microscopies, X-ray diffraction and X-ray photoelectron spectrum measurements. The NiCoO2/Ni foam with high specific area and porosity was directly used as the working electrode without any binders. The measured specific capacitance of NiCoO2 grown on Ni foam is 756 F/g at 0.75 A/g using a three-electrode setup in 1 M KOH. Considering the high capacity of NiCoO2 and the good stability of rGO, the NiCoO2/Ni foam//rGO hybrid supercapacitor combining NiCoO2/Ni foam and rGO shows very good properties, such as high specific capacitance (82 F/g at 2 A/g based on the total mass of active materials), high energy density (25.7 Wh/kg at 1500 W/kg based on the total mass of active materials), good stability (about 90% capacitance retention after 2000-cycle at 100 mV/s), and low charge ion transfer resistance.

  7. Atomic structure relaxation in nanocrystalline NiO studied by EXAFS spectroscopy: Role of nickel vacancies

    NASA Astrophysics Data System (ADS)

    Anspoks, A.; Kalinko, A.; Kalendarev, R.; Kuzmin, A.

    2012-11-01

    Nanocrystalline NiO samples have been studied using the Ni K-edge extended x-ray absorption fine structure (EXAFS) spectroscopy and recently developed modeling technique, combining classical molecular dynamics with ab initio multiple-scattering EXAFS calculations (MD-EXAFS). Conventional analysis of the EXAFS signals from the first two coordination shells of nickel revealed that (i) the second shell average distance R(Ni-Ni2) expands in nanocrystalline NiO compared to microcrystalline NiO, in agreement with overall unit cell volume expansion observed by x-ray diffraction; (ii) on the contrary, the first shell average distance R(Ni-O1) in nanocrystalline NiO shrinks compared to microcrystalline NiO; (iii) the thermal contribution into the mean-square relative displacement σ2 is close in both microcrystalline and nanocrystalline NiO and can be described by the Debye model; (iv) the static disorder is additionally present in nanocrystalline NiO in both the first Ni-O1 and second Ni-Ni2 shells due to nanocrystal structure relaxation. Within the MD-EXAFS method, the force-field potential models have been developed for nanosized NiO using as a criterion the agreement between the experimental and theoretical EXAFS spectra. The best solutions have been obtained for the 3D cubic-shaped nanoparticle models with nonzero Ni vacancy concentration Cvac: Cvac≈0.4-1.2% for NiO nanoparticles having the cube size of L≈3.6-4.2 nm and Cvac≈1.6-2.0% for NiO thin film composed of cubic nanograins with a size of L≈1.3-2.1 nm. Thus our results show that the Ni vacancies in nanosized NiO play important role in its atomic structure relaxation along with the size reduction effect.

  8. Laser ablation of Al-Ni alloys and multilayers

    NASA Astrophysics Data System (ADS)

    Roth, Johannes; Trebin, Hans-Rainer; Kiselev, Alexander; Rapp, Dennis-Michael

    2016-05-01

    Laser ablation of Al-Ni alloys and multilayers has been studied by molecular dynamics simulations. The method was combined with a two-temperature model to describe the interaction between the laser beam, the electrons, and the atoms. As a first step, electronic parameters for the alloys had to be found and the model developed originally for pure metals had to be generalized to multilayers. The modifications were verified by computing melting depths and ablation thresholds for pure Al and Ni. Here known data could be reproduced. The improved model was applied to the alloys Al_3Ni, AlNi and AlNi_3. While melting depths and ablation thresholds for AlNi behave unspectacular, sharp drops at high fluences are observed for Al_3Ni and AlNi_3. In both cases, the reason is a change in ablation mechanism from phase explosion to vaporization. Furthermore, a phase transition occurs in Al_3Ni. Finally, Al layers of various thicknesses on a Ni substrate have been simulated. Above threshold, 8 nm Al films are ablated as a whole while 24 nm Al films are only partially removed. Below threshold, alloying with a mixture gradient has been observed in the thin layer system.

  9. Measurement of {sup 63}Ni and {sup 59}Ni by accelerator mass spectrometry using characteristic projectile x-rays

    SciTech Connect

    McAninch, J.E.; Hainsworth, L.J.; Marchetti, A.A.

    1996-05-01

    The long-lived isotopes of nickel ({sup 59}Ni, {sup 63}Ni) have current and potential use in a number of applications including cosmic radiation studies, biomedical tracing, characterization of low-level radioactive wastes, and neutron dosimetry. Methods are being developed at LLNL for the routine detection of these isotopes by AMS. One intended application is in Hiroshima dosimetry. The reaction {sup 63}Cu(n,p){sup 63}Ni has been identified as one of a small number of reactions which might be used for the direct determination of the fast neutron fluence emitted by the Hiroshima bomb. AMS measurement of {sup 63}Ni(t{sub 1/2} = 100 y) requires the chemical removal of {sup 63}Cu, which is a stable isobar of {sup 63}Ni. Following the electrochemical separation of Ni from gram-sized copper samples, the Cu concentration is further lowered to < 2 x 10{sup -8} (Cu/Ni) using the reaction of Ni with carbon monoxide to form the gas Ni(CO){sub 4}. The Ni(CO){sub 4} is thermally decomposed directly in sample holders for measurement by AMS. After analysis in the AMS spectrometer, the ions are identified using characteristic projectile x-rays, allowing further rejection of remaining {sup 63}Cu. In a demonstration experiment, {sup 63}Ni was measured in Cu wires (2-20 g) which had been exposed to neutrons from a {sup 252}Cf source. We successfully measured {sup 63}Ni at levels necessary for the measurement of Cu samples exposed near the Hiroshima hypocenter. For the demonstration samples, the Cu content was chemically reduced by a factor of 10{sup 12} with quantitative retention of {sup 63}Ni. Detection sensitivity (3{sigma}) was {approximately}20 fg {sup 63}Ni in 1 mg Ni carrier ({sup 63}Ni/Ni {approx} 2 x 10{sup -11}). Significant improvements in sensitivity are expected with planned incremental changes in the methods. Preliminary results indicate that a similar sensitivity is achievable for {sup 59}Ni (t{sub 1/2} = 10{sup 5} y).

  10. Adjustment of temperature coefficient of resistance in NiCr/CuNi(Mn)/NiCr films

    NASA Astrophysics Data System (ADS)

    Brückner, W.; Baunack, St.; Elefant, D.; Reiss, G.

    1996-06-01

    The thin-film system Ni0.37Cr0.63/Cu0.57Ni0.42Mn0.01/Ni0.37Cr0. 63 with a typical thickness of 1 μm is used for low-ohmic precision resistors. The necessary adjustment of the temperature coefficient of resistance (TCR) by annealing has been studied by investigating the irreversible changes of the resistance during various annealing steps of NiCr/CuNi(Mn)/NiCr multilayers in comparison with single layers of CuNi(Mn) and NiCr. Auger depth profiles showed that the interdiffusion of CuNi(Mn) and NiCr results in an impoverishment of Ni in CuNi(Mn), explaining the TCR shift by comparison with data of Cu1-xNix bulk material. The decrease of the resistivity and the reduction of the width of the copper-nickel conductive layer by formation of a Ni0.6Cr0.2Cu0.2 interdiffusion zone phase (in accordance with the Cu-Ni-Cr phase diagram) cause a significant curvature of the resistance-temperature curve. As main result, it is shown that the NiCr base and cover layers and their interdiffusion with CuNi(Mn) play the decisive role in adjusting the TCR. It was checked that oxidation and topography effects have no remarkable influences.

  11. Li-Rich Layered Cathode Material Li[Li0.157Ni0.138Co0.134Mn0.571]O2 Synthesized with Solid-State Coordination Method

    NASA Astrophysics Data System (ADS)

    Liao, Da-qian; Xia, Chao-yang; Xi, Xiao-ming; Zhou, Chun-xian; Xiao, Ke-song; Chen, Xiao-qing; Qin, Shi-biao

    2016-06-01

    Lithium-rich layered material Li[Li0.157Ni0.138Co0.134Mn0.571]O2 was prepared with the solid-state coordination method. Lithium nitrate, nickel acetate, cobalt acetate, and manganese acetate were used as raw materials, and citric acid as solid complexing agent. The lithium-rich layered material was prepared by heat-treating the precursors of the solid-phase complex compound. The prepared materials exhibited typical layer structure, nanosize distribution, and excellent electrochemical performance, and the preparation process has the advantages of low cost and simplicity. The initial discharge capacity of the prepared material reached as high as 270 mAh/g, and the charge-transfer resistance of the electrode was about 165 Ω at 4.0 V.

  12. Structural, Magnetic and Microwave Absorption Characteristics of Ni0.5LixZn(0.5-x)Fe2O4 Nano-particles Prepared by Co-Precipitation Method

    NASA Astrophysics Data System (ADS)

    Rohadiana, D. N.; Jamal, Z. A. Z.; Jamaludin, S. B.; Bari, M. F.; Malek, M. F.; Meng, C. E.

    2011-12-01

    Synthesis of Ni0.5LixZn(0.5-x)Fe2O4 nano-particles were realized via co-precipitation method. X-ray diffractometer (XRD), vibrating sample magnetometer (VSM) and network analyzer measurements were performed on the samples to determine, respectively, the characteristics of the crystal structure, and the magnetic and microwave absorption properties of the samples. The XRD patterns showed that all the samples are of single phase spinel type ferrites without the presence of other phases. Patterns of decreasing lattice parameter and increasing crystallite size values were observed at increasing Li concentration. For the magnetic property, the saturation magnetization (Ms) was found to vary with increasing pattern at higher Li doping level. The microwave electromagnetic properties of the samples were studied at the frequency range of 8-15 GHz and the results showed the material has the potential to be an alternative microwave absorber. The results and mechanisms concerned are discussed.

  13. Magnetic and dielectric characterization of Co{sub 0.9}Ni{sub 0.1}Fe{sub 2}O{sub 4} prepared by hydroxide co-precipitation method

    SciTech Connect

    Mane, S. M.; Tirmali, P. M. Kulkarni, S. B.; Kolekar, C. B.

    2016-04-13

    Co{sub 1–x} Ni{sub x}Fe{sub 2}O{sub 4} (where x=0.1) were prepared by using the hydroxide co-precipitation method. An obtained precipitate was sintered at 1100°C by microwave sintering technique. The structural analysis confirms the single-phase cubic spinel structure with Fd-3m space group. The magnetic characterization was carried out at temperature 300K.Saturation magnetisation and coercivity is 77.22 and 908 Oe. Irreversibility is observed between the ZFC and FC curves at 100 Oe. The variation in the dielectric constant and loss tangent are studied at room temperature with increasing frequency. Continues decrease in the the dielectric constant with increasing frequency shows inverse dependence on frequency. Morphological and elemental studies were done by using the scanning electron microscope with EDAX.

  14. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure

    NASA Astrophysics Data System (ADS)

    Li, Wei; Liu, Ping; Zhang, Ke; Ma, Fengcang; Liu, Xinkuan; Chen, Xiaohong; He, Daihua

    2014-08-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized.

  15. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure

    PubMed Central

    2014-01-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized. PMID:25232296

  16. Martensitic transformation of FeNi nanofilm induced by interfacial stress generated in FeNi/V nanomultilayered structure.

    PubMed

    Li, Wei; Liu, Ping; Zhang, Ke; Ma, Fengcang; Liu, Xinkuan; Chen, Xiaohong; He, Daihua

    2014-01-01

    FeNi/V nanomultilayered films with different V layer thicknesses were synthesized by magnetron sputtering. By adjusting the thickness of the V layer, different interfacial compressive stress were imposed on FeNi layers and the effect of interfacial stress on martensitic transformation of the FeNi film was investigated. Without insertion of V layers, the FeNi film exhibits a face-centered cubic (fcc) structure. With the thickness of V inserted layers up to 1.5 nm, under the coherent growth structure in FeNi/V nanomultilayered films, FeNi layers bear interfacial compressive stress due to the larger lattice parameter relative to V, which induces the martensitic transformation of the FeNi film. As the V layer thickness increases to 2.0 nm, V layers cannot keep the coherent growth structure with FeNi layers, leading to the disappearance of interfacial compressive stress and termination of the martensitic transformation in the FeNi film. The interfacial compressive stress-induced martensitic transformation of the FeNi nanofilm is verified through experiment. The method of imposing and modulating the interfacial stress through the epitaxial growth structure in the nanomultilayered films should be noticed and utilized.

  17. Hydrogen in La2MgNi9D13: the role of magnesium.

    PubMed

    Denys, Roman V; Yartys, Volodymyr A; Webb, Colin J

    2012-04-02

    Reversible hydrogen storage capacity of the La(3-x)Mg(x)Ni(9) alloys, charged by gaseous hydrogen or by electrochemical methods, reaches its maximum at composition La(2)MgNi(9). As (La,Mg)Ni(3-3.5) alloys are the materials used in advanced metal hydride electrodes in Ni-MH batteries, this raises interest in the study of the structure-properties interrelation in the system La(2)MgNi(9)-H(2) (D(2)). In the present work, this system has been investigated by use of in situ synchrotron X-ray and neutron powder diffraction in H(2)/D(2) gas and by performing pressure-composition-temperature measurements. The saturated La(2)MgNi(9)D(13.1) hydride forms via an isotropic expansion and crystallizes with a trigonal unit cell (space group R3m (No.166); a = 5.4151(1) Å; c = 26.584(2) Å; V = 675.10(6) Å(3)). The studied hybrid structure is composed of a stacking of two layers resembling existing intermetallic compounds LaNi(5) (CaCu(5) type) and LaMgNi(4) (Laves type). These are occupied by D to form LaNi(5)D(5.2) and LaMgNi(4)D(7.9). The LaNi(5)D(5.2) slab has a typical structure observed for all reported LaNi(5)-containing hybrid structures of the AB(5) + Laves phase types. However, the Laves type slab LaMgNi(4)D(7.9) is different from the characterized individual LaMgNi(4)D(4.85) hydride. This results from the filling of a greater variety of interstitial sites in the La(2)MgNi(9)D(13)/LaMgNi(4)D(7.9), including MgNi(2), Ni(4), (La/Mg)(2)Ni(2), and (La/Mg)Ni(3), in contrast with individual LaMgNi(4)D(4.85) where only La(2)MgNi(2) and Ni(4) interstitials are occupied. Despite a random distribution of La and Mg in the structure, a local hydrogen ordering takes place with H atoms favoring occupation of two Mg-surrounded sites, triangles MgNi(2) and tetrahedra LaMgNi(2). A directional bonding between Ni, Mg, and hydrogen is observed and is manifested by a formation of the NiH(4) tetrahedra and MgH(6) octahedra, which are connected to each other by sharing H vertexes to form a

  18. Atomistic Modeling of Pd Site Preference in NiTi

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Mosca, Hugo O.

    2004-01-01

    An analysis of the site subsitution behavior of Pd in NiTi was performed using the BFS method for alloys. Through a combination of Monte Carlo simulations and detailed atom-by-atom energetic analyses of various computational cells, representing compositions of NiTi with up to 10 at% Pd, a detailed understanding of site occupancy of Pd in NiTi was revealed. Pd subsituted at the expense of Ni in a NiTi alloy will prefer the Ni-sites. Pd subsituted at the expense of Ti shows a very weak preference for Ti-sites that diminishes as the amount of Pd in the alloy increases and as the temperature increases.

  19. Atomistic structure of the coherent Ni/Ni[sub 3]Al interface

    SciTech Connect

    Farkas, D. . Dept. of Materials Science and Engineering); Campos, M.F. de; Souze, R.M. de; Goldenstein, H. . Dept. de Metalurgia)

    1994-02-01

    Most Ni-based superalloys are strengthened by the presence of coherent precipitates of an ordered fcc bases phase, known as [gamma][prime]. This phase is basically Ni[sub 3]Al. The precipitates are coherent up to a certain size and they present a cubic shape with faces oriented in the (100) planes of both matrix and precipitate. The detailed atomistic structure of this interface has not been studied. Interest in the use of ordered intermetallic compounds as possible structural materials has resulted in a large amount of work in Ni[sub 3]Al and in particular, the development of interatomic potentials for the Ni-Al system using the embedded atom technique. These potentials have been employed in the simulation of a variety of defects in Ni[sub 3]Al, including dislocation cores, grain boundaries and free surfaces. However, there is no simulation of the Ni/Ni[sub 3]Al interface structure using the embedded atom method. The objective of the present work is to carry out such a simulation. Besides the practical importance of the interface in superalloys, it is the simplest type of interface that can be modeled and it is a good starting point for interface work using the embedded atom technique.

  20. From one to three dimensions: corrugated ∞(1)[NiGe] ribbons as a building block in alkaline earth metal Ae/Ni/Ge phases with crystal structure and chemical bonding in AeNiGe (Ae = Mg, Sr, Ba).

    PubMed

    Hlukhyy, Viktor; Siggelkow, Lisa; Fässler, Thomas F

    2013-06-17

    The new equiatomic nickel germanides MgNiGe, SrNiGe, and BaNiGe have been synthesized from the elements in sealed tantalum tubes using a high-frequency furnace. The compounds were investigated by X-ray diffraction both on powders and single crystals. MgNiGe crystallizes with TiNiSi-type structure, space group Pnma, Z = 4, a = 6.4742(2) Å, b = 4.0716(1) Å, c = 6.9426(2) Å, wR2 = 0.033, 305 F(2) values, 20 variable parameters. SrNiGe and BaNiGe are isotypic and crystallize with anti-SnFCl-type structure (Z = 4, Pnma) with a = 5.727(1) Å, b = 4.174(1) Å, c = 11.400(3) Å, wR2 = 0.078, 354 F(2) values, 20 variable parameters for SrNiGe, and a = 5.969(4) Å, b = 4.195(1) Å, c = 11.993(5) Å, wR2 = 0.048, 393 F(2) values, 20 variable parameters for BaNiGe. The increase of the cation size leads to a reduction of the dimensionality of the [NiGe] polyanions. In the MgNiGe structure the nickel and germanium atoms build a ∞(3)[NiGe] network with magnesium atoms in the channels. In SrNiGe and BaNiGe the ∞(1)[NiGe] ribbons are separated by strontium/barium atoms, whereas in the known CaNiGe structure the ribbons are fused to two-dimmensional atom slabs. The crystal chemistry and chemical bonding in AeNiGe (Ae = Mg, Ca, Sr, Ba) are discussed. The experimental results are reconciled with electronic structure calculations performed using the tight-binding linear muffin-tin orbital (TB-LMTO-ASA) method.

  1. A comparative study of Ni0.7Zn0.3Fe2O4 obtained by sol-gel auto-combustion and flash combustion methods

    NASA Astrophysics Data System (ADS)

    Sutka, A.; Lagzdina, S.; Mezinskis, G.; Pludons, A.; Vitina, I.; Timma, L.

    2011-12-01

    In this study, the nickel-zinc ferrites were prepared via two different methods: the sol-gel auto combustion method and the flash combustion method. Obtained reaction products were sintered at different temperatures 900, 1100 and 1300 °C. The structural and microstructural, as well as electric and dielectric properties of different samples were discussed. The synthesis method has a marked effect on crystalline order, grain size and its distribution, electrical resistivity and dielectric properties.

  2. Phase separation and antisite defects in the thermoelectric TiNiSn half-Heusler alloys

    SciTech Connect

    Kirievsky, K.; Gelbstein, Y. Fuks, D.

    2013-07-15

    The half-Heusler TiNiSn alloys have recently gained an attention as promising candidates for thermoelectric applications. Improvement of these alloys for such applications can be obtained by both electronic and compositional optimizations. The latter can result in a miscibility gap, allowing a phase separation in the nano-scale and consequently a thermal conductivity reduction. Combination of ab initio calculations and statistical thermodynamics was applied for studying the relative stability of a number of superstructures in TiNiSn based alloys. The quasi-binary phase diagram beyond T=0 K for TiNiSn–TiNi{sub 2}Sn solid solutions was calculated using energy parameters extracted from the total energy calculations for ordered structures in the Ni sublattice. We demonstrated that a decomposition of the off-stoichiometric Ni-rich half-Heusler alloy into the stoichiometric TiNiSn phase and into Ni deficient Heusler TiNi{sub 2}Sn phase occurs at elevated temperatures—an effect which recently had been observed experimentally. Furthermore, favorable energetic conditions for antisite defects formation were deduced, based on calculations of the energy of formation, an effect which was explained as a cooperative process of partial disordering on the Ni sublattice. The influence of these two effects on improvement of the thermoelectric performance of TiNiSn based half Heusler compounds is discussed. - Graphical abstract: Phase separation and antisite defects in the thermoelectric TiNiSn alloy, are covered as methods for nanostructuring and thereby enhancement of the thermoelectric potential. - Highlights: • Ab initio calculations/statistical thermodynamics was applied for studying the TiNiSn system. • The phase diagram for TiNiSn–TiNi{sub 2}Sn solid solutions was calculated. • Decomposition of the Ni-rich HH into TiNiSn and Ni deficient TiNi{sub 2}Sn phases was observed. • Favorable energetic conditions for antisite defects formation were deduced.

  3. A comparative synthesis and physicochemical characterizations of Ni/Al2O3-MgO nanocatalyst via sequential impregnation and sol-gel methods used for CO2 reforming of methane.

    PubMed

    Aghamohammadi, Sogand; Haghighi, Mohammad; Karimipour, Samira

    2013-07-01

    Carbon dioxide reforming of methane is an interesting route for synthesis gas production especially over nano-sized catalysts. The present research deals with catalyst development for dry reforming of methane with the aim of reaching the most stable catalyst. Effect of preparation method, one of the most significant variables, on the properties of the catalysts was taken in to account. The Ni/Al2O3-MgO catalysts were prepared via sol-gel and sequential impregnation methods and characterized with XRD, FESEM, EDAX, BET and FTIR techniques. The reforming reactions were carried out using different feed ratios, gas hourly space velocities (GHSV) and reaction temperatures to identify the influence of operational variables. FESEM images indicate uniform particle size distribution for the sample synthesized with sol-gel method. It has been found that the sol-gel method has the potential to improve catalyst desired properties especially metal surface enrichment resulting in catalytic performance enhancement. The highest yield of products was obtained at 850 degrees C for both of the catalysts. During the 10 h stability test, CH4 and CO2 conversions gained higher values in the case of sol-gel made catalyst compared to impregnated one.

  4. Catalytic dechlorination of monochlorobenzene with a new type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant.

    PubMed

    Han, Yi; Li, Wei; Zhang, Minghui; Tao, Keyi

    2008-05-01

    A unique type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant was prepared and used for dechlorination of monochlorobenzene (MCB). The sample Ni(B)/Fe(B) was synthesized by an electroless plating method, in which nanoscale Ni(B) was deposited on the surface of nanoscale Fe(B) synthesized by chemical reduction. The results suggest that the nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant has higher dechlorination efficiency than Ni/Fe(B) catalytic reductant prepared by replacing Fe(B) with Ni(2+) in aqueous solution. The Ni content was found to be an important factor in catalytic dechlorination, with the dechlorination rate increasing with Ni content. The electroless plating method improve the efficiency of the Ni(2+) in the solution. Dechlorination takes place with the existence of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant via a pseudo-first-order reaction.

  5. Controllable synthesis and enhanced microwave absorbing properties of Fe3O4/NiFe2O4/Ni heterostructure porous rods

    NASA Astrophysics Data System (ADS)

    Li, Yana; Wu, Tong; Jin, Keying; Qian, Yao; Qian, Naxin; Jiang, Kedan; Wu, Wenhua; Tong, Guoxiu

    2016-11-01

    We developed a coordinated self-assembly/precipitate transfer/sintering method that allows the controllable synthesis of Fe3O4/NiFe2O4/Ni heterostructure porous rods (HPRs). A series of characterizations confirms that changing [Ni2+] can effectively control the crystal size, internal strain, composition, textural characteristics, and properties of HPRs. Molar percentages of Ni and NiFe2O4 in HPRs increase with [Ni2+] in various Boltzmann function modes. Saturation magnetization Ms and coercivity Hc show U-shaped change trends because of crystal size, composition, and interface magnetic coupling. High magnetic loss is maintained after decorating NiFe2O4 and Ni on the surface of Fe3O4 PRs. Controlling the NiFe2O4 interface layers and Ni content can improve impedance matching and dielectric losses, thereby leading to lighter weight, stronger absorption, and broader absorption band of Fe3O4/NiFe2O4/Ni HPRs than Fe3O4 PRs. An optimum EM wave absorbing property was exhibited by Fe3O4/NiFe2O4/Ni HPRs formed at [Ni2+] = 0.05 M. The maximum reflection loss (RL) reaches -58.4 dB at 13.68 GHz, which corresponds to a 2.1 mm matching thickness. The absorbing bandwidth (RL ≤ -20 dB) reaches 14.4 GHz with the sample thickness at 1.6-2.4 and 2.8-10.0 mm. These excellent properties verify that Fe3O4/NiFe2O4/Ni HPRs are promising candidates for new and effective absorptive materials.

  6. Ni(NiO)/single-walled carbon nanotubes composite: Synthesis of electro-deposition, gas sensing property for NO gas and density functional theory calculation

    SciTech Connect

    Li, Li; Zhang, Guo; Chen, Lei; Bi, Hong-Mei; Shi, Ke-Ying

    2013-02-15

    Graphical abstract: The Ni(NiO)/semiconducting single-walled carbon nanotubes composite collected from the cathode after electro-deposition shows a high sensitivity to low-concentration NO gas at room temperature (18 °C). Display Omitted Highlights: ► Ni(NiO) nanoparticles were deposited on semiconducting SWCNTs by electro-deposition. ► Ni(NiO)/semiconducting SWCNTs film shows a high sensitivity to NO gas at 18 °C. ►Theoretical calculation reveals electron transfer from SWCNTs to NO via Ni. -- Abstract: Single-walled carbon nanotubes which contains metallic SWCNTs (m-SWCNTs) and semiconducting SWCNTs (s-SWCNTs) have been obtained under electric arc discharge. Their separation can be effectively achieved by the electro-deposition method. The Ni(NiO)/s-SWCNTs composite was found on cathode where Ni was partially oxidized to NiO at ambient condition with Ni(NiO) nanoparticles deposited uniformly on the bundles of SWCNTs. These results were confirmed by Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis–NIR and TG characterizations. Furthermore, investigation of the gas sensing property of Ni(NiO)/s-SWCNTs composite film to NO gas at 18 °C demonstrated the sensitivity was approximately 5% at the concentration of 97 ppb. Moreover, density functional theory (DFT) calculations were performed to explore the sensing mechanism which suggested the adsorption of NO molecules onto the composite through N–Ni interaction as well as the proposition of electron transfer mechanisms from SWCNTs to NO via the Ni medium.

  7. Three-Dimensional EBSD Analysis of YSZ, NiO-YSZ and Ni-Alloy

    SciTech Connect

    Saraf, Laxmikant V.

    2012-01-03

    In this report, a method is discussed to perform successive milling on yttria-stabilized zirconia (YSZ), NiO-YSZ and Ni-alloy at the intervals of 85 nm 50 nm and 100 nm, respectively using a focused ion beam (FIB) followed by electron backscatter diffraction (EBSD) analysis on each slice. The EBSD data is then reconstructed to generate 3D volume. The 3D-EBSD band quality data is superimposed on inverse pole figure (IPF) grain orientation analysis to get a correlation with quality of band indexing. For the NiO-YSZ case, grain orientations and band quality factors were matched for grains {approx}250 nm diameters producing a high resolution 3D-EBSD data. For this case, a pore space in 3D volume was visible due to nanocrystalline NiO-YSZ grain network. The advantages of 3D EBSD are discussed in the context of its applications to SOFC research community.

  8. TEM studies of oxidized NiAl and Ni3Al cross sections

    NASA Technical Reports Server (NTRS)

    Doychak, J.; Ruhle, M.

    1989-01-01

    Cross sections of oxide scale/(Ni-Al) intermetallics were prepared by a new method and studied using primarily TEM. The cross sections were prepared by encasing an oxidized metal specimen sandwich in a low-melting-temperature zinc alloy. Observations of oxidized zirconium-doped beta-NiAl cross sections revealed crystallographic voids beneath an adherent Al2O3 scale. The oxide-metal interface was incoherent, but a high dislocation density in the metal near the interface suggested that a large tensile stress was induced by the attached oxide scale. A duplex Al2O3-NiAl2O4 scale formed on zirconium-doped and zirconium/boron-doped gamma-prime-Ni3Al alloys. Additional results are presented involving oxidation mechanisms and oxide-metal interface structures.

  9. Resistance to sulfur poisoning of Ni-based alloy with coinage (IB) metals

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2015-12-01

    The poisoning effects of S atom on the (1 0 0), (1 1 0) and (1 1 1) metal surfaces of pure Ni and Ni-based alloy with IB (coinage) metals (Cu, Ag, Au) are systematically studied. The effects of IB metal dopants on the S poisoning features are analyzed combining the density functional theory (DFT) results with thermodynamics data using the ab initio atomistic thermodynamic method. It is found that introducing IB doping metals into Ni surface can shift the d-band center downward from the Fermi level and weaken the adsorption of S on the (1 0 0) and (1 1 0) surfaces, and the S tolerance ability increases in the order of Ni, Cu/Ni, Ag/Ni and Au/Ni. Nevertheless, on the (1 1 1) surface, the S tolerance ability increases in the order of Ag/Ni (or Cu/Ni), Ni, and Au/Ni. When we increase the coverage of the IB metal dopants, we found that not only Au, but Cu and Ag can increase its S tolerance. We therefore propose that alloying can increase its S tolerance and alloying with Au would be a better way to increase the resistance to sulfur poisoning of the Ni anode as compared with the pure Ni and the Ag- or, Cu-doped Ni materials.

  10. Thermal expansion behavior of NiSi/NiSi2

    NASA Technical Reports Server (NTRS)

    Wilson, D. F.; Cavin, O. B.

    1992-01-01

    The thermal expansion of NiSi/NiSi2 for a range of temperatures from 293 to 1223 K was determined using high-temperature X-ray diffraction. While a linear relation with temperature was found for the lattice parameter of NiSi2, third-order relationships were found for the three lattice parameters of NiSi, with one of the parameters showing a decrease with increasing temperature. The volumetric expansion of both materials exhibited linear relationships.

  11. Properties of LiCoO{sub 2}-coated NiO MCFC cathode

    SciTech Connect

    Kuk, S.T.; Kim, C.K.; Chun, H.S.; Kwon, H.J.

    1996-12-31

    PVA-assisted sol-gel method is useful in producing metal oxides with large surface area at low temperature. We fabricated LiCoO{sub 2}-coated NiO(LC-NiO) cathode by PVA-assisted sol-gel method and measured its properties, The electrical conductivity of LC-NiO cathode was measured to be more than 5 times as high as that of NiO and unit cell test showed improved performance. From the SEM images and Raman spectra. we confirmed that the structure of LC-NiO was different from that of NiO. For 250 hours of steady operation of unit cells. the mean voltage of the cells were 0.78V for NiO and 0.85V for LiCoO{sub 2}-Coated NiO at a current density of l50mA/cm{sup 2}.

  12. Electronic, magnetic and Fermi properties investigates on quaternary Heusler NiCoCrAl, NiCoCrGa and NiFeCrGa

    NASA Astrophysics Data System (ADS)

    Wei, Xiao-Ping; Zhang, Ya-Ling; Chu, Yan-Dong; Sun, Xiao-Wei; Sun, Ting; Guo, Peng; Deng, Jian-Bo

    2015-07-01

    Using the full-potential local-orbital minimum-basis method within the framework of density functional theory, we study the electronic, magnetic and Fermi properties of three quaternary Heusler compounds: NiCoCrAl, NiCoCrGa and NiFeCrGa. Results identify that these compounds are half-metallic ferromagnets with integer spin magnetic moment, and their spin moments follow the Slater-Pauling rule. Accordingly, the origin of gap and magnetic moment are also discussed. In addition, the Fermi surface is further plotted to explore the behavior of electronic states in the vicinity of Fermi level for these compounds. Finally, we argue the influence of tetragonal deformation on electronic and magnetic properties. Meanwhile, the possible L21 disorder is also discussed for NiCoCrAl and NiCoCrGa.

  13. Intrinsic properties and strengthening mechanism of monocrystalline Ni-containing ternary concentrated solid solutions

    DOE PAGES

    Jin, K.; Gao, Y. F.; Bei, H.

    2017-04-07

    Ternary single-phase concentrated solid solution alloys (SP-CSAs), so-called "medium entropy alloys", not only possess notable mechanical and physical properties but also form a model system linking the relatively simple binary alloys to the complex high entropy alloys. Our knowledge of their intrinsic properties is vital to understand the material behavior and to prompt future applications. To this end, three model alloys NiCoFe, NiCoCr, and NiFe-20Cr have been selected and grown as single crystals. We measured their elastic constants using an ultrasonic method, and several key materials properties, such as shear modulus, bulk modulus, elastic anisotropy, and Debye temperatures have beenmore » derived. Furthermore, nanoindentation tests have been performed on these three alloys together with Ni, NiCo and NiFe on their (100) surface, to investigate the strengthening mechanisms. NiCoCr has the highest hardness, NiFe, NiCoFe and NiFe-20Cr share a similar hardness that is apparently lower than NiCoCr; NiCo has the lowest hardness in the alloys, which is similar to elemental Ni. The Labusch-type solid solution model has been applied to interpret the nanoindentation data, with two approaches used to calculate the lattice mismatch. Finally, by adopting an interatomic spacing matrix method, the Labusch model can reasonably predict the hardening effects for the whole set of materials.« less

  14. Preparation and characterization of Ni-doped carbon aerogel for supercapacitor

    NASA Astrophysics Data System (ADS)

    Wang, Shasha; Yan, Meifang; Liu, Haihua; Xu, Yuelong; Zhang, Lihui; Liu, Zhenfa

    2017-01-01

    Ni-doped carbon aerogel was prepared by impregnation methods, physical structure, and electrochemical properties were investigated. Electrochemical properties of prepared Ni-doped carbon aerogel and carbon aerogel electrodes were measured by galvanostatic charge/discharge measurements. The results show Ni-doped carbon aerogels maintain the elementary structure of carbon aerogel, but they exhibited higher specific capacitance than carbon aerogel.

  15. Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al3Ni2@Al nanoparticles as a high microwave absorption material

    NASA Astrophysics Data System (ADS)

    Pang, Yu; Xie, Xiubo; Li, Da; Chou, Wusheng; Liu, Tong

    2017-03-01

    The Al3Ni2@Al nanoparticles (NPs) were prepared from Ni45Al55 master alloy by hydrogen plasma-metal reaction method, and were subsequently dealloyed to produce porous Ni@NiO NPs of 36 nm. The pore size ranges from 0.7 to 1.6 nm, leading to large specific surface area of 69.5 m2/g and big pore volume of 0.507 cc/g. The saturation magnetization (MS) and coercivity (HC) of the microporous Ni@NiO NPs are 11.5 emu/g and 5.2 Oe. They exhibit high microwave absorption performance with a minimum reflection coefficient (RC) of -86.9 dB and an absorption bandwidth of 2.6 GHz (RC≤-10 dB) at thickness of 4.5 mm. The enhanced microwave absorption properties are attributed to the synergistic effect of the magnetic Ni core and dielectric NiO shell, and the micropore architecture. The NPs with micropore morphology and core/shell structure open a new way to modify the microwave absorption performance.

  16. Ni-Co laterite deposits

    USGS Publications Warehouse

    Marsh, Erin E.; Anderson, Eric D.

    2011-01-01

    Nickel-cobalt (Ni-Co) laterite deposits are an important source of nickel (Ni). Currently, there is a decline in magmatic Ni-bearing sulfide lode deposit resources. New efforts to develop an alternative source of Ni, particularly with improved metallurgy processes, make the Ni-Co laterites an important exploration target in anticipation of the future demand for Ni. This deposit model provides a general description of the geology and mineralogy of Ni-Co laterite deposits, and contains discussion of the influences of climate, geomorphology (relief), drainage, tectonism, structure, and protolith on the development of favorable weathering profiles. This model of Ni-Co laterite deposits represents part of the U.S. Geological Survey Mineral Resources Program's effort to update the existing models to be used for an upcoming national mineral resource assessment.

  17. Magnetization of nano-fine particles of Pd/Ni alloys

    NASA Astrophysics Data System (ADS)

    Nunomura, N.; Teranishi, T.; Miyake, M.; Oki, A.; Yamada, S.; Toshima, N.; Hori, H.

    1998-01-01

    In order to investigate the giant magnetic moment problem in nano-fine Pd alloys particles, enough amount of Pd/Ni fine particles with quite narrow diameter distribution have been prepared by chemical method. The magnetization of Pd/Ni alloy ultrafine particles has been systematically investigated by using a SQUID magnetometer. The magnetization remarkably increases above the concentration of 8% of Ni. This result indicates the giant moment in the ultrafine Pd/Ni alloy particles.

  18. Ionizing Radiation Effects in Ni Nanotubes

    NASA Astrophysics Data System (ADS)

    Shlimas, D.; Kozlovsky, A.; Shumskaya, A.; Kaniukov, E.; Ibragimova, M.; Zdorovets, M.; Kadyrzhanov, K.

    2017-01-01

    Polycrystalline nickel nanotubes with diameter of 380 nm and wall thickness 95 nm were synthesized by electrochemical method using PET track-etched membranes with thickness of 12 μm. A comprehensive study of the structural, morphological and electrical characteristics of Ni nanotubes irradiated with C+13 ions with energy 1.75 MeV/nucleon and fluence ranging from 109 to 5 × 1011 cm-2 was carried out. The ability of modification of structural parameters such as lattice parameter and the average size of crystallites and conductivity of Ni nanotubes by irradiation was shown.

  19. Surface Segregation in Cu-Ni Alloys

    NASA Technical Reports Server (NTRS)

    Good, Brian; Bozzolo, Guillermo; Ferrante, John

    1993-01-01

    Monte Carlo simulation is used to calculate the composition profiles of surface segregation of Cu-Ni alloys. The method of Bozzolo, Ferrante, and Smith is used to compute the energetics of these systems as a function of temperature, crystal face, and bulk concentration. The predictions are compared with other theoretical and experimental results.

  20. Vacuum-free, maskless patterning of Ni electrodes by laser reductive sintering of NiO nanoparticle ink and its application to transparent conductors.

    PubMed

    Lee, Daeho; Paeng, Dongwoo; Park, Hee K; Grigoropoulos, Costas P

    2014-10-28

    We introduce a method for direct patterning of Ni electrodes through selective laser direct writing (LDW) of NiO nanoparticle (NP) ink. High-resolution Ni patterns are generated from NiO NP thin films by a vacuum-free, lithography-free, and solution-processable route. In particular, a continuous wave laser is used for the LDW reductive sintering of the metal oxide under ambient conditions with the aid of reducing agents in the ink solvent. Thin (∼ 40 nm) Ni electrodes of glossy metallic surfaces with smooth morphology and excellent edge definition can be fabricated. By applying this method, we demonstrate a high transmittance (>87%), electrically conducting panel for a touch screen panel application. The resistivity of the Ni electrode is less than an order of magnitude higher compared to that of the bulk Ni. Mechanical bending test, tape-pull test, and ultrasonic bath test confirm the robust adhesion of the electrodes on glass and polymer substrates.

  1. Performance of Co/Al2O3/NiFe magnetic tunnel junctions prepared by a two-step rf plasma oxidation method

    NASA Astrophysics Data System (ADS)

    Yoon, K. S.; Park, J. H.; Choi, J. H.; Yang, J. Y.; Lee, C. H.; Kim, C. O.; Hong, J. P.; Kang, T. W.

    2001-08-01

    A two-step rf plasma oxidation technique of an insulating layer has been performed to enhance electrical and structural properties of magnetic tunnel junction (MTJ) devices. Comparison was made by analyzing properties of the MTJ oxidized by conventional rf and two-step rf plasma oxidation methods. Experimentally observed results give improved surface imaging and sufficient oxygen contents of the insulating layer under the two-step oxidation method. In addition, electrical breakdown voltage and magnetoresistance of the MTJ were increased from 0.7 to 1.8 V and from 4.5% to 6.8%, respectively, correlated with improved structural information.

  2. Comparison of NiS2 and α-NiS hollow spheres for supercapacitors, non-enzymatic glucose sensors and water treatment.

    PubMed

    Wei, Chengzhen; Cheng, Cheng; Cheng, Yanyan; Wang, Yan; Xu, Yazhou; Du, Weimin; Pang, Huan

    2015-10-21

    NiS2 hollow spheres are successfully prepared by a one-step template free method. Meanwhile, α-NiS hollow spheres can also be synthesized via the calcination of the pre-obtained NiS2 hollow spheres at 400 °C for 1 h in air. The electrochemical performances of the as-prepared NiS2 and α-NiS hollow sphere products are evaluated. When used for supercapacitors, compared with NiS2 hollow spheres, the α-NiS hollow sphere electrode shows a large specific capacitance of 717.3 F g(-1) at 0.6 A g(-1) and a good cycle life. Furthermore, NiS2 and α-NiS hollow spheres are successfully applied to fabricate non-enzymatic glucose sensors. In particular, the α-NiS hollow spheres exhibit good catalytic activity for the oxidation of glucose, a fast amperometric response time of less than 5 s, and the detection limit is estimated to be 0.08 μM. More importantly, compared with other normally co-existing interfering species, such as ascorbic acid, uric acid and dopamine, the electrode modified with α-NiS hollow spheres shows good selectivity. Moreover, the α-NiS hollow spheres also present good capacity to remove Congo red organic pollutants from wastewater by their surface adsorption ability.

  3. Structure relaxation and crystallization of the CoW-CoNiW-NiW electrodeposited alloys

    PubMed Central

    2014-01-01

    The structure of electrolytically deposited nanocrystalline alloys of the CoW-CoNiW-NiW systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures of 200°C to 300°C. The structural and compositional inhomogeneities were found in the CoW-CoNiW-NiW alloys, while the local changes in composition were found to reach 18 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface, and we found their nuclei density to range from 2 × 1023 /m3 to 3 × 1023 /m3. It was determined that the local diffusion coefficient ranged from 0.9 to 1.7 10−18 m2/s, which could be explained by the prevalence of surface diffusion. The data gathered in these investigations can be used to predict the thermal stability of CoW-CoNiW-NiW alloys. PMID:24506913

  4. Structure relaxation and crystallization of the CoW-CoNiW-NiW electrodeposited alloys

    NASA Astrophysics Data System (ADS)

    Pustovalov, Evgeny V.; Modin, Evgeny B.; Voitenko, Oleg V.; Fedorets, Aleksander N.; Dubinets, Aleksander V.; Grudin, Boris N.; Plotnikov, Vladimir S.; Grabchikov, Sergey S.

    2014-02-01

    The structure of electrolytically deposited nanocrystalline alloys of the CoW-CoNiW-NiW systems under low-temperature heating was investigated by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM), and analytical methods such as energy dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS). Structural relaxation and crystallization were investigated at temperatures of 200°C to 300°C. The structural and compositional inhomogeneities were found in the CoW-CoNiW-NiW alloys, while the local changes in composition were found to reach 18 at.%. Nanocrystals in the alloys grew most intensely in the presence of a free surface, and we found their nuclei density to range from 2 × 1023 /m3 to 3 × 1023 /m3. It was determined that the local diffusion coefficient ranged from 0.9 to 1.7 10-18 m2/s, which could be explained by the prevalence of surface diffusion. The data gathered in these investigations can be used to predict the thermal stability of CoW-CoNiW-NiW alloys.

  5. Ni biogeochemical cycle through geological time: insights from Ni isotope variations in modern and ancient marine metallifereous deposits

    NASA Astrophysics Data System (ADS)

    Gueguen, B.; Rouxel, O.; Ponzevera, E.; Sorensen, J. V.; Toner, B.; Bekker, A.

    2011-12-01

    Studies of isotopic composition of transition metals such as Fe, Cu, Zn, and Mo as biogeochemical tracers became popular recently. Since Ni is ubiquitous in marine metallifereous deposits and its concentration in water column is coupled to that of nutrients, it has a potential as a biogeochemical tracer. Isotopic analyses were performed on a Neptune MC-ICP-MS using a double-spike correction method for instrumental mass bias. Deep-sea ferromanganese crusts have been used to establish a record of seawater over the last 60 Myr. Our results show that Fe-Mn crusts from both Atlantic and Pacific oceans are systematically enriched in heavy isotopes relative to Bulk Silicate Earth with δ60/58Ni values ranging from 0.30 to 1.80% (2se = 0.04%). In contrast, Iron Formations (IF) with ages ranging from 3.8 to 0.7 Gyr display a wider range of values with a striking negative Ni isotope excursion down to -2.46% (2se = 0.03%) in Neoproterozoic IF. Although correlation between Ni isotope compositions, Ni concentrations and BIFs ages seems to be lacking, several Ni isotope excursions to either positive or negative Ni isotope values are notable prior to 2.4 Gyr. Methanogens were likely abundant in Precambrian water column until they retreated to pore waters and local environments once the oceans were oxygenated after the Great Oxidation Event (GOE). They preferentially uptake light Ni isotopes leaving isotopically heavier Ni in oceans. Our Ni isotope record of Precambrian IF does not show a unidirectional change across the GOE implying that Ni isotope composition of the Archean oceans was not dominated by this metabolism. Preliminary Ni adsorption experiments on Fe-Mn oxy-hydroxides show a maximum fractionation factor between the mineral phase and aqueous solution of -1.00% (2se = 0.03%). Hence, isotopic variations in Fe-Mn crusts and IF cannot be simply explained by adsorption processes, but require changes in composition of either Ni sources (local or global) to seawater (e

  6. The oxidation of Ni-rich Ni-Al intermetallics

    NASA Technical Reports Server (NTRS)

    Doychak, Joseph; Smialek, James L.; Barrett, Charles A.

    1988-01-01

    The oxidation of Ni-Al intermetallic alloys in the beta-NiAl phase field and in the two phase beta-NiAl/gamma'-Ni3Al phase field has been studied between 1000 and 1400 C. The stoichiometric beta-NiAl alloy doped with Zr was superior to other alloy compositions under cyclic and isothermal oxidation. The isothermal growth rates did not increase monotonically as the alloy Al content was decreased. The characteristically ridged alpha-Al2O3 scale morphology, consisting of cells of thin, textured oxide with thick growth ridges at cell boundaries, forms on oxidized beta-NiAl alloys. The correlation of scale features with isothermal growth rates indicates a predominant grain boundary diffusion growth mechanism. The 1200 C cyclic oxidation resistance decreases near the lower end of the beta-NiAl phase field.

  7. Synthesis Mechanism and Strengthening Effects of Laminated NiAl by Reaction Annealing

    NASA Astrophysics Data System (ADS)

    Du, Yan; Fan, Guohua; Wang, Qingwei; Geng, Lin

    2017-01-01

    N iA l with a laminated microstructure has been fabricated by reaction annealing of Ni-Al system at 1473 K (1200 °C). The laminated NiAl shows heterogeneity of chemical gradient and bimodal grain size distribution. The objective of this study is to investigate the synthesis mechanism and the strengthening effect of this laminated NiAl, therefore to promote further application of NiAl as a high-temperature structural material. Heat treatments at 1473 K (1200 °C) and subsequent characterization were utilized to study the synthesis mechanism. It shows that in original Al regions NiAl nuclei precipitate from Al(Ni) liquid phase and form fine-grained NiAl layers, whereas in original Ni regions NiAl nuclei precipitate from Ni(Al) saturated solution through diffusion and form coarse-grained NiAl layers. Moreover, heterogeneity of chemical gradient is generated through diffusion during annealing. The mechanical properties of laminated NiAl have also been studied via nanoindentation method. It shows that both chemical gradient and bimodal grain size distribution could strengthen the laminated NiAl.

  8. Controlled synthesis of mesoporous β-Ni(OH){sub 2} and NiO nanospheres with enhanced electrochemical performance

    SciTech Connect

    Xing, Shengtao; Wang, Qian; Ma, Zichuan; Wu, Yinsu; Gao, Yuanzhe

    2012-09-15

    Highlights: ► Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a simple complexation–precipitation method. ► Both ammonia and citrate played an important role for the formation of mesoporous nanospheres. ► β-Ni(OH){sub 2} and NiO nanospheres showed excellent capacitive properties due to their mesoporous structures and larger surface areas. -- Abstract: Uniform mesoporous β-Ni(OH){sub 2} and NiO nanospheres with hierarchical structures were synthesized by a facile complexation–precipitation method. The effects of ammonia and citrate on the structure and morphology of the products were thoroughly investigated by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption–desorption measurements. The results indicated that ammonia played an important role for the formation of flowerlike spheres assembled from nanosheets. The addition of citrate could remarkably reduce the particle sizes and increase the specific surface areas of flowerlike spheres. A possible formation mechanism based on the experimental results was proposed to understand their growing procedures. β-Ni(OH){sub 2} and NiO nanospheres prepared with the addition of citrate showed excellent capacitive properties due to their mesoporous structures and large surface areas, suggesting the importance of controlled synthesis of hierarchical nanostructures for their applications.

  9. Bulk Migration of Ni/NiO in Ni-YSZ during Reducing Conditions

    SciTech Connect

    Saraf, Laxmikant V.; Baer, Donald R.; Lea, Alan S.; Zhu, Zihua; Strohm, James J.; Sitzman, S. D.; King, David L.

    2010-02-09

    Understanding the migration of Ni/NiO in Ni-YSZ can potentially help to design a better solid oxide fuel cell (SOFC) anode. We have observed that extensive hydrogen reduction and methane steam reforming of Ni-YSZ caused bulk migration of Ni/NiO to at least ~ 5 µm deeper from the Ni-YSZ surface. No significant bulk migration effects were detected after simple thermal treatments in non-reducing/non-reforming environment. Surface analysis of a single zirconia grain in the first 10-20 nm region from annealed, hydrogen reduced and methane steam reformed Ni-YSZ shows Ni-enriched surface supporting earlier claims of Ni exsolution. 3D-EBSD analysis of thermally treated sample before exposing it to reducing and reforming environment indicated mixed NiO/YSZ phase with some porosity and random grain orientation. The surface analysis and mapping were carried out using ToF-SIMS and AES whereas EDS maps on FIB sliced areas on Ni-YSZ were utilized for the bulk analysis. The results provide additional information related to complex reactions occurring in SOFC during internal reforming conditions.

  10. Rapid Self-Assembly Spherical Li1.2Mn0.56Ni0.16Co0.08O2 with Improved Performances by Microwave Hydrothermal Method as Cathode for Lithium-Ion Batteries.

    PubMed

    Shi, Shaojun; Wang, Ting; Cao, Min; Wang, Jiawei; Zhao, Mengxi; Yang, Gang

    2016-05-11

    Spherical Li-rich Li1.2Mn0.56Ni0.16Co0.08O2 compound is rapidly synthesized through a facile microwave hydrothermal method followed by a high-temperature solid-state reaction. Homogenous spherical precursor can be precipitated through the microwave hydrothermal (MH) method within 30 min without rigorous coprecipitation condition. The as-prepared Li-rich compound exhibits a hierarchical structure composed of spherical secondary particles (2-3 μm) and small primary particles (150-250 nm) with pores. X-ray diffractometry (XRD) and Brunauer-Emmett-Teller (BET) tests prove that a well-formed layered structure and a large specific surface area containing pores are obtained through the MH method. Such structure is a benefit for the thorough contact between active materials and electrolyte to increase the reactive points. Thus, the as-prepared Li-rich compound exhibits perfect electrochemical performances with a high discharge capacity of 235.6 mAh g(-1) at a current density of 200 mA g(-1). Even at higher current densities of 1000 and 2000 mA g(-1), discharge capacities of 168.6 and 131.2 mAh g(-1) are still maintained, respectively. Furthermore, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic intermittent titration technique (GITT) are carried out to study the material prepared by microwave hydrothermal method. It is considered as an efficient way to synthesize Li-rich compound as cathode material for applications.

  11. Facile Preparation of Ag/NiO Composite Nanosheets and Their Antibacterial Activity

    NASA Astrophysics Data System (ADS)

    Shi, Cui-E.; Pan, Lu; Wang, Cheng-Run; He, Yi; Wu, Yong-Feng; Xue, Sai-Sai

    2016-01-01

    Sheet-like precursors of NiO and Ag/NiO with different Ag contents were synthesized by a facile and easily controlled hydrothermal method. The NiO and Ag/NiO composite nanosheets were prepared by calcination of the corresponding precursors at 400°C for 3 h. The as-synthesized samples were characterized by thermogravimetric analysis, x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The antibacterial activity of NiO and Ag/NiO composites to several gram-positive and gram-negative bacteria was examined. Results showed that NiO nanosheets hardly exhibited antibacterial activity; however, Ag/NiO composites displayed higher activity even with low Ag content.

  12. Very early warning of next El Niño.

    PubMed

    Ludescher, Josef; Gozolchiani, Avi; Bogachev, Mikhail I; Bunde, Armin; Havlin, Shlomo; Schellnhuber, Hans Joachim

    2014-02-11

    The most important driver of climate variability is the El Niño Southern Oscillation, which can trigger disasters in various parts of the globe. Despite its importance, conventional forecasting is still limited to 6 mo ahead. Recently, we developed an approach based on network analysis, which allows projection of an El Niño event about 1 y ahead. Here we show that our method correctly predicted the absence of El Niño events in 2012 and 2013 and now announce that our approach indicated (in September 2013 already) the return of El Niño in late 2014 with a 3-in-4 likelihood. We also discuss the relevance of the next El Niño to the question of global warming and the present hiatus in the global mean surface temperature.

  13. Structural and oxidation properties of CoNi nanowires

    NASA Astrophysics Data System (ADS)

    Aguilera-Granja, Faustino; Montejano-Carrizales, Juan Martin; Vogel, Eugenio E.

    2016-06-01

    Nanocylinders made out of CoNi alloys offer interesting properties which are dependent on the proportion of the constituent elements, the preparation methods and the thermal history of the sample. In the present paper we calculate the structural and electronic properties of Co1- x Ni x alloys at subnanoscopic level. SIESTA program is used to relax the structures following standard protocols. Relative positions of the minority atoms (Ni) are varied aiming to find the lowest energy configurations. It is found that Ni atoms minimize energy at surface positions mainly at the ends of the cylinders. The implications of this result in the magnetic properties of the systems are discussed. The work is continued to study the oxidation properties of the different possible surface compositions. It is found that surfaces of Ni are more resistant to oxidation than Co ones. The combination of the two previous results can lead to cylinders with high magnetic coercivity and relatively high resistance to oxidation.

  14. Microwave absorption properties of Ni/(C, silicides) nanocapsules

    PubMed Central

    2012-01-01

    The microwave absorption properties of Ni/(C, silicides) nanocapsules prepared by an arc discharge method have been studied. The composition and the microstructure of the Ni/(C, silicides) nanocapsules were determined by means of X-ray diffraction, X-ray photoelectric spectroscopy, and transmission electron microscope observations. Silicides, in the forms of SiOx and SiC, mainly exist in the shells of the nanocapsules and result in a large amount of defects at the ‘core/shell’ interfaces as well as in the shells. The complex permittivity and microwave absorption properties of the Ni/(C, silicides) nanocapsules are improved by the doped silicides. Compared with those of Ni/C nanocapsules, the positions of maximum absorption peaks of the Ni/(C, silicides) nanocapsules exhibit large red shifts. An electric dipole model is proposed to explain this red shift phenomenon. PMID:22548846

  15. Photosensitivity of the Ni-n-GaAs Schottky barriers

    SciTech Connect

    Melebaev, D.; Melebaeva, G. D.; Rud', V. Yu. Rud', Yu. V.

    2009-01-15

    The method of chemical deposition is used to form the structures with the Ni-n-GaAs Schottky barrier. The thickness of the Ni layers with a specular outer surface was varied within the range of 150-220 A. It was experimentally observed for the first time that photosensitivity of the obtained barriers with the semitransparent Ni layers illuminated is practically absent in the Fowler region of the spectrum at hv = 0.9-1.5 eV. This circumstance is related mainly to the fact that, in this case, the Ni layer side of the structure was illuminated, and radiation with the photon energy hv < 1.3 eV was effectively reflected from the nickel surface. It is established that the developed Ni-n-GaAs structures can be used as high-efficiency wide-band photoconverters of both visible and ultraviolet radiation.

  16. Porous bimetallic PdNi catalyst with high electrocatalytic activity for ethanol electrooxidation.

    PubMed

    Feng, Yue; Bin, Duan; Yan, Bo; Du, Yukou; Majima, Tetsuro; Zhou, Weiqiang

    2017-05-01

    Porous bimetallic PdNi catalysts were fabricated by a novel method, namely, reduction of Pd and Ni oxides prepared via calcining the complex chelate of PdNi-dimethylglyoxime (PdNi-dmg). The morphology and composition of the as-prepared PdNi were investigated by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Furthermore, the electrochemical properties of PdNi catalysts towards ethanol electrooxidation were also studied by electrochemical impedance spectrometry (EIS), cyclic voltammetry (CV) and chronoamperometry (CA) measurement. In comparison with porous Pd and commercial Pd/C catalysts, porous structural PdNi catalysts showed higher electrocatalytic activity and durability for ethanol electrooxidation, which may be ascribed to Pd and Ni property, large electroactive surface area and high electron transfer property. The Ni exist in the catalyst in the form of the nickel hydroxides (Ni(OH)2 and NiOOH) which have a high electron and proton conductivity enhances the catalytic activity of the catalysts. All results highlight the great potential application of the calcination-reduction method for synthesizing high active porous PdNi catalysts in direct ethanol fuel cells.

  17. Synthesis and magnetic properties of bacterial cellulose—ferrite (MFe2O4, M  =  Mn, Co, Ni, Cu) nanocomposites prepared by co-precipitation method

    NASA Astrophysics Data System (ADS)

    Sriplai, Nipaporn; Mongkolthanaruk, Wiyada; Pinitsoontorn, Supree

    2017-09-01

    The magnetic nanocomposites based on bacterial cellulose (BC) matrix and ferrite (MFe2O4, M  =  Mn, Co, Ni and Cu) nanoparticles (NPs) were fabricated. The never-dried and freeze-dried BC nanofibrils were used as templates and a co-precipitation method was applied for NPs synthesis. The nanocomposites were either freeze-dried or annealed before subjected to characterization. The x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy showed that only MnFe2O4 and CoFe2O4 NPs could be successfully incorporated in the BC nanostructures. The results also indicated that the BC template should be freeze-dried prior to the co-precipitation process. The magnetic measurement by a vibrating sample magnetometer (VSM) showed that the strongest ferromagnetic signal was found for BC-CoFe2O4 nanocomposites. The morphological investigation by a scanning electron microscope (SEM) showed the largest volume fraction of NPs in the BC-CoFe2O4 sample which was complimentary to the magnetic property measurement. Annealing resulted in the collapse of the opened nanostructure of the BC composites. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

  18. Tailoring the potential window of negative electrodes: A diagnostic method for understanding parasitic oxidation reactions in cells with 5 V LiNi0.5Mn1.5O4 positive electrodes

    NASA Astrophysics Data System (ADS)

    Levi, Mikhael D.; Dargel, Vadim; Shilina, Yuliya; Borgel, Valentina; Aurbach, Doron; Halalay, Ion C.

    2015-03-01

    We present herein a diagnostic method which provides insights into the interactions between parasitic reactions at battery electrodes and their consequences for battery performance degradation. We also provide a cautionary tale about misinterpreting or misrepresenting the significance of test data, as is sometimes found in the peer-reviewed literature or in developers' claims. Reversible cycling of the LiNi0.5Mn1.5O4 positive electrode in a full cell with an electrolyte solution containing no additives may appear achievable through tailoring of the operating potential window of the cell. Self-discharging of the negative stems from parasitic oxidation products formed on the positive. We show that either excess negative electrode capacity over the positive or initial pre-lithiation of the negative suppresses their detrimental effect on capacity retention. Simultaneous monitoring the potentials of the two electrodes vs. Li/Li+ during galvanostatic cycling of a full cell shows, however, that self-discharging of the negative still takes place. The latter process was tracked by the drift of the average potential of the cell towards higher values and leads to two characteristic patterns in the failure of full cells during their long-term cycling, depending on whether a cut-off voltage or a capacity limit is used as the control criterion during cycling.

  19. Synthesis and electrochemical properties of NiO nanospindles

    SciTech Connect

    Zhou, Hai; Lv, Baoliang; Xu, Yao; Wu, Dong

    2014-02-01

    Graphical abstract: NiO nanospindles with a different electrochemical activity as compared to those previous reports were synthesized via an agglomeration–dissolution–recrystallization growth process without the addition of any surfactant. - Highlights: • NiO nanospindles were synthesized without the addition of any surfactant. • The agglomeration–dissolution–recrystallization growth process was used to explain the precursors’ formation process of the spindle-like NiO. • As-obtained spindle-like NiO showed a different electrochemical activity as compared to those previous reports. - Abstract: NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

  20. Dry reforming of methane on Ni-Mg-Al nano-spheroid oxide catalysts prepared by the sol-gel method from hydrotalcite-like precursors

    NASA Astrophysics Data System (ADS)

    González, Albert R.; Asencios, Yvan J. O.; Assaf, Elisabete M.; Assaf, José M.

    2013-09-01

    Nanocapsular hydrotalcites (layered double hydroxides - LDHs) were synthesized by the sol-gel method and used as precursors of nano-structured mixed oxides containing various nickel loads (4, 15 and 19 wt%). The best conditions for the preparation of LDHs were analyzed and the structures of the resulting mixed oxides were studied. The optimal nickel load and calcining conditions were optimized. Finally, the resulting catalysts were tested in the dry reforming of methane for 8 h at 800 °C under atmospheric pressure. These materials showed high activity and stability, and the coke deposits were minimal on the catalyst prepared under optimal conditions (19 wt% nickel load and thermal treatment at 650 °C). The best catalyst formed amorphous carbon, which seems not to be prejudicial to the reaction.

  1. Synthesis, magnetic properties and X-ray analysis of Zn0.97X0.03O nanoparticles (X = Mn, Ni, and Co) using Scherrer and size-strain plot methods

    NASA Astrophysics Data System (ADS)

    Khorsand Zak, A.; Majid, W. H. Abd.; Ebrahimizadeh Abrishami, M.; Yousefi, Ramin; Parvizi, R.

    2012-04-01

    Un-doped and doped ZnO nanoparticles (Zn0.97X0.03O-NPs, X = Mn, Co, and Ni) were synthesized from a metal acetate precursor and acetic acid by a modified sol-gel combustion method. The compounds were synthesized at calcination temperatures of 650 °C for 1 h. The synthesized un-doped/doped ZnO-NPs were characterized by X-ray diffraction analysis (XRD) and high-magnification transmission electron microscopy (TEM). The XRD results revealed that the sample product was crystalline with a hexagonal wurtzite phase. The TEM showed ZnO-NPs nearly spherical shapes and a non-uniform shape for doped ZnO-NPs. The crystalline development in the ZnO-NPs was investigated by X-ray peak broadening. The size-strain plot (SSP) method was used to study the individual contributions of crystallite sizes and lattice strain on the peak broadening of the un-doped and doped ZnO-NPs. Physical parameters such as strain, stress and energy density values were calculated more precisely for all reflection peaks of XRD corresponding to the wurtzite hexagonal phase of ZnO lying in the range of 20-80° from the SSP results. The vibrating sample magnetometer (VSM) was also used to study the magnetic behavior of the samples in the ceramic form. The obtained results showed that strain play an important role in peak broadening; moreover, the mean crystalline size of the un-doped and doped ZnO-NPs estimated from the TEM and the SSP method were highly inter-correlated.

  2. Characterization and leaching of NiCd and NiMH spent batteries for the recovery of metals.

    PubMed

    Pietrelli, L; Bellomo, B; Fontana, D; Montereali, M

    2005-01-01

    Since NiMH and NiCd batteries are still used in the electronic devices market, a treatment and recycling plant has many advantages both from the environmental and the economic points of view. Unfortunately, there is no relationship between shape, size and chemical composition of spent batteries, consequently the characterization and the leaching method of the starting material becomes an important step of the overall treatment process in choosing the best conditions for the selective separation of the metals by hydrometallurgy. Leaching at 20 degrees C with H(2)SO(4) 2M for about 2h seems to be a good solution in terms of cost and efficiency for both battery types. The hydroxide compounds can be readily leached while Ni present as metallic form requires more aggressive conditions due to kinetic constraints. In this paper, the characterization of NiMH and NiCd spent batteries and the results of leaching tests in different conditions are reported.

  3. High coercive field and magnetization reversal in core-shell cum nanotwin driven Ni/NiO nanospheres.

    PubMed

    Okram, Gunadhor S; Soni, Ajay; Adroja, D T; Lalla, N P; Shripathi, T

    2011-03-01

    We report here nanotwin-core-shell Ni(core)NiO(shell) spheres of average size 25 nm prepared through polyol method. They exhibit high coercive field at 2 K, sharp peak at approximately 20 K in magnetization curve and magnetization reversal. Interestingly, exchange bias due to antiferromagnetic NiO shell is absent. Among other possibilities, anisotropy variations due to particle size distribution and twinning associated with disorder appear to play an important role. Further, magnetic interactions of twinned bigger spheres, which may also act as superferrimagnetic-like Ni multilayer cores, with superparamagnetic Ni of smaller spheres, might be the additional causes. These nanostructures therefore seem to have potential interest in memory effect.

  4. Monolayer dispersion of NiO in NiO/Al2O3 catalysts probed by positronium atom

    NASA Astrophysics Data System (ADS)

    Zhang, H. J.; Chen, Z. Q.; Wang, S. J.

    2012-01-01

    NiO/Al2O3 catalysts with different NiO loadings were prepared by impregnation method. The monolayer dispersion capacity of NiO is determined to be about 9 wt.% through XRD quantitative phase analysis. Positron lifetime spectra measured for NiO/Al2O3 catalysts comprise two long and two short lifetime components, where the long lifetimes τ3 and τ4 correspond to ortho-positronium (o-Ps) annihilation in microvoids and large pores, respectively. With increasing loading of NiO from 0 to 9 wt.%, τ4 drops drastically from 88 to 38 ns. However, when the NiO loading is higher than 9 wt.%, τ4 shows a slower decrease. Variation of λ4 (1/τ4) as a function of the NiO content can be well fitted by two straight lines with different slopes. The relative intensity of τ4 also shows a fast decrease followed by a slow decrease for the NiO content lower and higher than 9 wt.%, respectively. The coincidence Doppler broadening measurements reveal a continuous increase of S parameter with increasing NiO loading up to 9 wt.% and then a decrease afterwards. This is due to the variation in intensity of the narrow component contributed by the annihilation of para-positronium (p-Ps). Our results show that the annihilation behavior of positronium is very sensitive to the dispersion state of NiO on the surface of γ-Al2O3. When the NiO loading is lower than monolayer dispersion capacity, spin conversion of positronium induced by NiO is the dominant effect, which causes decrease of the longest lifetime and its intensity but increase of the narrow component intensity. After the NiO loading is higher than monolayer dispersion capacity, the spin conversion effect becomes weaker and inhibition of positronium formation by NiO is strengthened, which results in decrease of both the long lifetime intensity and the narrow component intensity. The reaction rate constant is determined to be (1.50 ± 0.04) × 1010 g mol-1s-1 and (3.43 ± 0.20) × 109 g mol-1 s-1 for NiO content below and above

  5. Monolayer dispersion of NiO in NiO/Al2O3 catalysts probed by positronium atom.

    PubMed

    Zhang, H J; Chen, Z Q; Wang, S J

    2012-01-21

    NiO/Al(2)O(3) catalysts with different NiO loadings were prepared by impregnation method. The monolayer dispersion capacity of NiO is determined to be about 9 wt.% through XRD quantitative phase analysis. Positron lifetime spectra measured for NiO/Al(2)O(3) catalysts comprise two long and two short lifetime components, where the long lifetimes τ(3) and τ(4) correspond to ortho-positronium (o-Ps) annihilation in microvoids and large pores, respectively. With increasing loading of NiO from 0 to 9 wt.%, τ(4) drops drastically from 88 to 38 ns. However, when the NiO loading is higher than 9 wt.%, τ(4) shows a slower decrease. Variation of λ(4) (1/τ(4)) as a function of the NiO content can be well fitted by two straight lines with different slopes. The relative intensity of τ(4) also shows a fast decrease followed by a slow decrease for the NiO content lower and higher than 9 wt.%, respectively. The coincidence Doppler broadening measurements reveal a continuous increase of S parameter with increasing NiO loading up to 9 wt.% and then a decrease afterwards. This is due to the variation in intensity of the narrow component contributed by the annihilation of para-positronium (p-Ps). Our results show that the annihilation behavior of positronium is very sensitive to the dispersion state of NiO on the surface of γ-Al(2)O(3). When the NiO loading is lower than monolayer dispersion capacity, spin conversion of positronium induced by NiO is the dominant effect, which causes decrease of the longest lifetime and its intensity but increase of the narrow component intensity. After the NiO loading is higher than monolayer dispersion capacity, the spin conversion effect becomes weaker and inhibition of positronium formation by NiO is strengthened, which results in decrease of both the long lifetime intensity and the narrow component intensity. The reaction rate constant is determined to be (1.50 ± 0.04) × 10(10) g mol(-1) s(-1) and (3.43 ± 0.20) × 10(9) g mol(-1) s(-1

  6. Synthesis and Magnetic Properties of NiSe, NiTe, CoSe, and CoTe

    NASA Astrophysics Data System (ADS)

    Umeyama, Norio; Tokumoto, Madoka; Yagi, Shota; Tomura, Masatoshi; Tokiwa, Kazuyasu; Fujii, Takenori; Toda, Ryo; Miyakawa, Nobuaki; Ikeda, Shin-Ichi

    2012-05-01

    Polycrystalline NiSe, NiTe, CoSe, and CoTe have been synthesized by two methods, i.e., (1) the solid-state reaction in an evacuated quartz ampoule (QA) and (2) the high-pressure (HP) technique (HP) in a Au capsule using a cubic anvil cell. All the obtained samples have the nickel arsenide-type hexagonal crystal structure, except CoTe (HP), and their estimated lattice parameters, a and c, show almost the same values within 0.8% in comparison between samples prepared by the QA method and those by the HP method. On the other hand, a distinct difference between samples prepared by QA and HP processes is found in the magnetization of NiSe and NiTe. In particular, for NiTe, the temperature dependence of magnetization indicates two transition temperatures at about 20 and 130 K in samples prepared by the HP process. However, samples of NiTex (x = 0.5, 0.66, 0.82, 1, 1.22, and 2) and NiTe containing Au prepared by QA process do not show similar magnetic orders in the temperature range between 2 and 300 K. Also, samples of NiSe (HP) show magnetic transition at ˜20 K, while those of NiSe (QA) show a magnetic inflection point at ˜10 K. To the best of our knowledge the remarkable difference in magnetic properties caused by the method of synthesis has not been reported. In this paper, we present comparative experimental results of magnetic, electric, and specific heat measurements of samples prepared by the two methods. A possible explanation for such a substantial difference in magnetic interaction will be discussed.

  7. ZnNi data

    DTIC Science & Technology

    2014-11-01

    carried out HE testing and passed, so that issue is resolved Concern over dezincification Keith Legg 847-680-9420 klegg@rowantechnology.com http...of the Zn-Ni plating 417 SCMS /GUEA, BR&T and ES3 are currently reviewing past industry de-zincification studies  Initial findings show that the...corrosion electro- potential is consistent throughout the corrosion process 417 SCMS /GUEA, BR&T and ES3 will identify any addition testing that

  8. The first principle study of Ni{sub 2}ScGa and Ni{sub 2}TiGa

    SciTech Connect

    Özduran, Mustafa; Turgut, Kemal; Arikan, Nihat; İyigör, Ahmet; Candan, Abdullah

    2014-10-06

    We computed the electronic structure, elastic moduli, vibrational properties, and Ni{sub 2}TiGa and Ni{sub 2}ScGa alloys in the cubic L2{sub 1} structure. The obtained equilibrium lattice constants of these alloys are in good agreement with available data. In cubic systems, there are three independent elastic constants, namely C{sub 11}, C{sub 12} and C{sub 44}. We calculated elastic constants in L2{sub 1} structure for Ni{sub 2}TiGa and Ni{sub 2}ScGa using the energy-strain method. The electronic band structure, total and partial density of states for these alloys were investigated within density functional theory using the plane-wave pseudopotential method implemented in Quantum-Espresso program package. From band structure, total and projected density of states, we observed metallic characters of these compounds. The electronic calculation indicate that the predominant contributions of the density of states at Fermi level come from the Ni 3d states and Sc 3d states for Ni{sub 2}TiGa, Ni 3d states and Sc 3d states for Ni{sub 2}ScGa. The computed density of states at Fermi energy are 2.22 states/eV Cell for Ni{sub 2}TiGa, 0.76 states/eV Cell for Ni{sub 2}ScGa. The vibrational properties were obtained using a linear response in the framework at the density functional perturbation theory. For the alloys, the results show that the L2{sub 1} phase is unstable since the phonon calculations have imagine modes.

  9. Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors

    PubMed Central

    Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

    2016-01-01

    In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al2O3 and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value. PMID:28344296

  10. Developments of the Physical and Electrical Properties of NiCr and NiCrSi Single-Layer and Bi-Layer Nano-Scale Thin-Film Resistors.

    PubMed

    Cheng, Huan-Yi; Chen, Ying-Chung; Li, Chi-Lun; Li, Pei-Jou; Houng, Mau-Phon; Yang, Cheng-Fu

    2016-02-25

    In this study, commercial-grade NiCr (80 wt % Ni, 20 wt % Cr) and NiCrSi (55 wt % Ni, 40 wt % Cr, 5 wt % Si) were used as targets and the sputtering method was used to deposit NiCr and NiCrSi thin films on Al₂O₃ and Si substrates at room temperature under different deposition time. X-ray diffraction patterns showed that the NiCr and NiCrSi thin films were amorphous phase, and the field-effect scanning electronic microscope observations showed that only nano-crystalline grains were revealed on the surfaces of the NiCr and NiCrSi thin films. The log (resistivity) values of the NiCr and NiCrSi thin-film resistors decreased approximately linearly as their thicknesses increased. We found that the value of temperature coefficient of resistance (TCR value) of the NiCr thin-film resistors was positive and that of the NiCrSi thin-film resistors was negative. To investigate these thin-film resistors with a low TCR value, we designed a novel bi-layer structure to fabricate the thin-film resistors via two different stacking methods. The bi-layer structures were created by depositing NiCr for 10 min as the upper (or lower) layer and depositing NiCrSi for 10, 30, or 60 min as the lower (or upper) layer. We aim to show that the stacking method had no apparent effect on the resistivity of the NiCr-NiCrSi bi-layer thin-film resistors but had large effect on the TCR value.

  11. Nonlocal Screening Effects on the Ni 2p Core Level Photoemission of the Linear-Chain Nickelate Y2BaNiO5

    NASA Astrophysics Data System (ADS)

    Okada, Kozo; Takeuchi, Yurika

    2017-06-01

    The Ni 2p X-ray photoemission spectrum (Ni 2p XPS) of the linear-chain nickelate Y2BaNiO5 is calculated by a Ni5O26 cluster model, adopting the numerically-exact diagonalization method based on the Lanczos algorithm. Particular attention is paid to how the Ni 2p core-hole charge is screened by the Ni 3d-O 2p valence electron system. The result shows that the leading d9L peak of the Ni 2p XPS has two components, as in the case of the Ni 2p XPS of NiO, where L denotes a ligand hole. The hole distribution analysis shows the importance of "nonlocal screening" that the Ni 3d holes apart from the core-hole site actively participate in the core-hole screening, and it also shows that the "local screening" is realized in the lowest-energy final state. The calculated spectrum of Y2BaNiO5 well reproduces that obtained experimentally.

  12. Ni-Co nanoparticles immobilized on a 3D Ni foam template as a highly efficient catalyst for borohydride electrooxidation in alkaline medium

    NASA Astrophysics Data System (ADS)

    Guo, Meisong; Cheng, Yu; Yu, Yanan; Hu, Jingbo

    2017-09-01

    Proton exchange membrane (PEM) fuel cells have drawn a great deal of attention due to the rapidly growing energy consumption. Recently, Ni- and Co-based materials have been considered as promising electorcatalysts owing to their multi-functionality. In this work, Ni and Co nanoparticles are directly immobilized on a three-dimensional Ni foam substrate (Ni-Co/NF) without any conductive agents or polymer binder by a facile ion implantation method. The structure and morphology of the Ni-Co/NF electrode were characterized by scanning electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. The performance of the Ni-Co/NF electrode in the electrochemical oxidation of NaBH4 is investigated by cyclic voltammetry and chronoamperometry. The Ni-Co/NF electrode exhibited excellent electrocatalytic activity and good stability during electrochemical reactions. These properties are attributed to the 3D porous structure of the Ni foam and the synergistic effect of Ni and Co nanoparticles. The enhanced electrocatalytic performance in NaBH4 electrooxidation compared with either Ni or Co nanoparticles alone suggests that the Ni-Co/NF is promising for fuel cell applications.

  13. Site preference of alloying elements in DO22-Ni3V phase: Phase-field and first-principles study

    NASA Astrophysics Data System (ADS)

    Zhang, Ding-Ni; Shangguan, Qian-Qian; Liu, Fu; Zhang, Ming-Yi

    2015-07-01

    Site preference of alloying elements in DO22-Ni3V phase was investigated using phase-field and first-principles method. The concentrations of alloying elements on sublattices of DO22-Ni3V phase were quantitatively studied using phase-field model based on microscopic diffusion equations. The phase-field computation results demonstrate that the concentration differences of alloying elements on the NiI and NiII site are attributed to the coordination environment difference. Host atoms Ni and substitutional ternary additions Al prefer to occupy NiI site. Antisite atoms V show site preference on the NiII site. Further reason of site preference of alloying elements on the two different Ni sites were studied using first-principles method to calculate the electronic structure of DO22-Ni3V phase. Calculation of density of states, orbitals population and charge population of the optimized Ni3V structure found that the electronic structures of NiI and NiII sites are different. Electronic structure difference, which is caused by coordination environment difference, is the essential reason for site selectivity behaviors of alloying elements on NiI and NiII sites.

  14. Novel preparation of highly dispersed Ni2P embedded in carbon framework and its improved catalytic performance

    NASA Astrophysics Data System (ADS)

    Wang, Shan; Wang, Kang; Wang, Xitao

    2016-11-01

    Highly dispersed Ni2P embedded in carbon framework with different phosphidation temperature was prepared through carbonizing Ni-alginate gel and followed by phosphidation with PPh3 in liquid phase. The significant effects of phosphidation temperature on Ni2P particle size and catalytic properties for isobutane dehydrogenation to isobutene were investigated. The results showed that Ni2P catalyst derived from the Ni-alginate gel (Ni2P-ADC), consisting of Ni2P particles embedded in carbon walls, possessed smaller particle size and more active site compared with Ni2P catalyst supported on active carbon (Ni2P/AC) prepared by impregnation method. The Ni2P-ADC catalyst phosphorized at 578 K for 3 h exhibited the highest catalytic performance, with the corresponding selectivity of isobutene approaching 89% and conversion approaching 15% after reaction for 4.5 h at 833 K, whereas Ni2P/AC catalyst prepared by impregnation method displays a much lower catalytic activity. The improved catalytic performance of the Ni2P-ADC can be ascribed to the smaller and highly dispersed Ni2P particles incorporated into carbon framework resulting from Ni-alginate gel.

  15. Density functional study of the electronic structure of NaNiO_2

    NASA Astrophysics Data System (ADS)

    Meskine, Hakime; Satpathy, S.

    2003-03-01

    It is well known that the two compounds LiNiO2 and NaNiO_2, in spite of being isovalent and structurally similar, exhibit different magnetic and electronic properties. While NaNiO2 is antiferromagnetic exhibiting ferrodistortive orbital ordering, LiNiO2 has no long-range order. We study the electronic structure of these compounds from density functional calculations using the linear muffin-tin orbitals (LMTO) method, focusing in particular, on the effect of the Jahn-Teller distortion of the NiO6 octahedron on the electronic and magnetic structure.

  16. Electrochemical sensing behaviour of Ni doped Fe3O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2014-01-01

    Ni doped Fe3O4 nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe3O4 nanoparticles. The optical property of Ni doped Fe3O4 nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe3O4 nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe3O4 nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  17. Thermophysical properties of Ni-containing single-phase concentrated solid solution alloys

    SciTech Connect

    Jin, Ke; Mu, Sai; An, Ke; Porter, Wallace D.; Samolyuk, German D.; Stocks, George Malcolm; Bei, Hongbin

    2016-12-27

    For this research temperature dependent thermophysical properties, including specific heat capacity, lattice thermal expansion, thermal diffusivity and conductivity, have been systematically studied in Ni and eight Ni-containing single-phase face-centered-cubic concentrated solid solution alloys, at elevated temperatures up to 1273 K. The alloys have similar specific heat values of 0.4–0.5 J·g-1·K-1 at room temperature, but their temperature dependence varies greatly due to Curie and K-state transitions. The lattice, electronic, and magnetic contributions to the specific heat have been separated based on first-principles methods in NiCo, NiFe, Ni-20Cr and NiCoFeCr. The alloys have similar thermal expansion behavior, with the exception that NiFe and NiCoFe have much lower thermal expansion coefficient in their ferromagnetic state due to magnetostriction effects. Calculations based on the quasi-harmonic approximation accurately predict the temperature dependent lattice parameter of NiCo and NiFe with < 0.2% error, but underestimated that of Ni-20Cr by 1%, compared to the values determined from neutron diffraction. In addition, all the alloys containing Cr have very similar thermal conductivity, which is much lower than that of Ni and the alloys without Cr, due to the large magnetic disorder.

  18. Thermophysical properties of Ni-containing single-phase concentrated solid solution alloys

    DOE PAGES

    Jin, Ke; Mu, Sai; An, Ke; ...

    2016-12-27

    For this research temperature dependent thermophysical properties, including specific heat capacity, lattice thermal expansion, thermal diffusivity and conductivity, have been systematically studied in Ni and eight Ni-containing single-phase face-centered-cubic concentrated solid solution alloys, at elevated temperatures up to 1273 K. The alloys have similar specific heat values of 0.4–0.5 J·g-1·K-1 at room temperature, but their temperature dependence varies greatly due to Curie and K-state transitions. The lattice, electronic, and magnetic contributions to the specific heat have been separated based on first-principles methods in NiCo, NiFe, Ni-20Cr and NiCoFeCr. The alloys have similar thermal expansion behavior, with the exception that NiFemore » and NiCoFe have much lower thermal expansion coefficient in their ferromagnetic state due to magnetostriction effects. Calculations based on the quasi-harmonic approximation accurately predict the temperature dependent lattice parameter of NiCo and NiFe with < 0.2% error, but underestimated that of Ni-20Cr by 1%, compared to the values determined from neutron diffraction. In addition, all the alloys containing Cr have very similar thermal conductivity, which is much lower than that of Ni and the alloys without Cr, due to the large magnetic disorder.« less

  19. Effects of Preparation Parameters on the Characteristics of NiP xB Y Nanomaterials

    NASA Astrophysics Data System (ADS)

    Lee, Shao-Pai; Chen, Yu-Wen

    2001-06-01

    A series of NiP x B y nanomaterials were prepared by a chemical reduction method under various preparation parameters. Experiment results show that the different preparation parameters affected the morphology, particle size, surface area and the composition of the sample. However, they did not influence the electronic state of nickel. The type of solution showed significant influence on the properties of the sample, whereas, the type of nickel salt did not. The particle size of NiPB, NiB, and NiP were 10-30 nm. The NiP sample prepared in the aqueous solution had the largest particle size 50-150 nm. If the solvent was 50% ethanol in water, the surface area of the sample significantly increased nine fold for NiP and four fold for NiPB powders. In contrast, the surface area of NiB did not increase. The NiPB, NiB, and NiP powders had a spherical morphology if they were prepared with aqueous solution. The NiPB prepared in 50% ethanol solution showed floss morphology and had a very high surface area.

  20. Electronic structure, magnetic and structural properties of Ni doped ZnO nanoparticles

    SciTech Connect

    Kumar, Shalendra; Vats, Prashant; Gautam, S.; Gupta, V.P.; Verma, K.D.; Chae, K.H.; Hashim, Mohd; Choi, H.K.

    2014-11-15

    Highlights: • XRD, and HR-TEM results show the single phase nature of Ni doped ZnO nanoparticles. • dc magnetization results indicate the RT-FM in Ni doped ZnO nanoparticles. • Ni L{sub 3,2} edge NEXAFS spectra infer that Ni ions are in +2 valence state. • O K edge NEXAFS spectra show that O vacancy increases with Ni doping in ZnO. - Abstract: We report structural, magnetic and electronic structural properties of Ni doped ZnO nanoparticles prepared by auto-combustion method. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and dc magnetization measurements. The XRD and HR-TEM results indicate that Ni doped ZnO nanoparticles have single phase nature with wurtzite lattice and exclude the presence of secondary phase. NEXAFS measurements performed at Ni L{sub 3,2}-edges indicates that Ni ions are in +2 valence state and exclude the presence of Ni metal clusters. O K-edge NEXAFS spectra indicate an increase in oxygen vacancies with Ni-doping, while Zn L{sub 3,2}-edge show the absence of Zn-vacancies. The magnetization measurements performed at room temperature shows that pure and Ni doped ZnO exhibits ferromagnetic behavior.

  1. Corrosion of NiTi Wires with Cracked Oxide Layer

    NASA Astrophysics Data System (ADS)

    Racek, Jan; Šittner, Petr; Heller, Luděk; Pilch, Jan; Petrenec, Martin; Sedlák, Petr

    2014-07-01

    Corrosion behavior of superelastic NiTi shape memory alloy wires with cracked TiO2 surface oxide layers was investigated by electrochemical corrosion tests (Electrochemical Impedance Spectroscopy, Open Circuit Potential, and Potentiodynamic Polarization) on wires bent into U-shapes of various bending radii. Cracks within the oxide on the surface of the bent wires were observed by FIB-SEM and TEM methods. The density and width of the surface oxide cracks dramatically increase with decreasing bending radius. The results of electrochemical experiments consistently show that corrosion properties of NiTi wires with cracked oxide layers (static load keeps the cracks opened) are inferior compared to the corrosion properties of the straight NiTi wires covered by virgin uncracked oxides. Out of the three methods employed, the Electrochemical Impedance Spectroscopy seems to be the most appropriate test for the electrochemical characterization of the cracked oxide layers, since the impedance curves (Nyquist plot) of differently bent NiTi wires can be associated with increasing state of the surface cracking and since the NiTi wires are exposed to similar conditions as the surfaces of NiTi implants in human body. On the other hand, the potentiodynamic polarization test accelerates the corrosion processes and provides clear evidence that the corrosion resistance of bent superelastic NiTi wires degrades with oxide cracking.

  2. Surface structure and electrochemical characteristics of Ti-V-Cr bcc-type solid solution alloys sintered with Ni

    SciTech Connect

    Tsuji, Yoichiro; Yamamoto, Osamu; Matsuda, Hiromu; Toyoguchi, Yoshinori

    2000-07-01

    Ti-V-Cr bcc-type solid solution alloys can absorb a large amount of hydrogen and be applied to active materials of the negative electrode in Ni-MH batteries. However, because of the insolubility of Ni into these alloys, the electrochemical characteristics like discharge capacity and cycle life were poor. In order to increase the discharge capacity of hydrogen absorbing alloy electrodes, Ti-V-Cr bcc-type alloy powders were sintered with Ni in order to form Ni contained surface layer on the alloy surface. As sintering temperature rose up, the surface composition changed from TiNi to Ti{sub 2}Ni. TiNi surface layer showed better electrochemical characteristics. For the Ni adding method, Ni electroless plating was preferred because of good adhesion. As a result of optimized conditions, a discharge capacity of 570 mAh/g and an improvement of cycle life were achieved.

  3. Theoretical study of electron-phonon interaction in [beta]-phase NiTi and Ni-Al alloys

    SciTech Connect

    Zhao, Guang-Lin.

    1992-09-17

    The electronic band structure of [beta]-phase NiTi and NiAl was calculated using a first-principles LCAO method, and then fitted by the nonorthogonal empirical tight binding method for the evaluation of electron-phonon (e-ph) matrix elements. Contribution of the e-ph interaction to phonon dynamical matrix was calculated by the method of Varma and Weber. It is found that an accurate calculation of e-ph interaction can explain the behavior of phonon anomalies in [beta]-phase NiTi and Ni-Al alloys. Fermi surface nesting and the symmetric properties of the e-ph interaction matrix elements are attributed as the source of the phonon anomalies and/or the soft phonon in these alloys. The temperature dependence of the phonon anomalies can be explained as a smearing effect of the Fermi surface.

  4. Theoretical study of electron-phonon interaction in {beta}-phase NiTi and Ni-Al alloys

    SciTech Connect

    Zhao, Guang-Lin

    1992-09-17

    The electronic band structure of {beta}-phase NiTi and NiAl was calculated using a first-principles LCAO method, and then fitted by the nonorthogonal empirical tight binding method for the evaluation of electron-phonon (e-ph) matrix elements. Contribution of the e-ph interaction to phonon dynamical matrix was calculated by the method of Varma and Weber. It is found that an accurate calculation of e-ph interaction can explain the behavior of phonon anomalies in {beta}-phase NiTi and Ni-Al alloys. Fermi surface nesting and the symmetric properties of the e-ph interaction matrix elements are attributed as the source of the phonon anomalies and/or the soft phonon in these alloys. The temperature dependence of the phonon anomalies can be explained as a smearing effect of the Fermi surface.

  5. Coatings on NiTi Alloy

    NASA Astrophysics Data System (ADS)

    Kei, C. C.; Yu, Y. S.; Racek, J.; Vokoun, D.; Šittner, P.

    2014-07-01

    Atomic layer deposition is introduced as a method suitable for preparation of Al2O3 layers on the surface of NiTi medical devices such as stents because of the excellent thickness control and conformal protective coating on complex structures. The corrosion properties of NiTi plates with Al2O3 coatings of various thicknesses in an environment similar to that occurring in the human body were studied using open circuit potential, potentiostatic electrochemical impedance spectroscopy, and cyclic polarization tests. It shows that the layer thickness plays a key role in the inhibition of corrosion. The thinner layers are more diffuse and make it easier for anodic reaction of passive NiTi with protective TiO2 underneath of Al2O3, while the thicker layers have the barrier effect with local pores initiating pitting corrosion. The results of our electrochemical experiments consistently show that corrosion properties of thick Al2O3 coatings on NiTi plate are inferior compared to the thin layers.

  6. Size Effect of YSZ Nanoparticles on Sintering of Ni Nanoparticles in Ni/YSZ Anode of Solid Oxide Fuel Cell via Multi-Nanoparticle Molecular Dynamics Simulation

    NASA Astrophysics Data System (ADS)

    Xu, Jingxiang; Higuchi, Yuji; Ozawa, Nobuki; Kubo, Momoji

    2015-03-01

    Sintering of Ni nanoparticles leads to the degradation of a Ni/YSZ porous electrode of solid oxide fuel cell. We reported that the YSZ nanoparticle framework plays an important role in inhibition of sintering by using our multi-nanoparticle molecular dynamics simulation method. Size of YSZ nanoparticles affects the framework of YSZ nanoparticles and changes the sintering in Ni/YSZ porous structure. However, the mechanism of different sintering behavior by changing the size of YSZ nanoparticle has not been revealed. In this study, we used our multi-nanoparticle molecular dynamics simulation method to investigate the size effect of YSZ nanoparticles on the sintering of Ni nanoparticles in the Ni/YSZ porous structure. Then, Ni nanoparticles make contact with each other and the sintering proceeds by growth of contact area between Ni nanoparticles when YSZ nanoparticles are large. In contrast, the sintering of Ni nanoparticles is suppressed when YSZ nanoparticles are small. It is found that interfacial area between Ni and YSZ in the small YSZ nanoparticles model is larger than that in the large YSZ nanoparticles model. Thus, the movement of Ni nanoparticles is disturbed, and the sintering is inhibited.

  7. Percolation framework to describe El Niño conditions

    NASA Astrophysics Data System (ADS)

    Meng, Jun; Fan, Jingfang; Ashkenazy, Yosef; Havlin, Shlomo

    2017-03-01

    Complex networks have been used intensively to investigate the flow and dynamics of many natural systems including the climate system. Here, we develop a percolation based measure, the order parameter, to study and quantify climate networks. We find that abrupt transitions of the order parameter usually occur ˜1 year before El Niño events, suggesting that they can be used as early warning precursors of El Niño. Using this method, we analyze several reanalysis datasets and show the potential for good forecasting of El Niño. The percolation based order parameter exhibits discontinuous features, indicating a possible relation to the first order phase transition mechanism.

  8. Percolation framework to describe El Niño conditions.

    PubMed

    Meng, Jun; Fan, Jingfang; Ashkenazy, Yosef; Havlin, Shlomo

    2017-03-01

    Complex networks have been used intensively to investigate the flow and dynamics of many natural systems including the climate system. Here, we develop a percolation based measure, the order parameter, to study and quantify climate networks. We find that abrupt transitions of the order parameter usually occur ∼1 year before El Niño events, suggesting that they can be used as early warning precursors of El Niño. Using this method, we analyze several reanalysis datasets and show the potential for good forecasting of El Niño. The percolation based order parameter exhibits discontinuous features, indicating a possible relation to the first order phase transition mechanism.

  9. Ni-MH spent batteries: a raw material to produce Ni-Co alloys.

    PubMed

    Lupi, Carla; Pilone, Daniela

    2002-01-01

    Ni-MH spent batteries are heterogeneous and complex materials, so any kind of metallurgical recovery process needs a mechanical pre-treatment at least to separate irony materials and recyclable plastic materials (like ABS) respectively, in order to get additional profit from this saleable scrap, as well as minimize waste arising from the braking separation process. Pyrometallurgical processing is not suitable to treat Ni-MH batteries mainly because of Rare Earths losses in the slag. On the other hand, the hydrometallurgical method, that offers better opportunities in terms of recovery yield and higher purity of Ni, Co, and RE, requires several process steps as shown in technical literature. The main problems during leach liquor purification are the removal of elements such as Mn, Zn, Cd, dissolved during the leaching step, and the separation of Ni from Co. In the present work, the latter problem is overcome by co-deposition of a Ni-35/40%w Co alloy of good quality. The experiments carried out in a laboratory scale pilot-plant show that a current efficiency higher than 91% can be reached in long duration electrowinning tests performed at 50 degrees C and 4.3 catholyte pH.

  10. Supercapacitor studies on Ni/NiO nanocomposites synthesized by humble sol-gel route with variation of Ni2+: CA ratio

    NASA Astrophysics Data System (ADS)

    Das, Himadri Tanaya; Elumulai, P.

    2017-05-01

    The Ni/NiO nanocomposites were prepared by citrate-assisted humble sol-gel method with key variation of metal nitrate and citric acid. A series of samples were obtained and characterized by X-ray diffraction (XRD), Raman spectroscopy, Scanning electron microscope (SEM) and UV-VIS spectroscopy. All samples were tested by cyclic voltammetry (CV) and galvanostatic charge-discharge studies. Excitingly, the Ni/ NiO composite resulted from 1:1 ratio exhibited a highest specific capacitance of 350 F g-1 at 0.5 Ag-1 with excellent stability and coulombic efficiency. This investigation has opened a wide window for exploring other transition metal-oxides systems, such that potential nanocomposites can be generated for energy storage applications.

  11. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    DOE PAGES

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; ...

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopymore » and indicates that the Fe atoms occupy Ni sites.« less

  12. Imaging Chemical Aggregation of Ni/NiO Particles from Reduced NiO-YSZ

    SciTech Connect

    Saraf, Laxmikant V.

    2011-07-20

    Energy dispersive X-ray spectroscopy (EDS) mapping of nickel oxide yttria-stabilized zirconia (NiO-YSZ) was carried out after various hydrogen reducing and methane steam reforming conditions. Nickel aggregation was visualized after methane steam reforming by correlating Ni K{sub {alpha}} map with scanning transmission electron microscopy (STEM) images. From the reduced O K{sub {alpha}} intensities in the Ni K{sub {alpha}} dominated regions after methane steam reforming, NiO reduction in to Ni can be interpreted. From correlation between Zr K{sub {alpha}} and O K{sub {alpha}} maps, high stability of YSZ was also realized. Examples of NiO-YSZ overlapped particles are considered to discuss chemical imaging of a single particle.

  13. Towards a full understanding of the nature of Ni(II) species and hydroxyl groups over highly siliceous HZSM-5 zeolite supported nickel catalysts prepared by a deposition-precipitation method.

    PubMed

    Chen, Bao-Hui; Chao, Zi-Sheng; He, Hao; Huang, Chen; Liu, Ya-Juan; Yi, Wen-Jun; Wei, Xue-Ling; An, Jun-Fang

    2016-02-14

    Highly siliceous HZSM-5 zeolite supported nickel catalysts prepared by a deposition-precipitation (D-P) method were characterized by Fourier transform infrared (FT-IR), hydrogen temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), N2-absorption/desorption, field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and (27)Al magic-angle nuclear magnetic resonance (MAS NMR) techniques. The results showed that the D-P of nickel species occurred predominantly on the internal surface of highly siliceous HZSM-5 zeolite, in which the internal silanol groups located on the hydroxylated mesopores or nanocavities played a key role. During the D-P process, nickel hydroxide was first deposited-precipitated via olation/polymerization of neutral hydroxoaqua nickel species over the HZSM-5 zeolite. With the progress of the D-P process, 1 : 1 nickel phyllosilicate was formed over the HZSM-5 via the hetero-condensation/polymerization between charged hydroxoaqua nickel species and monomer silicic species generated due to the partial dissolution of the HZSM-5 framework. The 1 : 1 nickel phyllosilicate could also be generated via the hydrolytic adsorption of hydroxoaqua nickel species and their subsequent olation condensation. After calcination, the deposited-precipitated nickel hydroxide was decomposed into nickel oxide, while the 1 : 1 nickel phyllosilicate was transformed into 2 : 1 nickel phyllosilicate. According to the above mechanism, Ni(ii) species were present both in the form of nickel oxide and 2 : 1 nickel phyllosilicate, which were mutually separated from each other, being highly dispersed over HZSM-5 zeolite.

  14. Properties of Ni and Ni–Fe nanowires electrochemically deposited into a porous alumina template

    PubMed Central

    Shimanovich, Dmitry L; Yanushkevich, Kazimir I; Prischepa, Sergej L; Outkina, Elena A

    2016-01-01

    The comparative analysis of the electrochemical deposition of Ni and Ni–Fe nanowires (NWs) into ordered porous alumina templates is presented. The method developed allows for obtaining NWs of 50 ± 5 nm in diameter and 25 μm in length, i.e., with an aspect ratio of 500. XRD data demonstrate the polycrystalline nature of Ni and Ni–Fe in a face-centered cubic close-packed lattice. Both fabricated materials, Ni and Ni–Fe, have shown ferromagnetic properties. The specific magnetization value of Ni–Fe NWs in the alumina template is higher than that of the Ni sample and bulk Ni, also the Curie temperature of the Ni–Fe sample (790 K) is higher than that of the Ni sample one or bulk Ni. PMID:28144520

  15. Synthesis of hierarchical flower-like NiO and the influence of surfactant

    NASA Astrophysics Data System (ADS)

    Liu, Shilin; Zeng, Wen; Chen, Ting

    2017-01-01

    The NiO nanoflowers were prepared by a facile surfactant assisted hydrothermal method using Ni(NO3)2-6H2O or NiCl2-6H2O as precursor compound. The microstructure of the samples was characterized by SEM and XRD. The gas sensing properties of the NiO nanoflowers toward ethanol was also investigated. The results show that surfactant plays a key role in the synthesis of flower-like NiO. The NiO nanoflowers show excellent sensing performances to ethanol gas. This morphology holds substantial promise for applying NiO as a potential gas sensing material for future sensor application.

  16. Aqueous phase reforming of glycerol over Ni-based catalysts for hydrogen production.

    PubMed

    Cho, Su Hyun; Moon, Dong Ju

    2011-08-01

    Aqueous phase reforming of glycerol over Ni-based catalysts for hydrogen production was carried out at 225 degrees C, 23 bar and LHSV = 4 h(-1). The Ni-based catalyst was prepared by an incipient wetness impregnation method. The catalysts before and after the reaction were characterized by N2 physisorption, CO chemisorption, XRD, TPR, SEM and TEM techniques. It was found that Ni(20 wt%)-Co(3 wt%)/gamma-Al2O3 catalyst showed higher glycerol conversion and hydrogen selectivity than Ni(20 wt%)/gamma-Al2O3 catalyst. There are no major changes in Ni particles after the reaction over Ni-Co/gamma-Al2O3 catalyst. The results suggest that the Ni-Co/gamma-Al2O3 catalyst can be applied to the hydrogen production system using APR of glycerol.

  17. Operationalizing TIGER NI Competencies for Online Assessment of Perceived Competency.

    PubMed

    Hunter, Kathy M; Dee, McGonigle; Hebda, Toni

    2012-01-01

    Competencies in nursing informatics (NI) are needed by every nurse. The TIGER Initiative published a set of NI competencies for every nurse in 2009. A research project focused on using these competencies is underway. A systematic instrument-development process is used to adapt these competencies for use in an online instrument. Results of a modified Delphi method, content-validity assessment, and pilot testing are related. Plans for ongoing research are shared.

  18. Ferromagnetic resonance in FeCoNi electroplated wires

    NASA Astrophysics Data System (ADS)

    García-Miquel, H.; Bhagat, S. M.; Lofland, S. E.; Kurlyandskaya, G. V.; Svalov, A. V.

    2003-08-01

    We have investigated the microwave properties (ferromagnetic resonance and ferromagnetic antiresonance) of FeCoNi magnetic tubes created by electroplating on CuBe wire. Important parameters such as the g factor, magnetization, anisotropy field, and damping parameter were obtained from the measurements. One sample, prepared by a method which entails rf-sputtering deposition of an additional FeNi layer, shows a clear ferromagnetic antiresonance.

  19. Synthesis of FeCoNi nanoparticles by galvanostatic technique

    SciTech Connect

    Budi, Setia; Hafizah, Masayu Elita; Manaf, Azwar

    2016-06-17

    Soft magnetic nanoparticles of FeCoNi have been becoming interesting objects for many researchers due to its potential application in electronic devices. One of the most promising methods for material preparation is the electrodeposition which capable of growing nanoparticles alloy directly onto the substrate. In this paper, we report our electrodeposition studies on nanoparticles synthesis using galvanostatic electrodeposition technique. Chemical composition of the synthesized FeCoNi was successfully controlled through the adjustment of the applied currents. It is revealed that the content of each element, obtained from quantitative analysis using atomic absorption spectrometer (AAS), could be modified by the adjustment of current in which Fe and Co content decreased at larger applied currents, while Ni content increased. The nanoparticles of Co-rich FeCoNi and Ni-rich FeCoNi were obtained from sulphate electrolyte at the range of applied current investigated in this work. Broad diffracted peaks in the X-ray diffractograms indicated typical nanostructures of the solid solution of FeCoNi.

  20. Mesoscale assembly of NiO nanosheets into spheres

    SciTech Connect

    Zhang Meng; Yan Guojin; Hou Yonggai; Wang Chunhua

    2009-05-15

    NiO solid/hollow spheres with diameters about 100 nm have been successfully synthesized through thermal decomposition of nickel acetate in ethylene glycol at 200 deg. C. These spheres are composed of nanosheets about 3-5 nm thick. Introducing poly(vinyl pyrrolidone) (PVP) surfactant to reaction system can effectively control the products' morphology. By adjusting the quantity of PVP, we accomplish surface areas-tunable NiO assembled spheres from {approx}70 to {approx}200 m{sup 2} g{sup -1}. Electrochemical tests show that NiO hollow spheres deliver a large discharge capacity of 823 mA h g{sup -1}. Furthermore, these hollow spheres also display a slow capacity-fading rate. A series of contrastive experiments demonstrate that the surface area of NiO assembled spheres has a noticeable influence on their discharge capacity. - Graphical abstract: The mesoscale assembly of NiO nanosheets into spheres have been achieved by a solvothermal method. N{sub 2} adsorption/desorption isotherms show the S{sub BET} of NiO is tunable. NiO spheres show large discharge capacity and slow capacity-fading rate.

  1. A New Polycrystalline Co-Ni Superalloy

    NASA Astrophysics Data System (ADS)

    Knop, M.; Mulvey, P.; Ismail, F.; Radecka, A.; Rahman, K. M.; Lindley, T. C.; Shollock, B. A.; Hardy, M. C.; Moody, M. P.; Martin, T. L.; Bagot, P. A. J.; Dye, D.

    2014-12-01

    In 2006, a new-ordered L12 phase, Co3(Al,W), was discovered that can form coherently in a face-centered cubic (fcc) A1 Co matrix. Since then, a community has developed that is attempting to take these alloys forward into practical applications in gas turbines. A new candidate polycrystalline Co-Ni γ/ γ' superalloy, V208C, is presented that has the nominal composition 36Co-35Ni-15Cr-10Al-3W-1Ta (at.%). The alloy was produced by conventional powder metallurgy superalloy methods. After forging, a γ' fraction of ~56% and a secondary γ' size of 88 nm were obtained, with a grain size of 2.5 μm. The solvus temperature was 1000°C. The density was found to be 8.52 g cm-3, which is similar to existing Ni alloys with this level of γ'. The alloy showed the flow stress anomaly and a yield strength of 920 MPa at room temperature and 820 MPa at 800°C, similar to that of Mar-M247. These values are significantly higher than those found for either conventional solution and carbide-strengthened Co alloys or the γ/ γ' Co superalloys presented in the literature thus far. The oxidation resistance, with a mass gain of 0.08 mg cm-2 in 100 h at 800°C, is also comparable with that of existing high-temperature Ni superalloys. These results suggest that Co-based and Co-Ni superalloys may hold some promise for the future in gas turbine applications.

  2. Nucleation and Growth of Tetrataenite (FeNi) in Meteorites

    NASA Astrophysics Data System (ADS)

    Goldstein, J. I.; Williams, D. B.; Zhang, J.

    1992-07-01

    The mineral tetrataenite (ordered FeNi) has been observed in chondrites, stony irons, and iron meteorites (1). FeNi is an equilibrium phase in the Fe-Ni phase diagram (Figure 1) and orders to tetrataenite at ~320 degrees C (2). The phase forms at temperatures at or below the eutectoid temperature (~400 degrees C) where taenite (gamma) transforms to kamacite (alpha) plus FeNi (gamma"). An understanding of the formation of tetrataenite can lead to a new method for determining cooling rates at low temperatures (<400 degrees C) for all types of meteorites. In a recent study of plessite in iron meteorites (3), two transformation sequences for the formation of tetrataenite were observed. In either sequence, during the cooling process, the taenite (gamma) phase initially undergoes a diffusionless transformation to a martensite (alpha, bcc) phase without a composition change. The martensite then decomposes either above or below the eutectoid temperature (~400 degrees C) during cooling or upon subsequent reheating. During martensite decomposition above the eutectoid, the taenite (gamma) phase nucleates by the reaction alpha(sub)2 ---> alpha + gamma and grows under volume diffusion control. The Ni composition of the taenite increases continuously following the equilibrium gamma/alpha + gamma boundary while the Ni composition of the kamacite matrix decreases following the alpha/alpha + gamma phase boundary (2), see Figure 1. Below the eutectoid temperature, the precipitate composition follows the equilibrium gamma"/alpha + gamma" boundary and reaches ~52 wt% Ni, the composition of FeNi, gamma". The kamacite (alpha) matrix composition approaches ~4 to 5 wt% Ni. The ordering transformation starts at ~320 degrees C forming the tetrataenite phase. During martensite decomposition below the eutectoid temperature, FeNi should form directly by the reaction alpha2 --> alpha + gamma" (FeNi). If this transformation sequence occurs, then the composition of kamacite and tetrataenite

  3. Thermodynamic modeling of poorly complexing metals in concentrated electrolyte solutions: an X-ray absorption and UV-Vis spectroscopic study of Ni(II) in the NiCl2-MgCl2-H2O system.

    PubMed

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg(-1) NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg(-1) NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system.

  4. Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

    PubMed Central

    Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

    2015-01-01

    Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at RNi-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

  5. Microwave synthesis and effect of CTAB on ferromagnetic properties of NiO, Co3O4 and NiCo2O4 nanostructures

    NASA Astrophysics Data System (ADS)

    Anandha Babu, G.; Ravi, G.; Hayakawa, Y.

    2015-04-01

    Cubic-structured NiO, Co3O4 and spinel-structured NiCo2O4 were synthesized via microwave route. The structural properties of NiO, Co3O4 and NiCo2O4 nanostructures were investigated by X-ray diffraction analysis, and it showed smaller crystallite size for NiO than Co3O4 and NiCo2O4 by using Williamson-Hall method. Flake-like and hexagonal plate-like morphologies were ascertained from HRSEM and TEM analyses. Optical properties of these materials were investigated by photoluminescence study, and it presents the band edge emission for all materials with supplementary emissions in visible region due to the presence of defects such as vacancy and interstitial. Raman and FTIR spectra provide the functional characteristics of NiO, Co3O4 and NiCo2O4 nanostructures. XPS measurement revealed the purity and composition of these nanostructures. Room temperature magnetic measurements were investigated using vibrating sample magnetometer. The low coercivity and remanent magnetization for NiO, Co3O4 and NiCo2O4 nanostructures confirmed that these nanoparticles exhibit a weak ferromagnetic behaviour.

  6. Effect of amorphous Mg{sub 50}Ni{sub 50} on hydriding and dehydriding behavior of Mg{sub 2}Ni alloy

    SciTech Connect

    Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

    2011-04-15

    Composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50} was prepared by mechanical milling starting with nanocrystalline Mg{sub 2}Ni and amorphous Mg{sub 50}Ni{sub 50} powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg{sub 50}Ni{sub 50} improved the hydriding and dehydriding kinetics of Mg{sub 2}Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: {yields} First study of the hydriding behavior of composite Mg{sub 2}Ni (25 wt.%) amorphous Mg{sub 50}Ni{sub 50}. {yields} Microstructural characterization of composite material using XRD and SEM was obtained. {yields} An improved effect of Mg{sub 50}Ni{sub 50} on the Mg{sub 2}Ni hydriding behavior was verified. {yields} The apparent activation energy for the hydrogen desorption of composite was obtained.

  7. Reactive Ni/Ti nanolaminates

    SciTech Connect

    Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

    2009-11-01

    Nickel/titanium nanolaminates fabricated by sputter deposition exhibited rapid, high-temperature synthesis. When heated locally, self-sustained reactions were produced in freestanding Ni/Ti multilayer foils characterized by average propagation speeds between approx0.1 and 1.4 m/s. The speed of a propagating reaction front was affected by total foil thickness and bilayer thickness (layer periodicity). In contrast to previous work with compacted Ni-Ti powders, no preheating of Ni/Ti foils was required to maintain self-propagating reactions. High-temperature synthesis was also stimulated by rapid global heating demonstrating low ignition temperatures (T{sub ig})approx300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T{sub ig}. Foils reacted in a vacuum apparatus developed either as single-phase B2 cubic NiTi (austenite) or as a mixed-phase structure that was composed of monoclinic B19{sup '} NiTi (martensite), hexagonal NiTi{sub 2}, and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

  8. Role of surface Ni and Ce species of Ni/CeO2 catalyst in CO2 methanation

    NASA Astrophysics Data System (ADS)

    Zhou, Guilin; Liu, Huiran; Cui, Kaikai; Jia, Aiping; Hu, Gengshen; Jiao, Zhaojie; Liu, Yunqi; Zhang, Xianming

    2016-10-01

    CeO2, which was used as support to prepare mesoporous Ni/CeO2 catalyst, was prepared by the hard-template method. The prepared NiO/CeO2 precursor and Ni/CeO2 catalyst were studied by H2-TPR, in-situ XPS, and in-situ FT-IR. The catalytic properties of the prepared Ni/CeO2 catalyst were also investigated by CO2 catalytic hydrogenation methanation. H2-TPR and in-situ XPS results showed that metal Ni species and surface oxygen vacancies could be formed by H2 reduction. In-situ FT-IR and in-situ XPS results indicated that CO2 molecules could be reduced by active metal Ni species and surface oxygen vacancies to generate active CO species and promote CO2 methanation. The Ni/CeO2 catalyst presented the high CO2 methanation activity, and CO2 conversion and CH4 selectivity reached 91.1% and 100% at 340 °C and atmospheric pressure.

  9. Increased Occurrence of Central-Pacific El Niño in ERSST Version 4

    NASA Astrophysics Data System (ADS)

    Diamond, M. S.; Bennartz, R.

    2015-12-01

    Interest in El Niño diversity has increased in the past decade, with much attention given to the hypothesis that El Niño comes in two distinct types: an Eastern-Pacific (EP) El Niño centered off the coast of Peru and a Central-Pacific (CP) El Niño centered near the International Date Line. It is widely believed that the CP type of El Niño has been increasing in frequency in recent decades. However, many findings regarding El Niño diversity are uncertain given the divergence of results from different classification schemes. We test the idea that the CP type of El Niño is a recent and increasingly frequent phenomenon by using the newly released Version 4 of NOAA's Extended Reconstructed Sea Surface Temperatures (ERSST v4) dataset with one popular central-location classification method and a new method based on observed spatial patterns of sea surface temperature anomalies. The new method selects an EP and a CP El Niño "end-member" from events that are universally classified one way or the other by preexisting methods and uses pattern correlation with these end-members to sort all El Niño years into EP-dominated, CP-dominated, or mixed influence (M) classes. The advantage of this end-member correlation approach is its simplicity, relying only on observed data without the need for statistical regression, while taking into account a larger portion of the equatorial Pacific than the traditional Niño 3, Niño 4, and related indices. The downside of this approach is the somewhat arbitrary nature of end-member selection, although this is mitigated through the use of transparent selection criteria. The updated ERSST dataset identifies significantly more CP El Niños than two older versions and an independent dataset when using the central-location method. The new pattern correlation method identifies more CP El Niños than EP El Niños for all datasets. The increase in CP El Niño identification in ERSST v4 is linked mostly to differences in the central Pacific in

  10. Corrosion Behavior of Ti-55Ni-1.2Co High Stiffness Shape Memory Alloys

    NASA Astrophysics Data System (ADS)

    Huang, Xu; Norwich, Dennis W.; Ehrlinspiel, Michael

    2014-07-01

    The corrosion behavior of high stiffness nominal Ti-55Ni-1.2Co (wt.%) shape memory alloys (SMAs) was systematically investigated in the present study including straight wires, wire-formed stents, and laser-cut stents. It was found that the corrosion behavior of Ti-55Ni-1.2Co alloys is comparable with those of binary NiTiNol counterparts, which is attributed to the small alloying amount of cobalt. Additionally, the corrosion resistance of high stiffness Ti-55Ni-1.2Co SMAs is independent of the stent-forming method. To explore the galvanic corrosion susceptibility between Ti-55Ni-1.2Co and binary NiTiNol alloys, a NiTiNol sleeve was laser welded to the Ti-55Ni-1.2Co stent. Interestingly, there is no galvanic corrosion observed in this NiTiCo-NiTiNol component, even after immersion of the component in phosphate-buffered saline solution at 37 °C for three months. This study will shed some light on the industrial applications of high stiffness Ti-55Ni-1.2Co shape memory alloys.

  11. Optical switching properties of Pd-Ni thin-film top-capped switchable mirrors

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Li; Bao, Shan-Hu; Xin, Yun-Chuan; Cao, Xun; Jin, Ping

    2015-09-01

    Switchable mirrors based on magnesium-nickel alloy thin films capped with catalytic Pd-Ni alloy thin films were prepared by a DC magnetron sputtering method. Their composition, structure and surface morphology were studied by XPS, XRD and AFM. Herein, the optical switching properties and durability of the switchable mirrors were investigated by varying the Ni content in the Pd-Ni alloys. Comparing pure Pd catalyst with Pd-Ni top-capped switchable mirrors, the latter show better hydrogenation and dehydrogenation kinetics, and the speed of hydrogen desorption is obviously improved with increasing Ni content in the Pd-Ni alloy. The Pd-Ni capped switchable mirrors also have better optical switching durability. The catalytic Pd layer with the addition of Ni does not influence the transmittance (hydride state) and reflectance (metallic state) of the switchable mirrors. In addition, replacing Pd with Pd-Ni alloy decreases the cost of the switchable mirrors: employing nickel in the alloy Pd89.2Ni10.8 can save about 11% use of Pd. Therefore, the Pd-Ni alloy can provide a cheaper catalytic thin film, and it is expected to have applications in energy-saving windows, hydrogen sensors and hydrogen storage materials.

  12. Pulsed-Current Electrochemical Codeposition and Heat Treatment of Ti-Dispersed Ni-Matrix Layers

    NASA Astrophysics Data System (ADS)

    Janetaisong, Pathompong; Boonyongmaneerat, Yuttanant; Techapiesancharoenkij, Ratchatee

    2016-08-01

    An electrochemical deposition is a fast and cost-efficient process to produce film or coating. In this research, Ni-Ti electrodeposition is developed by codepositing a Ti-dispersed Ni-matrix layer from a Ni-plating solution suspended with Ti particles. To enhance the coating uniformity and control the atomic composition, the pulsed current was applied to codeposit Ni-Ti layers with varying pulse duty cycles (10 to 100 pct) and frequencies (10 to 100 Hz). The microstructures and compositions of the codeposited layers were analyzed by scanning electron microscopy, X-ray diffraction, and X-ray fluorescent techniques. The pulsed current significantly improved the quality of the Ni-Ti layer as compared to a direct current. The Ni-Ti layers could be electroplated with a controlled composition within 48 to 51 at. pct of Ti. The optimal pulse duty cycle and frequency are 50 pct and 10 Hz, respectively. The standalone Ni-49Ti layers were removed from copper substrates by selective etching method and subsequently heat-treated under Ar-fed atmosphere at 1423 K (1150 °C) for 5 hours. The phase and microstructures of the post-annealed samples exhibit different Ni-Ti intermetallic compounds, including NiTi, Ni3Ti, and NiTi2. Yet, the contamination of TiN and TiO2 was also present in the post-annealed samples.

  13. Atomic diffusion in liquid Ni, NiP, PdNiP, and PdNiCuP alloys

    SciTech Connect

    Chathoth, S. Mavila; Meyer, A.; Koza, M.M.; Juranyi, F.

    2004-11-22

    We investigated the self-diffusion of Ni in liquid Ni, Ni{sub 80}P{sub 20}, Pd{sub 40}Ni{sub 40}P{sub 20}, and Pd{sub 43}Ni{sub 10}Cu{sub 27}P{sub 20} at temperatures up to 1795 K with incoherent, quasielastic neutron scattering. Values of measured self-diffusion coefficients vary over the accessible temperature ranges as a function of composition only within 10%. Although mixing has a drastic effect on the liquidus temperature and the undercooling capabilities, a relation between these properties and the atomic diffusion in the liquid is not observed. Apparently, diffusive motion is governed by the packing fraction of the atoms, that is very similar in these dense liquids.

  14. Synthesis of Lix[Ni0.225Co0.125Mn0.65]O2 as a positive electrode for lithium-ion batteries by optimizing its synthesis conditions via a hydroxide co-precipitation method

    NASA Astrophysics Data System (ADS)

    Jeon, Hyo-Jin; Monim, Syed Abdul; Kang, Chung-Soo; Son, Jong-Tae

    2013-09-01

    Lix[Ni0.225Co0.125Mn0.65]O2 cathode material for a lithium-ion battery was synthesized from metal hydroxide Ni0.225Co0.125Mn0.65(OH)2. The co-precipitated metal hydroxide was greatly influenced by synthesis conditions of pH, concentration of chelating agent, stirring speed, and co-precipitation temperature. The conditions were optimized by observing the spherical and uniform particles, as examined by scanning electron microscopy. The optimized pH, ammonia concentration stirring speed and co-precipitation temperature were determined to be 11-12, 0.36 M, 1000 rpm and 50 °C, respectively. The final products, Lix[Ni0.225Co0.125Mn0.65]O2 had a well-ordered hexagonal super lattice layered structure as established by Rietveld refinement of X-ray diffraction pattern. As a result, the Lix[Ni0.225Co0.125Mn0.65]O2 compound may be considered as a excellent candidate for cathode material of Lithium secondary battery in terms of cycle life, both safety and energy density, lower cost and low environmental impact.

  15. Fine-sized LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders prepared by combined process of gas-phase reaction and solid-state reaction methods

    NASA Astrophysics Data System (ADS)

    Ju, Seo Hee; Kang, Yun Chan

    The Ni-rich precursor powders with spherical shape and filled morphologies were prepared by spray pyrolysis from the spray solution with citric acid, ethylene glycol and a drying control chemical additive. The precursor powders with controlled morphologies formed the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size by solid-state reaction with lithium hydroxide. However, the cathode powders prepared from the spray solution without additives had irregular morphologies and were large in size. The precursor powders with hollow and porous morphologies formed cathode powders with irregular and aggregated morphologies. The composition ratios of the nickel, cobalt and manganese components were maintained in the as-prepared, precursor and cathode powders. The initial discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders with spherical shape and fine size tested at a temperature of 55 °C under a constant current density of 0.5 C was 215 mAh g -1. The discharge capacity of the LiNi 0.8Co 0.15Mn 0.05O 2 cathode powders decreased to 81% of the initial value after 30 cycles.

  16. Preparation of Sandwich-like NiCo2O4/rGO/NiO Heterostructure on Nickel Foam for High-Performance Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Li, Delong; Gong, Youning; Wang, Miaosheng; Pan, Chunxu

    2017-04-01

    A kind of sandwich-like NiCo2O4/rGO/NiO heterostructure composite has been successfully anchored on nickel foam substrate via a three-step hydrothermal method with successive annealing treatment. The smart combination of NiCo2O4, reduced graphene oxide (rGO), and NiO nanostructure in the sandwich-like nano architecture shows a promising synergistic effect for supercapacitors with greatly enhanced electrochemical performance. For serving as supercapacitor electrode, the NiCo2O4/rGO/NiO heterostructure materials exhibit remarkable specific capacitance of 2644 mF cm-2 at current density of 1 mA cm-2, and excellent capacitance retentions of 97.5% after 3000 cycles. It is expected that the present heterostructure will be a promising electrode material for high-performance supercapacitors.

  17. Double dumbbell shaped AgNi alloy by pulsed electrodeposition

    SciTech Connect

    Dhanapal, K.; Vasumathi, M.; Santhi, Kalavathy; Narayanan, V. Stephen, A.

    2014-01-28

    Silver-Nickel is the well-known thermally immiscible system that makes them quite complex for the formation of alloy. This kind of alloy can be attained from electrodeposition method. In the present work, AgNi alloy was synthesized by pulsed electrodeposition in a single bath two electrode system with the use of anodic alumina membrane. The prepared AgNi alloy and pure Ag were characterized with X-ray Diffraction (XRD) for structural confirmation, Scanning Electron Microscopy (SEM) for morphological, and magnetic properties by Vibrating Sample Magnetometer, respectively. The X-ray Diffraction study shows the formation of cubic structure for pure Ag. SEM analysis reveals the double dumbbell morphology for AgNi alloy and spherically agglomeration for pure silver. Hysteresis behaviour from VSM measurement indicates that the AgNi alloy have good ferro-magnetic properties.

  18. Conductive microemulsions for template CoNi electrodeposition.

    PubMed

    Serrà, Albert; Gómez, Elvira; Calderó, Gabriela; Esquena, Jordi; Solans, Conxita; Vallés, Elisa

    2013-09-21

    Microemulsions have been revealed as feasible templates to grow magnetic nanostructures using an electrodeposition method. Reducing agents are not required and the applied potential has been used as driving force of the nanostructure growth. A systematic study of conductive microemulsion systems to allow the CoNi electrodeposition process has been performed. Different surfactants and organic components have been tested to form microemulsions with a CoNi electrolytic bath as an aqueous component in order to define the microemulsions showing enough conductivity to perform an electrodeposition process from the aqueous component. By using microemulsions of the aqueous electrolyte solution-Triton X-100-diisopropyl adipate system, CoNi electrodeposition has been achieved, the structure of the deposits being dependent on the composition and structure of the microemulsion, which can act as a soft-template to obtain different discontinuous deposits. The magnetic properties of the CoNi deposits vary with their structure.

  19. Spatial classification of La Niña events

    NASA Astrophysics Data System (ADS)

    Voskresenskaya, E. N.; Marchukova, O. V.

    2017-01-01

    Thirty La Niña events have been selected from monthly mean sea surface temperature (SST) data of the Hadley Centre Global Sea Ice and Sea Surface Temperature (HadISST) and Centennial Observation-Based Estimates (COBE SST2) datasets from 1870 to 2013 based on a criterion of -0.5°C for a cold anomaly in the Niño 3.4 region (5° N-5° S, 170°-120° W) and its minimum duration of 5 months. The selected events are classified by hierarchical clustering analysis according to two characteristics: geographic coordinates and SST anomalies during the mature phase of La Niña. The objective classification method identifies two types of La Niña differing by the evolution of negative SST anomalies in the equatorial Pacific and by the Southern Oscillation Index.

  20. Atomistic Simulations of Ti Additions to NiAl

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Noebe, Ronald D.; Garg, Anita; Ferrante, John; Amador, Carlos

    1997-01-01

    The development of more efficient engines and power plants for future supersonic transports depends on the advancement of new high-temperature materials with temperature capabilities exceeding those of Ni-based superalloys. Having theoretical modelling techniques to aid in the design of these alloys would greatly facilitate this development. The present paper discusses a successful attempt to correlate theoretical predictions of alloy properties with experimental confirmation for ternary NiAl-Ti alloys. The B.F.S. (Bozzolo-Ferrante-Smith) method for alloys is used to predict the solubility limit and site preference energies for Ti additions of 1 to 25 at.% to NiAl. The results show the solubility limit to be around 5% Ti, above which the formation of Heusler precipitates is favored. These results were confirmed by transmission electron microscopy performed on a series of NiAl-Ti alloys.

  1. Support effects on hydrotreating activity of NiMo catalysts

    SciTech Connect

    Dominguez-Crespo, M.A. Arce-Estrada, E.M.; Torres-Huerta, A.M.

    2007-10-15

    The effect of the gamma alumina particle size on the catalytic activity of NiMoS{sub x} catalysts prepared by precipitation method of aluminum acetate at pH = 10 was studied. The structural characterization of the supports was measured by using XRD, pyridine FTIR-TPD and nitrogen physisorption. NiMo catalysts were characterized during the preparation steps (annealing and sulfidation) using transmission electron microscopy (TEM). Hydrogen TPR studies of the NiMo catalysts were also carried out in order to correlate their hydrogenating properties and their catalytic functionality. Catalytic tests were carried out in a pilot plant at 613, 633 and 653 K temperatures. The results showed that the rate constants of hydrodesulfurization (HDS), hydrodenitrogenation (HDN) and hydrodearomatizing (HDA) at 613-653 K decreased in the following order: A > B > C corresponding to the increase of NiMoS particle size associated to these catalysts.

  2. Electroplating and magnetostructural characterization of multisegmented Co54Ni46/Co85Ni15 nanowires from single electrochemical bath in anodic alumina templates

    PubMed Central

    2013-01-01

    Highly hexagonally ordered hard anodic aluminum oxide membranes, which have been modified by a thin cover layer of SiO2 deposited by atomic layer deposition method, were used as templates for the synthesis of electrodeposited magnetic Co-Ni nanowire arrays having diameters of around 180 to 200 nm and made of tens of segments with alternating compositions of Co54Ni46 and Co85Ni15. Each Co-Ni single segment has a mean length of around 290 nm for the Co54Ni46 alloy, whereas the length of the Co85Ni15 segments was around 430 nm. The composition and crystalline structure of each Co-Ni nanowire segment were determined by transmission electron microscopy and selected area electron diffraction techniques. The employed single-bath electrochemical nanowire growth method allows for tuning both the composition and crystalline structure of each individual Co-Ni segment. The room temperature magnetic behavior of the multisegmented Co-Ni nanowire arrays is also studied and correlated with their structural and morphological properties. PMID:23735184

  3. Facile approach to prepare hollow core–shell NiO microspherers for supercapacitor electrodes

    SciTech Connect

    Han, Dandan; Xu, Pengcheng; Jing, Xiaoyan; Wang, Jun; Song, Dalei; Liu, Jingyuan; Zhang, Milin

    2013-07-15

    A facile lamellar template method (see image) has been developed for the preparation of uniform hollow core–shell structure NiO (HCS–NiO) with a nanoarchitectured wall structure. The prepared NiO was found to be highly crystalline in uniform microstructures with high specific surface area and pore volume. The results indicated that ethanol interacted with trisodium citrate played an important role for the formation of hollow core–shell spheres. On the basis of the analysis of the composition and the morphology, a possible formation mechanism was investigated. NiO microspheres with hollow core–shell showed excellent capacitive properties. The exceptional cyclic, structural and electrochemical stability with ∼95% coulombic efficiency, and very low ESR value from impedance measurements promised good utility value of hollow core–shell NiO material in fabricating a wide range of high-performance electrochemical supercapacitors. - The hollow core–shell NiO was prepared with a facile lamellar template method. The prepared NiO show higher capacitance, lower ion diffusion resistance and better electroactive surface utilization for Faradaic reactions. - Highlights: • Formation of hollow core–shell NiO via a novel and facile precipitation route. • Exhibited uniform feature sizes and high surface area of hollow core–shell NiO. • Synthesized NiO has high specific capacitance ( 448 F g{sup 1}) and very low ESR value. • Increased 20% of long life cycles capability after 500 charge–discharge cycles.

  4. Ni/Al Multilayers Produced by Accumulative Roll Bonding and Sputtering

    NASA Astrophysics Data System (ADS)

    Simões, S.; Ramos, A. S.; Viana, F.; Emadinia, O.; Vieira, M. T.; Vieira, M. F.

    2016-10-01

    Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high heat release rate and can be triggered by an external impulse, are reasons why it has already attracted much research attention. There is a huge potential in the use of Ni/Al multilayers as a controllable and localized heat source for joining temperature-sensitive materials such as microelectronic components. The heat released and the phases resulting from the reaction of Ni and Al multilayers depend on the production methods, their composition, as well as the bilayer thickness and annealing conditions. The present research aims to explore the influence of these variables on the reaction of different multilayers, namely those produced by accumulative roll bonding (ARB) and sputtering. Structural evolution of Ni/Al multilayers with temperature was studied by differential scanning calorimetry, x-ray diffraction and scanning electron microscopy. Phase evolution, heat release rate and NiAl final grain size are controlled by the ignition method used to trigger the reaction of Ni and Al. The potential use of these multilayers in the diffusion bonding of TiAl was analyzed. The ARB multilayers allow the production of joints with higher strength than the joints produced with commercial multilayers (NanoFoil®) produced by sputtering. However, the formation of brittle intermetallic phases (Ni3Al, Ni2Al3 and NiAl3) compromises the mechanical properties of the joint.

  5. Raman studies of C-Ni/Ti films deposited on Si (100)

    NASA Astrophysics Data System (ADS)

    Belka, R.; Keczkowska, J.; Suchańska, M.; Firek, P.; Wronka, H.; Radomska, J.; Czerwosz, E.

    2015-09-01

    The thin films of carbon-nickel (C-Ni) nanocoposites were deposited on Ti-evaporated Si (100) substrate using Physical Vapour Deposition (PVD) method. Influence of evaporated titanium on carbonaceous structure of C-Ni films were investigated by Raman spectroscopy method. The fullerite-graphite structure was recognize using principal component analysis (PCA) of obtained Raman spectra.

  6. Structures and Properties of C-Doped NiCr Thin Film Deposited by Closed-Field Unbalanced Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Lai, Lifei; Wang, Jinxia; Wang, Hongtao; Bao, Mingdong

    2017-01-01

    The structures and properties of C-doped NiCr thin film as embedded thin film resistor (ETFR) materials were studied by closed-field, unbalanced magnetron sputtering method. The C-doped NiCr (NiCrC1) thin film had more stable electrical performance, better corrosion resistance, and higher hardness than NiCr thin film. The temperature coefficient of resistance (TCR) of NiCrC1 thin film deposited at room temperature (from 19.73 ppm/K to 173.7 ppm/K) was lower than that of NiCr thin film (from 157.8 ppm/K to 378.9 ppm/K), and the sheet resistor (154.25 Ω/Sq) was higher than that of NiCr thin film (62.84 Ω/Sq). The preferred orientations of C-doped NiCr thin film was Ni (111), while that of NiCr thin film was Ni (011). The carbon-doped NiCr thin film can reduce the defects and stress and change the preferred orientations. The dominant carbon in C-doped NiCr thin film had a graphite-like structure.

  7. First-principle calculation on mechanical and thermal properties of B2-NiSc with point defects

    NASA Astrophysics Data System (ADS)

    Yuan, Zhipeng; Cui, Hongbao; Guo, Xuefeng

    2017-01-01

    Using the first-principles plane-wave pseudo-potential method based on density functional theory, the effect of vacancy and anti-position defect on the mechanical and thermal properties of B2-NiSc intermetallics were discussed in detail. Several parameters, such as the shear modulus, bulk modulus, modulus of elasticity, C 11–C 11, the Debye temperature and Poisson's ratio, have been calculated to evaluate the effect of vacancy and anti-position defect on the hardness, ductility and thermal properties of B2-NiSc intermetallics. The results show that VNi, ScNi, VSc and NiSc the four point defects all make the crystal hardness decrease and improve plasticity of B2-NiSc intermetallics. The entropy, enthalpy and free energy of VNi, ScNi, VSc and NiSc are monotonously changed as temperature changes. From the perspective of free energy, NiSc is the most stable, while ScNi is the most unstable. Debye temperature of NiSc intermetallics with four different point defects shows VNi, ScNi, VSc and NiSc the four point defects all reduce the stability of B2-NiSc intermetallics. Project supported by the National Natural Science Foundation of China (Nos. 51301063, 51571086) and the Talent Introduction Foundation of Henan Polytechnic University (No. Y-2009).

  8. Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    NASA Astrophysics Data System (ADS)

    Wang, Z. X.; Wu, H. R.; Shan, X. L.; Lin, N. M.; He, Z. Y.; Liu, X. P.

    2016-12-01

    The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of the Ni modified layer was measured by nanoindenter. The results showed that the Ni modified layers exhibited triple-layer structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni3Ti, NiTi, Ti2Ni, AlNi3 and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of the Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surfaces of the untreated and treated Ti6Al4V samples using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different values, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of the Ni modified layer showed micro-cutting wearing.

  9. Microhardness of Ni-Cr alloys under different casting conditions.

    PubMed

    Bauer, José Roberto de Oliveira; Loguercio, Alessandro Dourado; Reis, Alessandra; Rodrigues Filho, Leonardo Eloy

    2006-01-01

    This study evaluated the microhardness of Ni-Cr alloys used in fixed prosthodontics after casting under different conditions. The casting conditions were: (1-flame/air torch) flame made of a gas/oxygen mixture and centrifugal casting machine in a non-controlled casting environment; (2-induction/argon) electromagnetic induction in an environment controlled with argon; (3-induction/vacuum) electromagnetic induction in a vacuum environment; (4-induction/air) electromagnetic induction in a non-controlled casting environment. The 3 alloys used were Ni-Cr-Mo-Ti, Ni-Cr-Mo-Be, and Ni-Cr-Mo-Nb. Four castings with 5 cylindrical, 15 mm-long specimens (diameter: 1.6 mm) in each casting ring were prepared. After casting, the specimens were embedded in resin and polished for Vickers microhardness (VH) measurements in a Shimadzu HMV-2 (1,000 g for 10 s). A total of 5 indentations were done for each ring, one in each specimen. The data was subjected to two-way ANOVA and Tukey's multiple comparison tests (alpha = 0.05). The VH values of Ni-Cr-Mo-Ti (422 +/- 7.8) were statistically higher (p < 0.05) than those of Ni-Cr-Mo-Nb (415 +/- 7.6). The lowest VH values were found for Ni-Cr-Mo-Be (359 +/- 10.7). The VH values obtained in the conditions induction/argon and induction/vacuum were similar (p > 0.05) and lower than the values obtained in the conditions induction/air and flame/air torch (p < 0.05). The VH values in the conditions induction/air and flame/air were similar (p > 0.05). The microhardness of the alloys is influenced by their composition and casting method. The hardness of the Ni-Cr alloys was higher when they were cast with the induction/air and flame/air torch methods.

  10. [Effect of aurum coating on corrosion resistance of Ni-Cr alloy].

    PubMed

    Chen, Zhi-hong; Liu, Li; Mao, Ying-jie

    2007-02-01

    To evaluate the effect of aurum coating on corrosion resistance of Ni-Cr alloy in artificial saliva environment. The corrosion potential (E(corr)), self-corrosion current density (I(corr)), and polarization resistance (R(p)) of three alloys were measured using electrochemical methods to compare the difference of corrosion resistance between aurum-coated Ni-Cr alloy and Ni-Cr alloy or Au alloy. Meanwhile, microstructural and phase diffraction was examined with field scanning electromicroscopy (FSEM) and surface chemical analysis was performed by energy diffraction X-ray (EDX). The I(corr) of aurum-coated Ni-Cr alloy was (0.70 +/- 0.20) x 10(-6) A/cm2, which was significantly higher than that of Au alloy (P < 0.05) and lower than that of Ni-Cr alloy (P < 0.05). R(p) of aurum-coated Ni-Cr alloy was (34.77 +/- 12.61) KOmega.cm2, which was higher than that of Ni-Cr alloy (P < 0.05) and lower than that of Au alloy (P < 0.05). The results of FSEM showed that the corrosion resistance of Ni-Cr alloy coated with aurum was better than that of Ni-Cr alloy. The results of EDX indicated that released Ni and Cr of Ni-Cr alloy coated with aurum after test were less than those of Ni-Cr alloy (P < 0.05). The corrosion resistance of aurum-coated Ni-Cr alloy is higher than that of Ni-Cr alloy.

  11. Anomalous magnetic behavior in nanocomposite materials of reduced graphene oxide-Ni/NiFe{sub 2}O{sub 4}

    SciTech Connect

    Kollu, Pratap E-mail: anirmalagrace@vit.ac.in; Prathapani, Sateesh; Varaprasadarao, Eswara K.; Mallick, Sudhanshu; Bahadur, D. E-mail: anirmalagrace@vit.ac.in; Santosh, Chella; Grace, Andrews Nirmala E-mail: anirmalagrace@vit.ac.in

    2014-08-04

    Magnetic Reduced Graphene Oxide-Nickel/NiFe{sub 2}O{sub 4} (RGO-Ni/NF) nanocomposite has been synthesized by one pot solvothermal method. Respective phase formations and their purities in the composite are confirmed by High Resolution Transmission Electron Microscope and X Ray Diffraction, respectively. For the RGO-Ni/NF composite material finite-size effects lead to the anomalous magnetic behavior, which is corroborated in temperature and field dependent magnetization curves. Here, we are reporting the behavior of higher magnetization values for Zero Field Cooled condition to that of Field Cooled for the RGO-Ni/NF nanocomposite. Also, the observed negative and positive moments in Hysteresis loops at relatively smaller applied fields (100 Oe and 200 Oe) are explained on the basis of surface spin disorder.

  12. Photoacoustic determination of thermal and electron transport properties of single crystal NiO

    NASA Astrophysics Data System (ADS)

    Nikolic, P. M.; Lukovic, D.; Savic, S.; Vasiljevic Radovic, D.; Radulovic, K.; Vujatovic, S.; Lukic, L.; Nikolic, M. V.; Bojicic, A.; Djuric, S.

    2005-06-01

    Thermal and electron transport properties of single crystal NiO were determined using the photoacoustic technique. NiO single crystals were prepared using the Verneuil method and were easily cleaved parallel to the (100) plane. All samples were of the p type. Atomic force microscopy images of cleaved NiO samples were made enabling a view of steps along the (001) direction and terraces, which were between 20 nm and 100 nm thick.

  13. Formation of Multiple-Phase Catalysts for the Hydrogen Storage of Mg Nanoparticles by Adding Flowerlike NiS.

    PubMed

    Xie, Xiubo; Ma, Xiujuan; Liu, Peng; Shang, Jiaxiang; Li, Xingguo; Liu, Tong

    2017-02-22

    In order to enhance the hydrogen storage properties of Mg, flowerlike NiS particles have been successfully prepared by solvothermal reaction method, and are subsequently ball milled with Mg nanoparticles (NPs) to fabricate Mg-5 wt % NiS nanocomposite. The nanocomposite displays Mg/NiS core/shell structure. The NiS shell decomposes into Ni, MgS and Mg2Ni multiple-phases, decorating on the surface of the Mg NPs after the first hydrogen absorption and desorption cycle at 673 K. The Mg-MgS-Mg2Ni-Ni nanocomposite shows enhanced hydrogenation and dehydrogenation rates: it can quickly uptake 3.5 wt % H2 within 10 min at 423 K and release 3.1 wt % H2 within 10 min at 573 K. The apparent hydrogen absorption and desorption activation energies are decreased to 45.45 and 64.71 kJ mol(-1). The enhanced sorption kinetics of the nanocomposite is attributed to the synergistic catalytic effects of the in situ formed MgS, Ni and Mg2Ni multiple-phase catalysts during the hydrogenation/dehydrogenation process, the porthole effects for the volume expansion and microstrain of the phase transformation of Mg2Ni and Mg2NiH4 and the reduced hydrogen diffusion distance caused by nanosized Mg. This novel method of in situ producing multiple-phase catalysts gives a new horizon for designing high performance hydrogen storage material.

  14. Domain Structures and Anisotropy in Exchange-coupled [Co/Pd]-NiFe and [Co/Ni]-NiFe Multilayers

    NASA Astrophysics Data System (ADS)

    Tryputen, Larysa; Chung, Sunjae; Mohseni, Majid; Nguyen, T. N. Anh; Åkerman, Johan; Guo, Feng; McMichael, Robert D.; Ross, Caroline A.

    2014-03-01

    Exchange-coupled multilayers [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe with strong perpendicular magnetic anisotropy have been proposed to use in spin-torque switching and oscillators devices with tilted fixed and free layer to improve their functional performance. We present an experimental study of the magnetization behavior of [Co/Pd]5-/NiFe and [Co/Ni]4-NiFe multilayers measured using magnetometry, magnetic force microscopy (MFM) and ferromagnetic resonance (FMR) as a function of the thickness of the top NiFe layer. We varied the thickness of the NiFe layer in [Co/Pd]5-NiFe (t), t = 0 - 80 nm and [Co/Ni]4-NiFe (t), t = 0.5 - 2.5 nm in order to study the interplay between perpendicular magnetization of the Co/Pd or Co/Ni multilayers and in-plane magnetization of the NiFe. Our magnetometry and FMR data suggest that the [Co/Ni]4/NiFe multilayer behaves like a homogeneous ferromagnetic film with anisotropy that reorients towards in-plane as the NiFe thickness increases, whereas the [Co/Pd]5/NiFe multilayer reveals more complex behavior in which the [Co/Pd] layer retains out-of-plane anisotropy while the magnetization of NiFe layer tilts in-plane with increasing thickness. MFM showed that domains with ~0.1 +/-m size were visible in [Co/Pd]-/NiFe with NiFe thickness of 20-80 nm. Multilayers were patterned into sub-100 nm dots using ion beam etching and their magnetization behavior are compared with unpatterned films.

  15. Solvotermal synthesis of NiO, Ni and NiS nanoparticles.

    PubMed

    Gutierrez, Angel; Perpiñán, M Felisa; Sánchez, Ana E; Torralba, M Carmen

    2013-01-01

    Nanoparticles of NiO, Ni or NiS have been obtained by solvothermal decomposition of different molecular precursors. The influence of several parameters, such as temperature, reaction time, solvent or capping agent used, in the nature and size of the obtained nanoparticle has been studied. The characterization by XRD and TEM techniques indicates that the nanoparticles of NiO exhibit average sizes of 3-8 nm, while those of Ni are in the 30-40 nm range. This difference in size has been attributed to the presence of molecules of the capping agent (n-octylamine or oleic acid) that surround the NiO nanoparticles but were not present in the nickel ones. The capping agent is, thus, preventing the aggregation of the smallest nanoparticles. The use of either a S-donor capping agent (4-mercaptopyridine) or a precursor having S-donor ligands (diethyldithiocarbamate) have led to the formation of NiS with average sizes around 35 nm. The magnetic properties of the nanoparticles have been studied, showing superparamagnetism and magnetic hysteresis below the blocking temperature, which, in time, is dependent of the particle size.

  16. The design of underwater superoleophobic Ni/NiO microstructures with tunable oil adhesion

    NASA Astrophysics Data System (ADS)

    Zhang, Enshuang; Cheng, Zhongjun; Lv, Tong; Li, Li; Liu, Yuyan

    2015-11-01

    Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from different microstructures on the surfaces. Moreover, the oil-adhesion controllability for different types of oils was also analyzed and the applications of the surface including oil droplet transportation and self-cleaning were discussed. The results reported herein provide a new feasible method for fabrication of underwater superoleophobic surfaces with controlled adhesion, and improve the understanding of the relationship between surface microstructures, adhesion, and the fabrication principle of tunable oil adhesive surfaces.Controlling oil adhesion in water is a fundamental issue in many practical applications for surfaces. Currently, almost all studies on underwater oil adhesion control are concentrated on regulating surface chemistry on polymer surfaces, and structure-dependent underwater oil adhesion is still rare, especially on inorganic materials. Herein, we report a series of underwater superoleophobic Ni/NiO surfaces with controlled oil adhesions by combining electro-deposition and heating techniques. The adhesive forces between an oil droplet and the surfaces can be adjusted from an extremely low (less than 1 μN) to a very high value (about 60 μN), and the tunable effect can be attributed to different wetting states that result from

  17. Engineering of high performance supercapacitor electrode based on Fe-Ni/Fe{sub 2}O{sub 3}-NiO core/shell hybrid nanostructures

    SciTech Connect

    Singh, Ashutosh K. E-mail: aksingh@bose.res.in; Mandal, Kalyan

    2015-03-14

    The present work reports on fabrication and supercapacitor applications of a core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures (HNs) electrode. The core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures have been fabricated through a two step method (nanowire fabrication and their controlled oxidation). The 1D hybrid nanostructure consists of highly porous shell layer (redox active materials NiO and Fe{sub 2}O{sub 3}) and the conductive core (FeNi nanowire). Thus, the highly porous shell layer allows facile electrolyte diffusion as well as faster redox reaction kinetics; whereas the conductive FeNi nanowire core provides the proficient express way for electrons to travel to the current collector, which helps in the superior electrochemical performance. The core/shell Fe-Ni/Fe{sub 2}O{sub 3}-NiO hybrid nanostructures electrode based supercapacitor shows very good electrochemical performances in terms of high specific capacitance nearly 1415 F g{sup −1} at a current density of 2.5 A g{sup −1}, excellent cycling stability and rate capability. The high quality electrochemical performance of core/shell hybrid nanostructures electrode shows its potential as an alternative electrode for forthcoming supercapacitor devices.

  18. Shape coexistence in 68Ni

    NASA Astrophysics Data System (ADS)

    Suchyta, S.; Liddick, S.; Bennet, M.; Larson, N.; Prokop, C.; Quinn, S.; Spyrou, A.; Chemey, A.; Simon, A.; Otsuka, T.; Tsunoda, Y.; Shimizu, N.; Honma, M.; Utsuno, Y.; Tripath, V.; Vonmoss, J.

    2013-10-01

    68 Ni has been a focus of recent work aiming to understand the apparent rapid development of collectivity along neutron-rich N = 40 nuclei, but despite many studies, is not entirely understood. The decay of the first excited 0+ state in 68Ni was investigated at the NSCL. Ions of 68Co were implanted into a planar germanium double-sided strip detector (GeDSSD). The beta decay of 68Co populated the first excited 0+ state in 68Ni and within hundreds of nanoseconds the decay of the first excited 0+ state was measured in the GeDSSD. Both the energy of the first excited 0+ state and the electric monopole transition strength from the first excited 0+ state were precisely determined. Comparisons to Monte Carlo Shell Model calculations suggest shape coexistence between spherical ground and oblate first excited 0+ states in 68Ni. The experimental results and theoretical interpretation will be presented.

  19. Synthesis and characterization of Ni-Au bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nik Roselina, N. R.; Azizan, A.; Hyie, Koay Mei; Murad, Mardziah Che; Abdullah, Abdul Hakim

    2015-04-01

    Bimetallic structure of nanoparticles is of great interest due to their extraordinary properties, especially in combining the specialty of the core and its shell. This work reports the effect of pH on the synthesis of Ni-Au (nickel-gold) bimetallic nanoparticles. The synthesis involves a two-step process where Ni nanoparticles were first synthesized using polyol method with hydrazine as the reducing agent. This was followed by the process of reducing AuCl4- to Au in the solution containing pre-prepared Ni to form Ni-Au bimetallic nanoparticles using sodium citrate as the reducing agent. The results obtained from Transmission Electron Microscopy (TEM) show that the process can possibly produce either core-shell structure, or mixture of Ni and Au nanoparticles. Magnetic property of core-shell structure investigated using Vibrating Sample Magnetometer (VSM) demonstrated typical characteristic of ferromagnetic with an increased magnetization as compared to Ni nanoparticles. The saturation magnetization (Ms) and coercivity (Hc) were obtained as 19.1 emu/g and 222.3 Oe, respectively.

  20. Silicidation of Ni(Yb) Film on Si(001)

    NASA Astrophysics Data System (ADS)

    Luo, Jia; Jiang, Yu-Long; Ru, Guo-Ping; Li, Bing-Zong; Chu, Paul K.

    2008-03-01

    The influence of the addition of Yb to Ni on the silicidation of Ni was investigated. The Ni(Yb) film was deposited on a Si(001) substrate by co-sputtering, and silicidation was performed by rapid thermal annealing (RTA). After silicidation, the sheet resistance of the silicide film was measured by the four-point probe method. X-ray diffraction and micro-Raman spectroscopy were employed to identify the silicide phases, and the redistribution of Yb after RTA was characterized by Rutherford backscattering spectrometry and Auger electron spectroscopy. The influence of the Yb addition on the Schottky barrier height (SBH) of the silicide/Si diode was examined by current voltage measurements. The experimental results reveal that the addition of Yb can suppress the formation of the high-resistivity Ni2Si phase, but the formation of low-resistivity NiSi phase is not affected. Furthermore, after silicidation, most of the Yb atoms accumulate in the surface layer and only a small number of Yb atoms pile up at the silicide/Si(001) interface. It is believed that the accumulation of a small amount of Yb at the silicide/Si(001) interface results in the SBH reduction observed in the Ni(Yb)Si/Si diode.

  1. Synthesis and characterization of immobilized Ni-Co bimetallic using Tapanuli clay for catalyst application

    SciTech Connect

    Nuryanti,; Juwono, Ariadne L.; Krisnandi, Yuni K.

    2016-04-19

    Heterogeneous catalysts hold various advantages, namely, easy to separate from their products, reusable and regarded as environmental friendly materials. The synthesis of immobilized Ni monometallic, Co monometallic and Ni-Co bimetallic by Tapanuli clay were carried out using intercalation method. Firstly, the synthesis of Na-Bentonite was conducted to provide sufficient area to immobilize bimetal in the clay interlayer. Secondly, Ni, Co and Ni-Co were immobilized in the Tapanuli clay interlayer. Several techniques, such as X-Ray Diffraction, Fourier Transform Infra Red and Energy Dispersive X-Ray Analysis were applied to characterize and compare the properties of the synthesized materials. The results showed that the insertion of Ni, Co and Ni-Co in the clay interlayer occurred through a cation exchange reaction. The Energy Dispersive X-Ray analysis for Ni-Co bimetallic showed that the immobilized Ni and Co in the clay is in the ratio of 1:1. Catalytic test with Gas Chromatography showed that Ni-Co bimetallic generates a higher yield percentage compared to Ni and Co monometallic.

  2. Effects of Co2+ doping on physicochemical behaviors of hierarchical NiO nanostructure

    NASA Astrophysics Data System (ADS)

    Ding, Caihua; Gao, WenChao; Zhao, Yongjie; Zhao, Yuzhen; Zhou, Heping; Li, Jingbo; Jin, Haibo

    2016-12-01

    A series of Co2+ doped NiO materials (Ni1-xCoxO with x = 0, 0.125, 0.25 and 0.5) were synthesized using a facile hydrothermal method followed by a calcination process. The effects of Co2+ doping on the structural, morphological, magnetic and catalytic properties of NiO were systematically investigated. The results indicated that Co2+ doping would bring about a series influence to the as-obtained NiO product. The XRD results indicated that within the region of 0 ≤ x ≤ 0.25 the doped products revealed a pure NiO phase. The elementary unit for the hierarchy NiO gradually transformed from nanosheets to nanoneedles with the increase of Co2+ doping content. As-obtained Co2+ doped NiO products showed ferromagnetism at room temperature and the magnetization value was increased with the increase of Co2+ doping content. The catalytic properties of NiO concerning the thermal decomposition of ammonium perchlorate (AP) were significantly improved via the introduction of Co2+. The Ni1-xCoxO products with x = 0.25 showed the best catalytic performance to AP, which could decrease the beginning and ending decomposition temperature of AP by 44 and 108 °C. The change of morphology, enhancement of electrical conductivity and the synergistic effect between Co2+ and NiO were the main factors responsible for the improvement of physicochemical behaviors.

  3. Formation of bcc and fcc during the coalescence of free and supported Fe and Ni clusters.

    PubMed

    Li, Guojian; Wang, Qiang; Sui, Xudong; Wang, Kai; Wu, Chun; He, Jicheng

    2015-09-07

    The formation of bcc and fcc during the coalescence of free and supported Fe and Ni clusters has been studied by molecular dynamics simulation using an embedded atom method. Structural evolution of the clusters, coalesced under varying temperature, Ni content and substrate conditions, was explored by interatomic energy, snapshots, pair distribution functions and bond order parameters. The results show that the formation of bcc and fcc is strongly related to Ni content, substrate and coalescence temperature. Free clusters coalesced at 1200 K form bcc at lower Ni contents with fcc forming at higher Ni concentrations and no observable coexistence of bcc and fcc. Differences in coalescence at 1000 K result from the coexistence of bcc and fcc within the Ni range of 50-70%. Free clusters supported on disordered Ni substrates were shown to transform from spherical morphology to islands of supported clusters with preferred epitaxial orientation. The Ni content required to form bcc and fcc coexistence on supported clusters at 1000 K decreased to 30-50% Ni. Free clusters possessing bcc and fcc generally stacked along the bcc (110) and fcc (111) facets, whereas supported clusters stacked along the (111) bcc and (100) fcc planes. Structural transformation was induced by clusters containing greater numbers of atoms. Spread over the substrate enhanced interatomic energy, order substrates affect the epitaxial growth direction and increase the melting points of the supported clusters. This study can be used to predict the nature of fcc and bcc formation in Fe-Ni films.

  4. Evaluation of electrodeposited ternary Ni-alloys for thermal stability

    NASA Astrophysics Data System (ADS)

    Kim, Myong Jin; Kim, Joung Soo; Kim, Dong Jin; Kim, Hong Pyo

    2011-04-01

    Electroplating methods for ternary Ni-alloys, such as Ni-P-Fe and Ni-P-B, in a Ni sulfamate solution on the inner wall surfaces of Alloy 600 tubing have been developed in order to use them to repair steam generator tubes damaged by a variety of corrosion mechanisms, in particular, by stress corrosion cracking. In this study, the stability of their microstructures and mechanical properties were evaluated to check if they could be used for a long period of time at the operating temperature of a PWR (pressurized water reactor) in nuclear power plants. The specimens were heat treated at 325 °C and 400 °C for 10, 20 and 30 days, followed by observation of their microstructures and measurement of their microhardness and tensile property. According to the experiment results, there was no noticeable change in their microstructures or microhardness with the heat treatment temperature and time conditions used in this study. For a Ni-P-B deposit, the ultimate tensile strength (UTS) slightly increased with the heat treatment time, while their elongation decreased. In the case of a Ni-P-Fe deposit, however, its tensile property varied with the applied current density. For a Ni-P-Fe deposit plated at an applied current density of 50 mA/cm2, its UTS slightly decreased, but its elongation slightly increased with the heat treatment time. We concluded that the thermal stability of the ternary Ni-alloy deposits used in this study is good enough to be used with the materials of operating nuclear power plants.

  5. Room temperature synthesis of Ni-based alloy nanoparticles by radiolysis.

    SciTech Connect

    Nenoff, Tina Maria; Berry, Donald T.; Lu, Ping; Leung, Kevin; Provencio, Paula Polyak; Stumpf, Roland Rudolph; Huang, Jian Yu; Zhang, Zhenyuan

    2009-09-01

    Room temperature radiolysis, density functional theory, and various nanoscale characterization methods were used to synthesize and fully describe Ni-based alloy nanoparticles (NPs) that were synthesized at room temperature. These complementary methods provide a strong basis in understanding and describing metastable phase regimes of alloy NPs whose reaction formation is determined by kinetic rather than thermodynamic reaction processes. Four series of NPs, (Ag-Ni, Pd-Ni, Co-Ni, and W-Ni) were analyzed and characterized by a variety of methods, including UV-vis, TEM/HRTEM, HAADF-STEM and EFTEM mapping. In the first focus of research, AgNi and PdNi were studied. Different ratios of Ag{sub x}- Ni{sub 1-x} alloy NPs and Pd{sub 0.5}- Ni{sub 0.5} alloy NP were prepared using a high dose rate from gamma irradiation. Images from high-angle annular dark-field (HAADF) show that the Ag-Ni NPs are not core-shell structure but are homogeneous alloys in composition. Energy filtered transmission electron microscopy (EFTEM) maps show the homogeneity of the metals in each alloy NP. Of particular interest are the normally immiscible Ag-Ni NPs. All evidence confirmed that homogeneous Ag-Ni and Pd-Ni alloy NPs presented here were successfully synthesized by high dose rate radiolytic methodology. A mechanism is provided to explain the homogeneous formation of the alloy NPs. Furthermore, studies of Pd-Ni NPs by in situ TEM (with heated stage) shows the ability to sinter these NPs at temperatures below 800 C. In the second set of work, CoNi and WNi superalloy NPs were attempted at 50/50 concentration ratios using high dose rates from gamma irradiation. Preliminary results on synthesis and characterization have been completed and are presented. As with the earlier alloy NPs, no evidence of core-shell NP formation occurs. Microscopy results seem to indicate alloying occurred with the CoNi alloys. However, there appears to be incomplete reduction of the Na{sub 2}WO{sub 4} to form the W

  6. Abnormal Intermetallic Compound Evolution in Ni/Sn/Ni and Ni/Sn-9Zn/Ni Micro Solder Joints Under Thermomigration

    NASA Astrophysics Data System (ADS)

    Zhao, N.; Deng, J. F.; Zhong, Y.; Huang, M. L.; Ma, H. T.

    2017-04-01

    Interfacial reactions in Ni/Sn/Ni and Ni/Sn-9Zn/Ni micro solder joints during thermomigration (TM) have been studied by reflowing solder joints on a hot plate. Asymmetrical growth and transformation of interfacial intermetallic compounds (IMCs) were clearly observed. The growth of the Ni3Sn4 IMC in the Ni/Sn/Ni solder joints was always fast at the cold end and relatively slow at the hot end. Only asymmetrical growth of the Ni5Zn21 IMC in the Ni/Sn-9Zn/Ni solder joints occurred at the beginning because Zn was the dominant TM species; however, asymmetrical transformation of the Ni5Zn21 IMC also occurred under the combined effect of Zn depletion and Ni dissolution and migration, resulting in formation of a thin τ-phase layer at the hot end and a thick τ-phase/Ni5Zn21/τ-phase sandwich structure at the cold end. TM of Ni and Zn atoms was identified towards the cold end, being responsible for the abnormal IMC evolution. Addition of Zn was found to slow the TM-induced IMC growth and Ni dissolution.

  7. Neutron-capture rates for explosive nucleosynthesis: the case of 68Ni(n, γ)69Ni

    NASA Astrophysics Data System (ADS)

    Spyrou, A.; Larsen, A. C.; Liddick, S. N.; Naqvi, F.; Crider, B. P.; Dombos, A. C.; Guttormsen, M.; Bleuel, D. L.; Couture, A.; Crespo Campo, L.; Lewis, R.; Mosby, S.; Mumpower, M. R.; Perdikakis, G.; Prokop, C. J.; Quinn, S. J.; Renstrøm, T.; Siem, S.; Surman, R.

    2017-04-01

    Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the 68Ni(n, γ)69Ni reaction rate. This is done by populating the compound nucleus 69Ni via the β decay of 69Co and measuring the γ-ray deexcitation of excited states in 69Ni. The β-Oslo method was used to extract the γ-ray strength function and the nuclear level density. In addition the half-life of 69Co was extracted and found to be in agreement with previous literature values. Before the present results, the 68Ni(n, γ)69Ni reaction was unconstrained and the purely theoretical reaction rate was highly uncertain. The new uncertainty on the reaction rate based on the present experiment (variation between upper and lower limit) is approximately a factor of 3. The commonly used reaction libraries JINA-REACLIB and BRUSLIB are in relatively good agreement with the experimental rate. The impact of the new rate on weak r-process calculations is discussed.

  8. Etude des interdiffusions en phase solide dans le contact Ni/AlAs

    NASA Astrophysics Data System (ADS)

    Députier, S.; Guivarc'h, A.; Caulet, J.; Poudoulec, A.; Guenais, B.; Minier, M.; Guérin, R.

    1995-04-01

    Solid-state interdiffusions between a thin film of nickel deposited under vacuum conditions and a thick layer of epitaxial AlAs on GaAs (001) and (111) substrates were investigated in the temperature range 200-600 ^{circ}C. Complementary analytical methods (RBS, X-ray diffraction, TEM) allow us to point out, according to annealing temperatures, successives steps of the interaction. These steps correspond either to ternary phases which were evidenced by the experimental determination of the Ni-Al-As phase diagram and labelled as A, B and D phases by comparison with the isostructural ternary phases in the Ni-Ga-As diagram or to mixture of ternaries and binaries, more or less strongly textured on the substrate. In fact, the nature of the observed phases is strongly depending on the AlAs substrate orientation, the kinetic of the reaction occurring being slower on AlAs(111) than on AlAs(001). On AlAs(001), a ternary B-phase + NiAl mixture is firstly observed, followed by a second mixture constituted of the ternary A-phase + NiAl and NiAs binaries, and finally, at the end of the interaction, the two binaries NiAl + NiAs appear. On AlAs(111), only two steps of interaction have been found; first of all, the ternary D-phase is obtained, before leading, at the end of the interaction, to the ternary B-phase + NiAl + NiAs mixture. In that case, the 600 ^{circ}C annealing is not sufficient to reach the mixture of the binaries NiAl + NiAs which, according to the ternary phase diagram, is the final stage of the Ni/AlAs interaction. The comparative study of the Ni/AlAs and Ni/GaAs interdiffusions shows that the binary NiAl is the “key” compound around which the Ni/AlAs interaction progresses when NiAs is the one of the Ni/GaAs interaction. The binary NiAl which is thermally stable and strongly textured on AlAs appears as an interesting candidate to prepare epitaxial NiAl/AlAs/GaAs heterostructures. Les interdiffusions en phase solide entre une couche mince de nickel d

  9. Supercoducting property of Zr-Cu-Al-Ni-Nb alloys

    NASA Astrophysics Data System (ADS)

    Okai, D.; Motoyama, G.; Kimura, H.; Inoue, A.

    The superconducting property of Zr55Cu(30-X)Al10Ni5NbX alloys prepared by arc melting and liquid quenching methods was investigated by magnetic susceptibility measurements. The crystalline alloys with X = 0∼25 at.% prepared by arc melting method exhibited superconductivity with maximum Tc,on of 10.1 K. The alloys (X = 10∼23 at.%) with crystalline particles embedded in an amorphous structure, which were fabricated by melt spinning method, showed superconductivity with Tc,on of less than 4.0 K. The superconducting property of the Zr-Cu-Al-Ni-Nb alloys was attributed to superconducting phases of Zr2Cu, Zr2Ni, Zr65Al10Nb25 and Zr-Nb contained in the Zr-Cu-Al-Ni-Nb alloys. The melt-spun Zr55Cu(30-X)Al10Ni5NbX (X = 10∼20 at.%) alloys exhibited glass transition at 718∼743 K and were found to be superconducting metallic glasses.

  10. Effect of boron and hydrogen on the electronic structure of Ni{sub 3}Al

    SciTech Connect

    Kioussi, N.; Watanabe, H.; Hemker, R.G.; Gourdin, W.: Gonis, A.; Johnson, P.E.

    1993-11-19

    Using first-principles electronic structure calculations based on the Linear-Muffin-Tin Orbital (LMTO) method, we have investigated the effects of interstitial born and hydrogen on the electronic structure of the Ll{sub 2} ordered intermetallic Ni{sub 3}Al. When it occupies an octahedral interstitial site entirely coordinated by six Ni atoms, we find that boron enhances the charge distribution found in the strongly-bound ``pure`` Ni{sub 3}Al crystal: Charge is depleted at Ni and Al region. Substitution Al atoms for two of the Ni atoms coordinating the boron, however, reduces the interstitial charge density between atomic planes. In contrast to boron, hydrogen appears to deplete the interstitial charge, even when fully coordinated by Ni atoms. We suggest that these results are broadly consistent with the notion of boron as a cohesion enhancer and hydrogen as an embrittler.

  11. The discharge properties of Na/Ni 3S 2 cell at ambient temperature

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Seon; Ahn, Hyo-Jun; Ryu, Ho-Suk; Kim, Dong-Ju; Cho, Gyu-Bong; Kim, Ki-Won; Nam, Tae-Hyun; Ahn, Jou Hyeon

    The discharge properties of a Na/Ni 3S 2 cell using 1 M NaCF 3SO 3 in tetra(ethylene glycol)dimethyl ether liquid electrolyte were investigated at room temperature. The products were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Electrochemical properties of Na/Ni 3S 2 cells were also presented by cyclic voltammetry and the galvanostatic current method. Na/Ni 3S 2 cells have an initial discharge capacity of 420 mAh g -1 with a plateau potential at 0.94 V versus Na/Na +. After the first discharge, Ni 3S 2 and Na react at room temperature and then form sodium sulfide (Na 2S) and nickel. Sodium ion can be partially deintercalated from Na 2S charge reaction. The discharge process can be explained as follows: Ni 3S 2 + 4Na ↔ 3Ni + 2Na 2S.

  12. High resistance to sulfur poisoning of Ni with copper skin under electric field

    NASA Astrophysics Data System (ADS)

    Xu, Xiaopei; Zhang, Yanxing; Yang, Zongxian

    2017-02-01

    The effects of sulfur poisoning on the (1 0 0), (1 1 0) and (1 1 1) surfaces of pure Ni and Cu/Ni alloy are studied in consideration of the effect of electric field. The effects of Cu dopants on the S poisoning characteristics are analyzed by the means of the density functional theory results in combination with thermodynamics data using the ab initio atomistic thermodynamic method. When the Cu concentration increases to 50% on the surface layer of the Cu/Ni alloy, the (1 1 0) surface becomes the most vulnerable to the sulfur poisoning. Ni with a copper skin can mostly decrease the sulfur poisoning effect. Especially under the electric field of 1.0 V/Å, the sulfur adsorption and phase transition temperature can be further reduced. We therefore propose that Ni surfaces with copper skin can be very effective to improve the resistance to sulfur poisoning of the Ni anode under high electric field.

  13. Solvothermal derived crystalline NiOx nanoparticles for high performance perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Yin, Xingtian; Liu, Jie; Ma, Jiaqi; Zhang, Chongxin; Chen, Peng; Que, Meidan; Yang, Yawei; Que, Wenxiu; Niu, Chunming; Shao, Jinyou

    2016-10-01

    A solvothermal method is employed to synthesize NiOx nanoparticles with good dispersibility. The synthesized NiOx nanoparticles are very homogenous with an average size of about 3-5 nm, and the X-ray diffraction suggests a good crystallinity for the nanoparticles. NiOx films are spin coated from a colloid precursor which is prepared by dispersing the NiOx nanoparticles into ethanol using a certain amount of acetic as the stabilizer. To obtain an efficient hole extraction layer, an annealing process at 300 °C degree is necessary to remove the residual acetic in the NiOx film. Finally, hysteresis-less NiOx-based perovskite solar cells with good reproducibility are achieved, and a highest power conversion efficiency (PCE) of 16.68% and a constant steady state PCE of 16.49% are also demonstrated.

  14. PEFC catalytic properties of Pt - Ni nanoparticles prepared by a plasma-gas-condensation

    NASA Astrophysics Data System (ADS)

    Umezawa, Michihisa; Ishikawa, Ryoichi; Miyazaki, Reona; Hihara, Takehiko

    2017-01-01

    Pt - Ni nanoparticles were fabricated via the gas phase method. Their performance as anode catalysts for the proton exchange membrane fuel cell was investigated as a function of Ni concentration. The microscopic configurations of the nanoparticles were rather heterogeneous; Pt-rich alloys existed in the core region of particles while a part of the surface layer was composed of the Ni-rich layer. Despite the Ni-rich layer in the shell region, the anode catalyst performance of the Pt - Ni nanoparticles was never deteriorated compared with that of the Pt ones. When the anode catalyst was composed of the Pt nanoparticles, a maximum power density of 112 mW/cm2 was obtained. However, 90% of the power density was still kept even when 40 at. % of Pt was replaced with Ni. The results suggest that a further decrease of Pt composition with maintaining its catalyst performance can be feasible by effective particle dispersing.

  15. Investigation of microstructure, electrical and photoluminescence behaviour of Ni-doped Zn0.96Mn0.04O nanoparticles: Effect of Ni concentration

    NASA Astrophysics Data System (ADS)

    Rajakarthikeyan, R. K.; Muthukumaran, S.

    2017-07-01

    ZnO, Zn0.96Mn0.04O and Ni-doped Zn0.96Mn0.04O nanoparticles with different Ni concentrations (0%, 2% and 4%) have been synthesized successfully by sol-gel method. The effects of Ni doping on the structural and optical properties were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and photoluminescence (PL) spectroscopy. The XRD pattern confirmed the existence of single phase wurtzite-like hexagonal structure throughout the Ni concentrations without any additional phases. The substitution of Ni created the lattice distortion due to the disparity of ionic radius between Zn and Ni which reduced the crystallite size. The microscopic images showed that the size of ZnO nanoparticles reduced by Ni-doping while the shape remains almost spherical/hexagonal type. The electrical conductivity found to be maximum at Ni = 2% due to the availability of more charge carriers generated by Ni. The decrease of electrical conductivity at higher doping (Ni = 4%) is due to the fact that the generation of more defects. The enhanced band gap from 3.73 eV (Ni = 0%) to 3.79 eV (Ni = 4%) by the addition of Ni explained by Burstein-Moss effect. The change in infra-red (IR) intensity and full width at half maximum (FWHM) corresponding to the frequency around defect states were caused by the difference in the bond lengths that occurs when Ni ion replaces Zn ion. The observed blue band emission from 474 nm to 481 nm is due to a radiative transition of an electron from the deep donar level of Zni to an acceptor level of neutral VZn and the origin of green band may be due to oxygen vacancies and intrinsic defects. The tuning of the band gap and the visible emission bands by Ni doping concluded that Ni-doped Zn0.96Mn0.04O is suitable for various nano-photo-electronics applications.

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  17. High-rate oxygen evolution reaction on Al-doped LiNiO2.

    PubMed

    Gupta, Asha; Chemelewski, William D; Buddie Mullins, C; Goodenough, John B

    2015-10-21

    LiNi0.8 Al0.2 O2 with a higher Ni(3+) /Li(+) ordering, synthesized by the solution-combustion method, gives oxygen-evolution-reaction (OER) activity in alkaline solution that is comparable to that of IrO2 . This confirms that the octahedral-site Ni(IV) /Ni(III) couple in an oxide is an active redox center for the OER with -redox energy pinned at the top of the O-2p bands.

  18. Coherent nuclear resonant scattering by {sup 61}Ni using the nuclear lighthouse effect

    SciTech Connect

    Roth, T.; Leupold, O.; Wille, H.-C.; Rueffer, R.; Quast, K.W.; Burkel, E.; Roehlsberger, R.

    2005-04-01

    We have observed coherent nuclear resonant scattering of synchrotron radiation from the 67.41-keV level of {sup 61}Ni. The time evolution of the forward scattering signal was recorded by employing the nuclear lighthouse effect. This method is used to investigate Moessbauer isotopes in a coherent scattering process with synchrotron radiation at high transition energies. The decay of the excited ensemble of nuclei in Ni metal shows quantum beats that allowed the determination of the magnetic hyperfine field at the {sup 61}Ni nucleus. Moreover, we determined the lifetime of the 67.41-keV level of {sup 61}Ni to be 7.4(1) ns.

  19. Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.

    PubMed

    Wang, Wendong; Song, Shan; Zhang, Xiaoni; Mitchell Spear, J; Wang, Xiaochang; Wang, Wen; Ding, Zhenzhen; Qiao, Zixia

    2014-07-01

    Observations of aluminum containing sediments/scales formed within the distribution pipes have been reported for several decades. In this study, the effect of Ni(2+) on the formation and transformation processes of aluminum hydroxide sediment in a simulated drinking water distribution system were investigated using X-ray diffraction spectrum (XRD), Fourier transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and thermodynamic calculation methods. It was determined that the existence of Ni(2+) had notable effects on the formation of bayerite. In the system without Ni(2+) addition, there was no X-ray diffraction signal observed after 400 d of aging. The presence of Ni(2+), however, even when present in small amounts (Ni/Al=1:100) the formation of bayerite would occur in as little as 3d at pH 8.5. As the molar ratio of Ni/Al increase from 1:100 to 1:10, the amount of bayerite formed on the pipeline increased further; meanwhile, the specific area of the pipe scale decreased from 160 to 122 m(2)g(-1). In the system with Ni/Al molar ratio at 1:3, the diffraction spectrum strength of bayerite became weaker, and disappeared when Ni/Al molar ratios increased above 1:1. At these highs Ni/Al molar ratios, Ni5Al4O11⋅18H2O was determined to be the major component of the pipe scale. Further study indicated that the presence of Ni(2+) promoted the formation of bayerite and Ni5Al4O11⋅18H2O under basic conditions. At lower pH (6.5) however, the existence of Ni(2+) had little effect on the formation of bayerite and Ni5Al4O11⋅18H2O, rather the adsorption of amorphous Al(OH)3 for Ni(2+) promoted the formation of crystal Ni(OH)2.

  20. Accessing Ni(III)-thiolate versus Ni(II)-thiyl bonding in a family of Ni-N2S2 synthetic models of NiSOD.

    PubMed

    Broering, Ellen P; Dillon, Stephanie; Gale, Eric M; Steiner, Ramsey A; Telser, Joshua; Brunold, Thomas C; Harrop, Todd C

    2015-04-20

    Superoxide dismutase (SOD) catalyzes the disproportionation of superoxide (O2(• -)) into H2O2 and O2(g) by toggling through different oxidation states of a first-row transition metal ion at its active site. Ni-containing SODs (NiSODs) are a distinct class of this family of metalloenzymes due to the unusual coordination sphere that is comprised of mixed N/S-ligands from peptide-N and cysteine-S donor atoms. A central goal of our research is to understand the factors that govern reactive oxygen species (ROS) stability of the Ni-S(Cys) bond in NiSOD utilizing a synthetic model approach. In light of the reactivity of metal-coordinated thiolates to ROS, several hypotheses have been proffered and include the coordination of His1-Nδ to the Ni(II) and Ni(III) forms of NiSOD, as well as hydrogen bonding or full protonation of a coordinated S(Cys). In this work, we present NiSOD analogues of the general formula [Ni(N2S)(SR')](-), providing a variable location (SR' = aryl thiolate) in the N2S2 basal plane coordination sphere where we have introduced o-amino and/or electron-withdrawing groups to intercept an oxidized Ni species. The synthesis, structure, and properties of the NiSOD model complexes (Et4N)[Ni(nmp)(SPh-o-NH2)] (2), (Et4N)[Ni(nmp)(SPh-o-NH2-p-CF3)] (3), (Et4N)[Ni(nmp)(SPh-p-NH2)] (4), and (Et4N)[Ni(nmp)(SPh-p-CF3)] (5) (nmp(2-) = dianion of N-(2-mercaptoethyl)picolinamide) are reported. NiSOD model complexes with amino groups positioned ortho to the aryl-S in SR' (2 and 3) afford oxidized species (2(ox) and 3(ox)) that are best described as a resonance hybrid between Ni(III)-SR and Ni(II)-(•)SR based on ultraviolet-visible (UV-vis), magnetic circular dichroism (MCD), and electron paramagnetic resonance (EPR) spectroscopies, as well as density functional theory (DFT) calculations. The results presented here, demonstrating the high percentage of S(3p) character in the highest occupied molecular orbital (HOMO) of the four-coordinate reduced form of NiSOD (Ni

  1. Ferrodistorsive orbital ordering in the layered nickelate NaNiO2: A density-functional study

    NASA Astrophysics Data System (ADS)

    Meskine, H.; Satpathy, S.

    2005-05-01

    The electronic structure and magnetism in the sodium nickelate NaNiO2 in the low-temperature phase is studied from density-functional calculations using the linear muffin-tin orbitals method. An antiferromagnetic solution with a magnetic moment of 0.7μB per Ni ion is found. A ferrodistorsive orbital ordering is shown to occur due to the Jahn-Teller distortion around the Ni+3 ion in agreement with the orbital ordering inferred from neutron diffraction. While the intralayer exchange is ferromagnetic, the interlayer exchange is weakly antiferromagnetic, mediated by a long Ni-O-Na-O-Ni superexchange path.

  2. The impact of NiO on microstructure and electrical property of solid oxide fuel cell anode

    PubMed Central

    Li, Yan; Luo, Zhong-yang; Yu, Chun-jiang; Luo, Dan; Xu, Zhu-an; Cen, Ke-fa

    2005-01-01

    Ni-Ce0.8Sm0.2O1.9 (Ni-SDC) cermet was selected as anode material for reduced temperature (800 °C) solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.8Sm0.2O1.9 (SDC), and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect of microstructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3·2Ni(OH)2·4H2O or Ni(NO3)2·6H2O decomposition technique. PMID:16252348

  3. NiO/SiC nanocomposite prepared by atomic layer deposition used as a novel electrocatalyst for nonenzymatic glucose sensing.

    PubMed

    Yang, Peng; Tong, Xili; Wang, Guizhen; Gao, Zhe; Guo, Xiangyun; Qin, Yong

    2015-03-04

    NiO nanoparticles are deposited onto SiC particles by atomic layer deposition (ALD). The structure of the NiO/SiC hybrid material is investigated by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The size of the NiO nanoparticles is flexible and can be adjusted by altering the cycle number of the NiO ALD. Electrochemical measurements illustrate that NiO/SiC prepared with 600 cycles for NiO ALD exhibits the highest glucose sensing ability in alkaline electrolytes with a low detection limit of 0.32 μM (S/N = 3), high sensitivity of 2.037 mA mM(-1) cm(-2), a linear detection range from approximately 4 μM to 7.5 mM, and good stability. Its sensitivity is about 6 times of that for commercial NiO nanoparticles and NiO/SiC nanocomposites prepared by a traditional incipient wetness impregnation method. It is revealed that the superior electrochemical ability of ALD NiO/SiC is ascribed to the strong interaction between NiO and the SiC substrate and the high dispersity of NiO nanoparticles on the SiC surface. These results suggest that ALD is an effective way to deposit NiO on SiC for nonenzymatic glucose sensing.

  4. The impact of NiO on microstructure and electrical property of solid oxide fuel cell anode.

    PubMed

    Li, Yan; Luo, Zhong-yang; Yu, Chun-jiang; Luo, Dan; Xu, Zhu-an; Cen, Ke-fa

    2005-11-01

    Ni-Ce(0.8)Sm(0.2)O(1.9) (Ni-SDC) cermet was selected as anode material for reduced temperature (800 degrees C) solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce(0.8)Sm(0.2)O(1.9) (SDC), and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect of microstructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO(3).2Ni(OH)(2).4H(2)O or Ni(NO(3))(2).6H(2)O decomposition technique.

  5. Structure, chemical ordering and thermal stability of Pt-Ni alloy nanoclusters.

    PubMed

    Cheng, Daojian; Yuan, Shuai; Ferrando, Riccardo

    2013-09-04

    Equilibrium structures, chemical ordering and thermal properties of Pt-Ni nanoalloys are investigated by using basin hopping-based global optimization, Monte Carlo (MC) and molecular dynamics (MD) methods, based on the second-moment approximation of the tight-binding potentials (TB-SMA). The TB-SMA potential parameters for Pt-Ni nanoalloys are fitted to reproduce the results of density functional theory calculations for small clusters. The chemical ordering in cuboctahedral (CO) Pt-Ni nanoalloys with 561 and 923 atoms is obtained from the so called semi-grand-canonical ensemble MC simulation at 100 K. Two ordered phases of L12 (PtNi3) and L10 (PtNi) are found for the CO561 and CO923 Pt-Ni nanoalloys, which is in good agreement with the experimental phase diagram of the Pt-Ni bulk alloy. In addition, the order-disorder transition and thermal properties of these nanoalloys are studied by using MC and MD methods, respectively. It is shown that the typical perfect L10 PtNi structure is relatively stable, showing high order-disorder transition temperature and melting point among these CO561 and CO923 Pt-Ni nanoalloys.

  6. Comparative investigation of NiO nano- and microstructures for structural, optical and magnetic properties

    NASA Astrophysics Data System (ADS)

    Manikandan, A.; Judith Vijaya, J.; John Kennedy, L.

    2013-03-01

    Nickel oxide (NiO) nano- and microstructures were synthesized by the microwave combustion method (MCM) and the conventional combustion method (CCM) using urea as the fuel. The as-synthesized NiO powders were characterized by X-ray powder diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM) analysis. The XRD results confirmed the formation of cubic phase NiO. The formation of NiO nano- and microstructures were confirmed by HR-SEM and HR-TEM and their possible formation mechanisms were also proposed. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra respectively. The band gap was measured using the Kubelka-Munk model and it shows 3.36 eV for NiO (MCM) and 2.70 eV for NiO (CCM). The magnetic properties of the synthesized NiO nano- and microstructures were investigated with a vibrating sample magnetometer (VSM) and their hysteresis loops were obtained at room temperature. The relatively high saturation magnetization (21.22 emu/g) of NiO-MCM shows that it is ferromagnetic and low saturation magnetization (7.43 emu/g) of NiO-CCM confirms the superparamagnetic behavior.

  7. Enhancing the Thermal and Upper Voltage Performance of Ni-Rich Cathode Material by a Homogeneous and Facile Coating Method: Spray-Drying Coating with Nano-Al2O3.

    PubMed

    Du, Ke; Xie, Hongbin; Hu, Guorong; Peng, Zhongdong; Cao, Yanbing; Yu, Fan

    2016-07-13

    The electrochemical performance of Ni-rich cathode material at high temperature (>50 °C) and upper voltage operation (>4.3 V) is a challenge for next-generation lithium-ion batteries (LIBs) because of the rapid capacity degradation over cycling. Here we report improved performance of LiNi0.8Co0.15Al0.05O2 materials via a LiAlO2 coating, which was prepared from a Ni0.80Co0.15Al0.05(OH)2 precursor by spray-drying coating with nano-Al2O3. Investigations by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and transmission electron microscopy revealed that an Al2O3 layer is uniformly distributed on the precursor and a LiAlO2 layer on the as-prepared cathode material. Such a coating shell acts as a scavenger to protect the cathode material from attack by HF and serious side reactions, which remarkably enhances the cycle performance at 55 °C and upper operating voltage (4.4 and 4.5 V). In particular, the sample with a 2% Al2O3 coating shows capacity retentions of 90.40%, 85.14%, 87.85%, and 81.1% after 150 cycles at a rate of 1.0C at room temperature, 55 °C, 4.4 V, and 4.5 V, respectively, which are significantly higher than those of the pristine one. This is mainly due to the significant improvement of the structural stability led by the effective coating technique, which could be extended to other cathode materials to obtain LIBs with enhanced safety and excellent cycling stability.

  8. Effect of a Ti capping layer on thermal stability of NiSi formed from Ni thin films deposited by metal-organic chemical vapor deposition using a Ni(iPr-DAD)2 precursor

    NASA Astrophysics Data System (ADS)

    Park, Jingyu; Jeon, Heeyoung; Kim, Hyunjung; Jang, Woochool; Kang, Chunho; Yuh, Junhan; Jeon, Hyeongtag

    2015-02-01

    Ni films were deposited by metal-organic chemical vapor deposition (MOCVD) using a novel Ni precursor, bis(1,4-di-isopropyl-1,3-diazabutadienyl)nickel [Ni(iPr-DAD)2], and NH3 gas. To optimize process conditions, the deposition temperature and reactant partial pressure were varied from 200 to 350 °C and from 0.2 to 0.99 Torr, respectively. Ni films deposited at 300 °C with a reactant pressure of 0.8 Torr exhibited excellent quality, and had a low carbon impurity concentration of around 4%. In addition, a sacrificial Ti capping layer was deposited by an in situ e-beam evaporator on top of the Ni films to enhance the thermal stability of the subsequently formed NiSi films. Both the Ti-capped and uncapped Ni films were annealed by a two-step method, with a first annealing conducted at 500 °C, followed by wet etching and then a second annealing carried out from 500 to 900 °C. The Ti capping layer did not affect the silicidation kinetic process, but by acting as an oxygen scavenger, it did enhance the morphological stability of the NiSi films and thus improve their electrical properties.

  9. Poly(o-phenylenediamine)/NiCoFe2O4 nanocomposites: Synthesis, characterization, magnetic and dielectric properties

    NASA Astrophysics Data System (ADS)

    Kannapiran, Nagarajan; Muthusamy, Athianna; Chitra, Palanisamy; Anand, Siddeswaran; Jayaprakash, Rajan

    2017-02-01

    In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe2O4 nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe2O4 nanoparticles. The NiCoFe2O4 nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe2O4 nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe2O4 nanocomposites. The average crystalline size of NiCoFe2O4 nanoparticles and PoPD/NiCoFe2O4 nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe2O4 nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe2O4 nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz.

  10. Modified Ni-Cu catalysts for ethanol steam reforming

    NASA Astrophysics Data System (ADS)

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-01

    Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N2 adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  11. Modified Ni-Cu catalysts for ethanol steam reforming

    SciTech Connect

    Dan, M.; Mihet, M.; Almasan, V.; Borodi, G.; Katona, G.; Muresan, L.; Lazar, M. D.

    2013-11-13

    Three Ni-Cu catalysts, having different Cu content, supported on γ-alumina were synthesized by wet co-impregnation method, characterized and tested in the ethanol steam reforming (ESR) reaction. The catalysts were characterized for determination of: total surface area and porosity (N{sub 2} adsorption - desorption using BET and Dollimer Heal methods), Ni surface area (hydrogen chemisorption), crystallinity and Ni crystallites size (X-Ray Diffraction), type of catalytic active centers (Hydrogen Temperature Programmed Reduction). Total surface area and Ni crystallites size are not significantly influenced by the addition of Cu, while Ni surface area is drastically diminished by increasing of Cu concentration. Steam reforming experiments were performed at atmospheric pressure, temperature range 150-350°C, and ethanol - water molar ration of 1 at 30, using Ar as carrier gas. Ethanol conversion and hydrogen production increase by the addition of Cu. At 350°C there is a direct connection between hydrogen production and Cu concentration. Catalysts deactivation in 24h time on stream was studied by Transmission Electron Microscopy (TEM) and temperature-programmed reduction (TPR) on used catalysts. Coke deposition was observed at all studied temperatures; at 150°C amorphous carbon was evidenced, while at 350°C crystalline, filamentous carbon is formed.

  12. Hierarchical NiCo2S4@NiFe LDH Heterostructures Supported on Nickel Foam for Enhanced Overall-Water-Splitting Activity.

    PubMed

    Liu, Jia; Wang, Jinsong; Zhang, Bao; Ruan, Yunjun; Lv, Lin; Ji, Xiao; Xu, Kui; Miao, Ling; Jiang, Jianjun

    2017-05-10

    Low-cost and highly efficient bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are intensively investigated for overall water splitting. Herein, we combined experimental research with first-principles calculations based on density functional theory (DFT) to engineer the NiCo2S4@NiFe LDH heterostructure interface for enhancing overall water-splitting activity. The DFT calculations exhibit strong interaction and charge transfer between NiCo2S4 and NiFe LDH, which change the interfacial electronic structure and surface reactivity. The calculated chemisorption free energy of hydroxide (ΔEOH) is reduced from 1.56 eV for pure NiFe LDH to 1.03 eV for the heterostructures, indicating a dramatic improvement in OER performance, while the chemisorption free energy of hydrogen (ΔEH) maintains almost invariable. By the use of the facile hydrothermal method, NiCo2S4 nanotubes, NiFe LDH nanosheets, and NiCo2S4@NiFe LDH heterostructures are prepared on nickel foam, of which the corresponding experimental OER overpotentials are 306, 260, and 201 mV at 60 mA cm(-2), respectively. These results are good agreement with the theoretical predictions. Meanwhile, the HER performance has little improvement, with an overpotential of about 200 mV at 10 mA cm(-2). Due to the dramatic improvement in OER performance, there was an enhancement in the overall water-splitting activity of the NiCo2S4@NiFe LDH heterostructures, with a low voltage of 1.6 V.

  13. Mechanical properties of NiTi and CuNiTi wires used in orthodontic treatment. Part 2: Microscopic surface appraisal and metallurgical characteristics

    PubMed Central

    Gravina, Marco Abdo; Canavarro, Cristiane; Elias, Carlos Nelson; Chaves, Maria das Graças Afonso Miranda; Brunharo, Ione Helena Vieira Portella; Quintão, Cátia Cardoso Abdo

    2014-01-01

    Objective This research aimed at comparing the qualitative chemical compositions and the surface morphology of fracture regions of eight types of Nickel (Ni) Titanium (Ti) conventional wires, superelastic and heat-activated (GAC, TP, Ormco, Masel, Morelli and Unitek), to the wires with addition of copper (CuNiTi 27ºC and 35ºC, Ormco) after traction test. Methods The analyses were performed in a scanning electronic microscope (JEOL, model JSM-5800 LV) with EDS system of microanalysis (energy dispersive spectroscopy). Results The results showed that NiTi wires presented Ni and Ti as the main elements of the alloy with minimum differences in their composition. The CuNiTi wires, however, presented Ni and Ti with a significant percentage of copper (Cu). As for surface morphology, the wires that presented the lowest wire-surface roughness were the superelastic ones by Masel and Morelli, while those that presented the greatest wire-surface roughness were the CuNiTi 27ºC and 35ºC ones by Ormco, due to presence of microcavity formed as a result of pulling out some particles, possibly of NiTi.4 The fracture surfaces presented characteristics of ductile fracture, with presence of microcavities. The superelastic wires by GAC and the CuNiTi 27ºC and the heat-activated ones by Unitek presented the smallest microcavities and the lowest wire-surface roughness with regard to fracture, while the CuNiTi 35ºC wires presented inadequate wire-surface roughness in the fracture region. Conclusion CuNiTi 35ºC wires did not present better morphologic characteristics in comparison to the other wires with regard to surfaces and fracture region. PMID:24713562

  14. Dehydrogenation properties and mechanisms of MgH2-NiCl2 and MgH2-NiCl2-graphene hydrogen storage composites

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Qu, H.; Yan, S.; Yin, L. R.; Zhou, D. W.

    2017-07-01

    The four hydrogen storage systems including pure MgH2, MgH2-5 wt%NiCl2, MgH2-10 wt%NiCl2 and MgH2-10 wt%NiCl2-10 wt%graphene were prepared by ball-milling in this work. Using experimental X-ray diffraction, scanning electron microscopy and differential scanning calorimetry testing methods in combination with first-principle calculations, the dehydrogenation properties and mechanisms of NiCl2 single-doped and NiCl2-graphene co-doped MgH2 composites were systematically investigated. Experimental results show that the NiCl2 single-doping is conductive to decreasing the size of MgH2 grains and particles. The co-doping of NiCl2 and graphene not only reduces the size of MgH2 grains and particles, but also contributes to the uniformity of MgH2 particles. As compared with milled pure MgH2, the dehydrogenation peak temperatures are decreased by 24 °C and 47 °C for the 10 wt%NiCl2 single-doped and 10 wt%NiCl2-10 wt%graphene co-doped MgH2 systems, respectively. It is demonstrated that the co-doping of NiCl2 and graphene exhibits the synergistic effects of confinement and catalysis on improving the dehydrogenation properties of MgH2. The first-principle calculations indicate that the co-doping of NiCl2 and graphene leads to the distortion of MgH2 atomic-configuration and results in the charge transfer between the dopants and MgH2, which induce the weakened structural stability and decreased dehydrogenation enthalpy of MgH2.

  15. Static atomic displacements in Ni-rich Ni-Al

    NASA Astrophysics Data System (ADS)

    Schönfeld, B.; Kostorz, G.; Celino, M.; Rosato, V.

    2001-05-01

    Short-range order and static atomic displacement parameters, previously determined from diffuse neutron scattering for Ni-8.9 at.% Al equilibrated at 775 K and quenched to room temperature, were used to study lattice relaxation effects in molecular-dynamics simulations. An occupation of average lattice sites with Ni and Al atoms compatible with the short-range ordered state was taken as the starting situation. Displacement parameters obtained from the relaxation simulations and from diffuse neutron scattering show general similarity in magnitude and dependence on distance. Also, the species dependence of the displacement parameters known from diffuse X-ray scattering investigations is reproduced in magnitude.

  16. Fabrication and characterization of a diluted magnetic semiconducting TM co-doped Al:ZnO (TM=Co, Ni) thin films by sol-gel spin coating method.

    PubMed

    Siddheswaran, R; Mangalaraja, R V; Tijerina, Eduardo P; Menchaca, J-Luis; Meléndrez, M F; Avila, Ricardo E; Jeyanthi, C Esther; Gomez, M E

    2013-04-01

    Effect of transition metal oxides (TM=Co and Ni) co-doping on the crystallinity, surface morphology, grain growth and magnetic properties of nanostructure Al:ZnO thin films has been studied for diluted magnetic semiconductor applications. Al:ZnO thin films were fabricated by sol-gel spin coating on p-type Si (100) substrates. Fabrication of hexagonal wurtzite TM co-doped Al:ZnO thin films having thickness 2μm was successfully achieved. The Raman spectra of the TM co-doped Al:ZnO thin films showed a broad vibrational mode in the range 520-540cm(-1) due to crystal defects created co-doping elements in the ZnO host lattice. Scanning electron microscopy (SEM) revealed that the films are composed of uniform size, polycrystalline dense ZnO particles with defect free, smooth surfaces. The surface roughness was further verified with atomic force microscopy (AFM). The energy dispersive X-ray spectroscopic analysis (EDX) confirmed the stoichiometric compositions of the TM co-doped Al:ZnO films. The magnetic measurements exhibited that the Co, Al:ZnO and Ni, Al:ZnO thin films were ferromagnetic at room temperature.

  17. Active Pt3Ni (111) Surface of Pt3Ni Icosahedron for Oxygen Reduction.

    PubMed

    Zhu, Jianbing; Xiao, Meiling; Li, Kui; Liu, Changpeng; Zhao, Xiao; Xing, Wei

    2016-11-09

    Highly active, durable oxygen reduction reaction (ORR) electrocatalysts are extremely important for fuel cell applications. Herein, we provide an efficient way to synthesis of activity Pt3M icosahedra by the one-pot hydrothermal method in the presence of glucosamine which can well adjust the reduction rate of Pt(4+) and efficiently control the morphology of final catalysts. Compared to Pt/C, the Pt3Ni icosahedra show 32-fold and 12-fold enhancement in specific and mass activity, respectively. Furthermore, robust durability was also observed in the accelerated durability test. Thus, this Pt3Ni icosahedron is found among the best Pt-based ORR catalysts, moreover, the findings also demonstrate how to mimic active extended surfaces in nanoscale.

  18. Molecular dynamics simulation of graphene growth at initial stage on Ni(100) facet for low flux C energy by CVD

    NASA Astrophysics Data System (ADS)

    Syuhada, Ibnu; Rosikhin, Ahmad; Fikri, Aulia; Noor, Fatimah A.; Winata, Toto

    2016-02-01

    In this study, atomic simulation for graphene growth on Ni (100) at initial stage via chemical vapor deposition method has been developed. The C-C atoms interaction was performed by Terasoff potential mean while Ni-Ni interaction was specified by EAM (Embedded Atom Modified). On the other hand, we used very simple interatomic potential to describe Ni-C interaction during deposition process. From this simulation, it shows that the formation of graphene is not occurs through a combined deposition mechanism on Ni substrate but via C segregation. It means, Ni-C amorphous is source for graphene growth when cooling down of Ni substrate. This result is appropriate with experiments, tight binding and quantum mechanics simulation.

  19. Molecular dynamics simulation of graphene growth at initial stage on Ni(100) facet for low flux C energy by CVD

    SciTech Connect

    Syuhada, Ibnu Rosikhin, Ahmad Fikri, Aulia Noor, Fatimah A. Winata, Toto

    2016-02-08

    In this study, atomic simulation for graphene growth on Ni (100) at initial stage via chemical vapor deposition method has been developed. The C-C atoms interaction was performed by Terasoff potential mean while Ni-Ni interaction was specified by EAM (Embedded Atom Modified). On the other hand, we used very simple interatomic potential to describe Ni-C interaction during deposition process. From this simulation, it shows that the formation of graphene is not occurs through a combined deposition mechanism on Ni substrate but via C segregation. It means, Ni-C amorphous is source for graphene growth when cooling down of Ni substrate. This result is appropriate with experiments, tight binding and quantum mechanics simulation.

  20. NiCo2S4@Co(OH)2 core-shell nanotube arrays in situ grown on Ni foam for high performances asymmetric supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Rui; Wang, Senlin; Huang, Zongchuan; Lu, Fengxia; He, Taobin

    2016-04-01

    In this paper, hierarchical NiCo2S4@Co(OH)2 nanotube arrays supported on Ni foam have been synthesised though a facile and commendable method. The smart combination of NiCo2S4 nanotubes and Co(OH)2 nanosheets exhibits brilliant synergistic effect for supercapacitors with significantly enhanced performances. The NiCo2S4@Co(OH)2 electrode shows a relatively high area capacitance of 9.6 F cm-2 at 2 mA cm-2 (almost 2 times as high as that of bare NiCo2S4 electrode), even at 32 mA cm-2, the area capacitance is maintained at 6.4 F cm-2. Moreover, an asymmetric supercapacitor is successfully assembled by using NiCo2S4@Co(OH)2 nanotubes as the positive electrode and active carbon (AC) as the negative electrode. The NiCo2S4@Co(OH)2//AC device achieves a relatively high energy density of 35.89 Wh kg-1 at a power density of 0.4 kW kg-1 with excellent cycling performance(70.01% capacitance retention over 5000 cycles). Such unique NiCo2S4@Co(OH)2 nanotube arrays not only demonstrate promising applications in energy storage but also remind researchers of the unlimited potential of heterostructured materials.

  1. Magnetic properties and electronic structure of Mn-Ni-Ga magnetic shape memory alloys.

    PubMed

    D'Souza, Sunil Wilfred; Roy, Tufan; Barman, Sudipta Roy; Chakrabarti, Aparna

    2014-12-17

    Influence of disorder, antisite defects, martensite transition and compositional variation on the magnetic properties and electronic structure of Mn(2)NiGa and Mn(1+x)Ni(2-x)Ga magnetic shape memory alloys have been studied by using full potential spin-polarized scalar relativistic Korringa-Kohn-Rostocker (FP-SPRKKR) method. Mn(2)NiGa is ferrimagnetic and its total spin moment increases when disorder in the occupancy of MnNi (Mn atom in Ni position) is considered. The moment further increases when Mn-Ga antisite defect [1] is included in the calculation. A reasonable estimate of TC for Mn(2)NiGa is obtained from the exchange parameters for the disordered structure. Disorder influences the electronic structure of Mn(2)NiGa through overall broadening of the density of states and a decrease in the exchange splitting. Inclusion of antisite defects marginally broaden the minority spin partial DOS (PDOS), while the majority spin PDOS is hardly affected. For Mn(1+x)Ni(2-x)Ga where 1 ⩾ x ⩾ 0, as x decreases, Mn(Mn) moment increases while Mn(Ni) moment decreases in both austenite and martensite phases. For x ⩾ 0.25, the total moment of the martensite phase is smaller compared to the austenite phase, which indicates possible occurrence of inverse magnetocaloric effect. We find that the redistribution of Ni 3d- Mn(Ni) 3d minority spin electron states close to the Fermi level is primarily responsible for the stability of the martensite phase in Mn-Ni-Ga.

  2. The effect of heating rate on the surface chemistry of NiTi.

    PubMed

    Undisz, Andreas; Hanke, Robert; Freiberg, Katharina E; Hoffmann, Volker; Rettenmayr, Markus

    2014-11-01

    The impact of the heating rate on the Ni content at the surface of the oxide layer of biomedical NiTi is explored. Heat treatment emulating common shape-setting procedures was performed by means of conventional and inductive heating for similar annealing time and temperature, applying various heating rates from ~0.25 K s(-1) to 250 K s(-1). A glow discharge optical emission spectroscopy method was established and employed to evaluate concentration profiles of Ni, Ti and O in the near-surface region at high resolution. The Ni content at the surface of the differently treated samples varies significantly, with maximum surface Ni concentrations of ~20 at.% at the lowest and ~1.5 at.% at the highest heating rate, i.e. the total amount of Ni contained in the surface region of the oxide layer decreases by >15 times. Consequently, the heating rate is a determinant for the biomedical characteristics of NiTi, especially since Ni available at the surface of the oxide layer may affect the hemocompatibility and be released promptly after surgical application of a respective implant. Furthermore, apparently contradictory results presented in the literature reporting surface Ni concentrations of ~3 at.% to >20 at.% after heat treatment are consistently explained considering the ascertained effect of the heating rate.

  3. Giant perpendicular magnetic anisotropy of an Ir monolayer on a NiAl(001) surface

    NASA Astrophysics Data System (ADS)

    Kim, Dongyoo; Yang, Jeonghwa; Hong, Jisang

    2009-08-01

    Using the state-of-the-art full potential linearized augmented plane-wave method, we have investigated the magnetic properties of Os and Ir monolayer (ML) film on NiAl(001) surface. It has been found that the one ML of Os and Ir film can have ferromagnetic ground state with magnetic moment of 0.35 and 0.64μB on Ni terminated surface, whereas both films display no sign of magnetic state on Al terminated surface. In addition, the surface Ni atom has an induced magnetic moment of 0.26μB in Ir/NiAl(001), while only 0.09μB is observed in Os/NiAl(001). We attribute the existence of magnetism to the interaction between 5d of adlayer and 3d of surface Ni. Moreover, we have obtained that the Os/NiAl(001) and Ir/NiAl(001) films show a perpendicular magnetic anisotropy (PMA). Surprisingly, it appears that the Ir/NiAl(001) has a giant PMA energy of 7.18 meV.

  4. Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

    SciTech Connect

    Dalavi, Shankar B.; Panda, Rabi N.; Raja, M. Manivel

    2015-06-24

    Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The result has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.

  5. Electrochemical and corrosion behaviors of sputtered TiNi shape memory films

    NASA Astrophysics Data System (ADS)

    Li, K.; Huang, X.; Zhao, Z. S.; Li, Y.; Fu, Y. Q.

    2016-03-01

    Electrochemical and corrosion behaviors of TiNi-based shape memory thin films were explored using electrochemical impedance spectroscopy (EIS) and polarization methods in phosphate buffered saline solutions at 37 °C. Compared with those of electro-polished and passivated bulk NiTi shape memory alloys, the break-down potentials of the sputter-deposited amorphous TiNi films were much higher. After crystallization, the break-down potentials of the TiNi films were comparable with that of the bulk NiTi shape memory alloy. Additionally, variation of composition of the TiNi films showed little influence on their corrosion behavior. The EIS data were fitted using a parallel resistance-capacitance circuit associated with passive oxide layer on the tested samples. The thickness of the oxide layer for the TiNi thin films was found much thinner than that of bulk NiTi shape memory alloy. During electrochemical testing, the oxide thickness of the bulk alloy reached its maximum at a voltage of 0.6-0.8 V, whereas those of TiNi films were increased continuously up to a voltage of 1.2 V.

  6. Preparation and electrocatalytic activity of nanocrystalline Ni-Mo-Co alloy electrode for hydrogen evolution.

    PubMed

    Xu, Lijian; Du, Jingjing; Chen, Baizhen

    2013-03-01

    Ni-Mo-Co alloy electrodes were prepared by electrodeposition technique with citric acid as a complexing agent. The influence of the main technical parameters such as the concentration of CoSO4 7H2O, the current density and the bath temperature on the component content in the Ni-Mo-Co alloy electrode were investigated by electron dispersive spectrometer (EDS), the microstructure and surface morphology of Ni-Mo-Co alloy electrodes were characterized by employing X-ray diffractometer (XRD) and scanning electron microscope (SEM), and the electrocatalytic activity of Ni-Mo-Co alloy electrode for hydrogen evolution was investigated by the method of the cathode polarization curves. The results showed that the excellent Ni-Mo-Co alloy electrode with 41.39 wt% Ni, 53.82 wt% Mo and 4.79 wt% Co was obtained when the concentration of CoSO4 x 7H2O was 8 g/L, the current density was 12 A/dm2 and the bath temperature was 25 degrees C. The mircostructure of the Ni-Mo-Co alloy was nanocrystalline and the average grain size was about 25 nm by calculating using Scherrer Equation. The electrocatalytic activity of Ni-Mo-Co alloy electrode for hydrogen evolution was better than that of Ni-Mo alloy electrode.

  7. Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

    NASA Astrophysics Data System (ADS)

    Dalavi, Shankar B.; Raja, M. Manivel; Panda, Rabi. N.

    2015-06-01

    Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The result has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.

  8. Enhanced field emission performance of NiMoO4 nanosheets by tuning the phase

    NASA Astrophysics Data System (ADS)

    Bankar, Prashant K.; Ratha, Satyajit; More, Mahendra A.; Late, Dattatray J.; Rout, Chandra Sekhar

    2017-10-01

    In this paper we report, large scale synthesis of α and β-NiMoO4 by a facile hydrothermal method and we observed that urea plays important role on the growth of β-NiMoO4 nanosheets. We have also carried out field emission (FE) investigations of α and β-NiMoO4 at a base pressure of ∼1 × 10-8 mbar. The obtained turn-on field at emission current density of 1 μA/cm2 for β-NiMoO4 nanosheets and α -NiMoO4 is 1.3 V/μm and 2.2 V/μm respectively were observed. The maximum field emission current density of 1.006 mA/cm2at an applied electric field of 2.7 V/μm was achieved for β-NiMoO4 nanosheets. Furthermore, we found that the β-NiMoO4 nanosheets possess good field emission performance compared to α-NiMoO4. The results indicate that NiMoO4can be used as a promising material in FE applications with possibility of tuning field emission performance by controlling the phase.

  9. Cohesive mechanism of the FeCr/Ni Interface: A first-principles study

    NASA Astrophysics Data System (ADS)

    Tan, Yong; Zheng, Haizhong; Li, Guifa; Xiong, Lingling; Peng, Ping

    2016-01-01

    Based on previous experimental results, a series of FeCr/Ni interface models have been constructed and analyzed using a first-principles pseudopotential plane-wave method. Several parameters, such as the ideal work of separation ( W), formation enthalpy (Δ H), cohesive energy (Δ E), and electronic structure were calculated in order to analyze the bonding performance and adhesion mechanisms of elements along an FeCr/Ni interface. The largest ideal work of separation was obtained for the Fe(100)/Ni(100) interface, which implies that this interface model presented the most stable structure among a series of crystal interface indices, e.g., (100), (110), and (111). With Cr doping, the W of the FeCr(100)/Ni(100) interface was increased by 101.571 mJ/m2. The corresponding ΔH and ΔE values also indicated that the FeCr(100)/Ni(100) interface model was strengthened by doping with chromium. Furthermore, the overlap population ratio, R LBOP ( R LBOP= 1.04), of FeCr(100)/Ni(100) was smaller than that of Fe(100)/Ni(100) ( R LBOP = 1.35), which implies that the toughness of the Fe(100)/Ni(100) interface can be improved by the presence of chromium impurities. Moreover, electronic structure analysis provided an understanding of the mechanical performance of the various Fe(Cr)/Ni interface models. Thus, our findings open a potential avenue for the comprehensive study of composite material designs.

  10. Straightforward prediction of the Ni1-x O layers stoichiometry by using optical and electrochemical measurements

    NASA Astrophysics Data System (ADS)

    Manceriu, Laura Maria; Colson, Pierre; Maho, Anthony; Eppe, Gauthier; Duy Nguyen, Ngoc; Labrugere, Christine; Rougier, Aline; Cloots, Rudi; Henrist, Catherine

    2017-06-01

    In this study, we propose a straightforward method for x determination in sub-stoichiometric nickel oxide (Ni1-x O) films prepared by ultrasonic spray pyrolysis on fluor-tin oxide (FTO) substrates by varying the post-deposition thermal treatment. The Ni3+ concentration, the flat band potential (Φfb) and the open circuit potential (V oc) were determined by electrochemical impedance analysis in aqueous media and correlated to the transmission of Ni1-x O films. An x-ray photoelectron spectroscopy study was also performed to quantify the amount of Ni3+ in the films and compare it with the one determined by electrochemical analysis. The electrochromic behavior of the Ni1-x O films in non-aqueous electrolyte was investigated as well. With increasing Ni3+ concentration the films became more brownish and more conductive, both V oc and Φfb values increased. Calibration curves of transmission at 550 nm or open circuit potential versus carrier concentration were plotted and allowed the prediction of x in an unknown Ni1-x O sample. The Ni1-x O films characterized by the highest Ni3+ concentration have a darker colored state but lower transmission modulation, due to their reduced specific surface and increased crystallinity.

  11. Room temperature ferromagnetism in nanocrystalline Ni-doped ZnO synthesized by co-precipitation

    NASA Astrophysics Data System (ADS)

    El-Hilo, M.; Dakhel, A. A.; Ali-Mohamed, A. Y.

    2009-07-01

    Ni-doped ZnO powder was synthesized by thermal co-decomposition of a mixture of bis(acetylacetonato) zinc(II)hydrate and bis(dimethylglyoximato)nickel(II) complexes. The samples were characterised by X-ray diffraction (XRD), Energy dispersion X-ray fluorescence (EDXRF), and FT-IR spectroscopy. The atomic ratio Ni/Zn of the samples was determined by the EDXRF method to be 1%, 4.3%, 7.4% and 22.5 wt%. The XRD studies show the formation of nanocrystalline (14-18 nm) of Ni-doped ZnO along with nanoparticles of NiO. By magnetic measurements, it was observed that powder contains 1%Ni, 4.3%Ni, 7.4%Ni exhibits superparamagnetic behaviour while the sample of 22.5%Ni prepared in closed atmospheric environment shows clear ferromagnetic (FM) loop at room temperature due to the formation of solid solution Zn 1-xNi xO.

  12. Shape coexistence in Ni68

    NASA Astrophysics Data System (ADS)

    Suchyta, S.; Liddick, S. N.; Tsunoda, Y.; Otsuka, T.; Bennett, M. B.; Chemey, A.; Honma, M.; Larson, N.; Prokop, C. J.; Quinn, S. J.; Shimizu, N.; Simon, A.; Spyrou, A.; Tripathi, V.; Utsuno, Y.; VonMoss, J. M.

    2014-02-01

    The internal-conversion and internal-pair-production decays of the first excited 0+ state in Ni68 are studied following the β decay of Co68. A novel experimental technique, in which the ions of Co68 were implanted into a planar germanium double-sided strip detector and which required digital pulse processing, is developed. The values for the energy of the first excited 0+ state and the electric monopole transition strength from the first excited 0+ state to the ground state in Ni68 are determined to be 1605(3) keV and 7.6(4)×10-3, respectively. Comparisons of the experimental results to Monte Carlo shell-model calculations suggest the coexistence between a spherical ground state and an oblate first excited 0+ state in Ni68.

  13. Hydrogen production via reforming of biogas over nanostructured Ni/Y catalyst: Effect of ultrasound irradiation and Ni-content on catalyst properties and performance

    SciTech Connect

    Sharifi, Mahdi; Haghighi, Mohammad; Abdollahifar, Mozaffar

    2014-12-15

    Highlights: • Synthesis of nanostructured Ni/Y catalyst by sonochemical and impregnation methods. • Enhancement of size distribution and active phase dispersion by employing sonochemical method. • Evaluation of biogas reforming over Ni/Y catalyst with different Ni-loadings. • Preparation of highly active and stable catalyst with low Ni content for biogas reforming. • Getting H{sub 2}/CO very close to equilibrium ratio by employing sonochemical method. - Abstract: The effect of ultrasound irradiation and various Ni-loadings on dispersion of active phase over zeolite Y were evaluated in biogas reforming for hydrogen production. X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray, Brunauer–Emmett–Teller, Fourier transform infrared analysis and TEM analysis were employed to observe the characteristics of nanostructured catalysts. The characterizations implied that utilization of ultrasound irradiation enhanced catalyst physicochemical properties including high dispersion of Ni on support, smallest particles size and high catalyst surface area. The reforming reactions were carried out at GHSV = 24 l/g.h, P = 1 atm, CH{sub 4}/CO{sub 2} = 1 and temperature range of 550–850 °C. Activity test displayed that ultrasound irradiated Ni(5 wt.%)/Y had the best performance and the activity remained stable during 600 min. Furthermore, the proposed reaction mechanism showed that there are three major reaction channels in biogas reforming.

  14. Thermal modeling of NiH2 batteries

    NASA Technical Reports Server (NTRS)

    Ponthus, Agnes-Marie; Alexandre, Alain

    1994-01-01

    The following are discussed: NiH2 battery mission and environment; NiH2 cell heat dissipation; Nodal software; model development general philosophy; NiH2 battery model development; and NiH2 experimental developments.

  15. One-Pot Solvothermal in Situ Growth of 1D Single-Crystalline NiSe on Ni Foil as Efficient and Stable Transparent Conductive Oxide Free Counter Electrodes for Dye-Sensitized Solar Cells.

    PubMed

    Bao, Chao; Li, Faxin; Wang, Jiali; Sun, Panpan; Huang, Niu; Sun, Yihua; Fang, Liang; Wang, Lei; Sun, Xiaohua

    2016-12-07

    One-dimensional single-crystal nanostructural nickel selenides were successfully in situ grown on metal nickel foils by two simple one-step solvothermal methods, which formed NiSe/Ni counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The nickel foil acted as the nickel source in the reaction process, a supporting substrate, and an electron transport "speedway". Electrochemical testing indicated that the top 1D single-crystal NiSe exhibited prominent electrocatalytic activity for I3(-) reduction. Due to the metallic conductivity of Ni substrate and the outstanding electrocatalytic activity of single-crystal NiSe, the DSSC based on a NiSe/Ni CE exhibited higher fill factor (FF) and larger short-circuit current density (Jsc) than the DSSC based on Pt/FTO CE. The corresponding power conversion efficiency (6.75%) outperformed that of the latter (6.18%). Moreover, the NiSe/Ni CEs also showed excellent electrochemical stability in the I(-)/I3(-) redox electrolyte. These findings indicated that single-crystal NiSe in situ grown on Ni substrate was a potential candidate to replace Pt/TCO as a cheap and highly efficient counter electrode of DSSC.

  16. Dominating Role of Ni(0) on the Interface of Ni/NiO for Enhanced Hydrogen Evolution Reaction.

    PubMed

    Wang, Jing; Mao, Shanjun; Liu, Zeyan; Wei, Zhongzhe; Wang, Haiyan; Chen, Yiqing; Wang, Yong

    2017-03-01

    The research of a robust catalytic system based on single NiOx electrocatalyst for hydrogen evolution reaction (HER) remains a huge challenge. Particularly, the factors that dominate the catalytic properties of NiOx-based hybrids for HER have not been clearly demonstrated. Herein, a convenient protocol for the fabrication of NiOx@bamboo-like carbon nanotube hybrids (NiOx@BCNTs) is designed. The hybrids exhibit superb catalytic ability and considerable durability in alkaline solution. A benchmark HER current density of 10 mA cm(-2) has been achieved at an overpotential of ∼79 mV. In combination with the experimental results and density functional theory (DFT) calculations, this for the first time definitely validates that the inherent high Ni(0) ratio and the Ni(0) on the interface of Ni/NiO play a vital role in the outstanding catalytic performance. Especially, the Ni(0) on the interface of Ni/NiO performs superior activity for water splitting compared with that of bulk Ni(0). These conclusions provide guidance for the rational design of the future non-noble metallic catalysts.

  17. Syntheses and structure of hydrothermally prepared CsNiX{sub 3} (X=Cl, Br, I)

    SciTech Connect

    Raw, Adam D.; Ibers, James A.; Poeppelmeier, Kenneth R.

    2012-08-15

    During reinvestigation of the hydrothermal synthesis reported earlier of the compound cesium nickel phosphide, 'CsNiP', we arrived at a new route to the synthesis of the cesium nickel halide compounds CsNiX{sub 3} (X=Cl, Br, I). The method has also been shown to extend to cobalt and iron compounds. Single crystals of these compounds were synthesized in phosphoric acid in sealed autoclaves. Their structures were determined by single-crystal X-ray diffraction methods. The compounds crystallize in the hexagonal space group P6{sub 3}/mmc in the BaNiO{sub 3} structure type. The synthetic method and the resultant crystallographic details for CsNiCl{sub 3} are essentially identical with those reported earlier for the synthesis and structure of 'CsNiP'. - Graphical abstract: The CsNiX{sub 3} (X=Cl, Br, I) structure. Cesium is blue, nickel is in dark green polyhedra, halide is brown. Highlights: Black-Right-Pointing-Pointer A hydrothermal approach to single crystal growth of cesium transition-metal halides. Black-Right-Pointing-Pointer Reexamination of 'CsNiP' to determine its composition as CsNiCl{sub 3}. Black-Right-Pointing-Pointer X-ray single-crystal structures of CsNiBr{sub 3} and CsNiI{sub 3}.

  18. NiCo2O4 nanostructure materials: morphology control and electrochemical energy storage.

    PubMed

    Zhang, Deyang; Yan, Hailong; Lu, Yang; Qiu, Kangwen; Wang, Chunlei; Zhang, Yihe; Liu, Xianming; Luo, Jingshan; Luo, Yongsong

    2014-11-14

    Three types of NiCo2O4 nanostructure, homogeneous NiCo2O4 nanoneedle arrays, heterogeneous NiCo2O4 nanoflake arrays and NiCo2O4 nanoneedle-assembled sisal-like microspheres are synthesized via facile solution methods in combination with thermal treatment. The NiCo2O4 nanoneedle arrays are evaluated as supercapacitor electrodes and demonstrate excellent electrochemical performances with a high specific capacitance (923 F g(-1) at 2 A g(-1)), good rate capability, and superior cycling stability. The superior capacitive performances are mainly due to the unique one dimensional porous nanoneedle architecture, which provides a faster ion/electron transfer rate, improved reactivity, and enhanced structural stability. The fabrication method presented here is facile, cost-effective and scalable, which may open a new pathway for real device applications.

  19. Controllable synthesis of layered Co-Ni hydroxide hierarchical structures for high-performance hybrid supercapacitors

    NASA Astrophysics Data System (ADS)

    Yuan, Peng; Zhang, Ning; Zhang, Dan; Liu, Tao; Chen, Limiao; Ma, Renzhi; Qiu, Guanzhou; Liu, Xiaohe

    2016-01-01

    A facile solvothermal method is developed for synthesizing layered Co-Ni hydroxide hierarchical structures by using hexamethylenetetramine (HMT) as alkaline reagent. The electrochemical measurements reveal that the specific capacitances of layered bimetallic (Co-Ni) hydroxides are generally superior to those of layered monometallic (Co, Ni) hydroxides. The as-prepared Co0.5Ni0.5 hydroxide hierarchical structures possesses the highest specific capacitance of 1767 F g-1 at a galvanic current density of 1 A g-1 and an outstanding specific capacitance retention of 87% after 1000 cycles. In comparison with the dispersed nanosheets of Co-Ni hydroxide, layered hydroxide hierarchical structures show much superior electrochemical performance. This study provides a promising method to construct hierarchical structures with controllable transition-metal compositions for enhancing the electrochemical performance in hybrid supercapacitors.

  20. Study of the Ni NiAl2O4 YSZ cermet for its possible application as an anode in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Reyes-Rojas, A.; Esparza-Ponce, H. E.; Reyes-Gasga, J.

    2006-05-01

    Nanocrystalline Ni-NiAl2O4-YSZ cermet with a possible application as anode in solid oxide fuel cells (SOFCs) has been developed. The powders were prepared by using an alternative solid-state method that includes the use of nickel acetylacetonate as an inorganic precursor to obtain a highly porous material after sintering at 1400 °C and oxide reduction ({\\mathrm {NiO\\mbox {--}Al_{2}O_{3}\\mbox {--}YSZ}} \\to {\\mathrm {Ni\\mbox {--}NiAl_{2}O_{4}\\mbox {--}YSZ}} ) at 800 °C for 8 h in a tubular reactor furnace using 10% H2/N2. Eight samples with 45% Ni and 55% Al2O3-YSZ in concentrations of Al2O3 oxides from 10 to 80 wt% of were mixed to obtain the cermets. The obtained material was compressed using unidirectional axial pressing and calcinations from room temperature to 800 °C. Good results were registered using a heating rate of 1 °C min-1 and a special ramp to avoid anode cracking. Thermal expansion, electrical conductivity, and structural characterization by thermo-mechanical analyser (TMA) techniques/methods, the four-point probe method for conductivity, scanning electron microscopy (SEM), x-ray energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and the Rietveld method were carried out. Cermets in the range 5.5 to 11% Al2O3 present a crystal size around 200 nm. An inversion degree (I) in the NiAl2O4 spinel structure of the cermets Ni-NiAl2O4-YSZ was found after the sintering and reduction processes. Good electrical conductivity and thermal expansion coefficient were obtained for the cermet with 12 wt% of spinel structure formation.

  1. The underlying biological mechanisms of biocompatibility differences between bare and TiN-coated NiTi alloys.

    PubMed

    Lifeng, Zhao; Yan, Hong; Dayun, Yang; Xiaoying, Lü; Tingfei, Xi; Deyuan, Zhang; Ying, Hong; Jinfeng, Yuan

    2011-04-01

    TiN coating has been demonstrated to improve the biocompatibility of bare NiTi alloys; however, essential biocompatibility differences between NiTi alloys before and after TiN coating are not known so far. In this study, to explore the underlying biological mechanisms of biocompatibility differences between them, the changes of bare and TiN-coated NiTi alloys in surface chemical composition, morphology, hydrophilicity, Ni ions release, cytotoxicity, apoptosis, and gene expression profiles were compared using energy-dispersive spectroscopy, scanning electron microscopy, contact angle, surface energy, Ni ions release analysis, the methylthiazoltetrazolium (MTT) method, flow cytometry and microarray methods, respectively. Pathways binding to networks and real-time polymerase chain reaction (PCR) were employed to analyze and validate the microarray data, respectively. It was found that, compared with the bare NiTi alloys, TiN coating significantly decreased Ni ions content on the surfaces of the NiTi alloys and reduced the release of Ni ions from the alloys, attenuated the inhibition of Ni ions to the expression of genes associated with anti-inflammatory, and also suppressed the promotion of Ni ions to the expression of apoptosis-related genes. Moreover, TiN coating distinctly improved the hydrophilicity and uniformity of the surfaces of the NiTi alloys, and contributed to the expression of genes participating in cell adhesion and other physiological activities. These results indicate that the TiN-coated NiTi alloys will help overcome the shortcomings of NiTi alloys used in clinical application currently, and can be expected to be a replacement of biomaterials for a medical device field.

  2. Comprehensive theoretical studies on the low-lying electronic states of NiF, NiCl, NiBr, and NiI.

    PubMed

    Zou, Wenli; Liu, Wenjian

    2006-04-21

    The low-lying electronic states of the nickel monohalides, i.e., NiF, NiCl, NiBr, and NiI, are investigated by using multireference second-order perturbation theory with relativistic effects taken into account. For the energetically lowest 11 lambda-S states and 26 omega states there into, the potential energy curves and corresponding spectroscopic constants (vertical and adiabatic excitation energies, equilibrium bond lengths, vibrational frequencies, and rotational constants) are reported. The calculated results are grossly in very good agreement with those solid experimental data. In particular, the ground state of NiI is shown to be different from those of NiF, NiCl, and NiBr, being in line with the recent experimental observation. Detailed analyses are provided on those states that either have not been assigned or have been incorrectly assigned by previous experiments.

  3. Coating Pt-Ni Octahedra with Ultrathin Pt Shells to Enhance the Durability without Compromising the Activity toward Oxygen Reduction.

    PubMed

    Park, Jinho; Liu, Jingyue; Peng, Hsin-Chieh; Figueroa-Cosme, Legna; Miao, Shu; Choi, Sang-Il; Bao, Shixiong; Yang, Xuan; Xia, Younan

    2016-08-23

    We describe a new strategy to enhance the catalytic durability of Pt-Ni octahedral nanocrystals in the oxygen reduction reaction (ORR) by conformally depositing an ultrathin Pt shell on the surface. The Pt-Ni octahedra were synthesized according to a protocol reported previously and then employed directly as seeds for the conformal deposition of ultrathin Pt shells by introducing a Pt precursor dropwise at 200 °C. The amount of Pt precursor was adjusted relative to the number of Pt-Ni octahedra involved to obtain Pt-Ni@Pt1.5L octahedra of 12 nm in edge length for the systematic evaluation of their chemical stability and catalytic durability compared to Pt-Ni octahedra. Specifically, we compared the elemental compositions of the octahedra before and after treatment with acetic and sulfuric acids. We also examined their electrocatalytic stability toward the ORR through an accelerated durability test by using a rotating disk electrode method. Even after treatment with sulfuric acid for 24 h, the Pt-Ni@Pt1.5L octahedra maintained their original Ni content, whereas 11 % of the Ni was lost from the Pt-Ni octahedra. After 10 000 cycles of ORR, the mass activity of the Pt-Ni octahedra decreased by 75 %, whereas the Pt-Ni@Pt1.5L octahedra only showed a 25 % reduction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. The Effects of El Niño on Precipitation in Southern California Climate Divisions: Year 2016 Precipitation Forecast.

    NASA Astrophysics Data System (ADS)

    Perez Cruz, L.; Idris, N.; El-Askary, H. M.

    2015-12-01

    Recently, it has been reported by the National Oceanic and Atmospheric Administration (NOAA) that there is very high chance not only for El Niño to continue through Northern Hemisphere winter 2015-16, but also a remarkable chance for El Niño to last into early spring 2016. This research aims at: 1) investigating the impact of El Niño on precipitation in the Southern California Climate Divisions: Climate Division 6 South Coast Drainage, and Division 7 South Coast Desert Basin. 2) Analyzing the precipitation of Southern California region using the Empirical Mode Decomposition Method (EMD). 3) Looking at the SOI components and compare it with the precipitation components of Southern California Climate Divisions. 4) Comparing precipitation data with Niño indices: Niño 1+2, Niño 3, Nino 3.4, and Niño 4. As results, we found a significant cross correlation of 0.7 between SOI component 10 and precipitation component 10 in Climate Division 6. Furthermore, among all the Niño indices, Niño 3 region displayed the best correlation. When we compared precipitation division 7 component 9 with Niño 3 component 10, a 0.95 cross correlation value was obtained. The lowest cross correlation value of (0.33) was obtained from Climate Division 6, precipitation component 7 with Niño 4 component 7.

  5. General solution growth of mesoporous NiCo2O4 nanosheets on various conductive substrates as high-performance electrodes for supercapacitors.

    PubMed

    Zhang, Genqiang; Lou, Xiong Wen David

    2013-02-20

    Mesoporous NiCo(2) O(4) nanosheets can be directly grown on various conductive substrates, such as Ni foam, Ti foil, stainless-steel foil and flexible graphite paper, through a general template-free solution method combined with a simple post annealing treatment. As a highly integrated binder- and conductive-agent-free electrode for supercapacitors, the mesoporous NiCo(2) O(4) nanosheets supported on Ni foam deliver ultrahigh capacitance and excellent high-rate cycling stability.

  6. Recent developments in TiNi-based shape memory alloys

    NASA Astrophysics Data System (ADS)

    Miyazaki, Shuichi; Kohl, Manfred

    1998-07-01

    Recently, a variety of manufacturing methods have enabled us to produce fine or thin shapes or unique structure of TiNi-based shape memory alloys: e.g., (a) rolled thin plates with a thickness less than 100 μm, (b) drawn fine wires with a diameter less than 50 μm, (c) drawn microtubes with an outer diameter less than 350 μm, (d) sputter-deposited thin films with a thickness less than 1 μm, (e) rapidly solidified ribbons of several tens μm thickness and (f) sintered porous structured materials. The characteristics and applications of these TiNi-based alloys are reviewed.

  7. Ferromagnetism in antiferromagnetic NiO-based thin films

    NASA Astrophysics Data System (ADS)

    Lin, Yuan-Hua; Zhan, Bin; Nan, Ce-Wen; Zhao, Rongjuan; Xu, Xiang; Kobayashi, M.

    2011-08-01

    Polycrystalline NiO-based thin films with Li or/and transition metal ions (V, Cr, Mn, Fe, Co, Cu, Zn) doping have been prepared by a sol-gel spin-coating method. Magnetization measurements reveal that V-, Fe-, and Mn-doped NiO thin films show obvious room-temperature ferromagnetic behaviors and ferromagnetic properties can be enhanced by the Li co-doping. Microstructure and X-ray core-level photoemission spectra analysis indicate that the ferromagnetism was not from the impurity TM metal cluster and may be ascribed to double exchange coupling effects via Li-induced holes.

  8. Direct lifetime measurements of the excited states in Ni72

    DOE PAGES

    Kolos, K.; Miller, D.; Grzywacz, R.; ...

    2016-03-22

    The lifetimes of the first excited 2+ and 4+ states in 72Ni were measured at the National Superconducting Cyclotron Laboratory with the recoil-distance Doppler-shift method, a model-independent probe to obtain the reduced transition probability. Excited states in 72Ni were populated by the one-proton knockout reaction of an intermediate energy 73Cu beam. γ-ray-recoil coincidences were detected with the γ-ray tracking array GRETINA and the S800 spectrograph. Our results provide evidence of enhanced transition probability B(E2;2+ → 0+) as compared to 68Ni, but do not confirm the trend of large B(E2) values reported in the neighboring isotope 70Ni obtained from Coulomb excitationmore » measurement. The results are compared to shell model calculations. Here, the lifetime obtained for the excited 4+1 state is consistent with models showing decay of a seniority ν = 4, 4+ state, which is consistent with the disappearance of the 8+ isomer in 72Ni.« less

  9. Magnetic anomalies in Fe-doped NiO nanoparticle

    NASA Astrophysics Data System (ADS)

    Pradeep, R.; Gandhi, A. C.; Tejabhiram, Y.; Mathar Sahib, I. K. Md; Shimura, Y.; Karmakar, L.; Das, D.; Wu, Sheng Yun; Hayakawa, Y.

    2017-09-01

    Undoped and iron-doped NiO nanoparticle were synthesized by standard hydrothermal method. A detailed study is carried out on the effect of dopant concentration on morphology, structural, resonance and magnetic properties of NiO nanoparticle by varying the Fe concentration from 0.01 to 0.10 M. The synchrotron-x-ray diffraction confirmed that no secondary phase was observed other than NiO. The x-ray photoelectron spectroscopy studies revealed that, Fe was primarily in the trivalent state, replacing the Ni2+ ion inside the octahedral crystal site of NiO. The Electron paramagnetic studies revealed the ferromagnetic cluster formation at high doping concentration (5 and 10%). The ZFC–FC curves displayed an average blocking temperature around 180 K due to particle size distribution. The anomalous behaviour of spontaneous exchange bias (H SEB) and magnetic remanence (M r) for all Fe-doped samples observed at 5 K showed an increase (0.1316–0.1384 emu g‑1) in the moment of frozen spin (M p) as the dopant concentration increased. The role of frozen spin moment in spontaneous exchange bias behaviour was discussed.

  10. Direct Lifetime Measurements of the Excited States in 72Ni

    NASA Astrophysics Data System (ADS)

    Kolos, K.; Miller, D.; Grzywacz, R.; Iwasaki, H.; Al-Shudifat, M.; Bazin, D.; Bingham, C. R.; Braunroth, T.; Cerizza, G.; Gade, A.; Lemasson, A.; Liddick, S. N.; Madurga, M.; Morse, C.; Portillo, M.; Rajabali, M. M.; Recchia, F.; Riedinger, L. L.; Voss, P.; Walters, W. B.; Weisshaar, D.; Whitmore, K.; Wimmer, K.; Tostevin, J. A.

    2016-03-01

    The lifetimes of the first excited 2+ and 4+ states in 72>Ni were measured at the National Superconducting Cyclotron Laboratory with the recoil-distance Doppler-shift method, a model-independent probe to obtain the reduced transition probability. Excited states in 72Ni were populated by the one-proton knockout reaction of an intermediate energy 73Cu beam. γ -ray-recoil coincidences were detected with the γ -ray tracking array GRETINA and the S800 spectrograph. Our results provide evidence of enhanced transition probability B (E 2 ;2+→0+) as compared to 68Ni, but do not confirm the trend of large B (E 2 ) values reported in the neighboring isotope 70Ni obtained from Coulomb excitation measurement. The results are compared to shell model calculations. The lifetime obtained for the excited 41+ state is consistent with models showing decay of a seniority ν =4 , 4+ state, which is consistent with the disappearance of the 8+ isomer in 72Ni.

  11. Chemical reactivity of Ni-Rh nanowires.

    PubMed

    Schoiswohl, J; Mittendorfer, F; Surnev, S; Ramsey, M G; Andersen, J N; Netzer, F P

    2006-09-22

    The properties of bimetallic Ni-Rh nanowires, fabricated by decorating the steps of vicinal Rh(111) surfaces by stripes of self-assembled Ni adatoms, have been probed by STM, photoemission, and ab initio density functional theory calculations. These Ni-Rh nanowires have specific electronic properties that lead to a significantly enhanced chemical reactivity towards oxygen. As a result, the Ni-Rh nanowires can be oxidized exclusively, generating novel quasi-one-dimensional oxide structures.

  12. Vibrations on Cu surfaces covered with Ni monolayer

    NASA Astrophysics Data System (ADS)

    Sklyadneva, I. Yu.; Rusina, G. G.; Chulkov, E. V.

    1999-08-01

    Vibrational modes on the Cu(100) and Cu(111) surfaces covered with a Ni monolayer have been calculated using the embedded-atom method. A detailed discussion of the dispersion relations and polarizations of adsorbate modes and surface phonons is presented. The dispersion of the Rayleigh phonon is in good agreement with the experimental EELS data. The changes in interatomic force constants are discussed.

  13. Estimate of conjugate gamma and gamma prime compositions in Ni-base superalloys

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.

    1977-01-01

    Approaches for estimating the composition of the matrix phase of alloys from the melt composition are reviewed. The first method is based on assigning essentially fixed stoichiometry to precipitating phases and is typified by PHACOMP. The second method uses analytical geometry to interpret phase diagrams and is applicable to a two-phase region of a six-component Ni-base system. The geometric method is also applicable to commercial Ni-base superalloys.

  14. Surface Composition of NiPd Alloys

    NASA Technical Reports Server (NTRS)

    Noebe, Ronald D.; Khalil, Joe; Bozzolo, Guillermo; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    Surface segregation in Ni-Pd alloys has been studied using the BFS method for alloys. Not only does the method predict an oscillatory segregation profile but it also indicates that the number of Pd-enriched surface planes can vary as a function of orientation. The segregation profiles were computed as a function of temperature, crystal face, and composition. Pd enrichment of the first layer is observed in (111) and (100) surfaces, and enrichment of the top two layers occurs for (110) surfaces. In all cases, the segregation profile shows oscillations that are actually related to weak ordering tendencies in the bulk. An atom-by-atom analysis was performed to identify the competing mechanisms leading to the observed surface behaviors. Large-scale atomistic simulations were also performed to investigate the temperature dependence of the segregation profiles as well as for analysis of the bulk structures. Finally, the observed surface behaviors are discussed in relation to the bulk phase structure of Ni-Pd alloys, which exhibit a tendency to weakly order.

  15. On the similarity of the bonding in NiS and NiO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    The bonding in NiS is found to be quite similar to that in NiO, having an ionic contribution arising from the donation of the Ni 4s electron to the S atom and a covalent component arising from bonds between the Ni 3d and the S 3p. The one-electron d bonds are found to be of equal strength for NiO and NiS, but the two-electron d bonds are weaker for NiS.

  16. On the similarity of the bonding in NiS and NiO

    NASA Technical Reports Server (NTRS)

    Bauschlicher, C. W., Jr.

    1985-01-01

    The bonding in NiS is found to be quite similar to that in NiO, having an ionic contribution arising from the donation of the Ni 4s electron to the S atom and a covalent component arising from bonds between the Ni 3d and the S 3p. The one-electron d bonds are found to be of equal strength for NiO and NiS, but the two-electron d bonds are weaker for NiS.

  17. Electroless plating of Ni thin films using foam of electrolyte

    NASA Astrophysics Data System (ADS)

    Furuhashi, Takahiro; Yamada, Yoshiyasu; Ichihara, Shoji; Takai, Akihiro; Usui, Hiroaki

    2016-02-01

    Electroless plating of Ni thin films was achieved in foam of electroplating solution in place of electroplating liquid. Commercial hypophosphite-based solution for Ni electroless plating was added with a surfactant of sulfuric acid monododecyl ester sodium salt (SDS) and bubbled with nitrogen gas to produce airy foam. Ni thin films were deposited by immersing iron substrates in the foam. Although stationary foam was inconvenient for electrodeposition by itself, film growth was enhanced by generating a flow of foam using substrate rotation and by adding SDS to a concentration of 0.1 to 0.3 wt %. No defects attributed to pinholes were observed on the film surface. This method was effective in reducing the net amount of plating solution necessary for film deposition.

  18. Direct Experimental Probe of the Ni(II)/Ni(III)/Ni(IV) Redox Evolution in LiNi0.5Mn1.5O4 Electrodes

    DOE PAGES

    Qiao, Ruimin; Wray, L. Andrew; Kim, Jung -Hyun; ...

    2015-11-11

    The LiNi0.5Mn1.5O4 spinel is an appealing cathode material for next generation rechargeable Li-ion batteries due to its high operating voltage of ~4.7 V (vs Li/Li+). Although it is widely believed that the full range of electrochemical cycling involves the redox of Ni(II)/(IV), it has not been experimentally clarified whether Ni(III) exists as the intermediate state or a double-electron transfer takes place. Here, combined with theoretical calculations, we show unambiguous spectroscopic evidence of the Ni(III) state when the LiNi0.5Mn1.5O4 electrode is half charged. This provides a direct verification of single-electron-transfer reactions in LiNi0.5Mn1.5O4 upon cycling, namely, from Ni(II) to Ni(III), thenmore » to Ni(IV). Additionally, by virtue of its surface sensitivity, soft X-ray absorption spectroscopy also reveals the electrochemically inactive Ni2+ and Mn2+ phases on the electrode surface. Our work provides the long-awaited clarification of the single-electron transfer mechanism in LiNi0.5Mn1.5O4 electrodes. Furthermore, the experimental results serve as a benchmark for further spectroscopic characterizations of Ni-based battery electrodes.« less

  19. Reaction of amorphous Ni-W and Ni-N-W films with substrate silicon

    NASA Technical Reports Server (NTRS)

    Zhu, M. F.; Suni, I.; Nicolet, M.-A.; Sands, T.

    1984-01-01

    Wiley et al. (1982) have studied sputtered amorphous films of Nb-Ni, Mo-Ni, Si-W, and Si-Mo. Kung et al. (1984) have found that amorphous Ni-Mo films as diffusion barriers between multilayer metallizations on silicon demonstrate good electrical and thermal stability. In the present investigation, the Ni-W system was selected because it is similar to the Ni-Mo system. However, W has a higher silicide formation temperature than Mo. Attention is given to aspects of sample preparation, sample characterization, the interaction between amorphous Ni-W films and Si, the crystallization of amorphous Ni(36)W(64) films on SiO2, amorphous Ni-N-W films, silicide formation and phase separation, and the crystallization of amorphous Ni(36)W(64) and Ni(30)N(21)W(49) layers.

  20. Experimental demonstration of single electron transistors featuring SiO{sub 2} plasma-enhanced atomic layer deposition in Ni-SiO{sub 2}-Ni tunnel junctions

    SciTech Connect

    Karbasian, Golnaz McConnell, Michael S.; Orlov, Alexei O.; Rouvimov, Sergei; Snider, Gregory L.

    2016-01-15

    The authors report the use of plasma-enhanced atomic layer deposition (PEALD) to fabricate single-electron transistors (SETs) featuring ultrathin (≈1 nm) tunnel-transparent SiO{sub 2} in Ni-SiO{sub 2}-Ni tunnel junctions. They show that, as a result of the O{sub 2} plasma steps in PEALD of SiO{sub 2}, the top surface of the underlying Ni electrode is oxidized. Additionally, the bottom surface of the upper Ni layer is also oxidized where it is in contact with the deposited SiO{sub 2}, most likely as a result of oxygen-containing species on the surface of the SiO{sub 2}. Due to the presence of these surface parasitic layers of NiO, which exhibit features typical of thermally activated transport, the resistance of Ni-SiO{sub 2}-Ni tunnel junctions is drastically increased. Moreover, the transport mechanism is changed from quantum tunneling through the dielectric barrier to one consistent with thermally activated resistors in series with tunnel junctions. The reduction of NiO to Ni is therefore required to restore the metal-insulator-metal (MIM) structure of the junctions. Rapid thermal annealing in a forming gas ambient at elevated temperatures is presented as a technique to reduce both parasitic oxide layers. This method is of great interest for devices that rely on MIM tunnel junctions with ultrathin barriers. Using this technique, the authors successfully fabricated MIM SETs with minimal trace of parasitic NiO component. They demonstrate that the properties of the tunnel barrier in nanoscale tunnel junctions (with <10{sup −15} m{sup 2} in area) can be evaluated by electrical characterization of SETs.

  1. Stability of NiTi-Pd and NiTi-Hf high temperature shape memory alloys

    SciTech Connect

    Zhu, Y.R.; Pu, Z.J.; Li, C.; Wu, K.H.

    1994-09-28

    The thermal cycling tests and high temperature aging tests were performed to characterize the stability of NiTi-Pd and NiTi-Hf high temperature shape memory alloys. These alloys have better stability than NiTi during thermal cycling. In addition, it also found that the NiTi-Pd and NiTi-Hf alloy have a very good stability in high temperature aging.

  2. Electrical and thermal transport in CeNi and LaNi

    NASA Astrophysics Data System (ADS)

    Rudajevová, Alexandra; Vasylyev, Denis; Musil, Ondřej

    2006-05-01

    We have measured the electrical resistivity and thermal conductivity of CeNi, LaNi and La 0.15Ce 0.85Ni in the temperature range 4-400 K simultaneously on the same specimen using the TTO option in PPMS (Quantum Design) facility. Anomalous behaviour of the resistivity and the Lorenz number for CeNi and La 0.15Ce 0.85Ni can be attributed to valence fluctuations.

  3. Local structure study of Fe dopants in Ni-deficit Ni3Al alloys

    SciTech Connect

    V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.; Lei, Hechang; Li, Lijun; Cekic, B.; Koteski, V.; Petrovic, C.

    2015-08-24

    We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor Vzz=1.6 1021Vm-2 matches well with the results of Mössbauer spectroscopy and indicates that the Fe atoms occupy Ni sites.

  4. Preparation of NiCo2S4 flaky arrays on Ni foam as binder-free supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Yang, Zeheng; Zhu, Xiao; Wang, Kun; Ma, Guo; Cheng, He; Xu, Feifei

    2015-08-01

    NiCo2S4 flaky structured arrays on nickel foam were prepared hydrothermally by means of an anion-exchange method, with NiCo2O4 nanorod arrays as precursors, and were directly applied as a binder-free supercapacitor electrode. Such a 3D structured electrode combines the advantages of both one dimensional and two dimensional materials, and can effectively improve the electrochemical performance. As a result, the as-prepared NiCo2S4 flaky structure electrode shows much enhanced electrochemical performance, with a high specific capacitance (2044 F g-1 at 1 A g-1) and good cycling stability (capacity retention of 77% after 2000 cycles), suggesting its promising application for electrochemical capacitors.

  5. Magneto-plasmonic study of aligned Ni, Co and Ni/Co multilayer in polydimethylsiloxane as magnetic field sensor

    NASA Astrophysics Data System (ADS)

    Hamidi, Seyedeh Mehri; Mosaeii, Babak; Afsharnia, Mina; Aftabi, Ali; Najafi, Mojgan

    2016-11-01

    We report the magneto-optical properties of aligned cobalt, Nickel and nickel/ Cobalt multilayer nanowires embedded in polydimethylsiloxane matrix. The NWs prepared by electrodeposition method in anodic alumina template and then dispersed in ethanol and placed in a heater to evaporate the ethanol and finally dispersed in polydimethylsiloxane matrix to reach to the composite. The used external magnetic field arranges the nanowires and our aligned nanowires were investigated by magneto-optical surface plasmon resonance techniques in two easy and hard axis configurations. Our results show the sufficient sensitivity in magneto-optical surface plasmon resonance of Nickel and cobalt arrays nanowires and because the different modulation mechanism in Ni and Co nanodisks, in Ni/Co multilayer we see the magnetization modulation of the excitation angle in accordance with magnetic field modulation of the SPP wave vector in each nanodisk. Finally, we show that the Ni/Co multilayer aligned nanowires can be used as efficient magnetic field sensor.

  6. Kinetics of Ni2Si growth from pure Ni and Ni(V) films on (111) and (100) Si

    NASA Astrophysics Data System (ADS)

    Harith, M. A.; Zhang, J. P.; Campisano, S. U.; Klaar, H.-J.

    1987-01-01

    The kinetics of Ni2Si growth from pure Ni and from Ni0.93V0.07 films on (111) and (100) silicon has been studied by the combination of He+ backscattering, x-ray diffraction, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) techniques. The activation energies are 1.5 and 1.0 eV for pure Ni and Ni(V) films, respectively while the pre-exponential factors in Ni(V) are 4 5 orders of magnitude smaller than in the pure Ni case. The variations in the measured rates are related to the different grain size of the growing suicide layers. The vanadium is rejected from the silicide layer and piles up at the metalsilicide interface.

  7. Kinetics of Ni Sorption in Soils: Roles of Soil Organic Matter and Ni Precipitation

    SciTech Connect

    Shi, Zhenqing; Peltier, Edward; Sparks, Donald L.

    2012-12-10

    The kinetics of Ni sorption to two Delaware agricultural soils were studied to quantitatively assess the relative importance of Ni adsorption on soil organic matter (SOM) and the formation of Ni layered double hydroxide (Ni-LDH) precipitates using both experimental studies and kinetic modeling. Batch sorption kinetic experiments were conducted with both soils at pH 6.0, 7.0, and 7.5 from 24 h up to 1 month. Time-resolved Ni speciation in soils was determined by X-ray absorption spectroscopy (XAS) during the kinetic experiments. A kinetics model was developed to describe Ni kinetic reactions under various reaction conditions and time scales, which integrated Ni adsorption on SOM with Ni-LDH precipitation in soils. The soil Ni speciation (adsorbed phases and Ni-LDH) calculated using the kinetics model was consistent with that obtained through XAS analysis during the sorption processes. Under our experimental conditions, both modeling and XAS results demonstrated that Ni adsorption on SOM was dominant in the short term and the formation of Ni-LDH precipitates accounted for the long-term Ni sequestration in soils, and, more interestingly, that the adsorbed Ni may slowly transfer to Ni-LDH phases with longer reaction times.

  8. Kinetics of Ni sorption in soils: roles of soil organic matter and Ni precipitation.

    PubMed

    Shi, Zhenqing; Peltier, Edward; Sparks, Donald L

    2012-02-21

    The kinetics of Ni sorption to two Delaware agricultural soils were studied to quantitatively assess the relative importance of Ni adsorption on soil organic matter (SOM) and the formation of Ni layered double hydroxide (Ni-LDH) precipitates using both experimental studies and kinetic modeling. Batch sorption kinetic experiments were conducted with both soils at pH 6.0, 7.0, and 7.5 from 24 h up to 1 month. Time-resolved Ni speciation in soils was determined by X-ray absorption spectroscopy (XAS) during the kinetic experiments. A kinetics model was developed to describe Ni kinetic reactions under various reaction conditions and time scales, which integrated Ni adsorption on SOM with Ni-LDH precipitation in soils. The soil Ni speciation (adsorbed phases and Ni-LDH) calculated using the kinetics model was consistent with that obtained through XAS analysis during the sorption processes. Under our experimental conditions, both modeling and XAS results demonstrated that Ni adsorption on SOM was dominant in the short term and the formation of Ni-LDH precipitates accounted for the long-term Ni sequestration in soils, and, more interestingly, that the adsorbed Ni may slowly transfer to Ni-LDH phases with longer reaction times.

  9. Field-Induced Slow Magnetic Relaxation in the Ni(I) Complexes [NiCl(PPh3)2]·C4H8O and [Ni(N(SiMe3)2)(PPh3)2].

    PubMed

    Lin, Weiquan; Bodenstein, Tilmann; Mereacre, Valeriu; Fink, Karin; Eichhöfer, Andreas

    2016-03-07

    Direct current (dc) and alternating current (ac) magnetic measurements have been performed on the three Ni(I) complexes: [NiCl(PPh3)3], [NiCl(PPh3)2]·C4H8O, and [Ni(N(SiMe3)2)(PPh3)2]. Fits of the dc magnetic data suggest an almost similar behavior of the three compounds, which display only moderate deviations from the spin-only values. The ac magnetic investigations reveal that the two complexes with trigonal planar coordination--[NiCl(PPh3)2]·C4H8O and [Ni(N(SiMe3)2)(PPh3)2]--display slow magnetic relaxation at low temperatures under applied dc fields, whereas tetrahedral [NiCl(PPh3)3] does not. Ground and excited states as well as magnetic data were calculated by ab initio wave function based multi-configurational methods, including dynamic correlation as well as spin-orbit coupling. The two trigonal planar complexes comprise well-isolated S = (1)/2 ground states, whereas two S = (1)/2 states with a splitting of less than 100 cm(-1) were found in the tetrahedral compound.

  10. Highly conductive NiCo2S4 urchin-like nanostructures for high-rate pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Haichao; Jiang, Jianjun; Zhang, Li; Wan, Houzhao; Qi, Tong; Xia, Dandan

    2013-09-01

    A 3D highly conductive urchin-like NiCo2S4 nanostructure has been successfully prepared using a facile precursor transformation method. Remarkably, the NiCo2S4 electroactive material demonstrates superior electrochemical performance with ultrahigh high-rate capacitance, very high specific capacitance, and excellent cycling stability.A 3D highly conductive urchin-like NiCo2S4 nanostructure has been successfully prepared using a facile precursor transformation method. Remarkably, the NiCo2S4 electroactive material demonstrates superior electrochemical performance with ultrahigh high-rate capacitance, very high specific capacitance, and excellent cycling stability. Electronic supplementary information (ESI) available: Experimental details, and the electrochemical performances of NiCo2O4, Co9S8 and NiS. See DOI: 10.1039/c3nr02958a

  11. Self-separation of freestanding diamond films using graphite interlayers precipitated from C-dissolved Ni substrates

    NASA Astrophysics Data System (ADS)

    Ito, Shinya; Nagai, Masatsugu; Matsumoto, Tsubasa; Inokuma, Takao; Tokuda, Norio

    2017-07-01

    Freestanding diamond films were fabricated by a new self-separation method. Thick poly-crystalline diamond films were grown on poly-crystalline Ni substrates by microwave plasma-enhanced chemical vapor deposition after the substrates were saturated with carbon via a saturation process using a carbon solid solution. This saturation process suppressed the erosion of diamond nuclei on the Ni substrates. During the cooling process after diamond growth, the carbon atoms dissolved in the Ni substrates became supersaturated and precipitated as graphite interlayers at the interfaces between the diamond films and Ni substrates. The graphite interlayers caused the thick diamond films to spontaneously separate from the Ni substrates without cracking, allowing the Ni substrates to be reused. This self-separation method provides a low-cost way to fabricate freestanding diamond films.

  12. Synthesis of porous NiO/CeO2 hybrid nanoflake arrays as a platform for electrochemical biosensing

    NASA Astrophysics Data System (ADS)

    Cui, Jiewu; Luo, Jinbao; Peng, Bangguo; Zhang, Xinyi; Zhang, Yong; Wang, Yan; Qin, Yongqiang; Zheng, Hongmei; Shu, Xia; Wu, Yucheng

    2015-12-01

    Porous NiO/CeO2 hybrid nanoflake arrays fabricated by a facile hydrothermal method were employed as substrates for electrochemical biosensors. The resulting NiO/CeO2 hybrid nanoflake arrays with a large specific surface area and good biocompatibility presented an excellent platform for electrochemical biosensing.Porous NiO/CeO2 hybrid nanoflake arrays fabricated by a facile hydrothermal method were employed as substrates for electrochemical biosensors. The resulting NiO/CeO2 hybrid nanoflake arrays with a large specific surface area and good biocompatibility presented an excellent platform for electrochemical biosensing. Electronic supplementary information (ESI) available: Optical photographs of the as-prepared samples, SEM, TEM, EDS, XRD and BET data of the samples are presented, I-t curves of glucose biosensors based on NiO and NiO/CeO2 NFAs, EIS results of different electrodes. See DOI: 10.1039/c5nr05924k

  13. Conversion of CH{sub 4}/CO{sub 2} to syngas over Ni-Co/Al{sub 2}O{sub 3}-ZrO{sub 2} nanocatalyst synthesized via plasma assisted co-impregnation method: Surface properties and catalytic performance

    SciTech Connect

    Rahemi, Nader; Haghighi, Mohammad; Akbar Babaluo, Ali; Fallah Jafari, Mahdi; Khorram, Sirous

    2013-09-07

    Ni/Al{sub 2}O{sub 3} catalyst promoted by Co and ZrO{sub 2} was prepared by co-impregnation method and treated with glow discharge plasma. The catalytic activity of the synthesized nanocatalysts has been tested toward conversion of CH{sub 4}/CO{sub 2} to syngas. The physicochemical characterizations like XRD, EDX, FESEM, TEM, BET, FTIR, and XPS show that plasma treatment results in smaller particle size, more surface concentration, and uniform morphology. The dispersion of nickel in plasma-treated nanocatalyst was also significantly improved, which was helpful for controlling the ensemble size of active phase atoms on the support surface. Improved physicochemical properties caused 20%–30% enhancement in activity of plasma-treated nanocatalyst that means to achieve the same H{sub 2} or CO yield, the plasma-treated nanocatalyst needed about 100 °C lower reaction temperature. The H{sub 2}/CO ratio got closer to 1 at higher temperatures and finally at 850 °C H{sub 2}/CO = 1 is attained for plasma-treated nanocatalyst. Plasma-treated nanocatalyst due to smaller Ni particles and strong interaction between active phase and support has lower tendency to keep carbon species on its structure and hence excellent stability can be observed for this catalyst.

  14. Hierarchical hollow urchin-like NiCo2O4 nanomaterial as electrocatalyst for oxygen evolution reaction in alkaline medium

    NASA Astrophysics Data System (ADS)

    Wang, Juan; Qiu, Tian; Chen, Xu; Lu, Yanluo; Yang, Wensheng

    2014-12-01

    Hierarchical hollow urchins of NiCo2O4 (HU-NiCo2O4) were synthesized by a hard templating method followed by thermal decomposition. The structure consists of three levels of hierarchy i.e., zero-dimensional nanoparticle with a diameter of about 6 nm, one-dimensional chain, and three-dimensional hollow urchin, respectively. Nanoparticle aggregates of NiCo2O4 (NA-NiCo2O4) were also synthesized by the same procedure in the absence of the hard template. Relative to NA-NiCo2O4, HU-NiCo2O4 features a well-connected three-dimensional porous structure, which is beneficial for diffusion of oxygen. Consequently, HU-NiCo2O4 displayed superior electrocatalytic activity towards oxygen evolution processes with lower overpotential, higher current density, and higher stability than NA-NiCo2O4.

  15. Investigation of Ni@CoO core-shell nanoparticle films synthesized by sequential layer deposition

    NASA Astrophysics Data System (ADS)

    Spadaro, M. C.; Luches, P.; Benedetti, F.; Valeri, S.; Turchini, S.; Bertoni, G.; Ferretti, A. M.; Capetti, E.; Ponti, A.; D'Addato, S.

    2017-02-01

    Films of Ni@CoO core-shell nanoparticles (NP Ni core size d ≈ 11 nm) have been grown on Si/SiOx and lacey carbon supports, by a sequential layer deposition method: a first layer of CoO was evaporated on the substrate, followed by the deposition of a layer of pre-formed, mass-selected Ni NPs, and finally an overlayer of CoO was added. The Ni NPs were formed by a magnetron gas aggregation source, and mass selected with a quadrupole mass filter. The morphology of the films was investigated with Scanning Electron Microscopy and Scanning Transmission Electron Microscopy. The Ni NP cores have a shape compatible with McKay icosahedron, caused by multitwinning occurring during their growth in the source, and the Ni NP layer shows the typical random paving growth mode. After the deposition of the CoO overlayer, CoO islands are observed, gradually extending and tending to merge with each other, with the formation of shells that enclose the Ni NP cores. In situ X-ray Photoelectron Spectroscopy showed that a few Ni atomic layers localized at the core-shell interface are oxidized, hinting at the possibility of creating an intermediate NiO shell between Ni and CoO, depending on the deposition conditions. Finally, X-ray Magnetic Circular Dichroism at the Ni L2,3 absorption edge showed the presence of magnetization at room temperature even at remanence, revealing the possibility of magnetic stabilization of the NP film.

  16. Tuning crystal phase of NiSx through electro-oxidized nickel foam: A novel route for preparing efficient electrocatalysts for oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Shang, Xiao; Rao, Yi; Dong, Bin; Han, Guan-Qun; Hu, Wen-Hui; Liu, Yan-Ru; Yan, Kai-Li; Chi, Jing-Qi; Chai, Yong-Ming; Liu, Chen-Guang

    2017-02-01

    A facile solvothermal sulfurization using electro-oxidized nickel foam (NF(Ox)) as support has been applied to prepare NiSx/NF(Ox) electrocatalyst with highly efficient activity for oxygen evolution reaction (OER). XRD patterns confirm the composition of NiSx/NF(Ox): two kinds of crystal phase including β-NiS and Ni3S2. While using bare NF as support under identical conditions, only Ni3S2 phase can be detected. SEM images reveal two kinds of morphologies of NiSx/NF(Ox) including pyramids structure of β-NiS and nanorod-like structure of Ni3S2, which implies the tuning effect of electro-pretreatment of NF on the selective preparation of NiSx crystal phase. It can be speculated that Ni(OH)2 layer derived from electro-oxidized NF is responsible for the growth of β-NiS while metallic Ni is transformed into Ni2S3 during sulfurization. Electrochemical measurements for OER indicate the enhanced electrocatalytic activity of NiSx/NF(Ox) with a small overpotential of 72 mV to reach 10 mA cm-2 compared with Ni3S2/NF, which may be ascribed to the improved electron-transfer kinetics relating to the unique atomic configurations and crystalline structures of β-NiS. The electro-oxidation pretreatment of nickel foam provides a simple and convenient method by tuning different NiSx crystal phases for preparing excellent OER eletrocatalysts.

  17. Hydroconversion of methyl laurate on bifunctional Ni2P/AlMCM-41 catalyst prepared via in situ phosphorization using triphenylphosphine

    NASA Astrophysics Data System (ADS)

    Zhao, Sha; Zhang, Zhena; Zhu, Kongying; Chen, Jixiang

    2017-05-01

    A series of Ni2P/AlMCM-41-x bifunctional catalysts with different Si/Al ratios (x) were synthesized by in situ phosphorization of Ni/AlMCM-41-x with triphenylphosphine (nominal Ni/P ratio of 0.75) at 300 °C on a fixed-bed reactor. For comparison, NiP/AlMCM-41-5-TPR was also prepared by the TPR method from the supported nickel phosphate with the Ni/P ratio of 1.0, during which metallic Ni rather than Ni2P formed. TEM images show that Ni and Ni2P particles uniformly distributed in Ni2P/AlMCM-41-x and NiP/AlMCM-41-5-TPR. The Ni2P/AlMCM-41-x acidity increased with decreasing the Si/Al ratio. In the hydroconversion of methyl laurate, the conversions were close to 100% on all catalysts at 360 °C, 3.0 MPa, methyl laurate WHSV of 2 h-1 and H2/methyl laurate ratio of 25. As to Ni2P/AlMCM-41-x, with decreasing the Si/Al ratio, the total selectivity to C11 and C12 hydrocarbons decreased, while the total selectivity to isoundecane and isododecane (Si-C11+i-C12) firstly increased and then decreased. Ni2P/AlMCM-41-5 gave the largest Si-C11+i-C12 of 43.2%. While NiP/AlMCM-41-5-TPR gave higher Si-C11+i-C12 than Ni2P/AlMCM-41-5, it was more active for the undesired Csbnd C bond cleavage and methanation. We propose that the in-situ phosphorization adopted here is a promising approach to preparing Ni2P-based bifunctional catalysts.

  18. Structural evaluation and nonlinear optical properties of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 nanocomposites

    NASA Astrophysics Data System (ADS)

    Rahulan, K. Mani; Padmanathan, N.; Philip, Reji; Balamurugan, S.; Kanakam, Charles C.

    2013-10-01

    Nanocomposites of Ni/NiO, Ni/NiCo2O4 and Co/Co3O4 have been synthesized by a chemical reduction technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images confirm the mixed composite nature of the sample and uniform particle size of approximately 13 nm. Formation of Ni/NiCo3O4 solid solution or NiCo2O4 spinel phase in the mixed composite is confirmed by energy dispersive X-ray (EDX) spectrum. Magnetic hysteresis (M-H) curves of the nanocomposites show excellent ferromagnetic (FM) nature at room temperature. Nonlinear optical transmission of the nanocomposites is measured using the open aperture Z-scan technique employing 7 nanosecond laser pulses at 532 nm. Experimental results show that NiO/NiO-Co3O4/Co3O4 nanocomposites exhibit good optical limiting performance. From the measurements and numerical fitting of the data to theory, it is found that nonlinear absorption has contributions from excited state absorption and two-photon absorption. Optical limiting is enhanced in Co3O4 and Ni/NiCo2O4 in which the Co3O4 content has a larger volume ratio.

  19. Mixed-state ferromagnetism in cubic Ni/ZrO2 nanocomposites by microwave combustion synthesis

    NASA Astrophysics Data System (ADS)

    Sahoo, Tapas R.; Panda, Sirish R.; Rath, Pragyan P.

    2016-09-01

    This article shows the magnetic phase diagram for Zr1-xNixO2 compositions synthesized by microwave combustion method. The samples show room temperature ferromagnetism over the entire range of Ni- doping. Ni2+/ZrO2 (<4 at% Ni) indicates a safe substitution limit to show dilute magnetic phase. There is a threshold limit to this Dilute Magnetic Semiconductor (DMS) phase up to ∼ 4%, above which this system serves as a model system for cluster induced magnetism. Microwave combustion method is a convenient and an inexpensive approach to evaluate magnetism in these high temperature phases, which is otherwise possible only by Physical vapor deposition techniques.

  20. Calculation of ion-scattering yields from simulated intermetallic surfaces: Ni-Al(110)

    SciTech Connect

    Shutthanandan, V.; Saleh, A.A. ); Denier van der Gon, A.W. ); Smith, R.J. )

    1993-12-15

    A recently developed formalism for calculating ion-scattering yields from simulated crystal surfaces has been extended to the case of bimetallic surfaces. MeV He[sup +] scattering yields are calculated for thin Ni films reacting with Al(110) surfaces. Interatomic potentials based on the embedded-atom method are used in a Monte Carlo approach to simulate the evolution of the Ni-Al interface as a function of Ni coverage. The calculated ion-scattering yields are in good quantitative agreement with the measured yields, showing two distinct stages of reaction and overlayer growth. Limitations of the simulation and measurement methods are discussed.

  1. Integration of Electrodeposited Ni-Fe in MEMS with Low-Temperature Deposition and Etch Processes.

    PubMed

    Schiavone, Giuseppe; Murray, Jeremy; Perry, Richard; Mount, Andrew R; Desmulliez, Marc P Y; Walton, Anthony J

    2017-03-22

    This article presents a set of low-temperature deposition and etching processes for the integration of electrochemically deposited Ni-Fe alloys in complex magnetic microelectromechanical systems, as Ni-Fe is known to suffer from detrimental stress development when subjected to excessive thermal loads. A selective etch process is reported which enables the copper seed layer used for electrodeposition to be removed while preserving the integrity of Ni-Fe. In addition, a low temperature deposition and surface micromachining process is presented in which silicon dioxide and silicon nitride are used, respectively, as sacrificial material and structural dielectric. The sacrificial layer can be patterned and removed by wet buffered oxide etch or vapour HF etching. The reported methods limit the thermal budget and minimise the stress development in Ni-Fe. This combination of techniques represents an advance towards the reliable integration of Ni-Fe components in complex surface micromachined magnetic MEMS.

  2. Gadolinium substitution effect on the thermomagnetic properties of Ni ferrite ferrofluids

    NASA Astrophysics Data System (ADS)

    Jacobo, Silvia E.; Arana, Mercedes; Bercoff, Paula G.

    2016-10-01

    This work is focused on the structural and magnetic characterization of Gd-doped Ni ferrite nanoparticles and the preparation of a ferrofluid for applications in heat-transfer devices. For this purpose, spinel ferrites NiFe2O4, and NiFe1.88Gd0.12O4 were prepared by the self-combustion method. The substituted sample was obtained with a small amount of Gd inclusion and the excess appeared as GdFeO3. The smallest nanoparticles of both samples were properly coated and dispersed in kerosene. Thermal conductivities of the produced ferrofluids were measured at 25 °C under an applied magnetic field. There is a significant enhancement in the thermal conductivity of the ferrofluid prepared with NiGd ferrite with respect to the one with Ni ferrite, in presence of a magnetic field. This effect is directly related to the well-known magnetocaloric effect of Gd.

  3. Electroless fabrication and supercapacitor performance of CNT@NiO-nanosheet composite nanotubes.

    PubMed

    Yu, W; Li, B Q; Ding, S J

    2016-02-19

    Composite nanostructures consisting of porous NiO nanosheets on carbon nanotubes (CNTs) are fabricated using a facile and low-cost electroless plating method. The CNTs, modified by a polymer, are adopted as the template upon which porous Ni nanosheets are grown using electroless plating. This is followed by removal of the polymer layer and oxidation of the Ni by controlled thermal annealing. The effect of reductant concentration on the morphology of the NiO nanosheets is studied. The electrochemical characteristics of the nanostructures are measured using chronopotentiometry. Experimental measurements show that the NiO nanosheet covered CNT composite nanostructures exhibit a relatively high specific capacitance of 1177 F g(-1) at a discharge current density of 2 A g(-1), while retaining 89.2% of its initial capacitance at a current density of 2 A g(-1) after 1000 cycles.

  4. Growth of Au on Ni(110): A Semiempirical Modeling of Surface Alloy Phases

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ibanez-Meier, Rodrigo; Ferrante, John

    1995-01-01

    Recent experiments using scanning tunneling microscopy show evidence for the formation of surface alloys of otherwise immiscible metals. Such is the case for Au deposited in Ni(110), where experiments by Pleth Nielsen el al.indicate that at low Au coverage (less than 0. 5 ML), Au atoms replace Ni atoms in the surface layer forming a surface alloy while the Ni atoms form islands on the surface. In this paper, we present results of a theoretical modeling of this phenomenon using the recently developed Bozzolo-Ferrante-Smith method for alloys. We provide results of an extensive analysis of the growth process that strongly support the conclusions drawn from the experiment: at very low coverages, there is a tendency for dimer formation on the overlayer, which later exchange positions with Ni atoms in the surface layer, thus accounting for the large number of substituted dimers. Ni island formation as well as other alternative short-range-order patterns are discussed.

  5. FeCoNi coated glass fibers in composite sheets for electromagnetic absorption and shielding behaviors

    NASA Astrophysics Data System (ADS)

    Lee, Joonsik; Jung, Byung Mun; Lee, Sang Bok; Lee, Sang Kwan; Kim, Ki Hyeon

    2017-09-01

    To evaluate the electromagnetic (EM) absorption and shield of magnetic composite sheet, we prepared the FeCoNi coated glass fibers filled in composite sheet. The FeCoNi was coated by electroless plating on glass fiber as a filler. The coated FeCoNi found that consist of mixtures of bcc and fcc phase. The magnetization and coercivity of coated FeCoNi are about 110 emu/g and 57 Oe, respectively. The permittivity and permeability of the FeCoNi composite sheet were about 21 and 1, respectively. Power absorption increased 95% with the increment of frequency up to 10 GHz. Inter-decoupling of this composite sheet showed maximum 30 dB at around 5.3 GHz, which is comparable to that of a conductive Cu foil. Shielding effectiveness (SE) was measured by using rectangular waveguide method. SE of composite obtained about 37 dB at X-band frequency region.

  6. Effect of hydrogenation on magnetic and electronic behaviour of Pr-Ni

    SciTech Connect

    Rana, Pooja Singh, Sanjay K. Verma, U. P.

    2014-04-24

    Magnetic and electronic properties of PrNi and PrNi-H have been investigated by using first principles approach. The ground state of both the compounds is base-centered orthorhombic CrB structure. Calculations are performed using full potential linearized augmented plane wave plus local orbitals (FP-L/APW) method including spin-polarization within the frame work of density functional theory (DFT). The electronic exchange-correlation energy is described by generalized gradient approximation (GGA). The hydrogen stored in PrNi, i.e., PrNi-H has been studied to analyze the effective changes in magnetic moments and electronic structures in comparison to PrNi. A comparative study of the density of states in both the compounds has also been presented.

  7. Integration of Electrodeposited Ni-Fe in MEMS with Low-Temperature Deposition and Etch Processes

    PubMed Central

    Schiavone, Giuseppe; Murray, Jeremy; Perry, Richard; Mount, Andrew R.; Desmulliez, Marc P. Y.; Walton, Anthony J.

    2017-01-01

    This article presents a set of low-temperature deposition and etching processes for the integration of electrochemically deposited Ni-Fe alloys in complex magnetic microelectromechanical systems, as Ni-Fe is known to suffer from detrimental stress development when subjected to excessive thermal loads. A selective etch process is reported which enables the copper seed layer used for electrodeposition to be removed while preserving the integrity of Ni-Fe. In addition, a low temperature deposition and surface micromachining process is presented in which silicon dioxide and silicon nitride are used, respectively, as sacrificial material and structural dielectric. The sacrificial layer can be patterned and removed by wet buffered oxide etch or vapour HF etching. The reported methods limit the thermal budget and minimise the stress development in Ni-Fe. This combination of techniques represents an advance towards the reliable integration of Ni-Fe components in complex surface micromachined magnetic MEMS. PMID:28772683

  8. Glycerol Steam Reforming Over Ni-Fe-Ce/Al2O3 Catalyst: Effect of Cerium.

    PubMed

    Go, Gwang-Sub; Go, Yoo-Jin; Lee, Hong-Joo; Moon, Dong-Ju; Park, Nam-Cook; Kim, Young-Chul

    2016-02-01

    In this work, hydrogen production from glycerol by steam reforming was studied using Ni-metal oxide catalysts. Ni-based catalyst becomes deactivated during steam reforming reactions because of coke deposits and sintering. Therefore, the aim of this study was to reduce carbon deposits and sintering on the catalyst surface by adding a promoter. Ni-metal oxide catalysts supported on Al2O3 were prepared via impregnation method, and the calcined catalyst was reduced under H2 flow for 2 h prior to the reaction. The characteristics of the catalysts were examined by XRD, TPR, TGA, and SEM. The Ni-Fe-Ce/Al2O3 catalyst, which contained less than 2 wt% Ce, showed the highest hydrogen selectivity and glycerol conversion. Further analysis of the catalysts revealed that the Ni-Fe-Ce/Al2O3 catalyst required a lower reduction temperature and produced minimum carbon deposit.

  9. Electroless fabrication and supercapacitor performance of CNT@NiO-nanosheet composite nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, W.; Li, B. Q.; Ding, S. J.

    2016-02-01

    Composite nanostructures consisting of porous NiO nanosheets on carbon nanotubes (CNTs) are fabricated using a facile and low-cost electroless plating method. The CNTs, modified by a polymer, are adopted as the template upon which porous Ni nanosheets are grown using electroless plating. This is followed by removal of the polymer layer and oxidation of the Ni by controlled thermal annealing. The effect of reductant concentration on the morphology of the NiO nanosheets is studied. The electrochemical characteristics of the nanostructures are measured using chronopotentiometry. Experimental measurements show that the NiO nanosheet covered CNT composite nanostructures exhibit a relatively high specific capacitance of 1177 F g-1 at a discharge current density of 2 A g-1, while retaining 89.2% of its initial capacitance at a current density of 2 A g-1 after 1000 cycles.

  10. Growth of Au on Ni(110): a BFS Modelling of Surface Alloy Phases

    NASA Technical Reports Server (NTRS)

    Bozzolo, Guillermo; Ibanez-Meier, Rodrigo; Ferrante, John

    1994-01-01

    Recent experiments using scanning tunneling microscopy show evidence for the formation of surface alloys of otherwise immiscible metals. Such is the case for Au deposited in Ni(11), where experiments by Pleth Nielsen et al. indicate that at low Au coverage (less than 0.5 ML), Au atoms replace Ni atoms in the surface layer forming a surface alloy while the Ni atoms form islands on the surface. In this work, we present results of a theoretical modeling of this phenomenon using the recently developed BFS method for alloys. We provide results of an extensive analysis of the growth process which strongly support the conclusions drawn from the experiment; at very low coverages, there is tendency for dimer formation on the overlayer, which later exchange positions with Ni atoms in the surface layer, thus accounting for the large number of substituted dimers. Ni island formations as well as other alternative short range order patterns are discussed.

  11. Understanding and engineering of NiGe/Ge junction formed by phosphorus ion implantation after germanidation

    SciTech Connect

    Oka, Hiroshi Minoura, Yuya; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

    2014-08-11

    Modulation of the effective electron Schottky barrier height (eSBH) of NiGe/Ge contacts induced by phosphorus ion implantation after germanide formation was investigated by considering local inhomogeneity in the eSBH. Systematic studies of NiGe/Ge contact devices having various germanide thicknesses and ion implantation areas indicated the threshold dopant concentration at the NiGe/Ge interface required for eSBH modulation and negligible dopant diffusion even at NiGe/Ge interface during drive-in annealing, leading to variation in the eSBH between the bottom and sidewall portions of the NiGe regions. Consequently, this method makes it possible to design source/drain contacts with low-resistivity Ohmic and ideal rectifying characteristics for future Ge-based transistors.

  12. Hydrogen storage behaviors of Ni-doped graphene Oxide/MIL-101 hybrid composites.

    PubMed

    Lee, Seul-Yi; Park, Soo-Jin

    2013-01-01

    In this work, Ni-doped graphene oxide/MIL-101 hybrid composites (Ni--GO/MIL) were prepared to investigate their hydrogen storage behaviors. Ni--GO/MIL was synthesized by adding Ni--GO in situ during the synthesis of MIL-101 using a hydrothermal process, which was conducted by conventional convection heating with Cr(III) ion as a metal center and telephthalic acid as organic ligands. The crystalline structures and morphologies were measured by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The specific surface area and micropore volume were investigated by N2/77 K adsorption isotherms using the Brunauer-Emmett-Teller (BET) method and Dubinin-Radushkevic (D-R) equation, respectively. The hydrogen storage capacity was investigated by BEL-HP at 77 K and 1 bar. The obtained results show that Ni--GO/MIL presents new directions for achieving novel hybrid materials with higher hydrogen storage capacity.

  13. Electrochemical sensing behaviour of Ni doped Fe{sub 3}O{sub 4} nanoparticles

    SciTech Connect

    Suresh, R.; Giribabu, K.; Manigandan, R.; Narayanan, V.; Vijayalakshmi, L.; Stephen, A.

    2014-01-28

    Ni doped Fe{sub 3}O{sub 4} nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe{sub 3}O{sub 4} nanoparticles. The optical property of Ni doped Fe{sub 3}O{sub 4} nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe{sub 3}O{sub 4} nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe{sub 3}O{sub 4} nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  14. Magnetization damping of an L10-FeNi thin film with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Ogiwara, Misako; Iihama, Satoshi; Seki, Takeshi; Kojima, Takayuki; Mizukami, Shigemi; Mizuguchi, Masaki; Takanashi, Koki

    2013-12-01

    We studied on the magnetic damping constants (α) for L10-FeNi and disordered FeNi employing three kinds of measurement methods. An L10-FeNi thin film exhibited high perpendicular magnetic anisotropy of 7.1 × 106 erg cm-3. At magnetic fields (H) lower than 2 kOe, α was estimated to be 0.091 ± 0.003. However, it was reduced down to 0.013 ± 0.001 with H, indicating that extrinsic contributions enhance α. The intrinsic α = 0.013 ± 0.001 was comparable to α = 0.009 ± 0.002 for the disordered FeNi. This suggests that L10-FeNi is a candidate achieving high magnetic anisotropy and low magnetization damping simultaneously.

  15. Structural and magnetic properties of FeNi thin films fabricated on amorphous substrates

    NASA Astrophysics Data System (ADS)

    Tashiro, T. Y.; Mizuguchi, M.; Kojima, T.; Koganezawa, T.; Kotsugi, M.; Ohtsuki, T.; Takanashi, K.

    2015-05-01

    FeNi films were fabricated by sputtering and rapid thermal annealing on thermally amorphous substrates to realize the formation of an L10-FeNi phase by a simple method. Structural and magnetic properties of FeNi films were investigated by varying the annealing temperature. L10-FeNi superlattice peaks were not observed in X-ray diffraction patterns, indicating no formation of L10-ordered phase, however, the surface structure systematically changed with the annealing temperature. Magnetization curves also revealed a drastic change depending on the annealing temperature, which indicates the close relation between the morphology and magnetic properties of FeNi films fabricated on amorphous substrates.

  16. Influence of Heat Treatment on the Mechanical Properties of Ni Films on 430 Stainless Steel Substrate

    NASA Astrophysics Data System (ADS)

    Pan, Yong; Cui, Junwei; Lei, Weixin; Zhou, Jie; Ma, Zengsheng

    2017-09-01

    Effects of heat treatment on the mechanical properties of Ni films on 430 stainless steel substrate were investigated. The Ni films were annealed at heat treatment temperatures ranging from 0 °C to 800 °C for 2 h. The surface morphology, composition, and texture orientation of Ni films were studied by scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction. The load-indentation depth curves of Ni films before and after heat treatment were measured by using nanoindentation method. In conjunction with finite element modeling and dimensional analysis, the stress-strain relationships of Ni films on 430 stainless steel substrate at different temperatures are successfully obtained by using a power-law hardening model.

  17. Adsorptive performance for methylene blue of magnetic Ni@activated carbon nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Panfeng; Xu, Jingcai; Zhang, Beibei; Li, Jing; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Hong, Bo; Gong, Jie; Ge, Hongliang; Wang, Xinqing

    2015-11-01

    Owing to the unique microporous structure and high specific surface area, activated carbon (AC) can act as a good candidate for functional materials. In this paper, Ni@AC magnetic nanocomposites with excellent magnetic response are synthesized by the hydrothermal method. All Ni@AC nanocomposites present ferromagnetism and Ni nanoparticles exist in the pores of AC. The saturation magnetization (Ms) increases with the increasing content of Ni, while the specific surface area and pore volume decrease. The S-50 sample possesses the parameters of the specific surface area of 1156.8 m2 ṡ g-1 and Ms of 3.5 emu/g. Furthermore, the methylene blue (MB) removal analysis indicates that 99% MB can be adsorbed in 50 min. The as-prepared Ni@AC nanocomposites present good adsorptive capacity of MB and can be separated easily from water by magnetic separation technique.

  18. Magnetic field effects on the electrodeposition of CoNiMo alloys

    NASA Astrophysics Data System (ADS)

    Aaboubi, Omar; Msellak, Khalid

    2017-02-01

    In this work we have examined the influence of applying homogeneous magnetic field (MF) up to 1.2T, on Cobalt- Nickel-Molybdenum (CoNiMo) alloys electrodeposition from citric bath. The surface morphology, chemical composition and the crystallographic texture has been investigated by X-ray diffraction (XRD), X-ray composition mapping and scanning electron microscopy (SEM) images. The mass transport behaviour during the electrodeposition process has been examined through the polarization curves and electrochemical impedance methods. As expected, under MF control an enhancement in the mass transport rate was observed leading to grains refinement and homogeneous distribution of the Co, Mo and Ni atoms in the obtained CoNiMo films. These findings highlight the synergistic combination of Ni, Co and Mo by promoting the MHD convection due to the Lorentz force acting during the Ni(II) and Co(II) ions reduction.

  19. Structural and magnetic properties of FeNi thin films fabricated on amorphous substrates

    SciTech Connect

    Tashiro, T. Y.; Mizuguchi, M. Kojima, T.; Takanashi, K.; Koganezawa, T.; Kotsugi, M.; Ohtsuki, T.

    2015-05-07

    FeNi films were fabricated by sputtering and rapid thermal annealing on thermally amorphous substrates to realize the formation of an L1{sub 0}-FeNi phase by a simple method. Structural and magnetic properties of FeNi films were investigated by varying the annealing temperature. L1{sub 0}-FeNi superlattice peaks were not observed in X-ray diffraction patterns, indicating no formation of L1{sub 0}-ordered phase, however, the surface structure systematically changed with the annealing temperature. Magnetization curves also revealed a drastic change depending on the annealing temperature, which indicates the close relation between the morphology and magnetic properties of FeNi films fabricated on amorphous substrates.

  20. Ultralong single-crystal metallic Ni2Si nanowires with low resistivity.

    PubMed

    Song, Yipu; Schmitt, Andrew L; Jin, Song

    2007-04-01

    Ultralong, single-crystal Ni2Si nanowires sheathed with amorphous silicon oxide were synthesized on a large scale by a chemical vapor transport (CVT) method, using iodine as the transport reagent and Ni2Si powder as the source material. Structural characterization using powder X-ray diffraction, electron microscopy, and energy-dispersive spectroscopy shows that the nanowires have Ni2Si-SiOx core-shell structure with single-crystal Ni2Si core and amorphous silicon oxide shell. The oxide shell is electrically insulating and can be removed by HF etching. Four-terminal electrical measurements show that the single-crystal nanowire has extremely low resistivity of 21 muOmega.cm and is capable of supporting remarkably high failure current density >108 A/cm2. These unique Ni2Si nanowires are very attractive nanoscale building blocks for interconnects and fully silicided (FUSI) gate applications in nanoelectronics.