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Sample records for random kajuka ni

  1. Fatigue life estimation of welded joints of an aluminium alloy under superimposed random load waves (follow-up report). Effects of high frequency components; Jujo random kajuka ni okeru aluminium gokin yosetsu tsugite no hiro jumyo suitei (zokuho). Koshuha seibun no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, I.; Maenaka, H.; Takada, A. [Ship Research Inst., Tokyo (Japan)

    1996-12-31

    In order to examine fatigue behavior of boxing welded joints of anticorrosion aluminum A 5083 P-O alloy, the residual stress measurements, static loading tests, elastic finite element analyses, constant amplitude fatigue tests, and random fatigue tests were conducted. For a load wave in the random loading fatigue tests, a direct current component, a zero-mean narrow band random process, and a high frequency component were combined and superimposed, to examine the effect of the high frequency component and the effect of the stress cycle count method and the mean stress correction on the life estimation. For the fatigue analysis, a reference stress, such as that considering the structural stress concentration, was proved effective in reducing the amount of scattering in the fatigue test results and in improving the life estimation accuracy. Accordingly, for the actual scale measurements, it is insufficient only to measure the stress at points far from the crack initiation place. It is required to analyze the fatigue by measuring the reference stress same as the basic data acquisition tests in the laboratory. 4 refs., 21 figs., 4 tabs.

  2. Fatigue life estimation of welded joints of an aluminium alloy under superimposed random load waves (follow-up report). Effects of high frequency components; Jujo random kajuka ni okeru aluminium gokin yosetsu tsugite no hiro jumyo suitei (zokuho). Koshuha seibun no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, I; Maenaka, H; Takada, A [Ship Research Inst., Tokyo (Japan)

    1997-12-31

    In order to examine fatigue behavior of boxing welded joints of anticorrosion aluminum A 5083 P-O alloy, the residual stress measurements, static loading tests, elastic finite element analyses, constant amplitude fatigue tests, and random fatigue tests were conducted. For a load wave in the random loading fatigue tests, a direct current component, a zero-mean narrow band random process, and a high frequency component were combined and superimposed, to examine the effect of the high frequency component and the effect of the stress cycle count method and the mean stress correction on the life estimation. For the fatigue analysis, a reference stress, such as that considering the structural stress concentration, was proved effective in reducing the amount of scattering in the fatigue test results and in improving the life estimation accuracy. Accordingly, for the actual scale measurements, it is insufficient only to measure the stress at points far from the crack initiation place. It is required to analyze the fatigue by measuring the reference stress same as the basic data acquisition tests in the laboratory. 4 refs., 21 figs., 4 tabs.

  3. Buckling model of longitudinal reinforcing bars under reverse cyclic load; Koban kurikaeshi kajuka ni okeru chukin no zakutsu model

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, Y.; Suda, K.; Ichinomiya, T.; Shinbo, H. [Kajima Corp., Tokyo (Japan)

    1994-10-31

    For RC (reinforced concrete) columns such as towers of long-span cable-stayed bridges or high-rise piers, there is desired development of an analytical method including a method of arranging reinforcing bars for increasing their ductility against strong earthquake motion. For this, it is necessary to investigate their characteristics after their being rendered to maximum load and their final states, and hence there must be newly investigated the properties of a plastic hinge formed on the bottom of the column, particularly determination of the buckling point of reinforcing bars and a hysteresis model after the buckling. In this study, there is developed a direct method of measuring the stress of reinforcing bars embedded in a model specimen which is conventionally difficult to be measured, and there is investigated the stress-strain hysteresis of the bars before and after the buckling thereof. The principle of the method of measuring the stress is such that only a local minimum portion of objective reinforcing bars is rendered to rf quenching, and a distortion gauge is sticked to the center of the quenching. This is based upon a fact that that portion keeps a linear relationship between the stress and the strain even if a host material is yielded. On the basis of an experimental result, a mechanism of buckling of these bars is clarified and a buckling model of the reinforcing bars at the plastic hinge. 6 refs., 15 figs., 2 tabs.

  4. Fatigue behavior of boxing welded joint under biaxial cyclic loads; 2juku kurikaeshi kajuka ni okeru kakumawashi yosetsu keishu no hiro kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, I.; Takada, A.; Akiyama, S.; Ushijima, M.; Maenaka, H. [Ministry of Transportation, Tokyo (Japan)

    1998-12-31

    Various forces such as gravity, wave induced force, inertial force etc. compositely act on a ship body from various directions. Therefore, while discussing strength or life of structural elements of ship body, it is necessary to understand the effects of the composite force condition. In this study, fatigue tests of boxing welded joint under rectangular biaxial cyclic loads are performed, the following results are obtained. Even under he biaxial cyclic loads, it is the same as the uniaxial test, the cracks occurred at the boxing weld toes propagate almost in the straight y-direction, but no oblique propagation of the cracks caused by the lad in the y-direction occurs. That the crack at initial stage of the crack progress is improved in y-direction can be illustrated by the facts that the residual stress in x-direction near the toes reaches to the yield stress, and the stress concentration in the welded toes is bigger in x-direction than that in y-direction. But as for prediction of the progress route, a further study including amplitude ratio of the biaxial loads, effects of width of test specimen is necessary. 4 refs., 12 figs., 4 tabs.

  5. Random cyclic constitutive models of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Yang Bing

    2004-01-01

    Experimental study is performed on the random cyclic constitutive relations of a new pipe stainless steel, 0Cr18Ni10Ti, by an incremental strain-controlled fatigue test. In the test, it is verified that the random cyclic constitutive relations, like the wide recognized random cyclic strain-life relations, is an intrinsic fatigue phenomenon of engineering materials. Extrapolating the previous work by Zhao et al, probability-based constitutive models are constructed, respectively, on the bases of Ramberg-Osgood equation and its modified form. Scattering regularity and amount of the test data are taken into account. The models consist of the survival probability-strain-life curves, the confidence strain-life curves, and the survival probability-confidence-strain-life curves. Availability and feasibility of the models have been indicated by analysis of the present test data

  6. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    International Nuclear Information System (INIS)

    Dawson, J. A.; Guo, Y.; Robertson, J.

    2015-01-01

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour

  7. Energetics of intrinsic defects in NiO and the consequences for its resistive random access memory performance

    Energy Technology Data Exchange (ETDEWEB)

    Dawson, J. A., E-mail: jad95@cam.ac.uk; Guo, Y.; Robertson, J. [Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

    2015-09-21

    Energetics for a variety of intrinsic defects in NiO are calculated using state-of-the-art ab initio hybrid density functional theory calculations. At the O-rich limit, Ni vacancies are the lowest cost defect for all Fermi energies within the gap, in agreement with the well-known p-type behaviour of NiO. However, the ability of the metal electrode in a resistive random access memory metal-oxide-metal setup to shift the oxygen chemical potential towards the O-poor limit results in unusual NiO behaviour and O vacancies dominating at lower Fermi energy levels. Calculated band diagrams show that O vacancies in NiO are positively charged at the operating Fermi energy giving it the advantage of not requiring a scavenger metal layer to maximise drift. Ni and O interstitials are generally found to be higher in energy than the respective vacancies suggesting that significant recombination of O vacancies and interstitials does not take place as proposed in some models of switching behaviour.

  8. Self-consistent electronic structure and segregation profiles of the Cu-Ni (001) random-alloy surface

    DEFF Research Database (Denmark)

    Ruban, Andrei; Abrikosov, I. A.; Kats, D. Ya.

    1994-01-01

    We have calculated the electronic structure and segregation profiles of the (001) surface of random Cu-Ni alloys with varying bulk concentrations by means of the coherent potential approximation and the linear muffin-tin-orbitals method. Exchange and correlation were included within the local......-density approximation. Temperature effects were accounted for by means of the cluster-variation method and, for comparison, by mean-field theory. The necessary interaction parameters were calculated by the Connolly-Williams method generalized to the case of a surface of a random alloy. We find the segregation profiles...

  9. Solution-processed flexible NiO resistive random access memory device

    Science.gov (United States)

    Kim, Soo-Jung; Lee, Heon; Hong, Sung-Hoon

    2018-04-01

    Non-volatile memories (NVMs) using nanocrystals (NCs) as active materials can be applied to soft electronic devices requiring a low-temperature process because NCs do not require a heat treatment process for crystallization. In addition, memory devices can be implemented simply by using a patterning technique using a solution process. In this study, a flexible NiO ReRAM device was fabricated using a simple NC patterning method that controls the capillary force and dewetting of a NiO NC solution at low temperature. The switching behavior of a NiO NC based memory was clearly observed by conductive atomic force microscopy (c-AFM).

  10. Pseudo-random data acquisition geometry in 3D seismic survey; Sanjigen jishin tansa ni okeru giji random data shutoku reiauto ni tsuite

    Energy Technology Data Exchange (ETDEWEB)

    Minegishi, M; Tsuburaya, Y [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1996-10-01

    Influence of pseudo-random geometry on the imaging for 3D seismic exploration data acquisition has been investigate using a simple model by comparing with the regular geometry. When constituting wave front by the interference of elemental waves, pseudo-random geometry data did not always provide good results. In the case of a point diffractor, the imaging operation, where the constituted wave front was returned to the point diffractor by the interference of elemental waves for the spatial alias records, did not always give clear images. In the case of multi point diffractor, good images were obtained with less noise generation in spite of alias records. There are a lot of diffractors in the actual geological structures, which corresponds to the case of multi point diffractors. Finally, better images could be obtained by inputting records acquired using the pseudo-random geometry rather than by inputting spatial alias records acquired using the regular geometry. 7 refs., 6 figs.

  11. A Novel Ni/WOX/W Resistive Random Access Memory with Excellent Retention and Low Switching Current

    Science.gov (United States)

    Chien, Wei-Chih; Chen, Yi-Chou; Lee, Feng-Ming; Lin, Yu-Yu; Lai, Erh-Kun; Yao, Yeong-Der; Gong, Jeng; Horng, Sheng-Fu; Yeh, Chiao-Wen; Tsai, Shih-Chang; Lee, Ching-Hsiung; Huang, Yu-Kai; Chen, Chun-Fu; Kao, Hsiao-Feng; Shih, Yen-Hao; Hsieh, Kuang-Yeu; Lu, Chih-Yuan

    2011-04-01

    The behavior of WOX resistive random access memory (ReRAM) is a strong function of the top electrode material, which controls the conduction mechanism and the forming process. When using a top electrode with low work function, the current conduction is limited by space charges. On the other hand, the mechanism becomes thermionic emission for devices with a high work function top electrode. These (thermionic) devices are also found to have higher initial resistance, reduced forming current, and larger resistance window. Based on these insights and considering the compatibility to complementary metal-oxide-semiconductor (CMOS) process, we proposed to use Ni as the top electrode for high performance WOX ReRAM devices. The new Ni/WOX/W device can be switched at a low current density less than 8×105 A/cm2, with RESET/SET resistance ratio greater than 100, and extremely good data retention of more than 300 years at 85 °C.

  12. Magnetic and magnetoelastic properties of the random anisotropy amorphous magnets Tb2(FexNi1-x)

    International Nuclear Information System (INIS)

    De la Fuente, C.; Arnaudas, J.I.; Del Moral, A.; Ciria, M.

    1996-01-01

    Amorphous Tb 2 (Fe x Ni 1-x ) compounds show the strongest random anisotropy known: D/J≅5.2, between crystal field and exchange strengths, separately obtained. The magnetic phase diagram shows two speri-magnetic phases. The effective magnetic moment is reduced, μ eff. (5 K, 12 T)≅7.2 μ B /Tb 3+ . Magnetostriction is very large and constant, λ t (5 K, 12 T)≅4.1.10 -3 . The local distribution of Tb 3+ ions is aspherical. (orig.)

  13. Ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys

    DEFF Research Database (Denmark)

    Ruban, Andrei; Abrikosov, I. A.; Skriver, Hans Lomholt

    1995-01-01

    We have studied the ground-state properties of ordered, partially ordered, and random Cu-Au and Ni-Pt alloys at the stoichiometric 1/4, 1/2, and 3/4 compositions in the framework of the multisublattice single-site (SS) coherent potential approximation (CPA). Charge-transfer effects in the random ...... for the ordered alloys are in good agreement with experimental data. For all the alloys the calculated ordering energy and the equilibrium lattices parameters are found to be almost exact quadratic functions of the long-range-order parameter....... and the partially ordered alloys are included in the screened impurity model. The prefactor in the Madelung energy is determined by the requirement that the total energy obtained in direct SS CPA calculations should equal the total energy given by the Connolly-Williams expansion based on Green’s function...

  14. Thin Co/Ni-based bottom pinned spin-transfer torque magnetic random access memory stacks with high annealing tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Tomczak, Y., E-mail: Yoann.Tomczak@imec.be [IMEC Kapeldreef 75, B-3001 Leuven (Belgium); Department of Chemistry, KU Leuven (University of Leuven), Celestijnenlaan 200F, B-3001 Leuven (Belgium); Swerts, J.; Mertens, S.; Lin, T.; Couet, S.; Sankaran, K.; Pourtois, G.; Kim, W.; Souriau, L.; Van Elshocht, S.; Kar, G.; Furnemont, A. [IMEC Kapeldreef 75, B-3001 Leuven (Belgium); Liu, E. [Department of Chemistry, KU Leuven (University of Leuven), Celestijnenlaan 200F, B-3001 Leuven (Belgium)

    2016-01-25

    Spin-transfer torque magnetic random access memory (STT-MRAM) is considered as a replacement for next generation embedded and stand-alone memory applications. One of the main challenges in the STT-MRAM stack development is the compatibility of the stack with CMOS process flows in which thermal budgets up to 400 °C are applied. In this letter, we report on a perpendicularly magnetized MgO-based tunnel junction (p-MTJ) on a thin Co/Ni perpendicular synthetic antiferromagnetic layer with high annealing tolerance. Tunnel magneto resistance (TMR) loss after annealing occurs when the reference layer loses its perpendicular magnetic anisotropy due to reduction of the CoFeB/MgO interfacial anisotropy. A stable Co/Ni based p-MTJ stack with TMR values of 130% at resistance-area products of 9 Ω μm{sup 2} after 400 °C anneal is achieved via moment control of the Co/Ta/CoFeB reference layer. Thinning of the CoFeB polarizing layer down to 0.8 nm is the key enabler to achieve 400 °C compatibility with limited TMR loss. Thinning the Co below 0.6 nm leads to a loss of the antiferromagnetic interlayer exchange coupling strength through Ru. Insight into the thickness and moment engineering of the reference layer is displayed to obtain the best magnetic properties and high thermal stability for thin Co/Ni SAF-based STT-MRAM stacks.

  15. Lowest lying 2+ and 3- vibrational states in Pb, Sn, and Ni isotopes in relativistic quasiparticle random-phase approximation

    International Nuclear Information System (INIS)

    Ansari, A.; Ring, P.

    2006-01-01

    The excitation energies and electric multipole decay rates of the lowest lying 2 + and 3 - vibrational states in Pb, Sn, and Ni nuclei are calculated following relativistic quasiparticle random-phase approximation formalism based on the relativistic Hartree-Bogoliubov mean field. Two sets of Lagrangian parameters, NL1 and NL3, are used to investigate the effect of the nuclear force. Overall there is good agreement with the available experimental data for a wide range of mass numbers considered here, and the NL3 set seems to be a better choice. However, strictly speaking, these studies point toward the need of a new set of force parameters that could produce more realistic single-particle levels, at least in vicinity of the Fermi surface, of a wide range of nuclear masses

  16. Mössbauer study on a two-dimensional random mixture with competing spin anisotropies K2Ni1- x Fe x F4

    Science.gov (United States)

    Ito, A.; Anma, T.

    1987-03-01

    Mössbauer measurements have been made on a two-dimensional (2D) random mixture K2Ni1- x Fe x F4 with competing spin anisotropies. The concentration versus temperature phase diagram predicted by Oguchi and Ishikawa for mixed systems with competition between orthorhombic anisotropies has been shown to exist in K2Ni1- x Fe x F4. The coexistence of two kinds of Mössbauer spectra is seen in the transition regions, and is believed to be an intrinsic property of this system.

  17. Moessbauer study on a two-dimensional random mixture with competing spin anisotropies K2Ni1-xFexF4

    International Nuclear Information System (INIS)

    Ito, A.; Anma, T.

    1987-01-01

    Moessbauer measurements have been made on a two-dimensional (2D) random mixture K 2 Ni 1-x Fe x F 4 with competing spin anisotropies. The concentration versus temperature phase diagram predicted by Oguchi and Ishikawa for mixed systems with competition between orthorhombic anisotropies has been shown to exist in K 2 Ni 1-x Fe x Fe 4 . The coexistence of two kinds of Moessbauer spectra is seen in the transition regions, and is believed to be an intrinsic property of this system. (orig.)

  18. Mean strain effects on the random cyclic strain-life relations of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Yang Bing

    2005-01-01

    Experimental study is performed on the mean strain effects on the random cyclic strain-life relations of the new nuclear material, 0Cr18Ni10Ti pipe steel. In order to save costs of specimens and tests, an improved maximum likelihood fatigue test method is applied to manage the present strain-controlled fatigue tests. Six straining ratios, respectively, -1, -0.52, 0.22, 0.029, 0.18, and 0.48, are applied to study the effects. Total 104 specimens are fatigued. Since the material exhibits an entirely relaxation effect of mean stress under the six ratios and, in addition, there is no effectively method for the description of the mean straining effects under this case, previous Zhao's random strain-life relations are therefore applied for effective characterization of the scattering test data under the six ratios on a basis of Coffin-Manson equation.Then the effects of the ratios are analyzed respectively on the average fatigue lives, the standard deviations of the logarithms of fatigue lives, and the fatigue lives under different survival probabilities and confidences. The results reveal that the ratios greater than zero exhibit a positive effect of about 1.3 to 1.6 times under the survival probability of 0.999 and the confidence of 95%. A negative effect is exhibited for the case of the ratios less than zero. In addition, the assessment of the effects from the sense of average fatigue lives might result in a wrong conclusion for the practice of higher reliabilities. The effects can be appropriately assessed from a probabilistic sense to take into account the average lives, the scattering regularity of test data, and the size of sampling. (author)

  19. Simultaneous use of traditional Chinese medicine (Si-Ni-Tang to treat septic shock patients: study protocol for a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Wu Shin-Hwar

    2011-08-01

    Full Text Available Abstract Background Even though there are continually upgraded recommendations for managing sepsis, such as "Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock", mortality is still high. Si-Ni-Tang, a remedy documented in Shanghan Lun, a medical collection from ancient China, is used for treating patients with sepsis and septic shock. Using a well-designed clinical trial, we are eager to survey the effectiveness of the concurrent use of this remedy in restoring these patients' hemodynamic status, or "Yang Qi". Methods/Design Patients admitted to our medical intensive care units with the diagnosis of septic shock, defined as persistent hypotension induced by sepsis despite adequate fluid resuscitation, are eligible for participation. The inclusion criteria include: age from 20 to 85 years, conditions meeting the definition of septic shock, use of vasopressors within 24 hours of entering the study, and use of a nasogastric tube for feeding. The enrolled patients are randomly allocated either to the Si-Ni-Tang group or the placebo group. The prescription of the trial drugs (Si-Ni-Tang/placebo is 2.25 grams 4 times a day for 7 days or till shock reversal (if shock reversal occurs in less than 7 days. Data, including duration of vasopressor infusion, gender, age, co-morbidities, APACHE II score, predicted mortality, ICU mortality, ICU length of stay, hospital mortality, hospital length of stay, source of sepsis, and culture results, are collected for the following analysis. Discussion Si-Ni-Tang is composed of processed Zingiber officinale, Glycyrrhiza uralensis, and Aconitum carmichaeli. Zingiber officinale and Glycyrrhiza uralensis are found to have the ability to reduce pro-inflammatory cytokine production, to inhibit lipopolisaccharide-induced macrophage activation and function, and to lessen the bacterial load and suppress acute and chronic inflammation. Aconitum carmichaeli is known to have

  20. Effects of thermal and particle-number fluctuations on the giant isovector dipole modes for the 58Ni nucleus in the finite-temperature random-phase approximation

    International Nuclear Information System (INIS)

    Nguyen Dinhdang; Nguyen Zuythang

    1988-01-01

    Using the realistic single-particle energy spectrum obtained in the Woods-Saxon nucleon mean-field potential, we calculate the BCS pairing gap for 58 Ni as a function of temperature taking into account the thermal and particle-number fluctuations. The strength distributions of the electric dipole transitions and the centroids of the isovector giant dipole resonance (IV-GDR) are computed in the framework of the finite-temperature random-phase approximation (RPA) based on the Hamiltonian of the quasiparticle-phonon nuclear model with separate dipole forces. It is shown that the change of the pairing gap at finite temperature can noticeably influence the IV-GDR localisation in realistic nuclei. By taking both thermal and quasiparticle fluctuations in the pairing gap into account the effect of the phase transition from superfluid to normal in the temperature dependence of the IV-GDR centroid is completely smeared out. (author)

  1. Effects of mean strain on the random cyclic stress-strain relations of 0Cr18Ni10Ti pipe steel

    International Nuclear Information System (INIS)

    Zhao Yongxiang; Yang Bing

    2005-01-01

    Experimental study is performed for the effects of the mean strain on the random cyclic stress-strain relations of the new nuclear material, 0Cr18Ni10Ti pipe steel. From saving the size of specimens, an improved maximum likelihood fatigue test method is proposed to operate the present strain-controlled fatigue tests. Six straining ratios, -1, -0.52, -0.22, 0.029, 0.18, and 0.48, respectively, are applied to study the effects. Fatigue test has been carried out on totally 104 specimens. The test results reveal that the material exhibits a Masing behaviour and the saturation hysteresis loops under the six ratios hold an entirely relaxation effect of mean stress. There is no effectively method for the description of the mean straining effects under this case. Previous Zhao's random stress-strain relations are therefore applied to characterizing effectively the scattering test data under the six ratios on a basis of Ramberg-Osgood equation. Then the effects of the ratios are analyzed respectively on the average stress amplitudes, the standard deviations of the stress amplitudes, and the stress amplitudes under different survival probabilities and confidences. The results reveal that the ratios act a relatively decreasing effect to the stress amplitudes under higher survival probabilities and confidences. The strongest effect appears at the ratio of 0.029, and a weaker effect acts as the distance increase of the ratio from the zero. In addition, it is indicated that the effects from the sense of average fatigue lives might result in a wrong conclusion. The effects can be appropriately assessed from a probabilistic sense to take into account the scattering regularity of test data and the size of sampling. (author)

  2. Assessment of postoperative pain after reciprocating or rotary NiTi instrumentation of root canals: a randomized, controlled clinical trial.

    Science.gov (United States)

    Relvas, João Bosko Formigas; Bastos, Mariana Mena Barreto; Marques, André Augusto Franco; Garrido, Angela Delfina Bitencourt; Sponchiado, Emílio Carlos

    2016-11-01

    The aim of this study was to assess postoperative pain in a prospective randomized clinical trial comparing two groups, using the Reciproc® system in one group and the ProTaper® rotary system in the other. The study included 78 male patients, aged 18-64 years (mean age of 26 years), with asymptomatic pulp necrosis in mandibular molar teeth (n = 78). The single-session endodontic treatment was performed by a single operator specialized in Endodontics. Mechanical preparation of the root canals was performed using the ProTaper® and Reciproc® instrumentation techniques. Postoperative pain was recorded using a verbal rating scale (VRS) and verbal description with well-defined categories at the three following time intervals: 24 h, 72 h, and 7 days after the endodontic procedure. The assessment of postoperative pain was recorded as no pain, mild pain, moderate pain, and severe pain or flare-up. Data were analyzed using the nonparametric Mann-Whitney test with the aid of the STATA® software. The incidence of postoperative pain in the ProTaper group (PT) 24 h after the endodontic procedure was 17.9 and 5.1 % after 72 h. In the Reciproc group (RP), the incidence after 24 h was 15.3 and 2.5 % after 72 h. No patients presented severe pain at the time intervals assessed. No significant difference (p > 0.05) in postoperative pain was found between the ProTaper® and Reciproc® instrumentation technique during endodontic treatment in this study. According to our findings and the results of the clinical trial, the occurrence of postoperative pain was low and similar between the reciprocating and rotary techniques during the time intervals assessed. These results are different from basic laboratory studies that affirm that the reciprocating techniques tend to promote more postoperative pain since extrusion of debris is greater.

  3. Nonlinear generalization of the quasiparticle random phase approximation for description of anharmonic effects in vibrational spectra: Application to the even Ni isotopes

    International Nuclear Information System (INIS)

    Li, C.T.; Klein, A.

    1979-01-01

    The theory of anharmonic nuclear vibrational motion (nonlinear equations-of-motion method) developed in the preceding paper is applied to atsup 60,62,64atNi, which exhibit one and two phonon quadrupole collective states. A model Hamiltonian consisting of a modified pairing plus quadrupole interaction is studied first by comparing the results of the nonlinear equations-of-motion method with those of an exact diagonalization. Contrary to popular opinion, the model chosen fails to produce a vibrational spectrum, except in the case of 60 Ni, and as a consequence, the nonlinear equations-of-motion method, designed specifically to describe vibrational spectra, accords well with the exact calculations only for this case. A simple method is then described, within the framework of the nonlinear equations-of-motion method, for refining the model Hamiltonian so as to bring it into accord with experiment. In practice, it is found that a simple additional parameter in the Hamiltonian suffices to yield descriptions of the quadrupole states in Ni isotopes comparable in precision to the most up-to-date versions (modified, adjusted, etc.) of the surface delta interaction model

  4. Magnetic field induced random pulse trains of magnetic and acoustic noises in martensitic single-crystal Ni2MnGa

    Science.gov (United States)

    Daróczi, Lajos; Piros, Eszter; Tóth, László Z.; Beke, Dezső L.

    2017-07-01

    Jerky magnetic and acoustic noises were evoked in a single variant martensitic Ni2MnGa single crystal (produced by uniaxial compression) by application of an external magnetic field along the hard magnetization direction. It is shown that after reaching the detwinning threshold, spontaneous reorientation of martensite variants (twins) leads not only to acoustic emission but magnetic two-directional noises as well. At small magnetic fields, below the above threshold, unidirectional magnetic emission is also observed and attributed to a Barkhausen-type noise due to magnetic domain wall motions during magnetization along the hard direction. After the above first run, in cycles of decreasing and increasing magnetic field, at low-field values, weak, unidirectional Barkhausen noise is detected and attributed to the discontinuous motion of domain walls during magnetization along the easy magnetization direction. The magnetic noise is also measured by constraining the sample in the same initial variant state along the hard direction and, after the unidirectional noise (as obtained also in the first run), a two-directional noise package is developed and it is attributed to domain rotations. From the statistical analysis of the above noises, the critical exponents, characterizing the power-law behavior, are calculated and compared with each other and with the literature data. Time correlations within the magnetic as well as acoustic signals lead to a common scaled power function (with β =-1.25 exponent) for both types of signals.

  5. Improvement of thermoelectric properties for half-Heusler TiNiSn by interstitial Ni defects

    International Nuclear Information System (INIS)

    Hazama, Hirofumi; Matsubara, Masato; Asahi, Ryoji; Takeuchi, Tsunehiro

    2011-01-01

    We have synthesized off-stoichiometric Ti-Ni-Sn half-Heusler thermoelectrics in order to investigate the relation between randomly distributed defects and thermoelectric properties. A small change in the composition of Ti-Ni-Sn causes a remarkable change in the thermal conductivity. An excess content of Ni realizes a low thermal conductivity of 2.93 W/mK at room temperature while keeping a high power factor. The low thermal conductivity originates in the defects generated by an excess content of Ni. To investigate the detailed defect structure, we have performed first-principles calculations and compared with x ray photoemission spectroscopy measurement. Based on these analyses, we conclude that the excess Ni atoms randomly occupy the vacant sites in the half-Heusler structure, which play as phonon scattering centers, resulting in significant improvement of the figure of merit without any substitutions of expensive heavy elements, such as Zr and Hf.

  6. Pain and discomfort experienced after placement of a conventional or a superelastic NiTi aligning archwire. A randomized clinical trial.

    Science.gov (United States)

    Fernandes, L M; Ogaard, B; Skoglund, L

    1998-01-01

    Two nickel-titanium arch-wire types commonly used for initial tooth alignment were compared with regard to the pain/discomfort patients experience during the initial phase of tooth movement. The two arch wires used were a superelastic nickel-titanium alloy, 0.014 inch Sentalloy, Light (GAC International Inc. Central Islip, NY, USA) and a 0.014 inch Nitinol (Unitek, Monrovia, CA, USA), a conventional nickel-titanium aligning archwire. One hundred and twenty-eight consecutive patients attending an orthodontic university clinic and 2 private practices for routine placement of a fixed appliance were randomly assigned one of these 2 initial arch wires. Assessments of pain/discomfort were made daily by means of a 100 mm visual analog scale (VAS) over the first 7-day period after bonding. On the first day, recordings were made every hour for the first 11 hours. The results showed that the level of discomfort increased continuously every hour after the insertion of either a Sentalloy or a Nitinol as first arch wires, with a peak in the first night, remaining high on the second day and decreasing thereafter to baseline level after 7 days. During the first 10 hours it was apparent that the pain/discomfort experienced after placement of a Sentalloy was less than that found with the Nitinol archwire, although a significant difference could be found at 4 hours only. No significant gender-specific differences were found in either archwire group. A significant difference between the upper and lower dental arches was observed during the first 11 hours after placement of either a Sentalloy or a Nitinol arch wire, with the lower arch having the higher pain experience.

  7. Ni hombres ni mujeres providenciales

    OpenAIRE

    Montaño Virreira, Sonia

    2000-01-01

    Debo advertir a la y el lector de este texto que lo que a continuación se presenta no es, ni de lejos, una propuesta realista, si por ella entendemos la traducción, enclave mujer, de las actuales tendencias de liderazgo político vigentes en la región. Por el contrario, intento argumentaren favor de un liderazgo que supere el caudillismo como estilo y se aproxime al máximo hacia el respeto de las formas, entendiendo que sin ellas no es posible construir la democracia. Para hacerlo reviso rápid...

  8. Decay of 57Ni

    International Nuclear Information System (INIS)

    Santos Scardino, A.M. dos.

    1987-01-01

    The decay of 57 Ni to 57 Co was studied by gamma ray spectroscopy using both singles and coincidence spectra. The sources were obtained with the 58 Ni (Y,n) 57 Ni reaction. Natural metallic nickel was irradiated in the bremsstrahluhng beam of the linear accelerator of the Instituto de Fisica da Universidade de Sao Paulo with 30 MeV electrons. The singles espectra were taken with 104 cc HPGe detector and the coincidences espectra with 27 and 53cc Ge(Li) and 104 cc. HPGe detectors. The energies of transitions that follow the 57 Ni decay were measured using 56 Co as standard (which was obtained by (Y,np) reaction in 58 Ni) and taking into account the cascade cross-over relations. (author) [pt

  9. Electrical Conductivity of Ni-YSZ Anode for SOFCs According to the Ni Powder Size Variations in Core-shell Structure

    International Nuclear Information System (INIS)

    Kang, Young Jin; Jung, Sung-Hun; An, Yong-Tae; Choi, Byung-Hyun; Ji, Mi-Jung

    2015-01-01

    Ni-YSZ (Y_2O_3-stabilized ZrO_2) core-shell structures were prepared by a high-speed mixing method, starting from Ni particles of three different average sizes of 0.2, 0.4, and 1.8 μm. The Ni-YSZ core-shell structures prepared using Ni particles of size 0.2, 0.4, and 1.8 μm exhibited dense core, porous core, and random-morphology core, respectively. Subsequently, nano structured cermet anodes were fabricated using the prepared Ni-YSZ core-shell powders. During the formation of cermet, the heat treatment of Ni-YSZ core-shell powder results in the eruption of Ni core out of the YSZ shell layers, thereby facilitating the formation of nano structured Ni-YSZ cermet. Systematic studies indicated that the morphology and electrical conductivity of the prepared Ni-YSZ core-shell powders and the cermet anode varied, depending on the initial particle size of the Ni particles. Of the different samples prepared in this study, the Ni-YSZ cermet prepared using Ni particles of size 0.4 μm showed the highest electrical conductivity at 750 ℃.

  10. Electrical Conductivity of Ni-YSZ Anode for SOFCs According to the Ni Powder Size Variations in Core-shell Structure

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Young Jin; Jung, Sung-Hun; An, Yong-Tae; Choi, Byung-Hyun; Ji, Mi-Jung [Korea Institute of Ceramic Engineering and Technology (KICET), Seoul (Korea, Republic of)

    2015-04-15

    Ni-YSZ (Y{sub 2}O{sub 3}-stabilized ZrO{sub 2}) core-shell structures were prepared by a high-speed mixing method, starting from Ni particles of three different average sizes of 0.2, 0.4, and 1.8 μm. The Ni-YSZ core-shell structures prepared using Ni particles of size 0.2, 0.4, and 1.8 μm exhibited dense core, porous core, and random-morphology core, respectively. Subsequently, nano structured cermet anodes were fabricated using the prepared Ni-YSZ core-shell powders. During the formation of cermet, the heat treatment of Ni-YSZ core-shell powder results in the eruption of Ni core out of the YSZ shell layers, thereby facilitating the formation of nano structured Ni-YSZ cermet. Systematic studies indicated that the morphology and electrical conductivity of the prepared Ni-YSZ core-shell powders and the cermet anode varied, depending on the initial particle size of the Ni particles. Of the different samples prepared in this study, the Ni-YSZ cermet prepared using Ni particles of size 0.4 μm showed the highest electrical conductivity at 750 ℃.

  11. Bridging exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rinaldi-Montes, Natalia, E-mail: nataliarin@gmail.com [Departamento de Física, Universidad de Oviedo, E-33007 Oviedo (Spain); Gorria, Pedro [Departamento de Física & IUTA, EPI, Universidad de Oviedo, E-33203 Gijón (Spain); Martínez-Blanco, David [Servicios Científico-Técnicos, Universidad de Oviedo, E-33006 Oviedo (Spain); Fuertes, Antonio B. [Instituto Nacional del Carbón, CSIC, E-33080 Oviedo (Spain); Fernández Barquín, Luis [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, E-39005 Santander (Spain); Puente-Orench, Inés [Instituto de Ciencia de Materiales de Aragón, CSIC-Universidad de Zaragoza and Institut Laue-Langevin, BP 156, F-38042 Grenoble Cedex 9 (France); Blanco, Jesús A. [Departamento de Física, Universidad de Oviedo, E-33007 Oviedo (Spain)

    2016-02-15

    Among all bi-magnetic core(transition metal)@shell(transition metal oxide) nanoparticles (NPs), Ni@NiO ones show an onset temperature for the exchange bias (EB) effect far below the Néel temperature of bulk antiferromagnetic NiO. In this framework, the role played by the magnetism of NiO at the nanoscale is investigated by comparing the microstructure and magnetic properties of NiO and Ni@NiO NPs. With the aim of bridging the two systems, the diameter of the NiO NPs (~4 nm) is chosen to be comparable to the shell thickness of Ni@NiO ones (~2 nm). The EB effect in Ni@NiO NPs is attributed to the exchange coupling between the core and the shell, with an interfacial exchange energy of ΔE~0.06 erg cm{sup −2}, thus comparable to previous reports on Ni/NiO interfaces both in thin film and NP morphologies. In contrast, the EB detected in NiO NPs is explained in a picture where uncompensated spins located on a magnetically disordered surface shell are exchange coupled to the antiferromagnetic core. In all the studied NPs, the variation of the EB field as a function of temperature is described according to a negative exponential law with a similar decay constant, yielding a vanishing EB effect around T~40–50 K. In addition, the onset temperature for the EB effect in both NiO and Ni@NiO NPs seems to follow a universal dependence with the NiO crystallite size. - Highlights: • Comparison of the exchange bias effect in NiO and Ni(core)@NiO(shell) nanoparticles. • Universal temperature dependence of the exchange bias effect. • Suggested similar physical origin of the effect in both systems. • Size and crystallinity of the NiO shell hold the key for exchange bias properties.

  12. OpenNI cookbook

    CERN Document Server

    Falahati, Soroush

    2013-01-01

    This is a Cookbook with plenty of practical recipes enriched with explained code and relevant screenshots to ease your learning curve. If you are a beginner or a professional in NIUI and want to write serious applications or games, then this book is for you. Even OpenNI 1 and OpenNI 1.x programmers who want to move to new versions of OpenNI can use this book as a starting point. This book uses C++ as the primary language but there are some examples in C# and Java too, so you need to have about a basic working knowledge of C or C++ for most cases.

  13. Critical Properties of Pure and Random Antiferromagnets

    DEFF Research Database (Denmark)

    Cowley, R. A.; Carneiro, K.

    1980-01-01

    Neutron scattering techniques have been used to study the critical properties of CoF2 and the randomly mixed systems: Co/ZnF2 and KMn/NiF3. The results for CoF2 are in excellent accord with the critical properties of the three-dimensional Ising model. In all of the random crystals studied the tra...

  14. Gd-Ni-Si system

    International Nuclear Information System (INIS)

    Bodak, O.I.; Shvets, A.F.

    1983-01-01

    By X-ray phase analysis method isothermal cross section of phase diagram of the Gd-Ni-Si system at 870 K is studied. The existence of nine previously known compounds (GdNisub(6.72)Sisub(6.28), GdNi 10 Si 2 , GdNi 5 Si 3 , GdNi 4 Si, GdNi 2 Si 2 , GdNiSi 3 , GdNiSi 2 , Gd 3 Ni 6 Si 2 and GdNiSi) is confirmed and three new compounds (GdNisub(0.2)Sisub(1.8), Gdsub(2)Nisub(1-0.8)Sisub(1-1.2), Gd 5 NiSi 4 ) are found. On the base of Gd 2 Si 3 compound up to 0.15 at. Ni fractions, an interstitial solid solution is formed up to 0.25 at Ni fractions dissolution continues of substitution type. The Gd-Ni-Si system is similar to the Y-Ni-Si system

  15. Internal carbonitriding behavior of Ni-V, Ni-Cr, and Ni-3Nb alloys

    International Nuclear Information System (INIS)

    Allen, A.T.; Douglass, D.L.

    1999-01-01

    Ni-2V, Ni-5V, Ni-12V, Ni-10Cr, Ni-20Cr, and Ni-3Nb alloys were carbonitrided in C 3 H 6 and NH 3 gas mixtures (bal H 2 ) over the range 700--1,000 C. Carbonitridation of Ni-12V and Ni-20Cr in C 3 H 6 /NH 3 /H 2 (1.5/1.5/97 v/o) and (1.5/10/88.5 v/o) produced duplex subscales consisting of near-surface nitrides with underlying carbides. Growth of each zone obeyed the parabolic rate law under most conditions. The presence of carbon generally did not effect the depth of the nitride zones compared to nitriding the alloys in NH 3 /H 2 (10/90 v/o). However, at 700 C, the nitride zones were deeper in the carbonitrided Ni-V alloys and Ni-20Cr. The presence of nitrogen generally increased the depth of the carbide zones in Ni-12V and Ni-20Cr compared to carburizing these alloys in C 3 H 6 /H 2 (1.5/98.5 v/o). VN, CrN, and NbN formed in Ni-V, Ni-Cr, and Ni-Nb alloys, respectively, whereas the underlying carbide layers contained V 4 C 3 in Ni-12V, Cr 3 C 2 above a zone of Cr 7 C 3 in Ni-20Cr, and NbC in Ni-3Nb. The solubilities and diffusivities of nitrogen and carbon in nickel were determined. Nitrogen and carbon each exhibited retrograde solubility with temperature in pure Ni in both carbonitriding environments. Nitrogen diffusion in nickel was generally lower in each carbonitriding mixture compared to nitrogen diffusion in a nitriding environment, except at 700 C when nitrogen diffusion was higher. Carbon diffusion in nickel was generally higher in the carbonitriding environments compared to carbon diffusion in a carburizing environment

  16. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  17. Calculated orientation dependence of surface segregations in Pt50Ni50

    DEFF Research Database (Denmark)

    Abrikosov, I. A.; Ruban, Andrei; Skriver, Hans Lomholt

    1994-01-01

    We present local-density calculations of surface segregation profiles in a random Pt50Ni50 alloy. We find that the concentration profiles of the three low-index surfaces oscillate and that the two most closely packed surfaces, i.e., (111) and (100), are enriched by Pt while Ni is found to segrega...

  18. Nipah Virus (NiV)

    Science.gov (United States)

    ... Form Controls Cancel Submit Search the CDC Nipah Virus (NiV) Note: Javascript is disabled or is not ... gov . Recommend on Facebook Tweet Share Compartir Nipah virus (NiV) is a member of the family Paramyxoviridae , ...

  19. Ni República parlamentaria ni presidencialista

    OpenAIRE

    Álvarez Tardío, Manuel

    2004-01-01

    Revista de Estudios Políticos (Nueva Época), Núm. 123. Enero-Marzo 2004 Este trabajo está dedicado al estudio de un aspecto básico del sistema político de la II República española (1931-1936): el modelo de presidencia de la República y de relaciones de la misma con el parlamento y el gobierno. Aquí se sostiene que la Segunda República, de acuerdo con su Constitución, no fue un régimen parlamentario ni presidencial. Combinó de forma extraña y ambigua elementos de ambos modelos. Probablement...

  20. Random walk on random walks

    NARCIS (Netherlands)

    Hilário, M.; Hollander, den W.Th.F.; Sidoravicius, V.; Soares dos Santos, R.; Teixeira, A.

    2014-01-01

    In this paper we study a random walk in a one-dimensional dynamic random environment consisting of a collection of independent particles performing simple symmetric random walks in a Poisson equilibrium with density ¿¿(0,8). At each step the random walk performs a nearest-neighbour jump, moving to

  1. Microstructural development in NiAl/Ni-Si-B/Ni transient liquid phase bonds

    International Nuclear Information System (INIS)

    Gale, W.F.; Orel, S.V.

    1996-01-01

    A transmission electron microscopy (TEM) based investigation of microstructural development during transient liquid phase bonding of near-stoichiometric NiAl to commercial purity nickel is presented in this article. The work described employed Ni-4.5 wt pct Si-3.2 wt pct B (BNi-3) melt-spun interlayers. The precipitation of both Ni-Al based phases and borides within the joint and adjacent substrate regions is discussed. The article considers martensite formation (within the NiAl substrate) and the precipitation of L1 2 type phases (both within the joint and at the interface with the NiAl substrate). The relative roles of the two substrate materials (NiAl and Ni) in the isothermal resolidification process are identified. The preferential formation of Ni 3 B boride phases in the Ni substrate near the original location of the Ni substrate-joint interface is discussed and contrasted with the absence of similar events in the NiAl substrate

  2. A cluster-randomized controlled trial of handrubs for prevention of infectious diseases among children in Colombia Ensayo controlado aleatorizado por conglomerados sobre el uso de antisépticos para las manos para la prevención de enfermedades infecciosas en los niños en Colombia

    Directory of Open Access Journals (Sweden)

    Juan C. Correa

    2012-06-01

    Full Text Available OBJECTIVE: To evaluate the effectiveness of alcohol-based handrubs (ABH in reducing acute diarrheal diseases (ADD and acute respiratory infections (ARI among children 1-5 years of age in childcare centers with limited tap water. METHODS: This was the first cluster-randomized controlled trial in a developing country. The study took place at 42 childcare centers with sporadic and limited water availability in six towns in Colombia. Participants were randomly assigned to use ABH as a complement to handwashing (intervention arm: 21 centers/794 children; or to continue existing handwashing practices (control arm: 21 centers/933 children. ADD and ARI cases were identified through teacher-reported signs and symptoms of illness. Adverse events were monitored. Hazard ratios (HR were obtained using Cox proportional hazards multivariate regression shared frailty models. RESULTS: Child-days of surveillance totaled 336 038. Loss to follow up was 14.5%. For both ADD and ARI, there were no differences in hazard ratios during the first trimester of the study. In the second and third trimesters, significant reductions in the risk of ADD were found in the intervention compared to control arm (HR = 0.55, P OBJETIVO: Evaluar la eficacia del uso de antisépticos para las manos a base de alcohol en la disminución de las enfermedades diarreicas agudas y las infecciones respiratorias agudas en niños de 1 a 5 años de edad en los centros de atención infantil donde el lavado de las manos con agua y jabón no es factible. MÉTODOS. El presente fue el primer ensayo controlado y aleatorizado por conglomerados llevado a cabo en un país en desarrollo. El estudio tuvo lugar en 42 centros de atención infantil con disponibilidad de agua esporádica y limitada ubicados en seis ciudades de Colombia. Se asignó aleatoriamente a los participantes a usar antisépticos a base de alcohol como complemento del lavado de las manos (grupo de intervención: 21 centros/794 niños o a

  3. Ni landsbyer i Danmark

    DEFF Research Database (Denmark)

    Larsen, Jacob Norvig

    Denne rapport beskriver en evaluering af statsstøttede forsøg med at styrke og udvikle mindre lokalsamfund. Forsøgene er gennemført i ni kommuner. Da der i disse år er stor opmærksomhed om de små byers og samfunds udviklingsmuligheder, har erfaringerne fra forsøgsprojekterne bred interesse. Forsø...

  4. Random magnetism

    International Nuclear Information System (INIS)

    Tahir-Kheli, R.A.

    1975-01-01

    A few simple problems relating to random magnetic systems are presented. Translational symmetry, only on the macroscopic scale, is assumed for these systems. A random set of parameters, on the microscopic scale, for the various regions of these systems is also assumed. A probability distribution for randomness is obeyed. Knowledge of the form of these probability distributions, is assumed in all cases [pt

  5. Radiation-induced segregation behavior in random and ordered face-centered cubic materials

    International Nuclear Information System (INIS)

    Bui, T.X.; Robertson, I.M.; Klatt, J.L.; Averback, R.S.; Kirk, M.A.

    1993-01-01

    Radiation-induced segregation has been studied in random solid solution alloys Ni-10%Al and Ni-6%Si, and in the ordered (L1 2 structure) intermetallics Ni 3 Si and Ni 3 Al. These materials were irradiated with 2 MeV He + ions at a temperature between 0.45 and 0.55T m and at an ion dose rate of approximately 1x10 -4 dpa per second. Subsequent Auger Electron Spectroscopy analysis showed that silicon segregated to the surface in the Ni-6% Si and Ni 3 Si alloys, and aluminum segregated away from the near surface region in the Ni-10% Al alloy. The Ni 3 Al samples exhibited no detectable segregation with respect to depth from the sample surface. The mechanisms that may give rise to this resistance to radiation induced segregation will be examined in terms of the mobility of the alloying constituents, ordering energies and atomic sizes. (orig.)

  6. Reduction mechanism of Ni2+ into Ni nanoparticles prepared from ...

    Indian Academy of Sciences (India)

    journal of. March 2009 physics pp. 577–586. Reduction mechanism of Ni2+ into Ni ..... and at high field, no domain wall is available and hence, the system becomes a .... [23] J Ding, T Tsuzuki, P G McCormick and R Street, J. Phys. D: Appl.

  7. Randomized random walk on a random walk

    International Nuclear Information System (INIS)

    Lee, P.A.

    1983-06-01

    This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time according to the occurrences of a stochastic point process. The probability of finding the particle in a particular position at a certain instant is obtained explicitly in the transform domain. It is found that the asymptotic behaviour for large time of the mean-square displacement of the particle depends critically on the assumed structure of the basic random walk, giving a diffusion-like term for an asymmetric walk or a square root law if the walk is symmetric. Many results are obtained in closed form for the Poisson process case, and these agree with those given previously by Kehr and Kunter. (author)

  8. Facile synthesis and microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere and multi-shelled NiO hollow sphere

    International Nuclear Information System (INIS)

    Wu, Hongjing; Wu, Guanglei; Wu, Qiaofeng; Wang, Liuding

    2014-01-01

    We reported the preparation of C@Ni–NiO core–shell hybrid solid spheres or multi-shelled NiO hollow spheres by combining a facile hydrothermal route with a calcination process in H 2 or air atmosphere, respectively. The synthesized C@Ni–NiO core–shell solid spheres with diameters of approximately 2–6 μm were in fact built from dense NiO nanoparticles coated by random two-dimensional metal Ni nanosheets without any visible pores. The multi-shelled NiO hollow spheres were built from particle-like ligaments and there are a lot of pores with size of several nanometers on the surface. Combined Raman spectra with X-ray photoelectron spectra (XPS), it suggested that the defects in the samples play a limited role in the dielectric loss. Compared with the other samples, the permeability of the samples calcined in H 2 and air was increased slightly and the natural resonance frequency shifted to higher frequency (7, 11 and 14 GHz, respectively), leading to an enhancement of microwave absorption property. For the sample calcined in H 2 , an optimal reflection loss less than − 10 was obtained at 7 GHz with a matching thickness of 5.0 mm. Our study demonstrated the potential application of C@Ni–NiO core–shell hybrid solid sphere or multi-shelled NiO hollow sphere as a more efficient electromagnetic (EM) wave absorber. - Highlights: • C@Ni–NiO core–shell hybrid solid sphere was synthesized by a facile method. • Multi-shelled NiO hollow sphere was synthesized by a facile method. • It suggested that the defects in the samples play a limited role in dielectric loss. • The permeability of the samples calcined in H 2 and air was increased. • Microwave absorbability of C@Ni–NiO core–shell hybrid solid sphere was investigated

  9. Reactive Ni/Ti nanolaminates

    International Nuclear Information System (INIS)

    Adams, D. P.; Bai, M. M.; Rodriguez, M. A.; McDonald, J. P.; Jones, E. Jr.; Brewer, L.; Moore, J. J.

    2009-01-01

    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 ∼0.1 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 ig )∼300-400 deg. C for nanolaminates. Ignition temperature was influenced by bilayer thickness with more coarse laminate designs exhibiting increased T 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 ' NiTi (martensite), hexagonal NiTi 2 , and B2 NiTi. Single-phase, cubic B2 NiTi generally formed when the initial bilayer thickness was made small.

  10. Electroplated Ni on the PN Junction Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm{sup 2}. The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased.

  11. Electroplated Ni on the PN Junction Semiconductor

    International Nuclear Information System (INIS)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae

    2015-01-01

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm 2 . The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased

  12. Effect of Ca, Ce or K oxide addition on the activity of Ni/SiO{sub 2} catalysts for the methane decomposition reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Beatriz; Torres-Garcia, Enelio [Instituto Mexicano del Petroleo, Programa de Procesos y Reactores, Eje C. 152, Mexico, D.F., C.P. 07730 (Mexico); Valenzuela, Miguel A.; Palacios, Jorge [Instituto Politecnico Nacional-ESIQIE, Lab. Catalisis y Materiales, Zacatenco, Mexico, D.F., C.P. 07738 (Mexico)

    2010-11-15

    To increase the activity and stability of Ni/SiO{sub 2} catalysts, a series of Ni-Ca, Ni-K and Ni-Ce promoted catalysts were prepared by successive impregnations. The textural properties, reducibility and catalytic performance in the methane decomposition reaction were investigated. The catalyst containing 30 wt.% Ni and 30 wt.% cerium oxide greatly increased the conversion of methane (90% of equilibrium value) and improved the stability, whereas the Ni-K and Ni-Ca were less active and stable than the Ni/SiO{sub 2} catalyst. The results suggest that Ce addition prevents the sintering of nickel particles during reduction process maintaining a random distribution between the silica and cerium oxide improving the distribution and migration of deposited carbon. (author)

  13. Neutron components of isoscalar giant quadrupole resonance states in 58,60,62,64Ni

    International Nuclear Information System (INIS)

    Antalik, R.

    1989-01-01

    The neutron-proton matrix element ratios (η) for isoscalar giant quadrupole resonance states of even Ni isotopes are investigated within the framework of the shell model quasiparticle random-phase approximation. The dependence of η ratios on radial neutron and proton ground state density distribution differences (Δ np ) is found to be about 1.0-1.5 Δ np . The theoretical η ratios are 14-23% lower than the hydrodynamical limit. The agreement between theoretical and experimental η ratios is observed for 58 Ni and 60 Ni isotopes. The η ratios for 62 Ni and 64 Ni suggested by the resonance π ± inelastic scattering cannot be interpreted even including the radial variations of the neutron fields. 18 refs.; 3 tabs

  14. Random Fields

    Science.gov (United States)

    Vanmarcke, Erik

    1983-03-01

    Random variation over space and time is one of the few attributes that might safely be predicted as characterizing almost any given complex system. Random fields or "distributed disorder systems" confront astronomers, physicists, geologists, meteorologists, biologists, and other natural scientists. They appear in the artifacts developed by electrical, mechanical, civil, and other engineers. They even underlie the processes of social and economic change. The purpose of this book is to bring together existing and new methodologies of random field theory and indicate how they can be applied to these diverse areas where a "deterministic treatment is inefficient and conventional statistics insufficient." Many new results and methods are included. After outlining the extent and characteristics of the random field approach, the book reviews the classical theory of multidimensional random processes and introduces basic probability concepts and methods in the random field context. It next gives a concise amount of the second-order analysis of homogeneous random fields, in both the space-time domain and the wave number-frequency domain. This is followed by a chapter on spectral moments and related measures of disorder and on level excursions and extremes of Gaussian and related random fields. After developing a new framework of analysis based on local averages of one-, two-, and n-dimensional processes, the book concludes with a chapter discussing ramifications in the important areas of estimation, prediction, and control. The mathematical prerequisite has been held to basic college-level calculus.

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

    International Nuclear Information System (INIS)

    Gupta, Vinay; Kawaguchi, Toshikazu; Miura, Norio

    2009-01-01

    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 3 O 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 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

  16. Residual resistivity and its anisotropy in random CoNi and CuNi ferromagnetic alloys

    Czech Academy of Sciences Publication Activity Database

    Turek, Ilja; Záležák, Tomáš

    2010-01-01

    Roč. 200, č. 5 (2010), 052029/1-052029/4 ISSN 1742-6588. [International Conference on Magnetism - ICM 2009. Karlsruhe, 26.07.2009-31.07.2009] Institutional research plan: CEZ:AV0Z20410507 Keywords : residual resistivity * anisotropic magnetoresistance * ferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism

  17. Preparation and electrochemical characteristics of porous hollow spheres of NiO nanosheets as electrodes of supercapacitors

    Science.gov (United States)

    Yu, Wei; Jiang, Xinbing; Ding, Shujiang; Li, Ben Q.

    2014-06-01

    Porous hollow nanospheres (or spherical shells) made of NiO nanosheets are synthesized and tested for the electrochemical performance of the electrodes made of these materials for supercapacitors. Preparation of the NiO sheet hollow spheres starts with synthesis of polystyrene nanospheres with carboxyl groups (CPS), followed by a two-step activation procedure and the subsequent nucleation and growth by electroless deposition of Ni on the CPS core to obtain CPS@Ni core-shell nanoparticles. The CPS core is eliminated and metallic Ni nanoshell is converted into NiO by calcinations at high temperatures. The material properties of as-prepared hollow NiO nanospheres are characterized by TEM, XRD and N2-absorption measurements. The electrochemical characteristics of the electrodes made of these nanostructured NiO materials are determined by the CV and galvanostatic measurements. These electrochemical tests indicate that electrodes made of the NiO nanosheet hollow spheres exhibit an improved reversible capacitance of 600 F g-1 after 1000 cycles at a high current density of 10 A g-1. It is believed that the good electrochemical performance of these electrodes is attributed to the improved OH- transport in the porous network structures associated with the hollow spheres of randomly oriented NiO nanosheets.

  18. Radiochemical method for 63Ni

    International Nuclear Information System (INIS)

    Holm, E.; Nilsson, U.; Hallstadius, L.

    1985-01-01

    A radianalytical method for the determination of 63 Ni content in environmental samples of activated corrosion products is described. After chemical separation and electrodepositing of 63 Ni on silver briquets, the chemical yield is determined by X-ray fluorescence analysis. For the detection of low-energy beta activity, an open gas flow GM-counter with an anticoincidence guard counter is put to use

  19. Random Generators and Normal Numbers

    OpenAIRE

    Bailey, David H.; Crandall, Richard E.

    2002-01-01

    Pursuant to the authors' previous chaotic-dynamical model for random digits of fundamental constants, we investigate a complementary, statistical picture in which pseudorandom number generators (PRNGs) are central. Some rigorous results are achieved: We establish b-normality for constants of the form $\\sum_i 1/(b^{m_i} c^{n_i})$ for certain sequences $(m_i), (n_i)$ of integers. This work unifies and extends previously known classes of explicit normals. We prove that for coprime $b,c>1$ the...

  20. Electronic structure of Ni/sub 3/Al and Ni/sub 3/Ga alloys

    CERN Document Server

    Pong, W F; Chang, Y K; Tsai, M H; Hsieh, H H; Pieh, J Y; Tseng, P K; Lee, J F; Hsu, L S

    1999-01-01

    This work investigates the charge transfer and Al(Ga) p-Ni d hybridization effects in the intermetallic Ni/sub 3/Al(Ni/sub 3/Ga) alloy using the NiL/sub 3.2/- and K-edge and Al(Ga)K X-ray absorption near edge structure (XANES) measurements. We find that the intensity of white-line features at the NiL/sub 3.2/-edge in the Ni/sub 3/Al(Ni /sub 3/Ga) alloy decreased in comparison with that of pure Ni, which can be attributed to the enhancement of Ni3d states filling and the depletion of the density of Ni 3d unoccupied states in the Ni/sub 3 /Al(Ni/sub 3/Ga) alloy. Two clear features are also observed in the Ni/sub 3/Al(Ni/sub 3/Ga) XANES spectrum at the Al(Ga) K-edge, which can be assigned to the Al(Ga) unoccupied 3p (4p) states and their hybridized states with the Ni 3d/4sp states above the Fermi level in Ni/sub 3/Al(Ni/sub 3/Ga). The threshold at Al K-edge XANES for Ni/sub 3/Al clearly shifts towards higher photon energies relative to that of pure Al, indicating that Al loses charges upon forming Ni/sub 3 /Al. ...

  1. Nitriding behavior of Ni and Ni-based binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fonovic, Matej

    2015-01-15

    Gaseous nitriding is a prominent thermochemical surface treatment process which can improve various properties of metallic materials such as mechanical, tribological and/or corrosion properties. This process is predominantly performed by applying NH{sub 3}+H{sub 2} containing gas atmospheres serving as the nitrogen donating medium at temperatures between 673 K and 873 K (400 C and 600 C). NH{sub 3} decomposes at the surface of the metallic specimen and nitrogen diffuses into the surface adjacent region of the specimen whereas hydrogen remains in the gas atmosphere. One of the most important parameters characterizing a gaseous nitriding process is the so-called nitriding potential (r{sub N}) which determines the chemical potential of nitrogen provided by the gas phase. The nitriding potential is defined as r{sub N} = p{sub NH{sub 3}}/p{sub H{sub 2}{sup 3/2}} where p{sub NH{sub 3}} and p{sub H{sub 2}} are the partial pressures of the NH{sub 3} and H{sub 2} in the nitriding atmosphere. In contrast with nitriding of α-Fe where the nitriding potential is usually in the range between 0.01 and 1 atm{sup -1/2}, nitriding of Ni and Ni-based alloys requires employing nitriding potentials higher than 100 atm{sup -1/2} and even up to ∞ (nitriding in pure NH{sub 3} atmosphere). This behavior is compatible with decreased thermodynamic stability of the 3d-metal nitrides with increasing atomic number. Depending on the nitriding conditions (temperature, nitriding potential and treatment time), different phases are formed at the surface of the Ni-based alloys. By applying very high nitriding potential, formation of hexagonal Ni{sub 3}N at the surface of the specimen (known as external nitriding) leads to the development of a compound layer, which may improve tribological properties. Underneath the Ni{sub 3}N compound layer, two possibilities exist: (i) alloying element precipitation within the nitrided zone (known as internal nitriding) and/or (ii) development of metastable and

  2. Ni4Ti3 precipitate structures in Ni-rich NiTi shape memory alloys

    International Nuclear Information System (INIS)

    Holec, D.; Bojda, O.; Dlouhy, A.

    2008-01-01

    Non-uniform distributions of Ni 4 Ti 3 precipitate crystallographic variants are investigated in a Ni-rich NiTi shape memory alloy after aging, assisted by external stress. A finite-element method model is presented that considers the elastic anisotropy of the B2 parent phase and also mutual misorientations of grains in a polycrystalline sample. On loading by the external stress, the stress is redistributed in the microstructure and the precipitation of some Ni 4 Ti 3 crystallographic variants becomes distinctly favorable in grain boundary regions since these variant configurations minimize the elastic interaction energy. The volume fraction of the affected grain boundary regions is calculated and the numerical results are compared with the data obtained by differential scanning calorimetry and transmission electron microscopy

  3. Ni4Ti3 precipitate structures in Ni-rich NiTi shape memory alloys

    Czech Academy of Sciences Publication Activity Database

    Holec, David; Bojda, Ondřej; Dlouhý, Antonín

    2008-01-01

    Roč. 481, Sp. Iss. (2008), s. 462-465 ISSN 0921-5093. [ESOMAT 2006. Bochum, 10.09.2006-15.09.2006] R&D Projects: GA ČR(CZ) GA106/05/0918 Institutional research plan: CEZ:AV0Z20410507 Keywords : NiTi shape memory alloys * Ni4Ti3 precipitates * Multi-step martensitic transformations Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.806, year: 2008

  4. Electronic structure of Ni-- and Ni2--ethylene cluster complexes

    International Nuclear Information System (INIS)

    Basch, H.; Newton, M.D.; Moskowitz, J.W.

    1978-01-01

    The electronic structure of metal cluster--ethylene complexes has been investigated by carrying out ab initio bonding pair-correlated, self-consistent field, and configuration interaction (CI) calculations on the NiC 2 H 4 and Ni 2 C 2 H 4 species. The π-NiC 2 H 4 and π-Ni 2 C 2 H 4 cluster complexes are found to be bound, the former only with CI, while disigma-Ni 2 C 2 H 4 has only a repulsive Ni 2 --C 2 H 4 ground state potential curve. The bonding in the π-type cluster complexes can be described as follows: The metal atom configuration is 3d 9 4s 1 with the 4s hybridized (by the metal 4p) away from the ethylene molecule, thereby allowing the π orbital to form a dative sigma bond with the metal atom. The bonding interaction is promoted by the presence of a second nickel atom behind the first one, leading to a 4s orbital electron deficiency of the bonded nickel atom and thus making this nickel atom a better electron acceptor. Back donation from the occupied metal 3d into the ethylene π* molecular orbital also takes place to some extent, and thus both features of the classical Dewar--Chatt--Duncanson model are observed. The π-Ni 2 C 2 H 4 species is analyzed in terms of the addition of a bare nickel atom to a π-NiC 2 H 4 cluster complex, with concomitant stabilization of the orbitals of the bonded nickel atom. A study of the excited electronic states of π-NiC 2 H 4 shows that low-lying 4s→π* and 3d→π* (M→L) charge transfer transitions are predicted. The former is not observed experimentally, probably due to the diffuse nature of the 4s orbital. The relationship between small cluster--ethylene complex systems and ethylene chemisorption on a nickel metal surface is discussed

  5. Random magnetism

    International Nuclear Information System (INIS)

    Tsallis, C.

    1980-03-01

    The 'ingredients' which control a phase transition in well defined system as well as in random ones (e.g. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' we find the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author) [pt

  6. Random magnetism

    International Nuclear Information System (INIS)

    Tsallis, C.

    1981-01-01

    The 'ingredients' which control a phase transition in well defined systems as well as in random ones (e.q. random magnetic systems) are listed and discussed within a somehow unifying perspective. Among these 'ingredients' the couplings and elements responsible for the cooperative phenomenon, the topological connectivity as well as possible topological incompatibilities, the influence of new degrees of freedom, the order parameter dimensionality, the ground state degeneracy and finally the 'quanticity' of the system are found. The general trends, though illustrated in magnetic systems, essentially hold for all phase transitions, and give a basis for connection of this area with Field theory, Theory of dynamical systems, etc. (Author) [pt

  7. Radioactive 63Ni in biological research

    International Nuclear Information System (INIS)

    Kasprzak, K.S.; Sunderman, F.W. Jr.

    1979-01-01

    Applications of 63 Ni in biological research are reviewed, with emphasis upon recent investigations of nickel metabolism and toxicology in experimental animals. The radiochemistry of 63 Ni is summarized, including consideration of the preparation of certain 63 Ni compounds (e.g. 63 Ni(CO) 4 and 63 Ni 3 S 2 ) that are of current interest in toxicology, teratology and cancer research. Practical guidance is given regarding the detection and determination of 63 Ni in biological materials by autoradiography and liquid scintillation spectrometry. (author)

  8. Superstructure of NiAs

    International Nuclear Information System (INIS)

    Nozue, Tatsuhiro; Kobayashi, Hisao; Kamimura, Takashi; Yamaguchi, Yasuo

    2001-01-01

    The structural transition in NiAs was studied by neutron diffraction on the single crystalline sample. The crystal structure of NiAs has been reported to be bottom-centered orthorhombic with Cmc2 1 symmetry (niccolite-type). The measurement of temperature dependence of the powder X-ray diffraction revealed that NiAs undergoes a structural transition to the NiAs-type at T t =335 K. In present neutron diffraction experiment at room temperature, we observed the reflections indexed on the basis of the orthorhombic unit cell. The intensities of these reflections are qualitatively explained in terms of the niccolite-type structure with taking account of three domain structures, except for the weak reflections indexed as (001), (003) and (012). Then, the intensities of (001), (002) and (004) reflections were measured in temperature range of 20 to 420 K. The temperature dependences of (002) and (004) reflections qualitatively agree with those of the calculated intensities using the atomic positions of niccolite-type structure. However, the temperature dependence of (001) reflection shows the anomaly around T t , which suggests the symmetry of crystal structure of NiAs is not the Cmc2 1 symmetry. (author)

  9. Critical Behaviour of a Two-Dimensional Random Antiferromagnet

    DEFF Research Database (Denmark)

    Als-Nielsen, Jens Aage; Birgeneau, R. J.; Guggenheim, H. J.

    1976-01-01

    A neutron scattering study of the order parameter, correlation length and staggered susceptibility of the two-dimensional random antiferromagnet Rb2Mn0.5Ni0.5F4 is reported. The system is found to exhibit a well-defined phase transition with critical exponents identical to those of the isomorphou...... pure materials K2NiF4 and K2MnF4. Thus, in these systems, which have the asymptotic critical behaviour of the two-dimensional Ising model, randomness has no measurable effect on the phase-transition behaviour....

  10. Thermal stability and electrical characteristics of NiSi films with electroplated Ni(W) alloy

    International Nuclear Information System (INIS)

    Xin Yuhang; Hu Anmin; Li Ming; Mao Dali

    2011-01-01

    In this study, an electroplating method to deposited Ni, crystalline NiW(c-NiW), amorphous NiW (a-NiW) films on P-type Si(1 0 0) were used to form Ni-silicide (NiSi) films. After annealed at various temperatures, sheet resistance of Ni/Cu, c-NiW/Cu and a-NiW/Cu was measured to observe the performance of those diffusion barrier layers. With W added in the barrier layer, the barrier performance was improved. The results of XRD and resistance measurement of the stacked Si/Ni(W)/Cu films reveal that Cu atom could diffuse through Ni barrier layer at 450 deg. C, could diffuse through c-NiW at 550 deg. C, but could hardly diffuse through a-NiW barrier layer. c-NiW layer has a better barrier performance than Ni layer, meanwhile the resistance is lower than a-NiW layer.

  11. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J.C.; Ibrahim, S.R.; Brincker, Rune

    Abstraet Thispaper demansirates how to use the Random Decrement (RD) technique for identification o flinear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing...

  12. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  13. Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Ibrahim, R.; Brincker, Rune

    1998-01-01

    This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...

  14. Random dynamics

    International Nuclear Information System (INIS)

    Bennett, D.L.; Brene, N.; Nielsen, H.B.

    1986-06-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model. (orig.)

  15. Random dynamics

    International Nuclear Information System (INIS)

    Bennett, D.L.

    1987-01-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: Gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model. (orig.)

  16. Random Dynamics

    Science.gov (United States)

    Bennett, D. L.; Brene, N.; Nielsen, H. B.

    1987-01-01

    The goal of random dynamics is the derivation of the laws of Nature as we know them (standard model) from inessential assumptions. The inessential assumptions made here are expressed as sets of general models at extremely high energies: gauge glass and spacetime foam. Both sets of models lead tentatively to the standard model.

  17. Giant magnetoimpedance effect in sputtered single layered NiFe film and meander NiFe/Cu/NiFe film

    International Nuclear Information System (INIS)

    Chen, L.; Zhou, Y.; Lei, C.; Zhou, Z.M.; Ding, W.

    2010-01-01

    Giant magnetoimpedance (GMI) effect on NiFe thin film is very promising due to its application in developing the magnetic field sensors with highly sensitivity and low cost. In this paper, the single layered NiFe thin film and NiFe/Cu/NiFe thin film with a meander structure are prepared by the MEMS technology. The influences of sputtering parameters, film structure and conductor layer width on GMI effect in NiFe single layer and meander NiFe/Cu/NiFe film are investigated. Maximum of the GMI ratio in single layer and sandwich film is 5% and 64%, respectively. The results obtained are useful for developing the high-performance magnetic sensors based on NiFe thin film.

  18. Electrical and magnetic properties of Fe-based bulk metallic glass with minor Co and Ni addition

    Energy Technology Data Exchange (ETDEWEB)

    Jung, H.Y. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); Stoica, M. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); POLITEHNICA University of Timisoara, P-ta Victoriei 2, Timisoara (Romania); Yi, S. [Department of Materials Science and Metallurgical Engineering, Kyungpook National University, 702–701 Daegu (Korea, Republic of); Kim, D.H. [Center for Non-crystalline Materials, Department of Metallurgical Engineering, Yonsei University, 120–749 Seoul (Korea, Republic of); Eckert, J. [IFW Dresden, Institute for Complex Materials, D–01069 Dresden (Germany); University of Technology Dresden, Institute of Materials Science, D–01062 Dresden (Germany)

    2014-09-01

    The effect of minor Co and Ni alloying on soft magnetic properties and electrical resistivity of Fe{sub 75.5}C{sub 7.0}Si{sub 3.3}B{sub 5.5}P{sub 8.7} (at%) bulk metallic glass has been investigated. Within examined compositional range (Co and Ni up to 4 at%, respectively), the saturation magnetization and electrical resistivity of the alloys continuously decrease with increasing Co or Ni content, while the Curie temperature and initial permeability increase. Comparing the effect of Co and Ni additions, the alloys with Co addition have much higher Curie temperature and saturation magnetization than the alloy with Ni addition. Also, the Co-added alloys show smaller coercivity and larger permeability than the Ni-added alloys. The present results suggest that minor addition of Co can provide better effectiveness to enhance the magnetic softness of Fe-based BMGs than minor Ni addition. - Highlights: • Soft magnetic characteristics of CI-based BMGs can be enhanced with minor Co and Ni alloying. • Minor Co addition can provide better effectiveness to enhance the magnetic softness of CI-based BMG than Ni addition. • Optimum Co addition enlarges atomic packing density and randomness of amorphous structure.

  19. High Ni in Archean tholeiites

    Science.gov (United States)

    Arndt, Nicholas T.

    1991-03-01

    Archean tholeiites generally have higher Ni, Co. Cr and Fe than most younger tholeiites with similar MgO contents. These characteristics cannot be attributed to high T or P batch melting in the Archean mantle, because, although such melts are enriched in siderophile elements, they have higher MgO than normal tholeiites. As primary melts fractionate to lower MgO, they lose Ni, Co and Cr. Nor can the differences between Archean and younger tholeiites be attributed to secular variation in mantle compositions because Archean komatiites have Ni, Co, Cr contents similar to modern (Gorgona) komatiites. It is suggested that the high siderophile element content of Archean tholeiites results from mixing of either komatiitic with basaltic magmas, as might occur in an ascending, melting mantle plume or column, or of komatiite and more evolved rocks, as may take place when komatiite encounters and assimilates crustal rocks.

  20. Smear layer and debris removal using manual Ni-Ti files compared with rotary Protaper Ni- Ti files - An In-Vitro SEM study.

    Science.gov (United States)

    Reddy, J M V Raghavendra; Latha, Prasanna; Gowda, Basavana; Manvikar, Varadendra; Vijayalaxmi, D Benal; Ponangi, Kalyana Chakravarthi

    2014-02-01

    Predictable successful endodontic therapy depends on correct diagnosis, effective cleaning, shaping and disinfection of the root canals and adequate obturation. Irrigation serves as a flush to remove debris, tissue solvent and lubricant from the canal irregularities; however these irregularities can restrict the complete debridement of root canal by mechanical instrumentation.Various types of hand and rotary instruments are used for the preparation of the root canal system to obtain debris free canals. The purpose of this study was to evaluate the amount of smear layer and debris removal on canal walls following the using of manual Nickel-Titanium (NiTi) files compared with rotary ProTaperNiTi files using a Scanning Electron Microscope in two individual groups. A comparative study consisting of 50 subjects randomized into two groups - 25 subjects in Group A (manual) and 25 subjects in Group B (rotary) was undertaken to investigate and compare the effects of smear layer and debris between manual and rotary NiTi instruments. Chi square test was used to find the significance of smear layer and debris removal in the coronal, middle and apical between Group A and Group B. Both systems of Rotary ProTaperNiTi and manual NiTi files used in the present study, did not create completely clean root canals. Manual NiTi files produced significantly less smear layer and debris compared to Rotary ProTaperNiTi instruments. Rotary instruments were less time consuming when compared to manual instruments. Instrument separation was not found to be significant with both the groups. Both systems of Rotary ProTaperNiTi and manual NiTi files used did not produce completely clean root canals. Manual NiTi files produced significantly less smear layer and debris compared to Rotary protaper instruments. How to cite the article: Reddy JM, Latha P, Gowda B, Manvikar V, Vijayalaxmi DB, Ponangi KC. Smear layer and debris removal using manual Ni-Ti files compared with rotary Protaper Ni-Ti files

  1. Relation between shape of Ni-particles and Ni migration in Ni-YSZ electrodes – a hypothesis

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Hauch, Anne; Sun, Xiufu

    2016-01-01

    This is an attempt to explain a phenomenon of total depletion of Ni next to the electrolyte in Ni-YSZ cermet electrodes in solid oxide electrolysis cells during electrolysis at high current density/overpotential. Intuitively, we would think that Ni would always migrate down the steam partial...

  2. Ni-NiO core-shell inverse opal electrodes for supercapacitors.

    Science.gov (United States)

    Kim, Jae-Hun; Kang, Soon Hyung; Zhu, Kai; Kim, Jin Young; Neale, Nathan R; Frank, Arthur J

    2011-05-14

    A general template-assisted electrochemical approach was used to synthesize three-dimensional ordered Ni core-NiO shell inverse opals (IOs) as electrodes for supercapacitors. The Ni-NiO IO electrodes displayed pseudo-capacitor behavior, good rate capability and cycling performance. © The Royal Society of Chemistry 2011

  3. CONFIGURATION-INTERACTION IN NI METAL AND NI-ALLOYS AND HIGH-ENERGY SPECTROSCOPY

    NARCIS (Netherlands)

    TANAKA, A; JO, T; SAWATZKY, GA

    We discuss the electronic state of Ni atoms in Ni metal and of Ni impurity in Cu and Au metals from the viewpoint of 3d configuration interaction (CI) using the Anderson impurity model including atomic multiplets. On the basis of the discussion, we give an interpretation for the Ni 2p-core X-ray

  4. Iodine capture by Hofmann-type clathrate Ni(II)(pz)[Ni(II)(CN)_4

    International Nuclear Information System (INIS)

    Massasso, Giovanni; Long, Jerome; Haines, Julien; Devautour-Vinot, Sabine; Maurin, Guillaume; Larionova, Joulia; Guerin, Christian; Guari, Yannick; Grandjean, Agnes; Onida, Barbara; Donnadieu, Bruno

    2014-01-01

    The thermally stable Hofmann-type clathrate framework Ni(II)(pz)[Ni(II)(CN)_4] (pz = pyrazine) was investigated for the efficient and reversible sorption of iodine (I_2) in the gaseous phase and in solution with a maximum adsorption capacity of 1 mol of I_2 per 1 mol of Ni(II)pz)[Ni(II)(CN)_4] in solution. (authors)

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    In order to clarify the heterogeneous nucleation potential of α-Ni grains on Ni 3 Si particles in Ni-Ni 3 Si eutectic alloy, the work of adhesion (W ad ), fracture toughness (G), interfacial energy (γ i ), and electronic structure of the index (0 0 1), (1 1 0) and (1 1 1) Ni/Ni 3 Si 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 Ni 3 Si. Since OM stacking interfaces have larger W ad , G and γ i than that of the top site stacking (OT) interfaces. The Ni/Ni 3 Si (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-Ni 3 Si eutectic alloy. The calculated interfacial energy of Ni/Ni 3 Si (0 0 1), (1 1 0) and (1 1 1) interfaces with OM stacking proves the excellent nucleation potency of Ni 3 Si 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.

  6. Density of Liquid Ni-Cr Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The density of liquid Ni-Cr alloy was measured by a modified sessile drop method. The density of liquid Ni-Cr alloywas found to decrease with increasing temperature and Cr concentration in the alloy. The molar volume of liquidNi-Cr alloy increases with increasing the Cr concentration in the alloy. The molar volume of Ni-Cr alloy determinedin the present work shows a positive deviation from the linear molar volume.

  7. On the origin of resistive switching volatility in Ni/TiO{sub 2}/Ni stacks

    Energy Technology Data Exchange (ETDEWEB)

    Cortese, Simone, E-mail: simone.cortese@soton.ac.uk; Trapatseli, Maria; Khiat, Ali; Prodromakis, Themistoklis [Nano Research Group, Electronics and Computer Science, University of Southampton, Southampton, Hampshire, SO17 1BJ (United Kingdom)

    2016-08-14

    Resistive switching and resistive random access memories have attracted huge interest for next generation nonvolatile memory applications, also thought to be able to overcome flash memories limitations when arranged in crossbar arrays. A cornerstone of their potential success is that the toggling between two distinct resistance states, usually a High Resistive State (HRS) and a Low Resistive State (LRS), is an intrinsic non-volatile phenomenon with the two states being thermodynamically stable. TiO{sub 2} is one of the most common materials known to support non-volatile RS. In this paper, we report a volatile resistive switching in a titanium dioxide thin film sandwiched by two nickel electrodes. The aim of this work is to understand the underlying physical mechanism that triggers the volatile effect, which is ascribed to the presence of a NiO layer at the bottom interface. The NiO layer alters the equilibrium between electric field driven filament formation and thermal enhanced ion diffusion, resulting in the volatile behaviour. Although the volatility is not ideal for non-volatile memory applications, it shows merit for access devices in crossbar arrays due to its high LRS/HRS ratio, which are also briefly discussed.

  8. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  9. Nanostructure analysis of friction welded Pd-Ni-P/Pd-Cu-Ni-P metallic glass interface

    International Nuclear Information System (INIS)

    Ohkubo, T.; Shoji, S.; Kawamura, Y.; Hono, K.

    2005-01-01

    Friction welded Pd 40 Ni 40 P 20 /Pd 40 Cu 30 Ni 10 P 20 metallic glass interface has been characterized by energy filtering transmission electron microscopy. The interface is fully amorphous with a gradual compositional change of Cu and Ni in the range of 30 nm. By annealing above T g , the interdiffusion of Cu and Ni progressed in the supercooled liquid region, and the crystallization occurred from the Pd 40 Ni 40 P 20 glass

  10. Investigation of Ni@CoO core-shell nanoparticle films synthesized by sequential layer deposition

    International Nuclear Information System (INIS)

    Spadaro, M.C.; Luches, P.; Benedetti, F.; Valeri, S.; Turchini, S.; Bertoni, G.; Ferretti, A.M.; Capetti, E.; Ponti, A.; D’Addato, S.

    2017-01-01

    Highlights: • We studied Ni/CoO core-shell nanoparticles (NP) obtained with a gas aggregation source. • The NP oxide shells were produced bye reactive deposition of Co in Oxygen atmosphere (p_O_2 ≈ 10"−"7 mbar). • XPS, SEM, STEM were used to obtain information on Ni chemical state and NP structure and morphology. • XMCD result showed evidence of remanent magnetization at room temperature. • We interpret XMCD results as due to stabilization induced by exchange bias due to AFM/FM coupling at the core/shell interface. - Abstract: Films of Ni@CoO core-shell nanoparticles (NP Ni core size d ≈ 11 nm) have been grown on Si/SiO_x 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 L_2_,_3 absorption edge showed the presence of magnetization at room temperature even at remanence, revealing the possibility of magnetic stabilization of the NP film.

  11. Investigation of Ni@CoO core-shell nanoparticle films synthesized by sequential layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Spadaro, M.C., E-mail: mariachiara.spadaro@unimore.it [CNR-NANO, via G. Campi 213/a, 41125 Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, 41125 Modena (Italy); Luches, P. [Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, 41125 Modena (Italy); Benedetti, F.; Valeri, S. [CNR-NANO, via G. Campi 213/a, 41125 Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, 41125 Modena (Italy); Turchini, S. [CNR-ISM, Via Fosso del Cavaliere 100, 00133 Roma (Italy); Bertoni, G. [CNR-IMEM, Parco Area delle Scienze 37/a, 43124 Parma (Italy); Ferretti, A.M.; Capetti, E.; Ponti, A. [Laboratorio di Nanotecnologie, Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche, via G. Fantoli 16/15, 20138 Milano (Italy); D’Addato, S. [CNR-NANO, via G. Campi 213/a, 41125 Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, 41125 Modena (Italy)

    2017-02-28

    Highlights: • We studied Ni/CoO core-shell nanoparticles (NP) obtained with a gas aggregation source. • The NP oxide shells were produced bye reactive deposition of Co in Oxygen atmosphere (p{sub O2} ≈ 10{sup −7} mbar). • XPS, SEM, STEM were used to obtain information on Ni chemical state and NP structure and morphology. • XMCD result showed evidence of remanent magnetization at room temperature. • We interpret XMCD results as due to stabilization induced by exchange bias due to AFM/FM coupling at the core/shell interface. - Abstract: Films of Ni@CoO core-shell nanoparticles (NP Ni core size d ≈ 11 nm) have been grown on Si/SiO{sub x} 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 L{sub 2,3} absorption edge showed the presence of magnetization at room temperature even at remanence, revealing the possibility of magnetic stabilization of the NP film.

  12. Study of dipole interaction in micron-width NiFe/Cu/NiFe/NiO wire using exchange anisotropy

    International Nuclear Information System (INIS)

    Kimura, Takashi; Itagaki, Yoshio; Wakaya, Fujio; Gamo, Kenji

    2001-01-01

    The dipole interaction between a NiFe layer pinned by a NiO and a free NiFe layer in a micron-wide NiFe/Cu/NiFe/NiO wire was studied by changing the direction of the exchange bias from the NiO layer. The effect of the dipole interaction when the exchange bias was perpendicular to the wire axis was larger than that when the exchange bias was parallel to the wire axis, and was consistently explained by the stray field caused by the magnetic charges of the pinned layer. It was demonstrated that this method, using exchange anisotropy, is useful for investigating the dipole interaction between ferromagnetic materials separated by a nonmagnetic material in small-scale magnetic multilayers. [copyright] 2001 American Institute of Physics

  13. Effects of Ni particle morphology on cell performance of Na/NiCl2 battery

    Science.gov (United States)

    Kim, Mangi; Ahn, Cheol-Woo; Hahn, Byung-Dong; Jung, Keeyoung; Park, Yoon-Cheol; Cho, Nam-ung; Lee, Heesoo; Choi, Joon-Hwan

    2017-11-01

    Electrochemical reaction of Ni particle, one of active cathode materials in the Na/NiCl2 battery, occurs on the particle surface. The NiCl2 layer formed on the Ni particle surface during charging can disconnect the electron conduction path through Ni particles because the NiCl2 layer has very low conductivity. The morphology and size of Ni particles, therefore, need to be controlled to obtain high charge capacity and excellent cyclic retention. Effects of the Ni particle size on the cell performance were investigated using spherical Ni particles with diameters of 0.5 μm, 6 μm, and 50 μm. The charge capacities of the cells with spherical Ni particles increased when the Ni particle size becomes smaller because of their higher surface area but their charge capacities were significantly decreased with increasing cyclic tests owing to the disconnection of electron conduction path. The inferior cyclic retention of charge capacity was improved using reticular Ni particles which maintained the reliable connection for the electron conduction in the Na/NiCl2 battery. The charge capacity of the cell with the reticular Ni particles was higher than the cell with the small-sized spherical Ni particles approximately by 26% at 30th cycle.

  14. The ternary Ni—Al—Co embedded-atom-method potential for γ/γ' Ni-based single-crystal superalloys: Construction and application

    International Nuclear Information System (INIS)

    Du Jun-Ping; Wang Chong-Yu; Yu Tao

    2014-01-01

    An Ni—Al—Co system embedded-atom-method potential is constructed for the γ(Ni)/γ'(Ni 3 Al) superalloy based on experiments and first-principles calculations. The stacking fault energies (SFEs) of the Ni(Co, Al) random solid solutions are calculated as a function of the concentrations of Co and Al. The calculated SFEs decrease with increasing concentrations of Co and Al, which is consistent with the experimental results. The embedding energy term in the present potential has an important influence on the SFEs of the random solid solutions. The cross-slip processes of a screw dislocation in homogenous Ni(Co) solid solutions are simulated using the present potential and the nudged elastic band method. The cross-slip activation energies increase with increasing Co concentration, which implies that the creep resistance of γ(Ni) may be improved by the addition of Co

  15. Random tensors

    CERN Document Server

    Gurau, Razvan

    2017-01-01

    Written by the creator of the modern theory of random tensors, this book is the first self-contained introductory text to this rapidly developing theory. Starting from notions familiar to the average researcher or PhD student in mathematical or theoretical physics, the book presents in detail the theory and its applications to physics. The recent detections of the Higgs boson at the LHC and gravitational waves at LIGO mark new milestones in Physics confirming long standing predictions of Quantum Field Theory and General Relativity. These two experimental results only reinforce today the need to find an underlying common framework of the two: the elusive theory of Quantum Gravity. Over the past thirty years, several alternatives have been proposed as theories of Quantum Gravity, chief among them String Theory. While these theories are yet to be tested experimentally, key lessons have already been learned. Whatever the theory of Quantum Gravity may be, it must incorporate random geometry in one form or another....

  16. Excitations in a Two-Dimensional Random Antiferromagnet

    DEFF Research Database (Denmark)

    Birgeneau, R. J.; Walker, L. R.; Guggenheim, H. J.

    1975-01-01

    Inelastic neutron scattering studies of the magnetic excitations in the planar Heisenberg random antiferromagnet Rb2Mn0.5Ni0.5F4 at 7K are reported. Two well-defined bands of excitations are observed. A simple mean crystal model is found to predict accurately the measured dispersion relations using...

  17. One dimensional motion of interstitial clusters and void growth in Ni and Ni alloys

    Science.gov (United States)

    Yoshiie, T.; Ishizaki, T.; Xu, Q.; Satoh, Y.; Kiritani, M.

    2002-12-01

    One dimensional (1-D) motion of interstitial clusters is important for the microstructural evolution in metals. In this paper, the effect of 2 at.% alloying with elements Si (volume size factor to Ni: -5.81%), Cu (7.18%), Ge (14.76%) and Sn (74.08%) in Ni on 1-D motion of interstitial clusters and void growth was studied. In neutron irradiated pure Ni, Ni-Cu and Ni-Ge, well developed dislocation networks and voids in the matrix, and no defects near grain boundaries were observed at 573 K to a dose of 0.4 dpa by transmission electron microscopy. No voids were formed and only interstitial type dislocation loops were observed near grain boundaries in Ni-Si and Ni-Sn. The reaction kinetics analysis which included the point defect flow into planar sink revealed the existence of 1-D motion of interstitial clusters in Ni, Ni-Cu and Ni-Ge, and lack of such motion in Ni-Si and Ni-Sn. In Ni-Sn and Ni-Si, the alloying elements will trap interstitial clusters and thereby reduce the cluster mobility, which lead to the reduction in void growth.

  18. First-principles calculations for the elastic properties of Ni-base model superalloys: Ni/Ni3Al multilayers

    International Nuclear Information System (INIS)

    Yun-Jiang, Wang; Chong-Yu, Wang

    2009-01-01

    A model system consisting of Ni[001](100)/Ni 3 Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2γ'+2γ to 10γ'+10γ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni 3 Al multilayer with 10γ'+10γ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the γ' phase volume fraction are calculated by varying the proportion of the γ and γ' phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni 3 Al multilayer can be well predicted by the Voigt–Reuss–Hill rule of mixtures. (classical areas of phenomenology)

  19. Comparative study of the magnetic properties of La3Ni2B‧O9 for B‧ = Nb, Taor Sb

    Science.gov (United States)

    Chin, Chun-Mann; Battle, Peter D.; Blundell, Stephen J.; Hunter, Emily; Lang, Franz; Hendrickx, Mylène; Paria Sena, Robert; Hadermann, Joke

    2018-02-01

    Polycrystalline samples of La3Ni2NbO9 and La3Ni2TaO9 have been characterised by X-ray and neutron diffraction, electron microscopy, magnetometry and muon spin relaxation (μSR); the latter technique was also applied to La3Ni2SbO9. On the length scale of a neutron diffraction experiment, the six-coordinate sites of the monoclinic perovskite structure are occupied in a 1:1 ordered manner by Ni and a randomNi/⅔B‧ mixture. Electron microscopy demonstrated that this 1:1 ordering is maintained over microscopic distances, although diffuse scattering indicative of short-range ordering on the mixed site was observed. No magnetic Bragg scattering was observed in neutron diffraction patterns collected from La3Ni2B‧O9 (B‧ = Nb or Ta) at 5 K although in each case μSR identified the presence of static spins below 30 K. Magnetometry showed that La3Ni2NbO9 behaves as a spin glass below 29 K but significant short-range interactions are present in La3Ni2TaO9 below 85 K. The contrasting properties of these compounds are discussed in terms of their microstructure.

  20. Microstructural characterization of Ni/YSZ based SOFC anodes after cyclic reduction and oxidation using electron microscopy

    International Nuclear Information System (INIS)

    Waldbillig, D.; He, A.; Ivey, D.

    2003-01-01

    The effect of redox cycling on the microstructure, of an SOFC anode, was studied using two approaches. Bulk samples were redox cycled and then examined in the SEM. In addition, electron transparent samples were prepared, redox cycled, and then examined in the TEM. Significant microstructural changes were observed. The anode in the as received condition consists of NiO particles several microns in size, YSZ grains about one micron in size and intergranular porosity. After the first reduction, the overall Ni grain size remains the same as the consumed NiO and epitaxial growth of Ni crystals on NiO grains is observed. The amount of intergranular porosity increases and very fine (50 nm) intragranular pores are formed throughout the Ni grains. This increase in the amount of porosity is expected due to the large volume change that occurs upon reduction. When samples are reoxidized the NiO particles in the SEM images appear spongy with much smaller pores than the as received, oxidized samples. The reoxidized anode consists of fine (<100 nm), randomly oriented grains of NiO. The grain refinement that occurs upon reoxidation is likely due to the large number of intragranular pores that occur upon reduction, which serve as nucleation sites. Rereduced samples were also very fine grained (<200 nm) and contained significant amounts of small intergranular porosity. The YSZ grains were unaffected by the redox cycles. (author)

  1. Synthesis and characterization of β-Ni(OH)2 up grown nanoflakes by SILAR method

    International Nuclear Information System (INIS)

    Kulkarni, S.B.; Jamadade, V.S.; Dhawale, D.S.; Lokhande, C.D.

    2009-01-01

    In this paper we report a 'bottom up' approach to synthesize β-Ni(OH) 2 nanoflakes using novel successive ionic layer adsorption and reaction (SILAR) method. Ni(OH) 2 thin films have been deposited on glass substrate using aqueous alkaline nickel chloride as nickel ion source and double distilled water maintained at 353 K temperature as hydroxyl ion source. The structural, surface morphological, optical and electrical properties of films are examined. The nanocrystallinity and β-phase of Ni(OH) 2 are confirmed by X-ray diffraction and FT-IR studies. Scanning electron microscope study revealed microporous and random distribution of well up grown interlocked nanoflakes. Optical absorption studies show wide optical band gap of 3.26 eV for β-Ni(OH) 2 . The electrical properties revealed that β-Ni(OH) 2 has negative temperature coefficient of resistance with p-type semiconducting behaviour. The electrochemical property studied by cyclic voltametry in 2 M KOH electrolyte solution revealed pseudo capacitive behaviour, when β-Ni(OH) 2 thin film employed as working electrode in three electrode electrochemical cell with platinum as counter electrode and saturated calomel as reference electrode. The specific capacitance of 350 F g -1 is obtained with nanoflake like morphology.

  2. Flowsheet for 63Ni production

    International Nuclear Information System (INIS)

    Williams, D.F.; Knauer, J.B.; O'Kelley, G.D.; Wiggins, J.T.; Porter, C.E.

    1992-01-01

    The production of large quantities of high specific activity 63 Ni (>10Ci/g) requires both a highly enriched 62 Ni target and a long irradiation period at high neutron flux. Trace impurities in the nickel and associated target materials are also activated and account for a significant fraction of the discharged activity and essentially all of the gamma activity. While most of these undesirable activation products (mainly transition metals) can be easily removed as chloride complexes during anion exchange, chromium, present as 51 Cr, and manganese, present as 54 Mn, are exceptions and require solvent extraction of the in-cell product to achieve the desired purity. In addition to summarizing the current development and production experience, optimized flowsheets are discussed

  3. Microstructural investigations of Ni and Ni2Al3 coatings exposed in biomass power plants

    DEFF Research Database (Denmark)

    Wu, D. L.; Dahl, K. V.; Christiansen, T. L.

    2018-01-01

    The present work investigates the corrosion resistance of Ni and Ni2Al3 coated austenitic stainless steel (TP347H) tubes, which were exposed in a biomass-fired boiler with an outlet steam temperature of 540 °C for 6757 h. The Ni2Al3 coating was produced by electroplating Ni followed by low...... temperature pack cementation. After exposure, microstructural investigations were performed by light optical and electron microscopy (SEM-EDS). Electroplated Ni coatings were not protective in straw firing power plants and exhibited similar corrosion morphology as uncoated tubes. For Ni2Al3 coatings...

  4. Influence of ni thickness on oscillation coupling in Cu/Ni multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Gagorowska, B; Dus-Sitek, M [Institute of Physics, Czestochowa University of Technology, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland)

    2007-08-15

    The results of investigation of magnetic properties of [Cu/Ni]x100 were presented. Samples were deposited by face-to-face sputtering method onto the silicon substrate, the thickness of Cu layer was constant (d{sub Cu} = 2 nm) and the thickness of Ni layer - variable (1 nm {<=} d{sub Ni} {<=} 6 nm). In Cu/Ni multilayers, for the thickness of Ni layer bigger than 2 nm antiferromagnetic coupling (A-F) were observed, for the thickness of Ni smaller than 2 nm A-F coupling is absent.

  5. Influence of ni thickness on oscillation coupling in Cu/Ni multilayers

    International Nuclear Information System (INIS)

    Gagorowska, B; Dus-Sitek, M

    2007-01-01

    The results of investigation of magnetic properties of [Cu/Ni]x100 were presented. Samples were deposited by face-to-face sputtering method onto the silicon substrate, the thickness of Cu layer was constant (d Cu = 2 nm) and the thickness of Ni layer - variable (1 nm ≤ d Ni ≤ 6 nm). In Cu/Ni multilayers, for the thickness of Ni layer bigger than 2 nm antiferromagnetic coupling (A-F) were observed, for the thickness of Ni smaller than 2 nm A-F coupling is absent

  6. DNA complexes with Ni nanoparticles: structural and functional properties

    Energy Technology Data Exchange (ETDEWEB)

    Tatarinova, Olga N.; Smirnov, Igor P. [Research Institute for Physico-Chemical Medicine of the Federal Medical-Biological Agency of the Russian Federation (Russian Federation); Safenkova, Irina V. [A.N. Bach Institute of Biochemistry (Russian Federation); Varizhuk, Anna M.; Pozmogova, Galina E., E-mail: pozmge@gmail.com [Research Institute for Physico-Chemical Medicine of the Federal Medical-Biological Agency of the Russian Federation (Russian Federation)

    2012-10-15

    Supramolecular complexes of biopolymers based on magnetic nanoparticles play an important role in creation of biosensors, implementation of theragnostic and gene therapeutic methods and biosafety evaluation. We investigated the impact of DNA interactions with nanoparticles of nickel (nNi) on the integrity and functionality of DNA. Data obtained by mass spectrometry, electrophoresis, TEM and AFM microscopy techniques, bacterial transformation, and real-time PCR provide evidence that ssDNA and plasmid DNA (pDNA) efficiently form complexes with nNi. AFM data suggest that the complexes are necklace-type structures, in which nanoparticles are randomly distributed along the DNA chains, rather than highly entangled clot-type structures. After desorption, observed DNA characteristics in bioanalytical and biological systems remain unchanged. Only supercoiled pDNA was nicked, but remained, as well as a plasmid-nNi complex, active in expression vector assays. These results are very important for creation of new methods of DNA immobilization and controlled manipulation.

  7. DNA complexes with Ni nanoparticles: structural and functional properties

    International Nuclear Information System (INIS)

    Tatarinova, Olga N.; Smirnov, Igor P.; Safenkova, Irina V.; Varizhuk, Anna M.; Pozmogova, Galina E.

    2012-01-01

    Supramolecular complexes of biopolymers based on magnetic nanoparticles play an important role in creation of biosensors, implementation of theragnostic and gene therapeutic methods and biosafety evaluation. We investigated the impact of DNA interactions with nanoparticles of nickel (nNi) on the integrity and functionality of DNA. Data obtained by mass spectrometry, electrophoresis, TEM and AFM microscopy techniques, bacterial transformation, and real-time PCR provide evidence that ssDNA and plasmid DNA (pDNA) efficiently form complexes with nNi. AFM data suggest that the complexes are necklace-type structures, in which nanoparticles are randomly distributed along the DNA chains, rather than highly entangled clot-type structures. After desorption, observed DNA characteristics in bioanalytical and biological systems remain unchanged. Only supercoiled pDNA was nicked, but remained, as well as a plasmid–nNi complex, active in expression vector assays. These results are very important for creation of new methods of DNA immobilization and controlled manipulation.

  8. Exclusive study of Ni+Ni and Ni+Au central collisions: phase coexistence and spinodal decomposition; Etude exclusive des collisions centrales Ni+Ni et Ni+Au: coexistence de phase et decomposition spinodale

    Energy Technology Data Exchange (ETDEWEB)

    Guiot, B

    2002-12-01

    The INDRA multidetector allowed us to study the Ni+Ni collisions at 32A MeV and the Ni+Au collisions at 52,4 MeV. Central collisions leading to 'quasi-fused' systems were isolated using multidimensional analysis techniques: the Discriminant Analysis and the Principal Component Analysis. Comparison with a statistical model shows that the selected events are compatible with thermodynamical equilibrium. The average thermal excitation energy is 5A MeV for both systems. Calculations of heat capacities show that the deexcitation of the hot sources are akin to a liquid-gas phase transition of nuclear matter. Indeed heat capacities exhibit a negative branch as expected for a phase transition of a finite system. The dynamics of this phase transition has been investigated by applying the charge correlation method. An enhanced production of events with equal-sized fragments has been evidenced for Ni+Au at 52A MeV. No signal was found for Ni+Ni at 32A MeV. Finally this method was improved by taking into account the total charge conservation. The signal is seen more clearly for Ni+Au at 52A MeV, but is ambiguous for Ni+Ni at 32A MeV. The path followed in the state diagram, or the involved time scales, seem to be different for these systems. (authors)

  9. niños preescolares

    Directory of Open Access Journals (Sweden)

    Claudia Rosario Portilla Ramírez

    2007-01-01

    Full Text Available Este estudio explora la relación entre la escritura y la comprensión de la referencia a través de una tarea de sinonimia en niños entre 5 y 6 años de edad, de origen latinoamericano, escolarizados en Barcelona (España. Las variables relacionadas con la tarea de sinonimia fueron (a la comprensión de la entidad lingüística nombre y (b el nivel de conceptualización de la escritura de los niños y la presencia de etiquetas escritas durante la tarea. Para la tarea de sinonimia se utilizaron pares de sinónimos dialectales del español (de Latinoamérica y de la Península Ibérica. Los resultados mostraron una diferenciación en el razonamiento de los niños, la cual dependía de la comparación entre lenguaje oral y lenguaje escrito en el desarrollo de la tarea, evidenciando una mayor aceptación de la sinonimia en la modalidad de lenguaje oral que en la modalidad de lenguaje escrito.

  10. Reinvestigation of 56Ni decay

    International Nuclear Information System (INIS)

    Sur, B.; Norman, E.B.; Lesko, K.T.; Browne, E.; Larimer, R.

    1990-01-01

    In a series of experiments, we have reinvestigated the decay of the doubly magic nucleus 56 Ni, which is believed to be copiously produced in supernovae. We have confirmed its previously known decay scheme and half-life, and have searched for several rare decay modes. We establish an upper limit of 5.8x10 -7 for the branching ratio of the second forbidden unique β + decay to the 158-keV level in 56 Co, leading to a lower limit of 2.9x10 4 yr for the half-life of fully ionized 56 Ni nuclei in cosmic rays. We also establish an upper limit of 5.0x10 -3 for the branching ratio of the isospin forbidden Fermi electron capture transition to the 1451-keV level in 56 Co, which in turn leads to an upper limit of 124 keV for the isospin mixing Coulomb matrix element of the 56 Ni ground state

  11. On the nature of Ni···Ni interaction in a model dimeric Ni complex.

    Science.gov (United States)

    Kamiński, Radosław; Herbaczyńska, Beata; Srebro, Monika; Pietrzykowski, Antoni; Michalak, Artur; Jerzykiewicz, Lucjan B; Woźniak, Krzysztof

    2011-06-07

    A new dinuclear complex (NiC(5)H(4)SiMe(2)CHCH(2))(2) (2) was prepared by reacting nickelocene derivative [(C(5)H(4)SiMe(2)CH=CH(2))(2)Ni] (1) with methyllithium (MeLi). Good quality crystals were subjected to a high-resolution X-ray measurement. Subsequent multipole refinement yielded accurate description of electron density distribution. Detailed inspection of experimental electron density in Ni···Ni contact revealed that the nickel atoms are bonded and significant deformation of the metal valence shell is related to different populations of the d-orbitals. The existence of the Ni···Ni bond path explains the lack of unpaired electrons in the complex due to a possible exchange channel.

  12. Synthesis of Ni core NiO shell nanostructure and magnetic investigation for shell thickness determination

    International Nuclear Information System (INIS)

    Arabi, H.; Bruck, E.; Tichelaar, F.D.

    2007-01-01

    Full text: Nickel oxide has received a considerable amount of attention in recent years for its catalytic, electronic and magnetic properties. Ni nanoparticles with an average size of 8 nm were prepared by dc - arc discharge in argon atmosphere. A current of 130 A and 300 milli bar pressure of argon have been applied. The produced Ni nanoparticles were annealed for oxidizing in air at 350 for six hours to produce antiferromagnetic NiO particles. The structure of Ni and NiO nanoparticles and size estimation of them studied by means of X-ray diffraction. The size and morphology of the particles were also characterized by high resolution transmission microscopy (TEM). The Ni core NiO shell structure, resulting from the oxidation process, were studied by magnetic properties measurements. A quantum design squid magnetometer, model MPMS5S was used for measuring saturation magnetization of both nanoparticles of Ni with and without NiO layer. By knowing the density of Ni and NiO, we were able to deduce the thickness of the Ni core and NiO outer layer. They are around 3 and 5 nanometers respectively. (authors)

  13. Magnetic behaviour of arrays of Ni nanowires by electrodeposition into self-aligned titania nanotubes

    International Nuclear Information System (INIS)

    Prida, V.M.; Hernandez-Velez, M.; Cervera, M.; Pirota, K.; Sanz, R.; Navas, D.; Asenjo, A.; Aranda, P.; Ruiz-Hitzky, E.; Batallan, F.; Vazquez, M.; Hernando, B.; Menendez, A.; Bordel, N.; Pereiro, R.

    2005-01-01

    Arrays of Ni nanowires electrodeposited into self-aligned and randomly disordered titania nanotube arrays grown by anodization process are investigated by X-ray diffraction, SEM, rf-GDOES and VSM magnetometry. The titania nanotube outer diameter is about 160 nm, wall thickness ranging from 60 to 70 nm and 300 nm in depth. The so-obtained Ni nanowires reach above 100 nm diameter and 240 nm length, giving rise to coercive fields of 98 and 200 Oe in the perpendicular or parallel to the nanowires axis hysteresis loops, respectively. The formation of magnetic vortex domain states is also discussed

  14. Exclusive study of Ni+Ni and Ni+Au central collisions: phase coexistence and spinodal decomposition

    International Nuclear Information System (INIS)

    Guiot, B.

    2002-12-01

    The INDRA multidetector allowed us to study the Ni+Ni collisions at 32A MeV and the Ni+Au collisions at 52,4 MeV. Central collisions leading to 'quasi-fused' systems were isolated using multidimensional analysis techniques: the Discriminant Analysis and the Principal Component Analysis. Comparison with a statistical model shows that the selected events are compatible with thermodynamical equilibrium. The average thermal excitation energy is 5A MeV for both systems. Calculations of heat capacities show that the deexcitation of the hot sources are akin to a liquid-gas phase transition of nuclear matter. Indeed heat capacities exhibit a negative branch as expected for a phase transition of a finite system. The dynamics of this phase transition has been investigated by applying the charge correlation method. An enhanced production of events with equal-sized fragments has been evidenced for Ni+Au at 52A MeV. No signal was found for Ni+Ni at 32A MeV. Finally this method was improved by taking into account the total charge conservation. The signal is seen more clearly for Ni+Au at 52A MeV, but is ambiguous for Ni+Ni at 32A MeV. The path followed in the state diagram, or the involved time scales, seem to be different for these systems. (authors)

  15. Atomistic calculations of hydrogen interactions with Ni3Al grain boundaries and Ni/Ni3Al interfaces

    International Nuclear Information System (INIS)

    Baskes, M.I.; Angelo, J.E.; Moody, N.R.

    1995-01-01

    Embedded Atom Method (EAM) potentials have been developed for the Ni/Al/H system. The potentials have been fit to numerous properties of this system. For example, these potentials represent the structural and elastic properties of bulk Ni, Al, Ni 3 Al, and NiAl quite well. In addition the potentials describe the solution and migration behavior of hydrogen in both nickel and aluminum. A number of calculations using these potentials have been performed. It is found that hydrogen strongly prefers sites in Ni 3 Al that are surrounded by 6 Ni atoms. Calculations of the trapping of hydrogen to a number of grain boundaries in Ni 3 Al have been performed as a function of hydrogen chemical potential at room temperature. The failure of these bicrystals under tensile stress has been examined and will be compared to the failure of pure Ni 3 Al boundaries. Boundaries containing a preponderance of nickel are severely weakened by hydrogen. In order to investigate the potential embrittlement of γ/γ' alloys, trapping of hydrogen to a spherical Ni 3 Al precipate in nickel as a function of chemical potential at room temperature has been calculated. It appears that the boundary is not a strong trap for hydrogen, hence embrittlement in these alloys is not primarily due to interactions of hydrogen with the γ/γ interface

  16. Random pulse generator

    International Nuclear Information System (INIS)

    Guo Ya'nan; Jin Dapeng; Zhao Dixin; Liu Zhen'an; Qiao Qiao; Chinese Academy of Sciences, Beijing

    2007-01-01

    Due to the randomness of radioactive decay and nuclear reaction, the signals from detectors are random in time. But normal pulse generator generates periodical pulses. To measure the performances of nuclear electronic devices under random inputs, a random generator is necessary. Types of random pulse generator are reviewed, 2 digital random pulse generators are introduced. (authors)

  17. Random matrices and random difference equations

    International Nuclear Information System (INIS)

    Uppuluri, V.R.R.

    1975-01-01

    Mathematical models leading to products of random matrices and random difference equations are discussed. A one-compartment model with random behavior is introduced, and it is shown how the average concentration in the discrete time model converges to the exponential function. This is of relevance to understanding how radioactivity gets trapped in bone structure in blood--bone systems. The ideas are then generalized to two-compartment models and mammillary systems, where products of random matrices appear in a natural way. The appearance of products of random matrices in applications in demography and control theory is considered. Then random sequences motivated from the following problems are studied: constant pulsing and random decay models, random pulsing and constant decay models, and random pulsing and random decay models

  18. Structural features in Ni-Al alloys

    International Nuclear Information System (INIS)

    Abylkalykova, R.B.; Kveglis, L.I.; Rakhimova, U.A.; Nasokhova, Sh.B.; Tazhibaeva, G.B.

    2007-01-01

    Purpose of the work is study of structural transformations under diverse memory effect in Ni-Al alloys. Examination were conducted in following composition samples: Ni -75 at.% and Al - 25 at.%. The work is devoted to clarification reasons both formation atom-ordered structures in inter-grain boundaries of bulk samples under temperature action and static load. Revealed inter-grain inter-boundary layers in Ni-Al alloy both bulk and surface state have complicated structure

  19. Compositional and structural characterisation of Ni-phyllosilicates in hydrous silicate type Ni-laterite deposits

    OpenAIRE

    Villanova de Benavent, Cristina

    2015-01-01

    Ni-bearing Mg-phyllosilicates (commonly known as garnierites) are significant ore minerals in many Ni-laterite deposits worldwide. However, the characterisation of these mineral phases is complex, as well as their classification and nomenclature, due to their fine-grained nature, low crystallinity and frequent occurrence as mixtures. The aim of this study is to shed some light to the nature of the Ni-bearing Mg-phyllosilicates occurring at the Falcondo Ni-laterite. In this deposit, these ...

  20. Thermal capture cross section for 58Ni (n,γ)59 Ni reaction

    International Nuclear Information System (INIS)

    Carbonari, A.W.; Pecequilo, B.R.S.

    1989-01-01

    The 58 Ni total thermal capture cross section was determined by suming the partial cross sections calculated for the primary transitions of the reaction 58 Ni (n,γ) 59 Ni. The primary transitions energies and intensities were determined from the 58 Ni thermal neutrons prompt gamma capture gamma rays spectrum in the 3.7 to 9.3 MeV region. The obtained value for the total cross section was 4.52 + 0.10b. (author) [pt

  1. Formation enthalpy of NiBe and Ni5Be21

    International Nuclear Information System (INIS)

    Ivanov, M.I.; Karpova, T.F.; Dalago, N.Yu.

    1981-01-01

    The method of dissolution calorimetry is used to determine standard enthalpies of NiBe and Ni 5 Be 21 formation, which are 84.8+-2.2 and (-669+-37)kJ/mol. The enthalpy values of NiBe and Ni 5 Be 21 at 331 K are shown to coincide (within the limits of errors of these values) with the values at the standard temperature of 298.15 K [ru

  2. Effects of Ni vacancy, Ni antisite, Cr and Pt on the third-order elastic constants and mechanical properties of NiAl

    KAUST Repository

    Wu, Shaohua; Wu, Xiaozhi; Wang, Rui; Liu, Qing; Gan, Liyong

    2014-01-01

    Effects of Ni vacancy, Ni antisite in Al sublattice, Cr in Al sublattice, Pt in Ni sublattice on the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of the B2 NiAl have been investigated using the first-principles methods. Lattice constant and the SOECs of NiAl are in good agreement with the previous results. The brittle/ductile transition map based on Pugh ratio G/B and Cauchy pressure Pc shows that Ni antisite, Cr, Pt and pressure can improve the ductility of NiAl, respectively. Ni vacancy and lower pressure can enhance the Vickers hardness Hv of NiAl. The density of states (DOS) and the charge density difference are also used to analysis the effects of vacancy, Ni antisite, Cr and Pt on the mechanical properties of NiAl, and the results are in consistent with the transition map. © 2014 Elsevier Ltd. All rights reserved.

  3. Effects of Ni vacancy, Ni antisite, Cr and Pt on the third-order elastic constants and mechanical properties of NiAl

    KAUST Repository

    Wu, Shaohua

    2014-12-01

    Effects of Ni vacancy, Ni antisite in Al sublattice, Cr in Al sublattice, Pt in Ni sublattice on the second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of the B2 NiAl have been investigated using the first-principles methods. Lattice constant and the SOECs of NiAl are in good agreement with the previous results. The brittle/ductile transition map based on Pugh ratio G/B and Cauchy pressure Pc shows that Ni antisite, Cr, Pt and pressure can improve the ductility of NiAl, respectively. Ni vacancy and lower pressure can enhance the Vickers hardness Hv of NiAl. The density of states (DOS) and the charge density difference are also used to analysis the effects of vacancy, Ni antisite, Cr and Pt on the mechanical properties of NiAl, and the results are in consistent with the transition map. © 2014 Elsevier Ltd. All rights reserved.

  4. Creep and shrinkage of Mo(Ni)

    International Nuclear Information System (INIS)

    Kaysser, W.A.; Hofmann-Amtenbrink, M.; Petzow, G.

    1984-01-01

    To avoid some of the errors inherent in a quantitative interpretation of shrinkage of powder compacts as Mo-Ni, other experiments were looked for, where the influence of Ni on the material transport properties of Mo could be measured semi-quantitatively during heating up to temperature and subsequent isothermal annealing. The bending of thin Mo foils under small loads was found to be an experimental arrangement, where variations in stress, in Ni-concentration and in intrinsic material properties could be realized. The results of these creep experiments will be compared in a qualitative sense with sintering experiments in Mo-Ni done under similar conditions as the creep experiments

  5. Structure-activity relations for Ni-containing zeolites during NO reduction. II. Role of the chemical state of Ni

    NARCIS (Netherlands)

    Mosqueda Jimenez, B.I.; Jentys, A.; Seshan, Kulathuiyer; Lercher, J.A.

    2003-01-01

    The influence of the metal in Ni-containing zeolites used as catalysts for the reduction of NO with propane and propene was studied. In the fresh catalysts, Ni is located in ion exchange positions for Ni/MOR, Ni/ZSM-5, and Ni/MCM-22. The formation of carbonaceous deposits, the removal of Al from

  6. Ni-P/Zn-Ni compositionally modulated multilayer coatings - Part 2: Corrosion and protection mechanisms

    Science.gov (United States)

    Bahadormanesh, Behrouz; Ghorbani, Mohammad

    2018-06-01

    The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the deposition current density. The corrosion resistance of the deposits was studied and compared with that of monolayers of Ni-P and Zn-Ni alloys via Tafel polarization, EIS and salt spray tests. Characterization of corrosion products by means of EDS and XRD revealed more details from the corrosion mechanism of the monolayers and multilayers. The corrosion current density of Ni-P/Zn-Ni CMMCs were around one tenth of Zn-Ni monolayer. The CMMC with incomplete layers performed lower polarization resistance and higher corrosion current density compared to the CMMC with complete layers. The electrical circuit that was proposed for modeling the corrosion process based on the EIS spectrum, proved that layering reduces the porosity and consequently improves the barrier properties. Although, layering of Zn-Ni layers with Ni-P deposits increased the time to red rust in salt spray test, the time for white rust formation decreased. The corrosion mechanism of both Zn-Ni and Ni-P (containing small amount of Zn) was preferential dissolution of Zn and the corrosion products were comprised of mainly Zn hydroxychloride and Zn hydroxycarbonate. Also, Ni and P did not take part in the corrosion products. Based on the electrochemical character of the layers and the morphology of the corroded surface, the corrosion mechanism of multilayers was discussed.

  7. Joining of Ni-TiC FGM and Ni-Al Intermetallics by Centrifugal Combustion Synthesis

    International Nuclear Information System (INIS)

    Ohmi, Tatsuya; Matsuura, Kiyotaka; Iguchi, Manabu; Mizuma, Kiminori

    2008-01-01

    A centrifugal combustion synthesis (CCS) process has been investigated to join a Ni-Al intermetallic compound and a Ni-TiC cermet. The cermet, a tubular graphite mold, and a green compact of reactants consisting of Al, Ni and NiO were set in a centrifugal caster. When the combustion synthesis reaction was induced in the centrifugal force field, a synthesized molten Ni-Al alloy flowed into the graphite mold and joined to the cermet. The soundness of the joint interface depended on the volume percentage of TiC phase in the cermet. A lot of defects were formed near the interface between the Ni-TiC cermet and the cast Ni-Al alloy when the volume percentage of TiC was 50% or higher. For this kind of cermet system, using a functionally graded cermet such as Ni-10 vol.%TiC/Ni-25 vol.%TiC/Ni-50 vol.%TiC overcame this difficulty. The four-point bending strength of the joined specimen consisting of the three-layered FGM cermet and cast Ni-29 mol%Al alloy was 1010 MPa which is close to the result for a Ni-29 mol%Al alloy specimen

  8. Dynamic recovery in nanocrystalline Ni

    International Nuclear Information System (INIS)

    Sun, Z.; Van Petegem, S.; Cervellino, A.; Durst, K.; Blum, W.; Van Swygenhoven, H.

    2015-01-01

    The constant flow stress reached during uniaxial deformation of electrodeposited nanocrystalline Ni reflects a quasi-stationary balance between dislocation slip and grain boundary (GB) accommodation mechanisms. Stress reduction tests allow to suppress dislocation slip and bring recovery mechanisms into the foreground. When combined with in situ X-ray diffraction it can be shown that grain boundary recovery mechanisms play an important role in producing plastic strain while hardening the microstructure. This result has a significant consequence for the parameters of thermally activated glide of dislocations, such as athermal stress and activation volume, which are traditionally derived from stress/strain rate change tests

  9. Morphological control of Ni/NiO core/shell nanoparticles and production of hollow NiO nanostructures

    International Nuclear Information System (INIS)

    Chopra, Nitin; Claypoole, Leslie; Bachas, Leonidas G.

    2010-01-01

    Chemical synthesis coupled with a microwave irradiation process allowed for the control of size (6-40 nm), shape, and shell thickness of Ni/NiO core/shell nanoparticles. In this unique synthetic route, the size of Ni nanoparticles (NiNPs) was strongly influenced by the nickel salt-to-stabilizer ratio and the amount of the stabilizer. Interestingly, it was observed that the shape of the nanoparticles was altered by varying the reaction time, where longer reaction times resulted in annealing effects and rupture of the stabilizer micelle leading to distinct shapes of Ni/NiO core/shell nanostructures. Product cooling rate was another important parameter identified in this study that not only affected the shape, but also the crystal structure of the core/shell nanoparticles. In addition, a simple and cost-effective method of microwave irradiation of NiNPs led to the formation of distinctly shaped hollow NiO nanoparticles. These high surface area core/shell nanoparticles with well-controlled morphologies are important and can lead to significant advancement in the design of improved fuel cells, electrochromic display devices, and catalysis systems.

  10. Morphological control of Ni/NiO core/shell nanoparticles and production of hollow NiO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Chopra, Nitin [University of Alabama, Department of Metallurgical and Materials Engineering, Center for Materials for Information Technology (MINT) (United States); Claypoole, Leslie [Fairmont State University (United States); Bachas, Leonidas G., E-mail: bachas@uky.ed [University of Kentucky, Department of Chemistry (United States)

    2010-10-15

    Chemical synthesis coupled with a microwave irradiation process allowed for the control of size (6-40 nm), shape, and shell thickness of Ni/NiO core/shell nanoparticles. In this unique synthetic route, the size of Ni nanoparticles (NiNPs) was strongly influenced by the nickel salt-to-stabilizer ratio and the amount of the stabilizer. Interestingly, it was observed that the shape of the nanoparticles was altered by varying the reaction time, where longer reaction times resulted in annealing effects and rupture of the stabilizer micelle leading to distinct shapes of Ni/NiO core/shell nanostructures. Product cooling rate was another important parameter identified in this study that not only affected the shape, but also the crystal structure of the core/shell nanoparticles. In addition, a simple and cost-effective method of microwave irradiation of NiNPs led to the formation of distinctly shaped hollow NiO nanoparticles. These high surface area core/shell nanoparticles with well-controlled morphologies are important and can lead to significant advancement in the design of improved fuel cells, electrochromic display devices, and catalysis systems.

  11. Topics in random walks in random environment

    International Nuclear Information System (INIS)

    Sznitman, A.-S.

    2004-01-01

    Over the last twenty-five years random motions in random media have been intensively investigated and some new general methods and paradigms have by now emerged. Random walks in random environment constitute one of the canonical models of the field. However in dimension bigger than one they are still poorly understood and many of the basic issues remain to this day unresolved. The present series of lectures attempt to give an account of the progresses which have been made over the last few years, especially in the study of multi-dimensional random walks in random environment with ballistic behavior. (author)

  12. Burner Rig Hot Corrosion of a Single Crystal Ni-48Al-Ti-Hf-Ga Alloy

    Science.gov (United States)

    Nesbitt, James A.; Darolia, Ram; Cuy, Michael D.

    1998-01-01

    The hot corrosion resistance of a single crystal Ni-48Al-1Ti-0.5Hf-0.2Ga alloy was examined in a Mach 0.3 burner rig at 900 C for 300 hours. The combustion chamber was doped with 2 ppmw synthetic sea salt. The hot corrosion attack produced a random mound morphology on the surface. Microstructurally, the hot corrosion attack appeared to initiate with oxide-filled pits which were often broad and shallow. At an intermediate stage, the pits increased in size to incorporate unoxidized Ni islands in the corrosion product. The rampant attack stage, which was observed only at sharp sample corners, was characterized by rapid inward growth of alumina in finger-like protrusions incorporating significant amounts of Al-depleted Ni islands. Aluminum consumption in the oxide fingers resulted in the growth of a gamma' layer ahead of the advancing oxide fingers.

  13. Burner rig hot corrosion of a single crystal Ni-48Al-Ti-Hf-Ga alloy

    Energy Technology Data Exchange (ETDEWEB)

    Nesbitt, J.A.; Darolia, R.; Cuy, M.D.

    1999-07-01

    The hot corrosion resistance of a single crystal Ni-48Al-1Ti-0.5Hf-0.2Ga alloy was examined in a Mach 0.3 burner rig at 900 C for 300 hours. The combustion chamber was doped with 2 ppmw synthetic sea salt. The hot corrosion attack produced a random mound morphology on the surface. Microstructurally, the hot corrosion attack appeared to initiate with oxide-filled pits which were often broad and shallow. At an intermediate stage, the pits increased in size to incorporate unoxidized Ni islands in the corrosion product. The rampant attack stage, which was observed only at sharp sample corners, was characterized by rapid inward growth of alumina in finger-like protrusions incorporating significant amounts of Al-depleted Ni islands. Aluminum consumption in the oxide fingers resulted in the growth of a {gamma}{prime} layer ahead of the advancing oxide fingers.

  14. Uncertainty-driven nuclear data evaluation including thermal (n,α) applied to 59Ni

    Science.gov (United States)

    Helgesson, P.; Sjöstrand, H.; Rochman, D.

    2017-11-01

    This paper presents a novel approach to the evaluation of nuclear data (ND), combining experimental data for thermal cross sections with resonance parameters and nuclear reaction modeling. The method involves sampling of various uncertain parameters, in particular uncertain components in experimental setups, and provides extensive covariance information, including consistent cross-channel correlations over the whole energy spectrum. The method is developed for, and applied to, 59Ni, but may be used as a whole, or in part, for other nuclides. 59Ni is particularly interesting since a substantial amount of 59Ni is produced in thermal nuclear reactors by neutron capture in 58Ni and since it has a non-threshold (n,α) cross section. Therefore, 59Ni gives a very important contribution to the helium production in stainless steel in a thermal reactor. However, current evaluated ND libraries contain old information for 59Ni, without any uncertainty information. The work includes a study of thermal cross section experiments and a novel combination of this experimental information, giving the full multivariate distribution of the thermal cross sections. In particular, the thermal (n,α) cross section is found to be 12.7 ± . 7 b. This is consistent with, but yet different from, current established values. Further, the distribution of thermal cross sections is combined with reported resonance parameters, and with TENDL-2015 data, to provide full random ENDF files; all of this is done in a novel way, keeping uncertainties and correlations in mind. The random files are also condensed into one single ENDF file with covariance information, which is now part of a beta version of JEFF 3.3. Finally, the random ENDF files have been processed and used in an MCNP model to study the helium production in stainless steel. The increase in the (n,α) rate due to 59Ni compared to fresh stainless steel is found to be a factor of 5.2 at a certain time in the reactor vessel, with a relative

  15. Continuum mechanics simulations of NiO/Ni-YSZ composites during reduction and re-oxidation

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Frandsen, Henrik Lund; Kaiser, Andreas

    2010-01-01

    for the dimensional change arises from the volumetric change related to the phase change NiO ↔ Ni. The measurable change in bulk length is given by the ceramic YSZ backbone as a response to the stress created by the chemical strain. The different subprocesses described in the model for YSZ were elastic and anelastic...... expansion, diffusional creep, grain boundary sliding (GBS) and microcracking due to excessive stress. In the Ni/NiO phase, nonelastic strains in terms of diffusional and power law creep were implemented, and additionally for NiO deformation due to microcracking and/or pseudoplasticity. Semi...

  16. Niños y niñas como cuidadores familiares

    OpenAIRE

    María Rosa Estupiñán Aponte

    2015-01-01

    En el contexto familiar, el cuidado de otra persona por parte de niños y niñas constituye un terreno inexplorado tanto en su significado como en las implicaciones que podrían darse en el proceso. Aunque históricamente se ha asignado el cuidado familiar a las mujeres generando condiciones de inequidad, incrementada con los cambios sociales de los últimos tiempos, es necesario reconocer que en muchos hogares niños y niñas se han visto obligados a desempeñar esta labor sin la preparación ni las ...

  17. .';.:NI~

    African Journals Online (AJOL)

    al wat ons werd was. Na middagete op 29 Junie, is ek per kar suid om die grand te gaan besigtig en om te sien hoe my stellings, van die vyandelike oogpunt, daaruit .... van Gatt se optrede moes die. Nieu-Seelanders, in 'n briljante nagaanval, met gevelde bajonette, 'n weg baan deur die vyand am daardie nag te ontvlug.

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

    International Nuclear Information System (INIS)

    Seenivasan, H.; Tiwari, Ashwani K.

    2013-01-01

    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)

  19. Creatividad en niños superdotados

    OpenAIRE

    González Román, María del Pilar

    1992-01-01

    Se ha realizado un estudio sobre la creatividad en los niños superdotados. Analizándose los diferentes modelos de creatividad y superdotacion avalados por un estudio empírico, en el cual se han valorado las diferencial que existen entre los niños superdotados y contraste a nivel verbal y grafico-espacial.

  20. Preparation of one-step NiO/Ni-CGO composites using factorial design

    International Nuclear Information System (INIS)

    Araujo, A.J.M. de; Sousa, A R.O. de; Camposa, L.F.A.; Macedo, D.A.; Loureiro, F. J.A.; Fagg, D.P.

    2016-01-01

    This work deals with the synthesis, processing and characterization of NiO/Ni- CGO composite materials as potential solid oxide fuel cell (SOFC) anodes. The particulate materials were obtained by a one-step synthesis method and characterized by thermal analysis (prior to calcination) and X-ray diffraction (calcined powder). The ceramic processing of samples containing from 30 to 70 wt.% NiO was carried out by factorial design. Besides the NiO content controlled during the chemical synthesis, the impacts of the pore-former content (citric acid, used in proportions of 0, 7.5 and 15 wt.%) and the sintering temperature (1300, 1350 and 1400 °C) were also investigated. The open porosity of NiO-CGO composites and reduced Ni-CGO cermets was modeled as a function of factors (NiO content, citric acid content and sintering temperature) and interaction of factors. (author)

  1. Nanoscale structural heterogeneity in Ni-rich half-Heusler TiNiSn

    International Nuclear Information System (INIS)

    Douglas, Jason E.; Pollock, Tresa M.; Chater, Philip A.; Brown, Craig M.; Seshadri, Ram

    2014-01-01

    The structural implications of excess Ni in the TiNiSn half-Heusler compound are examined through a combination of synchrotron x-ray and neutron scattering studies, in conjunction with first principles density functional theory calculations on supercells. Despite the phase diagram suggesting that TiNiSn is a line compound with no solid solution, for small x in TiNi 1+x Sn there is indeed an appearance—from careful analysis of the scattering—of some solubility, with the excess Ni occupying the interstitial tetrahedral site in the half-Heusler structure. The analysis performed here would point to the excess Ni not being statistically distributed, but rather occurring as coherent nanoclusters. First principles calculations of energetics, carried out using supercells, support a scenario of Ni interstitials clustering, rather than a statistical distribution.

  2. Microstructural aspects of Ni-based superalloy 693

    International Nuclear Information System (INIS)

    Dutta, R.S.; Sengupta, P.; Tewari, R.; Kain, V.; Dey, G.K.; Sharma, A.K.; Raj, K.

    2009-01-01

    Alloy 693 is an austenitic, precipitation-hardenable Ni-based superalloy. It is a promising material for high temperature fuel cell, petrochemical processing industry, high temperature waste and biomass incinerators and as thermal processing equipment, burner nozzles, melter pot material and in other areas. Microstructure plays quite often a major role in regulating the properties of the materials. Keeping this in view, optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM) were employed to characterize the microstructure of Alloy 693. Microanalyses of the phases were performed by using electron probe microanalysis (EPMA) and TEM along with energy dispersive spectroscopy (EDS). The alloy in as-received condition under an optic microscope and SEM revealed the presence of predominantly finer intergranular precipitates and randomly distributed coarser precipitates of various morphologies. EPMA of spherical-shaped coarse precipitate indicated that the major constituent of this precipitate has been chromium. Besides this, niobium-rich irregular-shaped coarse precipitate was also detected. The finer grain boundary precipitates in the alloy appeared to be of Cr-carbide. TEM examination on as-received alloy indicated very uniform distribution of a large volume fraction of fine precipitates in the austenite matrix. Selected area diffraction (SAD) pattern, dark-field TEM and detailed analyses confirmed that these fine precipitates have been ordered Ni 3 Al type phase. TEM investigation also revealed the presence of coarse particles of various morphologies. Analyses of such particles indicated this phase as M 6 C type. EDS analyses indicated that the major constituents of these coarse particles have been Cr and Ni. Minor elements like Fe, Al and Nb were also detected in all the particles with some variation of their contents from particle to particle. TEM investigation on annealed (1373 K/30 minutes, WQ) specimen of Alloy 693

  3. Microstructural evolution of Ni40Zr60 alloy during early stage of mechanical alloying of intermetallic compounds NiZr2 and Ni11Zr9

    International Nuclear Information System (INIS)

    Lee Peeyew; Koch, C.C.

    1994-01-01

    The microstructural change of Ni 40 Zr 60 alloy during mechanical alloying of mixtures of the intermetallic compounds NiZr 2 and Ni 11 Zr 9 has been studied by transmission electron microscopy. A specific ''cauliflower'' phase was formed during early stage of mechanical alloying process. It is suggested that the solid state reaction between intermetallic compounds NiZr 2 and Ni 11 Zr 9 is not the only origin for the formation of the ''cauliflower'' phase. ((orig.))

  4. Magnetic properties and crystalline structures of Fe{sub 21}Ni{sub 79} nanowire arrays

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kwan Hyi; Lee, Woo Young; Lee, Hwa Young; Jeung, Won Young [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2002-04-01

    Fe{sub 21}Ni{sub 79} nanowire arrays have been fabricated by the electroforming method using AAO (anodic aluminum oxide) as a template, which was prepared by anodizing the pure aluminum foil. According to the magnetic property of Fe{sub 21}Ni{sub 79} nanowire prepared, it was found to have the coercivity more than 1 kOe due to the shape anisotropy and squareness (Mr/Ms) very close to 1. Especially, it could be noted that Fe{sub 21}Ni{sub 79} nanowire showed the preferred crystallographic orientation of (220). Annealing treatment of Fe{sub 21}Ni{sub 79} nanowire at 500 degree C resulted in the enhancement of coercivity by 18% while the squareness was not varied by annealing treatment. However, the random orientation of Fe{sub 21}Ni{sub 79} disk and the preferred orientation of nanowire arrays were maintained without respect to the annealing treatment up to 500 degree C.

  5. Magnetization reversal dynamics in exchange-coupled NiO - Co bilayers

    International Nuclear Information System (INIS)

    Camarero, J.; Pennec, Y.; Bonfim, M.; Vogel, J.; Pizzini, S.; Fontaine, A.; Cartier, M.; Fettar, F.; Dieny, B.

    2001-01-01

    We performed a detailed study of the magnetization reversal in polycrystalline exchange-coupled NiO/Co bilayers over 10 decades of field sweep rate dH/dt for different NiO and Co thicknesses. For all sweep rates and thicknesses, the symmetry of the hysteresis loops shows that an identical pinning strength has to be overcome in both directions of the reversal. At low dH/dt the reversal is governed by domain wall displacement while domain nucleation is dominant at higher ones. The dH/dt at which the transition between the two regimes takes place depends on the relative thickness of the NiO and Co layers. It increases (decreases) when the Co (NiO) thickness is increased. Experimentally, it was found that the energy barrier varies linearly with the square root of the area corresponding to the activation (Barkhausen) volume which is consistent with a random walk model of the coupling between antiferromagnetic and ferromagnetic layers. The results can be explained in terms of a thermally activated switching of the NiO magnetization dragged by the Co reversal. [copyright] 2001 American Institute of Physics

  6. The atomistic origin of the extraordinary oxygen reduction activity of Pt3Ni7 fuel cell catalysts.

    Science.gov (United States)

    Fortunelli, Alessandro; Goddard Iii, William A; Sementa, Luca; Barcaro, Giovanni; Negreiros, Fabio R; Jaramillo-Botero, Andrés

    2015-07-01

    Recently Debe et al. reported that Pt 3 Ni 7 leads to extraordinary Oxygen Reduction Reaction (ORR) activity. However, several reports show that hardly any Ni remains in the layers of the catalysts close to the surface ("Pt-skin effect"). This paradox that Ni is essential to the high catalytic activity with the peak ORR activity at Pt 3 Ni 7 while little or no Ni remains close to the surface is explained here using large-scale first-principles-based simulations. We make the radical assumption that processing Pt-Ni catalysts under ORR conditions would leach out all Ni accessible to the solvent. To simulate this process we use the ReaxFF reactive force field, starting with random alloy particles ranging from 50% Ni to 90% Ni and containing up to ∼300 000 atoms, deleting the Ni atoms, and equilibrating the resulting structures. We find that the Pt 3 Ni 7 case and a final particle radius around 7.5 nm lead to internal voids in communication with the exterior, doubling the external surface footprint, in fair agreement with experiment. Then we examine the surface character of these nanoporous systems and find that a prominent feature in the surface of the de-alloyed particles is a rhombic structure involving 4 surface atoms which is crystalline-like but under-coordinated. Using density-functional theory, we calculate the energy barriers of ORR steps on Pt nanoporous catalysts, focusing on the O ad -hydration reaction (O ad + H 2 O ad → OH ad + OH ad ) but including the barriers of O 2 dissociation (O 2ad → O ad + O ad ) and water formation (OH ad + H ad → H 2 O ad ). We find that the reaction barrier for the O ad -hydration rate-determining-step is reduced significantly on the de-alloyed surface sites compared to Pt(111). Moreover we find that these active sites are prevalent on the surface of particles de-alloyed from a Pt-Ni 30 : 70 initial composition. These simulations explain the peak in surface reactivity at Pt 3 Ni 7 , and provide a rational guide to

  7. Microstructure and tribological properties of NiMo/Mo2Ni3Si intermetallic 'in-situ' composites

    International Nuclear Information System (INIS)

    Gui Yongliang; Song Chunyan; Yang Li; Qin Xiaoling

    2011-01-01

    Research highlights: → Wear resistant NiMo/Mo 2 Ni 3 Si intermetallic 'in-situ' composites was fabricated successfully with Mo-Ni-Si powder blends as the starting materials. Microstructure of the NiMo/Mo 2 Ni 3 Si composites consists of Mo 2 Ni 3 Si primary dendrites, binary intermetallic phase NiMo and small amount of Ni/NiMo eutectics structure. The NiMo/Mo 2 Ni 3 Si composites exhibited high hardness and outstanding tribological properties under room-temperature dry-sliding wear test conditions which were attributed to the covalent-dominant strong atomic bonds and excellent combination of strength and ductility and toughness. - Abstract: Wear resistant NiMo/Mo 2 Ni 3 Si intermetallic 'in-situ' composites with a microstructure of ternary metal silicide Mo 2 Ni 3 Si primary dendritic, the long strip-like NiMo intermetallic phase, and a small amount of Ni/NiMo eutectics structure were designed and fabricated using molybdenum, nickel and silicon elemental powders. Friction and wear properties of NiMo/Mo 2 Ni 3 Si composites were evaluated under different contact load at room-temperature dry-sliding wear test conditions. Microstructure, worn surface morphologies and subsurface microstructure were characterized by OM, XRD, SEM and EDS. Results indicate that NiMo/Mo 2 Ni 3 Si composites have low fiction coefficient, excellent wear resistance and sluggish wear-load dependence. The dominant wear mechanisms of NiMo/Mo 2 Ni 3 Si composites are soft abrasion and slightly superficial oxidative wear.

  8. Nonenzymatic Glucose Sensor Based on In Situ Reduction of Ni/NiO-Graphene Nanocomposite

    Directory of Open Access Journals (Sweden)

    Xiaohui Zhang

    2016-10-01

    Full Text Available Ni/NiO nanoflower modified reduced graphene oxide (rGO nanocomposite (Ni/NiO-rGO was introduced to screen printed electrode (SPE for the construction of a nonenzymatic electrochemical glucose biosensor. The Ni/NiO-rGO nanocomposite was synthesized by an in situ reduction process. Graphene oxide (GO hybrid Nafion sheets first chemical adsorbed Ni ions and assembled on the SPE. Subsequently, GO and Ni ions were reduced by hydrazine hydrate. The electrochemical properties of such a Ni/NiO-rGO modified SPE were carefully investigated. It showed a high activity for electrocatalytic oxidation of glucose in alkaline medium. The proposed nonenzymatic sensor can be utilized for quantification of glucose with a wide linear range from 29.9 μM to 6.44 mM (R = 0.9937 with a low detection limit of 1.8 μM (S/N = 3 and a high sensitivity of 1997 μA/mM∙cm−2. It also exhibited good reproducibility as well as high selectivity.

  9. Enthalpy of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys

    International Nuclear Information System (INIS)

    Witusiewicz, V.T.; Sommer, F.

    2000-01-01

    Since the Al-Cu-Ni-Zr system is a basis for the production of bulk amorphous materials by rapid solidification techniques from the liquid state, it is of great scientific interest to determine the partial and the integral thermodynamic functions of liquid and undercooled liquid alloys. Such data, as was pointed out previously, are important in order to understand their extremely good glass-forming ability in multicomponent metallic systems as well as for processing improvements. In order to measure the thermodynamic properties of the Al-Cu-Ni-Zr quaternary, it is necessary to have reliable thermochemical data for its constituent canaries and ternaries first. In a series of articles, the authors have reported in detail the thermodynamic properties of liquid Al-Cu, Al-Ni, Cu-Ni, Cu-Zr, Al-Zr, Al-Cu-Ni, and Al-Cu-Zr alloys. This article deals with the direct calorimetric measurements of the partial and the integral enthalpies of mixing of liquid Ni-Zr and Cu-Ni-Zr alloys and the heat capacity of liquid Ni 26 Zr 74 . In a subsequent article, the authors will present similar data for the liquid ternary Al-Ni-Zr and for the liquid quaternary Al-Cu-Ni-Zr alloys

  10. The Ni-YSZ interface

    DEFF Research Database (Denmark)

    Jensen, Karin Vels

    The anode/electrolyte interface in solid oxide fuel cells (SOFC) is known to cause electrical losses. Geometrically simple Ni/yttria-stabilised zirconia (YSZ) interfaces were examined to gain information on the structural and chemical changes occurring during experiments at 1000°C in an atmosphere...... of 97% H2/3% H2O. Electrochemical impedance spectroscopy at open circuit voltage (OCV) and at anodic and cathodic polarisations (100 mV) was performed. A correlation of the electrical data with the structure development and the chemical composition was attempted. Nickel wires with different impurity...... between polarised and non-polarised samples. With pure nickel wires, however, the microstructures depended on the polarisation/non-polarisation conditions. At non-polarised conditions a hill and valley type structure was found. Anodic polarisation produced an up to 1 μm thick interface layer consisting...

  11. Study of the central collisions in the reactions Ni + Al and Ni + Ni at 28 A.MeV; Etude des collisions centrales dans les reactions Ni + Al et Ni + Ni a 28 A.MeV

    Energy Technology Data Exchange (ETDEWEB)

    Lebreton, L.

    1995-12-01

    The work is in characterisation of mechanisms in the energy range of onset of multifragmentation (excitation energy of composed nucleus around 4 - 5 AMeV). This work focused on an experiment performed at the SARA facility, in Grenoble, using the AMPHORA multi detection array. I have been particularly interested in central collisions in the Ni + Al and Ni + Ni systems. The possibility to detect complete events for Ni + Al, and quasi-complete events for the Ni + Ni case, is the reason of this choice. Furthermore Ni + Ni presents the interest of a symmetrical system, for which the excitation energy per nucleon is maximum. The study of these reactions has been focused on the quasi-complete events (events for which at least 80 % of the total charge has been detected). Heavy ions produced in peripheral collisions are very likely emitted along the beam line or stopped in the plastic detectors, energy thresholds are too high for the quasi-target products detection, consequently by requiring complete or quasi-complete measurement of the total charge, we are able to detect mostly central events. The knowledge of informations like charge, energy or detection angles allows to isolate the source(s) and to reconstruct the size and the excitation energy of the source(s). Comparisons with simulations like sequential emission (GEMINI code), very deep inelastic collision or instantaneous emission (Berliner code) allows to characterise the first stage of the collision (binary collisions or central collisions) and the type of deexcitation of the source(s). Some calculations was also performed with the statistical model code MODGAN. Indeed azimuthal correlations seem to be a good tool in getting more information about involved reaction mechanisms. Comparisons with MODGAN provide information about angular momentum of the source and time delay between emissions of the two particles (separation between sequential or instantaneous process). (author). 69 refs.

  12. Electrochemical preparation and characteristics of Ni-Co-LaNi{sub 5} composite coatings as electrode materials for hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Wu Gang; Li Ning; Dai Changsong; Zhou Derui

    2004-02-15

    Electrocatalytic activity for the hydrogen evolution reaction on Ni-Co-LaNi{sub 5} composite electrodes prepared by electrochemical codeposition technique was evaluated. The relationship between the current density for hydrogen evolution reaction and the amount of LaNi{sub 5} particles in Ni-Co baths is like the well-known 'volcano plot'. The Surface morphology and microstructure of Ni-Co-LaNi{sub 5} coatings were determined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The kinetic parameters were determined from electrochemical steady-state Tafel polarization and electrochemical impedance spectroscopy technology in 1 M NaOH solution. The values obtained for the apparent energies of activation are 32.48, 46.29 and 57.03 kJ mol{sup -1} for the Ni-Co-LaNi{sub 5}, Ni-Co and Ni electrodes, respectively. The hydrogen evolution reaction on Ni-Co-LaNi{sub 5} proceeds via Volmer-Tafel reaction route with the mixed rate determining characteristics. The composite coating Ni-Co-LaNi{sub 5} is catalytically more active than Ni and Ni-Co electrodes due to the increase in its real surface areas and the decrease in the apparent free energy of activation caused by the electrocatalytic synergistic effect of the Ni-Co alloys and the hydrogen storage intermetallic particles on the electrode surface.

  13. Electrochemical preparation and characteristics of Ni-Co-LaNi5 composite coatings as electrode materials for hydrogen evolution

    International Nuclear Information System (INIS)

    Wu Gang; Li Ning; Dai Changsong; Zhou Derui

    2004-01-01

    Electrocatalytic activity for the hydrogen evolution reaction on Ni-Co-LaNi 5 composite electrodes prepared by electrochemical codeposition technique was evaluated. The relationship between the current density for hydrogen evolution reaction and the amount of LaNi 5 particles in Ni-Co baths is like the well-known 'volcano plot'. The Surface morphology and microstructure of Ni-Co-LaNi 5 coatings were determined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The kinetic parameters were determined from electrochemical steady-state Tafel polarization and electrochemical impedance spectroscopy technology in 1 M NaOH solution. The values obtained for the apparent energies of activation are 32.48, 46.29 and 57.03 kJ mol -1 for the Ni-Co-LaNi 5 , Ni-Co and Ni electrodes, respectively. The hydrogen evolution reaction on Ni-Co-LaNi 5 proceeds via Volmer-Tafel reaction route with the mixed rate determining characteristics. The composite coating Ni-Co-LaNi 5 is catalytically more active than Ni and Ni-Co electrodes due to the increase in its real surface areas and the decrease in the apparent free energy of activation caused by the electrocatalytic synergistic effect of the Ni-Co alloys and the hydrogen storage intermetallic particles on the electrode surface

  14. Synthesis of Supported NiPt Bimetallic Nanoparticles, Methods for Controlling the Surface Coverage of Ni Nanoparticles With Pt, Methods Of Making NiPt Multilayer Core-Shell Structures and Application of the Supported Catalysts for CO2 Reforming

    KAUST Repository

    Li, Lidong; Anjum, Dalaver H.; Zhou, Lu; Laveille, Paco; Basset, Jean-Marie

    2015-01-01

    Embodiments of the present disclosure provide for supported Ni/Pt bimetallic nanoparticles, compositions including supported NiPt nanoparticles, methods of making supported NiPt nanoparticles, methods of using supported NiPt nanoparticles

  15. Synthesis of Supported NiPt Bimetallic Nanoparticles, Methods for Controlling the Surface Coverage of Ni Nanoparticles With Pt, Methods Of Making NiPt Multilayer Core-Shell Structures and Application of the Supported Catalysts for CO2 Reforming

    KAUST Repository

    Li, Lidong

    2015-06-25

    Embodiments of the present disclosure provide for supported Ni/Pt bimetallic nanoparticles, compositions including supported NiPt nanoparticles, methods of making supported NiPt nanoparticles, methods of using supported NiPt nanoparticles, and the like.

  16. Growth of single-crystal W whiskers during humid H2/N2 reduction of Ni, Fe-Ni, and Co-Ni doped tungsten oxide

    International Nuclear Information System (INIS)

    Wang Shiliang; He Yuehui; Zou Jou; Wang Yong; Huang Han

    2009-01-01

    Numbers of W whiskers were obtained by reducing Ni, Ni-Fe, and Ni-Co doped tungsten oxide in a mixed atmosphere of humid H 2 and N 2 . The phases and morphologies of the reduction products were characterized by XRD and SEM. Intensive TEM and EDS analyses showed that the obtained whiskers were W single crystals which typical have alloyed particles (Ni-W, Fe-Ni, or Co-Ni-W) at the growth tips. The formed W whiskers were presumed to be induced by the alloyed particles. Our experimental results revealed that, during the reduction process of tungsten oxide, the pre-reduced Ni, Fe-Ni, or Co-Ni particles not only served as nucleation aids for the initial growth of W phase from W oxide but also played the roles of catalysts during the reductive decomposition of gaseous WO 2 (OH) 2 .

  17. Exchange bias variations of the seed and top NiFe layers in NiFe/FeMn/NiFe trilayer as a function of seed layer thickness

    International Nuclear Information System (INIS)

    Sankaranarayanan, V.K.; Yoon, S.M.; Kim, C.G.; Kim, C.O.

    2005-01-01

    Development of exchange bias at the seed and top NiFe layers in the NiFe (t nm)/FeMn(10 nm)/NiFe(5 nm) trilayer structure is investigated as a function of seed layer thickness, in the range of 2-20 nm. The seed NiFe layer shows maximum exchange bias at 4 nm seed layer thickness. The bias shows inverse thickness dependence with increasing thickness. The top NiFe layer on the other hand shows only half the bias of the seed layer which is retained even after the sharp fall in seed layer bias. The much smaller bias for the top NiFe layer is related to the difference in crystalline texture and spin orientations at the top FeMn/NiFe interface, in comparison to the bottom NiFe/FeMn interface which grows on a saturated NiFe layer with (1 1 1) orientation

  18. An Ultrastable and High-Performance Flexible Fiber-Shaped Ni-Zn Battery based on a Ni-NiO Heterostructured Nanosheet Cathode.

    Science.gov (United States)

    Zeng, Yinxiang; Meng, Yue; Lai, Zhengzhe; Zhang, Xiyue; Yu, Minghao; Fang, Pingping; Wu, Mingmei; Tong, Yexiang; Lu, Xihong

    2017-11-01

    Currently, the main bottleneck for the widespread application of Ni-Zn batteries is their poor cycling stability as a result of the irreversibility of the Ni-based cathode and dendrite formation of the Zn anode during the charging-discharging processes. Herein, a highly rechargeable, flexible, fiber-shaped Ni-Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni-NiO heterostructured nanosheets as the cathode. Benefiting from the improved conductivity and enhanced electroactivity of the Ni-NiO heterojunction nanosheet cathode, the as-fabricated fiber-shaped Ni-NiO//Zn battery displays high capacity and admirable rate capability. More importantly, this Ni-NiO//Zn battery shows unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g -1 ) electrolytes. Moreover, a peak energy density of 6.6 µWh cm -2 , together with a remarkable power density of 20.2 mW cm -2 , is achieved by the flexible quasi-solid-state fiber-shaped Ni-NiO//Zn battery, outperforming most reported fiber-shaped energy-storage devices. Such a novel concept of a fiber-shaped Ni-Zn battery with impressive stability will greatly enrich the flexible energy-storage technologies for future portable/wearable electronic applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Synthesis of a novel Au nanoparticles decorated Ni-MOF/Ni/NiO nanocomposite and electrocatalytic performance for the detection of glucose in human serum.

    Science.gov (United States)

    Chen, Jingyuan; Xu, Qin; Shu, Yun; Hu, Xiaoya

    2018-07-01

    A nonenzymatic glucose electrochemical sensor was constructed based on Au nanoparticles (AuNPs) decorated Ni metal-organic-framework (MOF)/Ni/NiO nanocomposite. Ni-MOF/Ni/NiO nanocomposite was synthesized by one-step calcination of Ni-MOF. Then AuNPs were loaded onto the Ni-based nanocomposites' surface through electrostatic adsorption. Through characterization by transmission electron microscopy (TEM), high resolution TEM (HRTEM) and energy disperse spectroscopy (EDS) mapping, it is found that the AuNPs were well distributed on the surface of Ni-based nanocomposite. Cyclic voltammetric (CV) study showed the electrocatalytic activity of Au-Ni nanocomposite was highly improved after loading AuNPs onto it. Amperometric study demonstrated that the Au-Ni nanocomposites modified glassy carbon electrode (GCE) exhibited a high sensitivity of 2133.5 mA M -1 cm -2 and a wide linear range (0.4-900 μM) toward the oxidation of glucose with a detection limit as low as 0.1 μM. Moreover, the reproducibility, selectivity and stability of the sensor all exhibited outstanding performance. We applied the as-fabricated high performance sensor to measure the glucose levels in human serum and obtained satisfactory results. It is believed that AuNPs decorated Ni MOF/Ni/NiO nanocomposite provides a new platform for developing highly performance electrochemical sensors in practical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Ni antagelser om Situationel Dialektisk Videnskabsteori

    DEFF Research Database (Denmark)

    Dakwar, Julia Rytter; Lorentzen, Anne-Christine Rosfeldt; Smedegaard, Flemming

    2017-01-01

    I artiklen præsenteres et præliminært bud på en Situationel Dialektisk Videnskabsteori (SDV) i form af ni antagelser. Situationel, fordi antagelserne ikke er statiske, men alle overvejelser og valg under de enkelte antagelser er afhængige af situationen. Dialektisk, fordi alle ni antagelser...... opererer med dialektiske modsætninger, og alle videnskabsteoretiske valg ses som valg på kontinua. De ni antagelser, som bliver præsenteret og diskuteret i artiklen, er: Antagelse 1: Teori og praksis fordrer hinanden Antagelse 2: Del og helhed hænger sammen Antagelse 3: Forbundne sagsforhold påvirker...

  1. New developments in Ni/Ti multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, I; Hoghoj, P [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)

    1997-04-01

    It is now 20 years since super-mirrors were first used as a neutron optical element. Since then the field of multilayer neutron-optics has matured with multilayers finding their way to application in many neutron scattering instruments. However, there is still room for progress in terms of multilayer quality, performance and application. Along with work on multilayers for neutron polarisation Ni/Ti super-mirrors have been optimised. The state-of-the-art Ni/Ti super-mirror performance and the results obtained in two neutron-optics applications of Ni/Ti multilayers are presented. (author).

  2. Site occupancy of Fe in ternary Ni 75-x

    Indian Academy of Sciences (India)

    The results of a detailed structural and magnetic study clearly indicate that regardless of the thermal history of the samples, Fe has a strong preference for the Ni sites in Ni-poor (non-stoichiometric) Ni75Al25 alloys. Fe substitution has a profound effect on the nature of magnetism in Ni75Al25.

  3. Reduction of a Ni/Spinel Catalyst for Methane Reforming

    DEFF Research Database (Denmark)

    Kehres, Jan; Andreasen, Jens Wenzel; Fløystad, Jostein Bø

    2015-01-01

    microscopy (HRTEM) was performed on the fresh catalyst sample. The Ni particles in the fresh catalyst sample were observed to exhibit a Ni/NiO core/shell structure. A decrease of the Ni lattice parameter is observed during the reduction in a temperature interval from 413 – 453 K, which can be related...

  4. Influence of Ni Solute segregation on the intrinsic growth stresses in Cu(Ni) thin films

    International Nuclear Information System (INIS)

    Kaub, T.M.; Felfer, P.; Cairney, J.M.; Thompson, G.B.

    2016-01-01

    Using intrinsic solute segregation in alloys, the compressive stress in a series of Cu(Ni) thin films has been studied. The highest compressive stress was noted in the 5 at.% Ni alloy, with increasing Ni concentration resulting in a subsequent reduction of stress. Atom probe tomography quantified Ni's Gibbsian interfacial excess in the grain boundaries and confirmed that once grain boundary saturation is achieved, the compressive stress was reduced. This letter provides experimental support in elucidating how interfacial segregation of excess adatoms contributes to the post-coalescence compressive stress generation mechanism in thin films. - Graphical abstract: Cu(Ni) film stress relationship with Ni additions. Atom probe characterization confirms solute enrichment in the boundaries, which was linked to stress response.

  5. NiCo-lead zirconium titanate-NiCo trilayered magnetoelectric composites prepared by electroless deposition

    International Nuclear Information System (INIS)

    Zhou, M. H.; Wang, Y. G.; Bi, K.; Fan, H. P.; Zhao, Z. S.

    2015-01-01

    The NiCo layers with various Ni/Co atomic ratio have been successfully electroless deposited on PZT layers by varying the bath composition. As the cobalt atomic ratio in the deposited layer increases from 17.2 to 54.8 wt%, the magnetostrictive coefficient decreases. The magnetoelectric effect depends strongly on the magnetostrictive properties of magnetostrictive phase. The magnetoelectric coefficient of NiCo/PZT/NiCo trilayers increases with Ni/Co atomic ratio of the deposited NiCo layers increasing from 45:55 to 83:17. A maximum ME voltage coefficient of α E,31 = 2.8 V ⋅ cm −1 ⋅ Oe −1 is obtained at a frequency of about 88 kHz, which makes these trilayers suitable for applications in actuators, transducers and sensors

  6. NiCo-lead zirconium titanate-NiCo trilayered magnetoelectric composites prepared by electroless deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, M. H.; Wang, Y. G.; Bi, K., E-mail: bike@bupt.edu.cn [State Key Laboratory of Information Photonics and Optical Communications and School of Science, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Fan, H. P. [School of Mechanical and Electrical Engineering, Qingdao Technological University Qindao College, Qingdao 266106 (China); Zhao, Z. S. [Shandong Engineering Consulting Institute, Jinan 250013 (China)

    2015-04-15

    The NiCo layers with various Ni/Co atomic ratio have been successfully electroless deposited on PZT layers by varying the bath composition. As the cobalt atomic ratio in the deposited layer increases from 17.2 to 54.8 wt%, the magnetostrictive coefficient decreases. The magnetoelectric effect depends strongly on the magnetostrictive properties of magnetostrictive phase. The magnetoelectric coefficient of NiCo/PZT/NiCo trilayers increases with Ni/Co atomic ratio of the deposited NiCo layers increasing from 45:55 to 83:17. A maximum ME voltage coefficient of α{sub E,31} = 2.8 V ⋅ cm{sup −1} ⋅ Oe{sup −1} is obtained at a frequency of about 88 kHz, which makes these trilayers suitable for applications in actuators, transducers and sensors.

  7. Fe-solubility of Ni7S6 and Ni9S8: Thermodynamic analysis

    International Nuclear Information System (INIS)

    Waldner, P.

    2011-01-01

    Experimental data on phase equilibria have been used for thermodynamic analysis of the iron solubility of the nickel sulfides Ni 7 S 6 and Ni 9 S 8 . For both compounds, a two-sublattice approach within the framework of the compound energy formalism has been applied to perform Gibbs free energy modelling at 0.1 MPa total pressure consistently embedded in recent thermodynamic assessment studies of other iron-nickel-sulfides. The predicted maxima of iron solubility around 3 at% of Ni 7 S 6 and 5.5 at% of Ni 9 S 8 are confirmed by experimental data. The calculations of complex ternary phase relations with Fe-bearing Ni 7 S 6 and Ni 9 S 8 gain further improvement. The first internally consistent description of all thermodynamically stable phases known in the literature for the iron-nickel-sulfur system is completed.

  8. Phase stability and magnetism in NiPt and NiPd alloys

    International Nuclear Information System (INIS)

    Paudyal, Durga; Mookerjee, Abhijit

    2004-01-01

    We show that the differences in stability of 3d-5d NiPt and 3d-4d NiPd alloys arise mainly due to relativistic corrections. The magnetic properties of disordered NiPd and NiPt alloys also differ due to these corrections, which lead to increase in the separation between the s-d bands of 5d elements in these alloys. For the magnetic case we also analyse the results in terms of splitting of majority and minority spin d band centres of the 3d elements. We further examine the effect of relativistic corrections to the pair energies and order-disorder transition temperatures in these alloys. The magnetic moments and Curie temperatures have also been studied along with the short range ordering/segregation effects in NiPt/NiPd alloys

  9. Random broadcast on random geometric graphs

    Energy Technology Data Exchange (ETDEWEB)

    Bradonjic, Milan [Los Alamos National Laboratory; Elsasser, Robert [UNIV OF PADERBORN; Friedrich, Tobias [ICSI/BERKELEY; Sauerwald, Tomas [ICSI/BERKELEY

    2009-01-01

    In this work, we consider the random broadcast time on random geometric graphs (RGGs). The classic random broadcast model, also known as push algorithm, is defined as: starting with one informed node, in each succeeding round every informed node chooses one of its neighbors uniformly at random and informs it. We consider the random broadcast time on RGGs, when with high probability: (i) RGG is connected, (ii) when there exists the giant component in RGG. We show that the random broadcast time is bounded by {Omicron}({radical} n + diam(component)), where diam(component) is a diameter of the entire graph, or the giant component, for the regimes (i), or (ii), respectively. In other words, for both regimes, we derive the broadcast time to be {Theta}(diam(G)), which is asymptotically optimal.

  10. Quantumness, Randomness and Computability

    International Nuclear Information System (INIS)

    Solis, Aldo; Hirsch, Jorge G

    2015-01-01

    Randomness plays a central role in the quantum mechanical description of our interactions. We review the relationship between the violation of Bell inequalities, non signaling and randomness. We discuss the challenge in defining a random string, and show that algorithmic information theory provides a necessary condition for randomness using Borel normality. We close with a view on incomputablity and its implications in physics. (paper)

  11. Precipitation of Ni4Ti3-variants in a polycrystalline Ni-rich NiTi shape memory alloy

    Czech Academy of Sciences Publication Activity Database

    Bojda, Ondřej; Eggeler, G.; Dlouhý, Antonín

    2005-01-01

    Roč. 53, č. 1 (2005), s. 99-104 ISSN 1359-6462 R&D Projects: GA ČR(CZ) GA106/05/0918 Institutional research plan: CEZ:AV0Z20410507 Keywords : NiTi shape memory alloys * Ni4Ti3 precipitation * Transmission electron microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.228, year: 2005

  12. Ni-Ni ion pair excitation transfer in D sub(3h) symmetry

    International Nuclear Information System (INIS)

    Terrile, M.C.

    1990-01-01

    The mechanisms contributing to excitation transfer are examined for Ni-Ni ion pairs in order to explain the delocalized character of electronic excitations observed in CsNiF sub(3). Using both first-and second-order perturbation theory and from symmetry arguments, the kind of interactions giving matrix elements between states connecting different sites for the position of the excitation are discussed. (author)

  13. Electronic structure of graphene on Ni surfaces with different orientation

    International Nuclear Information System (INIS)

    Pudikov, D.A.; Zhizhin, E.V.; Rybkin, A.G.; Rybkina, A.A.; Zhukov, Y.M.; Vilkov, O. Yu.; Shikin, A.M.

    2016-01-01

    An experimental study of the graphene, synthesized by propylene cracking on Ni surfaces with different orientation: (100) and (111), using angle-resolved photoemission, has been performed. It has been shown that graphene on Ni(111) had a perfect lateral structure due to consistency of their lattices, whereas graphene/Ni(100) consisted of a lot of domains. For both systems electronic structure was quite similar and demonstrated a strong bonding of graphene to the underlying Ni surface. After Au intercalation the electronic structure of graphene in both systems was shifted to the Fermi level and became linear in the vicinity of the K point of the Brillouin zone. - Highlights: • Graphene on Ni(111) is well-ordered, whereas on Ni(100) – multi-domain. • Graphene on Ni(111) and Ni(100) is strongly bonded with substrate. • Intercalation of Au atoms restores the linearity in dispersion and makes graphene quasi-free on both Ni(100) and Ni(111).

  14. How random is a random vector?

    Science.gov (United States)

    Eliazar, Iddo

    2015-12-01

    Over 80 years ago Samuel Wilks proposed that the "generalized variance" of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the "Wilks standard deviation" -the square root of the generalized variance-is indeed the standard deviation of a random vector. We further establish that the "uncorrelation index" -a derivative of the Wilks standard deviation-is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: "randomness measures" and "independence indices" of random vectors. In turn, these general notions give rise to "randomness diagrams"-tangible planar visualizations that answer the question: How random is a random vector? The notion of "independence indices" yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  15. How random is a random vector?

    International Nuclear Information System (INIS)

    Eliazar, Iddo

    2015-01-01

    Over 80 years ago Samuel Wilks proposed that the “generalized variance” of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the “Wilks standard deviation” –the square root of the generalized variance–is indeed the standard deviation of a random vector. We further establish that the “uncorrelation index” –a derivative of the Wilks standard deviation–is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: “randomness measures” and “independence indices” of random vectors. In turn, these general notions give rise to “randomness diagrams”—tangible planar visualizations that answer the question: How random is a random vector? The notion of “independence indices” yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

  16. Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Kabir, L.; Mandal, A.R. [Department of Physics, Visva-Bharati, Santiniketan-731 235 (India); Mandal, S.K., E-mail: sk_mandal@hotmail.co [Department of Physics, Visva-Bharati, Santiniketan-731 235 (India)

    2010-04-15

    We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni{sup 2+} clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni{sup 2+} clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

  17. Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

    Science.gov (United States)

    Kabir, L.; Mandal, A. R.; Mandal, S. K.

    2010-04-01

    We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni 2+ clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni 2+ clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

  18. Polymer stabilized Ni-Ag and Ni-Fe alloy nanoclusters: Structural and magnetic properties

    International Nuclear Information System (INIS)

    Kabir, L.; Mandal, A.R.; Mandal, S.K.

    2010-01-01

    We report here the structural and magnetic behaviors of nickel-silver (Ni-Ag) and nickel-iron (Ni-Fe) nanoclusters stabilized with polymer (polypyrrole). High resolution transmission electron microscopy (HRTEM) indicates Ni-Ag nanoclusters to stabilize in core-shell configuration while that of Ni-Fe nanoclusters in a mixed type of geometry. Structural characterizations by X-ray diffraction (XRD) reveal the possibility of alloying in such bimetallic nanoclusters to some extent even at temperatures much lower than that of bulk alloying. Electron paramagnetic resonance (EPR) spectra clearly reveal two different absorption behaviors: one is ascribed to non-isolated Ni 2+ clusters surrounded by either silver or iron giving rise to a broad signal, other (very narrow signal) being due to the isolated superparamagnetic Ni 2+ clusters or bimetallic alloy nanoclusters. Results obtained for Ni-Ag and Ni-Fe nanoclusters have been further compared with the behavior exhibited by pure Ni nanoclusters in polypyrrole host. Temperature dependent studies (at 300 and 77 K) of EPR parameters, e.g. linewidth, g-value, line shape and signal intensity indicating the significant influence of surrounding paramagnetic silver or ferromagnetic iron within polymer host on the EPR spectra have been presented.

  19. Modeling and simulation of NiO dissolution and Ni deposition in molten carbonate fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Suk Woo; Choi, Hyung-Joon; Lim, Tae Hoon [Korea Institute of Science & Technology, Seoul (Korea, Republic of)] [and others

    1996-12-31

    Dissolution of NiO cathode into the electrolyte matrix is an important phenomena limiting the lifetime of molten carbonate fuel cell (MCFC). The dissolved nickel diffuses into the matrix and is reduced by dissolved hydrogen leading to the formation of metallic nickel films in the pores of the matrix. The growth of Ni films in the electrolyte matrix during the continuous cell operation results eventually in shorting between cathode and anode. Various mathematical and empirical models have been developed to describe the NiO dissolution and Ni deposition processes, and these models have some success in estimating the lifetime of MCFC by correlating the amount of Ni deposited in the matrix with shorting time. Since the exact mechanism of Ni deposition was not well understood, deposition reaction was assumed to be very fast in most of the models and the Ni deposition region was limited around a point in the matrix. In fact, formation of Ni films takes place in a rather broad region in the matrix, the location and thickness of the film depending on operating conditions as well as matrix properties. In this study, we assumed simple reaction kinetics for Ni deposition and developed a mathematical model to get the distribution of nickel in the matrix.

  20. Layering and temperature-dependent magnetization and anisotropy of naturally produced Ni/NiO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, S. D.; Trachylis, D.; Velgakis, M. J. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Kapaklis, V.; Joensson, P. E.; Papaioannou, E. Th. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Delimitis, A. [Chemical Process Engineering Research Institute (CPERI), Centre for Research and Technology Hellas (CERTH), 57001 Thermi, Thessaloniki (Greece); Poulopoulos, P. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Materials Science Department, University of Patras, 26504 Patras (Greece); Fumagalli, P. [Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, D-14195 Berlin-Dahlem (Germany); Politis, C. [Laboratory of High-Tech Materials, School of Engineering, University of Patras, 26504 Patras (Greece); Department of Materials Science and Engineering, University of Texas at Arlington, Arlington, Texas 76019 (United States)

    2012-09-01

    Ni/NiO multilayers were grown by magnetron sputtering at room temperature, with the aid of the natural oxidation procedure. That is, at the end of the deposition of each single Ni layer, air is let to flow into the vacuum chamber through a leak valve. Then, a very thin NiO layer ({approx}1.2 nm) is formed. Simulated x-ray reflectivity patterns reveal that layering is excellent for individual Ni-layer thickness larger than 2.5 nm, which is attributed to the intercalation of amorphous NiO between the polycrystalline Ni layers. The magnetization of the films, measured at temperatures 5-300 K, has almost bulk-like value, whereas the films exhibit a trend to perpendicular magnetic anisotropy (PMA) with an unusual significant positive interface anisotropy contribution, which presents a weak temperature dependence. The power-law behavior of the multilayers indicates a non-negligible contribution of higher order anisotropies in the uniaxial anisotropy. Bloch-law fittings for the temperature dependence of the magnetization in the spin-wave regime show that the magnetization in the multilayers decreases faster as a function of temperature than the one of bulk Ni. Finally, when the individual Ni-layer thickness decreases below 2 nm, the multilayer stacking vanishes, resulting in a dramatic decrease of the interface magnetic anisotropy and consequently in a decrease of the perpendicular magnetic anisotropy.

  1. XRD studies on solid state amorphisation in electroless Ni/P and Ni/B deposits

    International Nuclear Information System (INIS)

    Sampath Kumar, P.; Kesavan Nair, P.

    1996-01-01

    The decomposition of electroless Ni-P and Ni-B deposits on annealing at various temperature is studied using x-ray diffraction techniques employing profile deconvolution and line profile analysis. It appears that solid state amorphisation takes place in the Ni-B deposits in a narrow temperature range just prior to the onset of crystallization of amorphous phase. In the case of Ni-P deposits no evidence for solid state amorphisation could be obtained. Thermodynamic and kinetic considerations also support such a conclusion

  2. Ni adsorption and Ni-Al LDH precipitation in a sandy aquifer: An experimental and mechanistic modeling study

    NARCIS (Netherlands)

    Regelink, I.C.; Temminghoff, E.J.M.

    2011-01-01

    Mining activities and industries have created nickel (Ni) contaminations in many parts of the world. The objective of this study is to increase our understanding of Ni adsorption and Nickel-Aluminium Layered Double Hydroxide (Ni-Al LDH) precipitation to reduce Ni mobility in a sandy soil aquifer. At

  3. Core/shell AgNi/PtAgNi nanoparticles as methanol-tolerant oxygen reduction electrocatalysts

    International Nuclear Information System (INIS)

    Wu, Dengfeng; Cheng, Daojian

    2015-01-01

    A core/shell AgNi/PtAgNi nanoparticle (NP) was synthesized via a new seed-mediated growth method in organic solvent medium. The as-synthesized AgNi/PtAgNiNP exhibits an AgNi core coated with PtAgNi shell, which was confirmed by transmission electron microscopy (TEM), ultraviolet–visible absorption spectroscopy and X-ray Photoelectron Spectroscopy (XPS). The AgNi/PtAgNiNPs/C catalyst possesses higher oxygen reduction reaction (ORR) activity and better durability compared with the commercial Pt/C catalyst. It is found that the ORR polarization curve of the AgNi/PtAgNiNPs/C catalyst shows an onset potential of 0.91 V vs. RHE, which is superior to the commercial Pt/C (0.88 V vs. RHE). In addition, the AgNi/PtAgNiNPs/C catalyst shows much better durability than the commercial Pt/C catalyst. More interestingly, the AgNi/PtAgNiNPs/C catalyst displays much higher methanol tolerance than the commercial Pt/C catalyst in 0.1 M KOH solution in the presence of 0.5 M methanol. Our results show that core/shell AgNi/PtAgNiNPs possess selective activity for ORR even in the presence of methanol, showing potential application as methanol-tolerant cathode catalysts in direct methanol fuel cells.

  4. Grain boundaries in Ni3Al. 2

    International Nuclear Information System (INIS)

    Kung, H.; Sass, S.L.

    1992-01-01

    This paper discusses the dislocation structure of small angle tilt and twist boundaries in ordered Ni 3 Al, with and without boron, investigated using transmission electron microscopy. Dislocation with Burgers vectors that correspond to anti-phase boundary (APB)-coupled superpartials were found in small angle twist boundaries in both boron-free and boron-doped Ni 3 Al, and a small angle tilt boundary in boron-doped Ni 3 Al. The boundary structures are in agreement with theoretical models proposed by Marcinkowski and co-workers. The APB energy determined from the dissociation of the grain boundary dislocations was lower than values reported for isolated APBs in Ni 3 Al. For small angle twist boundaries the presence of boron reduced the APB energy at the interface until it approached zero. This is consistent with the structure of these boundaries containing small regions of increased compositional disorder in the first atomic plane next to the interface

  5. Ni-ZrB2 electrocomposites

    International Nuclear Information System (INIS)

    Pushpavanam, M.; Natarajan, S.R.

    1992-01-01

    New generation materials require high temperature oxidation resistance besides many other tribological properties. Ni-ZrB 2 composites and their properties are dealt with in this paper. (author). 7 refs., 3 figs., 4 tabs

  6. Not in Traffic Surveillance (NiTS)

    Data.gov (United States)

    Department of Transportation — The Not-in-Traffic Surveillance (NiTS) system is a virtual data collection system designed to provide counts and details regarding fatalities and injuries that occur...

  7. Niños y Violencia

    OpenAIRE

    International Child Development Centre

    1997-01-01

    Este Innocenti Digest explora la violencia de los niños y hacia los niños, usando el marco de la Convención de los Derechos del Niño de las Naciones Unidas. Se centra en la violencia interpersonal, tanto intrafamiliar como extrafamiliar. Se incluye el abuso sexual y la explotación ya que a pesar de no implicar obligatoriamente violencia o coerción, la mayor parte de la evidencia demuestra su efectos dañinos tanto físicos como psicológicos. También se discute la implicación de los niños en los...

  8. Collision strengths for transitions in Ni XIX

    Indian Academy of Sciences (India)

    4l configurations of Ni XIX, for which flexible atomic code. (FAC) has been ... atomic data (namely energy levels, radiative rates, collision strengths, excitation rates, etc.) ... Zhang and Sampson, who adopted the Coulomb–Born-exchange.

  9. Root morphology of Ni-treated plants

    International Nuclear Information System (INIS)

    Leskova, A.; Fargasova, A.; Giehl, R. F. H.; Wiren, N. von

    2015-01-01

    Plant roots are very important organs in terms of nutrient and water acquisition but they also serve as anchorages for the aboveground parts of the plants. The roots display extraordinary plasticity towards stress conditions as a result of integration of environmental cues into the developmental processes of the roots. Our aim was to investigate the root morphology of Arabidopsis thaliana plants exposed to a particular stress condition, excess Ni supply. We aimed to find out which cellular processes - cell division, elongation and differentiation are affected by Ni, thereby explaining the seen root phenotype. Our results reveal that a distinct sensitivity exists between roots of different order and interference with various cellular processes is responsible for the effects of Ni on roots. We also show that Ni-treated roots have several auxin-related phenotypes. (authors)

  10. Density and Structure Analysis of Molten Ni-W Alloys

    Institute of Scientific and Technical Information of China (English)

    Feng XIAO; Liang FANG

    2004-01-01

    Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773~1873 K with a sessile drop method.The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.

  11. High-resolution electron microscopy study of Ni81Fe19 film with Co33Cr67 buffer layer

    International Nuclear Information System (INIS)

    Xu, Q.Y.; Wang, Z.M.; Shen, F.; Du, Y.W.; Zhang, Z.

    2003-01-01

    The anisotropic magnetoresistance (AMR) in permalloy Ni 81 Fe 19 film deposited on a 1.2 nm Co 33 Cr 67 buffer layer was significantly enhanced. The high-resolution electron microscopy was used to study the microstructure of Ni 81 Fe 19 film with and without Co 33 Cr 67 buffer layer. It was found that Co 33 Cr 67 buffer layer can induce good (1 1 1) texture, while without Co 33 Cr 67 buffer layer, Ni 81 Fe 19 film show randomly oriented grain structure. The Δρ/ρ enhancement is attributed to the decrease in the resistivity ρ of the Ni 81 Fe 19 film due to the formation of the large (1 1 1) textured grains in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer. However, the surface roughness of substrate may limit the (1 1 1) textured grain size and induce additional grain boundaries in Ni 81 Fe 19 film with Co 33 Cr 67 buffer layer, limit the enhancement of the AMR effect

  12. Enhanced sensitivity in non-enzymatic glucose detection by improved growth kinetics of Ni-based nanostructures

    Science.gov (United States)

    Urso, M.; Pellegrino, G.; Strano, V.; Bruno, E.; Priolo, F.; Mirabella, S.

    2018-04-01

    Ni-based nanostructures are attractive catalytic materials for many electrochemical applications, among which are non-enzymatic sensing, charge storage, and water splitting. In this work, we clarify the synthesis kinetics of Ni(OH)2/NiOOH nanowalls grown by chemical bath deposition at room temperature and at 50 °C. We applied the results to non-enzymatic glucose sensing, reaching a highest sensitivity of 31 mA cm-2mM-1. Using scanning electron microscopy, x-ray diffraction analysis and Rutherford backscattering spectrometry we found that the growth occurs through two regimes: first, a quick random growth leading to disordered sheets of Ni oxy-hydroxide, followed by a slower growth of well-aligned sheets of Ni hydroxide. A high growth temperature (50 °C), leading mainly to well-aligned sheets, offers superior electrochemical properties in terms of charge storage, charge carrier transport and catalytic action, as confirmed by cyclic voltammetry and electrochemical impedance spectroscopy analyses. The reported results on the optimization and application of low-cost synthesis of these Ni-based nanostructures have a large potential for application in catalysis, (bio)sensing, and supercapacitors areas.

  13. Fe-Cr-Ni system alloys

    International Nuclear Information System (INIS)

    Levin, F.L.

    1986-01-01

    Phase diagram of Fe-Cr-Ni system, which is the basic one for production of corrosion resistant alloys, is considered. Data on corrosion resistance of such alloys are correlated depending on a number of factors: quality and composition of modifying elements, corrosion medium, temperature, alloy structure, mechanical and thermal treatment. Grades of Fe-Ni-Cr alloys are presented, and fields of their application are pointed out

  14. Synthesis of Ni3Ta, Ni2Ta and NiTa by high-energy ball milling and subsequent heat treatment

    International Nuclear Information System (INIS)

    Benites, H.S.N.; Silva, B.P da; Ramos, A.S.; Silva, A.A.A.P.; Coelho, G.C.; Lima, B.B. de

    2014-01-01

    The tantalum has relevance for the development of multicomponent Ni-based superalloys which are hardened by solid solution and precipitation mechanisms. Master alloys are normally used in the production step in order to produce refractory metals and alloys. The present work reports on the synthesis of Ni_3Ta, Ni_2Ta and NiTa by high-energy ball milling and subsequent heat treatment. The elemental Ni-25Ta, Ni-33Ta and Ni-50Ta (at.-%) powder mixtures were ball milled under Ar atmosphere using stainless steel balls and vials, 300 rpm and a ball-to-powder weight ratio of 10:1. Following, the as-milled samples were uniaxially compacted and heat-treated at 1100 deg C for 4h under Ar atmosphere. The characterization of as-milled and heat-treated samples was conducted by means of X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. A large amount of Ni_3Ta, Ni_2Ta and NiTa was formed in the mechanically alloyed heat-treated Ni-25Ta, Ni-33Ta and Ni-50Ta alloys. (author)

  15. Structural Investigation of Fe-Ni-S and Fe-Ni-Si Melts by High-temperature Fluorescence XAFS Measurements

    International Nuclear Information System (INIS)

    Manghnani, Murli H.; Balogh, John; Hong Xinguo; Newville, Matthew; Amulele, G.

    2007-01-01

    Iron-nickel (Fe-Ni) alloy is regarded as the most abundant constituent of Earth's core, with an amount of 5.5 wt% Ni in the core based on geochemical and cosmochemical models. The structural role of nickel in liquid Fe-Ni alloys with light elements such as S or Si is poorly understood, largely because of the experimental difficulties of high-temperature melts. Recently, we have succeeded in acquiring Ni K-edge fluorescence x-ray absorption fine structure (XAFS) spectra of Fe-Ni-S and Fe-Ni-Si melts and alloys. Different structural environment of Ni atoms in Fe-Ni-S and Fe-Ni-Si melts is observed, supporting the effect of light elements in Fe-Ni melts

  16. The complex transfer reaction (14C, 15O) on Ni, Zn and Ge targets: existence and mass of 69Ni

    International Nuclear Information System (INIS)

    Dessagne, P.; Bernas, M.; Langevin, M.; Pougheon, F.; Roussel, P.; Morrison, G.C.

    1984-01-01

    The ( 14 C, 15 O) complex transfer reaction has been studied at 72 MeV incident energy on 58 Ni, 60 Ni, 62 Ni, 64 Ni, 68 Zn, 70 Zn and 74 Ge, 76 Ge targets. Spectra and differential cross sections have been measured in a 5 0 angular range centred around a laboratory angle of 6 0 . The nucleus 69 Ni has been observed and its mass determined for the first time

  17. Electroless Ni-P/Ni-B duplex coatings: preparation and evaluation of microhardness, wear and corrosion resistance

    International Nuclear Information System (INIS)

    Narayanan, T.S.N. Sankara; Krishnaveni, K.; Seshadri, S.K.

    2003-01-01

    The present work deals with the formation of Ni-P/Ni-B duplex coatings by electroless plating process and evaluation of their hardness, wear resistance and corrosion resistance. The Ni-P/Ni-B duplex coatings were prepared using dual baths (acidic hypophosphite- and alkaline borohydride-reduced electroless nickel baths) with both Ni-P and Ni-B as inner layers and with varying single layer thickness. Scanning electron microscopy (SEM) was used to assess the duplex interface. The microhardness, wear resistance and corrosion resistance of electroless nickel duplex coatings were compared with electroless Ni-P and Ni-B coatings of similar thickness. The study reveals that the Ni-P and Ni-B coatings are amorphous in their as-plated condition and upon heat-treatment at 450 deg. C for 1 h, both Ni-P and Ni-B coatings crystallize and produce nickel, nickel phosphide and nickel borides in the respective coatings. All the three phases are formed when Ni-P/Ni-B and Ni-B/Ni-P duplex coatings are heat-treated at 450 deg. C for 1 h. The duplex coatings are uniform and the compatibility between the layers is good. The microhardness, wear resistance and corrosion resistance of the duplex coating is higher than Ni-P and Ni-B coatings of similar thickness. Among the two types of duplex coatings studied, hardness and wear resistance is higher for coatings having Ni-B coating as the outer layer whereas better corrosion resistance is offered by coatings having Ni-P coating as the outer layer

  18. Heavy metal environmental impact. Nickel (Ni); Impatto ambientale da metalli pesanti. Il Nichel (Ni)

    Energy Technology Data Exchange (ETDEWEB)

    Bressa, G. [Padua Univ. Padua (Italy). Dipt. di Farmacologia, Lab. di Tossicologia

    2001-02-01

    Nickel (Ni) is a heavy metal in over 3.000 different alloys used to produce kitchen utensils, batteries, coins, etc.. Human extractive and industrial activities are therefore a cause for environmental dispersion of this metal into the biosphere. This shows how in urban areas car traffic and house-heating are the main sources of nickel pollution. Nickel is relatively non-toxic, such as iron, cobalt, copper and zinc; nevertheless prolonged inhalation of dust containing such compounds as Ni O or NiCl{sub 2} concurs in the outbreak of respiratory pathologies. The carcinogenic effect of such compounds as Ni S, Ni O and Ni(CO){sub 4} has been confirmed by experiments on laboratory animals. Ni potentially toxic concentrations, and as a consequence of potential environmental impact, are to be mainly found in populated areas where the main sources are represented by industries and landfills. [Italian] Il nichel (Ni) e' un metallo presente in oltre 3.000 differenti leghe che vengono utilizzate per la produzione di utensili da cucina, batterie, monete, ecc.. Le attivita' estrattive ed industriali dell'uomo sono quindi causa di una dispersione del metallo nella biosfera. Sono stati riscontrati elevati tassi di Ni nell'atmosfera di aree urbane. Cio' sta a dimostrare che nelle aree urbane il traffico automobilistico e il riscaldamento domestico sono le fonti principali di inquinamento da tale metallo. Il nichel e' relativamente atossico, analogamente a ferro, cobalto, rame e zinco, tuttavia l'inalazione protratta di polveri contenenti composti come il NiO o il NiCl{sub 2} contribuisce al manifestarsi di patologie dell'apparato respiratorio. E' stato confermato sperimentalmente su animali da laboratorio l'effetto cancerogeno di alcuni composti quali NiS, NiO e Ni(CO){sub 4}. Concentrazioni potenzialmente tossiche di Ni, e quindi di probabile impatto ambientale, sono maggiormente da ricercare nelle zone antropizzate dove le fonti

  19. Ultrathin NiO/NiFe2O4 Nanoplates Decorated Graphene Nanosheets with Enhanced Lithium Storage Properties

    International Nuclear Information System (INIS)

    Du, Dejian; Yue, Wenbo; Fan, Xialu; Tang, Kun; Yang, Xiaojing

    2016-01-01

    Highlights: • Ultrathin NiO/NiFe 2 O 4 nanoplates derived from NiFe layered double hydroxides are fabricated on the graphene. • NiO/NiFe 2 O 4 nanoplates on the graphene show superior electrochemical performance compared to pure NiO/NiFe 2 O 4 aggregates. • The effects of the content and the particle size/component of NiO/NiFe 2 O 4 on the electrochemical performances are studied. • Graphene-encapsulated NiO/NiFe 2 O 4 is prepared and shows slightly decreased performance compared to graphene-based composite. - Abstract: As anode materials for lithium-ion batteries, bicomponent metal oxide composites show high reversible capacities; but the morphology and particle size of the composites are hardly controllable, which may reduce their electrochemical properties. In this work, ultrathin NiO/NiFe 2 O 4 nanoplates with a diameter of 5 ∼ 7 nm and a thickness of ∼2 nm are controllably fabricated on the graphene derived from NiFe layered double hydroxides (NiFe-LDHs), and exhibit superior electrochemical performance compared to pure NiO/NiFe 2 O 4 aggregates without graphene. The nanosized NiO and NiFe 2 O 4 plates are separated from each other and the graphene substrate can prevent the aggregation of NiO/NiFe 2 O 4 as well as enhance the electronic conductivity of the composite, which is beneficial to improving the electrochemical performance. Moreover, the effects of the content and the particle size/component of NiO/NiFe 2 O 4 on the electrochemical performances are also studied in order to achieve optimal performance. Ultrathin NiO/NiFe 2 O 4 nanoplates are further encapsulated by graphene nanosheets and show slightly decreased performance compared to those supported by graphene nanosheets. The different electrochemical behaviors of graphene-containing composites may be attributed to the different interactions between graphene nanosheets and NiO/NiFe 2 O 4 nanoplates.

  20. Abnormal resistance switching behaviours of NiO thin films: possible occurrence of both formation and rupturing of conducting channels

    Energy Technology Data Exchange (ETDEWEB)

    Liu Chunli; Chae, S C; Chang, S H; Lee, S B; Noh, T W [ReCOE and FPRD, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Lee, J S; Kahng, B [Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Kim, D-W [Division of Nano Sciences and Department of Physics, Ewha Womens University, Seoul 120-750 (Korea, Republic of); Jung, C U [Department of Physics, Hankuk University of Foreign Studies, Yongin, Gyeonggi-do 449-791 (Korea, Republic of); Seo, S; Ahn, S-E [Samsung Advanced Institute of Technology, Suwon 440-600 (Korea, Republic of)], E-mail: twnoh@snu.ac.kr

    2009-01-07

    We report a detailed study on the abnormal resistance switching behaviours observed in NiO thin films which show unipolar resistance switching phenomena. During the RESET process, in which the NiO film changed from a low resistance state to a high resistance state, we sometimes observed that the resistance became smaller than the initial value. We simulated the resistance switching by using a random circuit breaker network model. We found that local conducting channels could be formed as well as ruptured during the RESET process, which result in the occurrence of such abnormal switching behaviours.

  1. Investigation into the MgF2-NiF2, CaF2-NiF2, SrF2-NiF2 systems

    International Nuclear Information System (INIS)

    Ikrami, D.D.; Petrov, S.V.; Fedorov, P.P.; Ol'khovaya, L.A.; Luginina, A.A.; AN SSSR, Moscow. Inst. Fizicheskikh Problem; AN SSSR, Moscow. Inst. Kristallografii)

    1984-01-01

    Using the methods of differential thermal and X-ray phase analyses the systems MgF 2 -NiF 2 , CaF 2 -NiF 2 , SrF 2 -NiF 2 have been studied. In the system SrF 2 -NiF 2 the only orthorhombic compounds SrNiF 4 (a=14.43; b=3.93; c=5.66 (+-0.01 A)) is formed. SrNiF 4 density constitutes: dsub(X-ray)=4.60+-0.01 g/cm 3 , dsub(exp.)=4.60+-0.03 g/cm 3 . Refraction indices are as follows SrNiF 4 :Ng=1.500; Nsub(m)=1.497; Nsub(p)=1.479. SrNiF 4 magnetic ordering temperature Tsub(N) approximately 100 K

  2. Microstructure and mechanical properties of sputter deposited Ni/Ni{sub 3}Al multilayer films at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-15

    Highlights: • Ni/Ni{sub 3}Al multilayers are prepared by magnetron sputtering. • Both grain size and phase constitution of annealed Ni/Ni{sub 3}Al multilayers are dependent on individual layer thickness. • The hardness of annealed Ni/Ni{sub 3}Al multilayers varies with individual layer thickness and annealing temperature. • 40 nm Ni/Ni{sub 3}Al multilayer exhibits excellent hardness at elevated temperature. - Abstract: Nano-structured Ni/Ni{sub 3}Al multilayer was prepared by magnetron sputtering, with individual layer thicknesses h varying from 10 to 160 nm. The microstructure and hardness of Ni/Ni{sub 3}Al multilayer were investigated by X-ray diffraction, transmission electron microscopy and nanoindentation. The results show that the hardness increases with decreasing h for as-deposited and 500 °C annealed multilayers. When annealed at 700 °C, the hardness approach a peak value at h = 40 nm with followed by softening at smaller h. The influence of individual layer thickness, grain size as well as formation of ordered Ni{sub 3}Al on strengthening mechanisms of Ni/Ni{sub 3}Al multilayers at elevated temperature are discussed.

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

    Directory of Open Access Journals (Sweden)

    Ruoyu Zhang

    2016-12-01

    Full Text Available 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.

  4. Ni(salen): a system that forms many solvates with interacting Ni atoms

    NARCIS (Netherlands)

    Siegler, M.A.M.; Lutz, M.

    2009-01-01

    Recrystallization of [N,N’-Ethylene-bis(salicylideneiminato)]-nickel(II) [Ni(salen)] has been carried out from a large selection of solvents. Crystals can be either solvent free or solvates. This study is based on X-ray crystal structure determinations, which include the redetermination of Ni(salen)

  5. Thermal stability of electrodeposited Ni and Ni-Co layers; an EBSD-study

    DEFF Research Database (Denmark)

    Rasmussen, Anette Alsted; Gholinia, A.; Trimby, P.W.

    2004-01-01

    The influence of heat treatment on the microstructure and the microtexture of electrodeposited Ni and Ni-Co layers was investigated with Electron Backscatter Diffraction (EBSD) with high resolution. Samples were annealed for 1 hour at 523 K and 673 K, the temperature region wherein...

  6. The role of Ni in sulfided carbon-supported Ni-Mo hydrodesulfurization catalysts

    NARCIS (Netherlands)

    Bouwens, S.M.A.M.; Barthe-Zahir, N.; Beer, de V.H.J.; Prins, R.

    1991-01-01

    The thiophene hydrodesulfurization activities of Ni and Ni---Mo sulfide catalysts supported on activated carbon were measured at atmospheric pressure and the catalyst structures were studied by means of X-ray photoelectron spectroscopy, dynamic oxygen chemisorption, and chemical sulfur analysis. The

  7. Mechanical properties of NiO/Ni-YSZ composites depending on temperature, porosity and redox cycling

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Mogensen, Mogens Bjerg

    2009-01-01

    The Impulse Excitation Technique (IET) was used to determine the elastic modulus and specific damping of different Ni/NiO-YSZ composites suitable for use in solid oxide fuel cells (SOFC). The porosity of the as-sintered samples varied from 9 to 38% and that of the reduced ones from 31 to 52%. For...

  8. Climate Prediction Center - El Niño/La Niña Home

    Science.gov (United States)

    Weather Service NWS logo - Click to go to the NWS home page Climate Prediction Center Site Map News Information CPC Web Team HOME > El Niño/La Niña Forecasts Current U.S. Climate Outlook SST Forecasts Temperature and Anomalies NOAA/ National Weather Service National Centers for Environmental Prediction Climate

  9. Synthesis and magnetic properties of multilayer Ni/Cu and NiFe/Cu ...

    Indian Academy of Sciences (India)

    The diameter of wires can be easily varied by pore size of alumina, ranging ... saturated HgCl2 solution to remove the remaining Al, and then dipped in 5 wt% ... for NiFe alloy it is 1.3 V, that is higher than for Ni/Cu nanowires to diminish Cu.

  10. Effect of solute atoms on swelling in Ni alloys and pure Ni under He + ion irradiation

    Science.gov (United States)

    Wakai, E.; Ezawa, T.; Imamura, J.; Takenaka, T.; Tanabe, T.; Oshima, R.

    2002-12-01

    The effects of solute atoms on microstructural evolutions have been investigated using Ni alloys under 25 keV He + irradiation at 500 °C. The specimens used were pure Ni, Ni-Si, Ni-Co, Ni-Cu, Ni-Mn and Ni-Pd alloys with different volume size factors. The high number densities of dislocation loops about 1.5×10 22 m -3 were formed in the specimens irradiated to 1×10 19 ions/m 2, and they were approximately equivalent, except for Ni-Si. The mean size of loops tended to increase with the volume size factor of solute atoms. In a dose of 4×10 20 ions/m 2, the swelling was changed from 0.2% to 4.5%, depending on the volume size factors. The number densities of bubbles tended to increase with the absolute values of the volume size factor, and the swelling increased with the volume size factors. This suggests that the mobility of helium and vacancy atoms may be influenced by the interaction of solute atoms with them.

  11. Bonding Strength of Ni/Ni3Al Interface with Different Lattice Misfit

    Institute of Scientific and Technical Information of China (English)

    Ping PENG; Caixing ZHENG; Shaochang HAN; Zhaohui JIN; Rui YANG; Zhuangqi HU

    2003-01-01

    The interfacial binding covalent bond density (CBD) and the local environmental total bond order (LTBO) of the Ni/Ni3Alinterface with different lattice misfits (δ) were calculated by using first-principles discrete variation Xα method. It was foundthat

  12. Electrochemical Behaviour of Ni and Ni-PVC Electrodes for the Electroxidation of Ethanol

    International Nuclear Information System (INIS)

    Mohd Syafiq Hamdan; Norazzizi Nordin; Siti Fathrita Mohd Amir; Riyanto; Mohamed Rozali Othman

    2011-01-01

    In this study, two nickel based electrodes were prepared; nickel foil and nickel-polyvinylchloride (Ni-PVC), in order to study their electrochemical behavior using cyclic voltammetry, CV and chronocoulometry, CC. Ni electrode was prepared from Ni metal foil while Ni-PVC electrode was prepared by mixing a weighed portion of Ni powder and PVC in THF solvent, swirled until the suspension was homogeneous and drying the suspension in an oven at 50 degree Celsius for 3 h. The dry sample was then placed in a 1 cm diameter stainless steel mould and pressed at 10 ton/ cm 2 . From CV data, Ni-PVC electrode showed a better electrochemical behavior compared to Ni metal foil electrode. The use of Ni-PVC electrode at higher concentration of supporting electrolyte (1.0 M KOH) was better than at lower concentration of the same supporting electrolyte in electroxidation of ethanol. In addition to acetic acid, the oxidation of ethanol also produced ethyl acetate and acetaldehyde. (author)

  13. Room-temperature ferromagnetism in Dy films doped with Ni

    Energy Technology Data Exchange (ETDEWEB)

    Edelman, I. [Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036 (Russian Federation)], E-mail: ise@iph.krasn.ru; Ovchinnikov, S. [Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Siberian Federal University, Av. Svobodnyi 71, Krasnoyarsk 660074 (Russian Federation); Markov, V.; Kosyrev, N.; Seredkin, V.; Khudjakov, A.; Bondarenko, G. [Kirensky Institute of Physics, Siberian Division, Russian Academy of Sciences, Akademgorodok, Krasnoyarsk 660036 (Russian Federation); Kesler, V. [Institute of Semiconductor Physics, Siberian Division, Russian Academy of Sciences, Av. Akademika Lavrent' eva 13, Novosibirsk 630090 (Russian Federation)

    2008-09-01

    Temperature, magnetic field and spectral dependences of magneto-optical effects (MOEs) in bi-layer films Dy{sub (1-x)}Ni{sub x}-Ni and Dy{sub (1-x)}(NiFe){sub x}-NiFe were investigated, x changes from 0 to 0.06. Peculiar behavior of the MOEs was revealed at temperatures essentially exceeding the Curie temperature of bulk Dy which is explained by the magnetic ordering of the Dy layer containing Ni under the action of two factors: Ni impurities distributed homogeneously over the whole Dy layer and atomic contact of this layer with continues Ni layer. The mechanism of the magnetic ordering is suggested to be associated with the change of the density of states of the alloy Dy{sub (1-x)}Ni{sub x} owing to hybridization with narrow peaks near the Fermi level character for Ni.

  14. Room-temperature ferromagnetism in Dy films doped with Ni

    International Nuclear Information System (INIS)

    Edelman, I.; Ovchinnikov, S.; Markov, V.; Kosyrev, N.; Seredkin, V.; Khudjakov, A.; Bondarenko, G.; Kesler, V.

    2008-01-01

    Temperature, magnetic field and spectral dependences of magneto-optical effects (MOEs) in bi-layer films Dy (1-x) Ni x -Ni and Dy (1-x) (NiFe) x -NiFe were investigated, x changes from 0 to 0.06. Peculiar behavior of the MOEs was revealed at temperatures essentially exceeding the Curie temperature of bulk Dy which is explained by the magnetic ordering of the Dy layer containing Ni under the action of two factors: Ni impurities distributed homogeneously over the whole Dy layer and atomic contact of this layer with continues Ni layer. The mechanism of the magnetic ordering is suggested to be associated with the change of the density of states of the alloy Dy (1-x) Ni x owing to hybridization with narrow peaks near the Fermi level character for Ni

  15. Elementary martensitic transformation processes in Ni-rich NiTi single crystals with Ni4Ti3 precipitates

    International Nuclear Information System (INIS)

    Michutta, J.; Somsen, Ch.; Yawny, A.; Dlouhy, A.; Eggeler, G.

    2006-01-01

    The present study shows that multiple-step martensitic transformations can be observed in aged Ni-rich NiTi single crystals. Ageing of solution-annealed and water-quenched Ni-rich NiTi single crystals results in a homogeneous precipitation of coherent Ni 4 Ti 3 particles. When the interparticle spacing reaches a critical value (order of magnitude: 200 nm), three distinct transformation processes are observed on cooling from the high-temperature phase using differential scanning calorimetry and in situ transmission electron microscopy. The transformation sequence begins with the formation of R-phase starting from all precipitate/matrix interfaces (first step). The transformation continues with the formation of B19' and its subsequent growth along all precipitate/matrix interfaces (second step). Finally, the matrix in between the precipitates transforms to B19' (third step). Elementary transformation mechanisms which account for two- and three-step transformations in a system with small-scale microstructural heterogeneities were identified

  16. Probing the semi-magicity of $^{68}$Ni via the $^{3}$H($^{66}$Ni,$^{68}$Ni)p two-neutron transfer reaction in inverse kinematics

    CERN Multimedia

    Reiter, P; Blazhev, A A; Kruecken, R; Franchoo, S; Mertzimekis, T; Darby, I G; Van de walle, J; Raabe, R; Elseviers, J; Gernhaeuser, R A; Sorlin, O H; Georgiev, G P; Bree, N C F; Habs, D; Chapman, R; Gaudefroy, L; Diriken, J V J; Jenkins, D G; Kroell, T; Axiotis, M; Huyse, M L; Patronis, N

    We propose to perform the two-neutron transfer reaction $^{3}$H($^{66}$Ni, $^{68}$Ni)$p$ using the ISOLDE radioactive ion beam at 2.7 $A$ MeV and the MINIBALL + T-REX setup to characterize the 0$^{+}$ and 2$^{+}$ states in $^{68}$Ni.

  17. Mechanical alloying of the FeNi-Ag system

    International Nuclear Information System (INIS)

    Gonzalez, G.; Ibarra, D.; Ochoa, J.; Villalba, R.; Sagarzazu, A.

    2007-01-01

    The Fe-Ni-Ag system is of particular interest for its potential applications as soft magnetic granular material with small magnetic grains embedded in a non-magnetic metal matrix. Under equilibrium conditions: Fe-Ag and Ni-Ag are immiscible and Fe-Ni shows complete solubility. These materials are particularly important for magnetoresistivity properties. The properties of these alloys are closely related to their microstructure; therefore, a detailed study of the transformations occurring during milling was undertaken using pre-alloyed Fe x Ni 100-x (x = 30, 50 and 70) further milled with different Ag content to give the following alloys compositions (Fe x -Ni 100-x ) 100-y Ag y (y = 5, 20, 60). Consolidation of the mechanically alloyed powders by sintering at 950 o C was performed. Morphological and structural characterization of the sintered powders was carried out by scanning and transmission electron microscopy and X-ray diffraction. Fe 30 Ni 70 and Fe 50 Ni 50 formed ordered FeNi 3 compound. Fe 70 Ni 30 showed the formation of a mixture of γ-(Fe,Ni) and α-Fe(Ni) solid solutions. The mixture of these systems with Ag showed the metal solid solutions surrounded by Ag islands of Fe x Ni y -Ag, There was also evidence of Ag diffusing into the γ-(Fe,Ni). High Ag content (60%) shows formation of islands of FeNi surrounded by Ag. Sintering is always improved with the Ag content

  18. Effect of amount of glycine as fuel in obtaining nanocomposite Ni/NiO

    International Nuclear Information System (INIS)

    Simoes, A.N.; Simoes, V.N.; Neiva, L.S.; Quirino, M.R.; Vieira, D.A.; Gama, L.

    2010-01-01

    This paper proposes to investigate the effect of the amount of glycine in obtaining nanocomposite Ni/NiO synthesized by combustion reaction technique. The amount of glycine used was calculated on the stoichiometric composition of 50% and 100%. Characterizations by X-ray diffraction (XRD), N2 adsorption by the BET method and scanning electron microscopy (SEM) were performed with powder of Ni/NiO result. The analysis of X-ray diffraction showed the presence of crystalline NiO phase in the presence of nickel as a secondary phase, whose amount increased with the amount of glycine. Increasing the concentration of glycine also caused an increase in surface area, which ranged from 1.1 to 1.4 m 2 /g. The micrographs revealed the formation of soft agglomerates with porous appearance and easy dispersions. It can be concluded that the synthesis is effective to obtain nanosized powders. (author)

  19. Neutron enrichment at midrapidity in 58Ni + 58Ni at 52 MeV/u

    International Nuclear Information System (INIS)

    Theriault, D.; Vallee, A.; Gingras, L.; Larochelle, Y.; Roy, R.; April, A.; Beaulieu, L.; Grenier, F.; Lemieux, F.; Moisan, J.; Samri, M.; Saint-Pierre, C.; Turbide, S.; Yennello, S.J.; Martin, E.; Winchester, E.

    2003-01-01

    By combining data from a charged particle 58 Ni + 58 Ni experiment at 52 MeV/u with an 36 Ar + 58 Ni experiment at 50 MeV/u for which free neutrons have been detected, an increase in the neutron to proton ratio of the whole nuclear material at midrapidity has been experimentally observed in the reaction 58 Ni + 58 Ni at 52 MeV/u. The neutron to proton ratio is measured above the initial neutron to proton ratio of the system. Neutron to proton ratio of the quasi-projectile emission is analysed for the same reactions and is seen to decrease below the ratio of the initial system. (authors)

  20. Do Mechanical and Physicochemical Properties of Orthodontic NiTi Wires Remain Stable In Vivo?

    Directory of Open Access Journals (Sweden)

    Michał Sarul

    2016-01-01

    Full Text Available Introduction and Aim. Exceptional properties of the NiTi archwires may be jeopardized by the oral cavity; thus its long-term effect on the mechanical and physiochemical properties of NiTi archwires was the aim of work. Material and Methods. Study group comprised sixty 0.016 × 0.022 NiTi archwires from the same manufacturer evaluated (group A after the first 12 weeks of orthodontic treatment. 30 mm long pieces cut off from each wire prior to insertion formed the control group B. Obeying the strict rules of randomization, all samples were subjected to microscopic evaluation and nanoindentation test. Results. Both groups displayed substantial presence of nonmetallic inclusions. Heterogeneity of the structure and its alteration after usage were found in groups B and A, respectively. Conclusions. Long-term, reliable prediction of biomechanics of NiTi wires in vivo is impossible, especially new archwires from the same vendor display different physiochemical properties. Moreover, manufacturers have to decrease contamination in the production process in order to minimize risk of mutual negative influence of nickel-titanium archwires and oral environment.

  1. Magnetoresistance of nanogranular Ni/NiO controlled by exchange anisotropy

    International Nuclear Information System (INIS)

    Del Bianco, L.; Spizzo, F.; Tamisari, M.; Allia, P.

    2013-01-01

    A link between exchange anisotropy and magnetoresistance has been found to occur in a Ni/NiO sample consisting of Ni nanocrystallites (mean size ∼13 nm, Ni content ∼33 vol%) dispersed in a NiO matrix. This material shows metallic-type electric conduction and isotropic spin-dependent magnetoresistance as well as exchange bias effect. The latter is the outcome of an exchange anisotropy arising from the contact interaction between the Ni phase and the NiO matrix. Combined analysis of magnetization M(H) and magnetoresistance MR(H) loops measured in the 5–250 K temperature range after zero-field-cooling (ZFC) and after field-cooling (FC) from 300 K reveals that the magnetoresistance is influenced by exchange anisotropy, which is triggered by the FC process and can be modified in strength by varying the temperature. Compared to the ZFC case, the exchange anisotropy produces a horizontal shift of the FC MR(H) loop along with a reduction of the MR response associated to the reorientation of the Ni moments. A strict connection between magnetoresistance and remanent magnetization of FC loops on one side and the exchange field on the other, ruled by exchange anisotropy, is indicated. - Highlights: • Nanogranular Ni/NiO with giant magnetoresistance (MR) and exchange bias effect. • Exchange anisotropy produces a shift of the field-cooled MR(H) loop and reduces MR. • MR, remanence of field-cooled loops and exchange field are three correlated quantities. • It is possible to control MR of nanogranular systems through the exchange anisotropy

  2. Ferromagnetic resonance study of sputtered NiFe/V/NiFe heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Alayo, W., E-mail: willian.rodriguez@ufpel.edu.br [Departamento de Física – IFM, Universidade Federal de Pelotas, 96010-900 Rio Grande do Sul (Brazil); Pelegrini, F. [Instituto de Física, Universidade Federal de Goiás, Goiânia, 74001-970 (Brazil); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, RJ, 22290-180 (Brazil)

    2015-03-01

    The Ni{sub 81}Fe{sub 19}/V/Ni{sub 81}Fe{sub 19} heterostructures has been produced by magnetron sputtering and analyzed by ferromagnetic resonance. Two systems were investigated: the non symmetrical NiFe(50 Å)/V(t)/NiFe(30 Å) trilayers and the symmetrical NiFe(80 Å)/V(t)/NiFe(80 Å) trilayers, with variable ultrathin V thickness t. Ferromagnetic exchange coupling was evidenced for t below 10 Å by the excitation of the optic mode, in the case of the non symmetrical samples, and by the observation of a single resonance mode for the symmetrical trilayers. For larger V thickness, all samples exhibited two modes, which were attributed to the resonance of the individual NiFe layers with different effective magnetizations. The analysis with the equilibrium and resonance conditions provided the exchange coupling constants and effective magnetizations. - Highlights: • We present a study of symmetrical and non symmetrical NiFe/V/NiFe trilayers deposited on Si single crystals by ferromagnetic resonance (FMR) at room temperature. • For the non symmetrical trilayers, the FMR spectra show the optic and acoustic modes for samples with very thin V layer thicknesses, evidencing ferromagnetic exchange coupling, whereas, for larger V thickness, the spectra exhibited two well resolved modes associated to each independent NiFe layer. For the symmetrical trilayers, strong ferromagnetic exchange coupling is evidenced by the observation of a single resonance mode. • The analysis with the equilibrium condition and dispersion relation provides the exchange coupling constants and effective magnetizations.

  3. Hydrogen absorption kinetics and structural properties of Mg85Ni10Ca5 and Mg90Ni10

    International Nuclear Information System (INIS)

    Aoki, Masakazu; Saito, Katsushi; Towata, Shin-ichi

    2005-01-01

    Mg 85 Ni 10 Ca 5 and Mg 90 Ni 10 were prepared by melting mixtures of the elements in mild steel crucibles and pouring them into copper molds. Hydrogen absorption kinetics and structural properties of the alloys were characterized by the volumetric method using a Sievert's apparatus, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallite size of Mg in Mg 85 Ni 10 Ca 5 , which is evaluated by XRD peak broadening, is about 50% smaller than that in Mg 90 Ni 10 . In addition, the nanometer-scale structure composed of Mg, Mg 2 Ni, Mg 2 Ca was observed in Mg 85 Ni 10 Ca 5 . Mg 85 Ni 10 Ca 5 shows better hydrogen absorption kinetics than Mg 90 Ni 10 in the temperature range of room temperature to 573 K. The better absorption kinetics of Mg 85 Ni 10 Ca 5 is mainly attributed to the nanometer-scale structure

  4. Sputtering Yields of Si and Ni from the Ni1-xSix System Studied by Rutherford Backscattering Spectrometry

    Science.gov (United States)

    Kim, Su Chol; Yamaguchi, Satoru; Kataoka, Yoshihide; Iwami, Motohiro; Hiraki, Akio; Satou, Mamoru; Fujimoto, Fuminori

    1982-01-01

    Sputtering yields of Si and Ni from thin layer films of Ni-Si compounds (Ni1-xSix), including the pure materials (Ni and Si), caused by 5 keV Ar+ ion bombardment were investigated using backscattering spectrometry. The sputtering yield for Si from Ni1-xSix increased with increasing Si concentration. However, there is an abrupt decrease in the yield for Si concentrations above NiSi2 to pure Si. This is in clear contrast to the sputtering yield of Ni from Ni1-xSix which increased with increasing Ni concentration monotonously. These results are discussed on the basis of both the difference in the atomic density and the electronic state of the alloy.

  5. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    Science.gov (United States)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  6. Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

    International Nuclear Information System (INIS)

    Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias; Stocks, Malcolm; Caro, Alfredo

    2015-01-01

    The aim of this study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. According to our study, the salient features for the ternary alloy are a negative SRO parameter between Ni–Cr and a positive between Cr–Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni–Cr and Ni–Fe pairs and positive for Cr–Cr and Fe–Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. The predicted SRO has an impact on point-defect energetics, electron–phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys

  7. Ni/boride interfaces and environmental embrittlement in Ni-based superalloys: A first-principles study

    International Nuclear Information System (INIS)

    Sanyal, Suchismita; Waghmare, Umesh V.; Hanlon, Timothy; Hall, Ernest L.

    2011-01-01

    Highlights: ► Fracture strengths of Ni/boride interfaces through first-principles calculations. ► Fracture strengths of Ni/boride interfaces are higher than Ni/Ni 3 Al and NiΣ5 grain boundaries. ► Ni/boride interfaces have higher resistance to O-embrittlement than Ni/Ni 3 Al and NiΣ5 grain boundaries. ► CrMo-borides are more effective than Cr-borides in resisting O-embrittlement. ► Electronegativity differences between alloying elements correlate with fracture strengths. - Abstract: Motivated by the vital role played by boride precipitates in Ni-based superalloys in improving mechanical properties such as creep rupture strength, fatigue crack growth rates and improved resistance towards environmental embrittlement , we estimate fracture strength of Ni/boride interfaces through determination of their work of separation using first-principles simulations. We find that the fracture strength of Ni/boride interfaces is higher than that of other commonly occurring interfaces in Ni-alloys, such as Ni Σ-5 grain boundaries and coherent Ni/Ni 3 Al interfaces, and is less susceptible to oxygen-induced embrittlement. Our calculations show how the presence of Mo in Ni/M 5 B 3 (M = Cr, Mo) interfaces leads to additional reduction in oxygen-induced embrittlement. Through Electron-Localization-Function based analyses, we identify the electronic origins of effects of alloying elements on fracture strengths of these interfaces and observe that chemical interactions stemming from electronegativity differences between different atomic species are responsible for the trends in calculated strengths. Our findings should be useful towards designing Ni-based alloys with higher interfacial strengths and reduced oxygen-induced embrittlement.

  8. Nickel distribution and isotopic fractionation in a Brazilian lateritic regolith: Coupling Ni isotopes and Ni K-edge XANES

    Science.gov (United States)

    Ratié, G.; Garnier, J.; Calmels, D.; Vantelon, D.; Guimarães, E.; Monvoisin, G.; Nouet, J.; Ponzevera, E.; Quantin, C.

    2018-06-01

    Ultramafic (UM) rocks are known to be nickel (Ni) rich and to weather quickly, which makes them a good candidate to look at the Ni isotope systematics during weathering processes at the Earth's surface. The present study aims at identifying the Ni solid speciation and discussing the weathering processes that produce Ni isotope fractionation in two deep laterite profiles under tropical conditions (Barro Alto, Goiás State, Brazil). While phyllosilicates and to a lower extent goethite are the main Ni-bearing phases in the saprolitic part of the profile, iron (Fe) oxides dominate the Ni budget in the lateritic unit. Nickel isotopic composition (δ60Ni values) has been measured in each unit of the regolith, i.e., rock, saprock, saprolite and laterite (n = 52). δ60Ni varies widely within the two laterite profiles, from -0.10 ± 0.05‰ to 1.43 ± 0.05‰, showing that significant Ni isotope fractionation occurs during the weathering of UM rocks. Overall, our results show that during weathering, the solid phase is depleted in heavy Ni isotopes due to the preferential sorption and incorporation of light Ni isotopes into Fe oxides; the same mechanisms likely apply to the incorporation of Ni into phyllosilicates (type 2:1). However, an isotopically heavy Ni pool is observed in the solid phase at the bottom of the saprolitic unit. This feature can be explained by two hypotheses that are not mutually exclusive: (i) a depletion in light Ni isotopes during the first stage of weathering due to the preferential dissolution of light Ni-containing minerals, and (ii) the sorption or incorporation of isotopically heavy Ni carried by percolating waters (groundwater samples have δ60Ni of 2.20 and 2.27‰), that were enriched in heavy Ni isotopes due to successive weathering processes in the overlying soil and laterite units.

  9. The acceleration intermediate phase (NiS and Ni3S2) evolution by nanocrystallization in Li/NiS2 thermal batteries with high specific capacity

    Science.gov (United States)

    Jin, Chuanyu; Zhou, Lingping; Fu, Licai; Zhu, Jiajun; Li, Deyi; Yang, Wulin

    2017-06-01

    The intermediate phase of NiS2 is thought to be a bottleneck currently to improve the overall performance of Li/NiS2 thermal batteries because of its low conductivity and close formation enthalpy between NiS2 and the intermediate phase (NiS, Ni3S2, etc). For improving the discharge performances of Li/NiS2 thermal batteries, the nano NiS2 with an average size of 85 ± 5 nm is designated as a cathode material. The electrochemical measurements show that the specific capacity of nano NiS2 cathode is higher than micro NiS2. The nano NiS2 cathode exhibits excellent electrochemical performances with high specific capacities of 794 and 654 mAh g-1 at current density of 0.1 and 0.5 A cm-2 under a cut-off voltage of 0.5 V, respectively. These results show that the rapid intermediate phase evolution from the nanocrystallization can obviously enhance use efficiency of NiS2 and improve discharge performances of thermal batteries.

  10. 4.0-nm-thick amorphous Nb–Ni film as a conducting diffusion barrier layer for integrating ferroelectric capacitor on Si

    International Nuclear Information System (INIS)

    Dai, X.H.; Guo, J.X.; Zhang, L.; Jia, D.M.; Qi, C.G.; Zhou, Y.; Li, X.H.; Shi, J.B.; Fu, Y.J.; Wang, Y.L.; Lou, J.Z.; Ma, L.X.; Zhao, H.D.; Liu, B.T.

    2015-01-01

    Highlights: • 4-nm-thick amorphous Nb–Ni film is first used as the conducting barrier layer. • No obvious interdiffusion/reaction can be found from the LSCO/PZT/LSCO/Nb–Ni/Si. • The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties. • Ultrathin amorphous Nb–Ni film is ideal to fabricate silicon-based FRAM. - Abstract: We have successfully integrated La 0.5 Sr 0.5 CoO 3 /PbZr 0.4 Ti 0.6 O 3 /La 0.5 Sr 0.5 CoO 3 (LSCO/PZT/LSCO) capacitors on silicon substrate using a ∼4.0-nm-thick amorphous Nb–Ni film as the conducting diffusion barrier layer. Transmission electron microscopy technique confirms that the Nb–Ni film is still amorphous after fabrication of the capacitors, and the interfaces related to Nb–Ni are clean and sharp without any findable interdiffusion/reaction. The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties, such as large remanent polarization of ∼22.1 μC/cm 2 , small coercive voltage of ∼1.27 V, good fatigue-resistance, and small pulse width dependence, implying that ultrathin amorphous Nb–Ni film is ideal as the conducting diffusion barrier layer to fabricate high-density silicon-based ferroelectric random access memories

  11. Room temperature isotherms for Mo and Ni

    International Nuclear Information System (INIS)

    Masse, J.L.

    1986-11-01

    Isotherms at room temperature for Mo and Ni are proposed. They are of three types: BIRCH, KEANE and BORN-MIE. The adjustable constants appearing in these isotherms have been determined from experimental quantities at zero pressure. An evaluation of the limit of (δB T /δP) T as P #-> # ∞, where B T is the isothermal bulk modulus, has been also used. These three isotherms obtained for Mo and Ni are compared with isotherms derived from shock-wave data according to the PRIETO's model. There is a good agreement between these and these derived from shock-wave data. The three isotherms proposed for Mo and Ni can be considered as valid until pressures of several B To , where B To is the bulk modulus B T at P = o [fr

  12. Advances in developing TiNi nanoparticles

    International Nuclear Information System (INIS)

    Castro, A. Torres; Cuellar, E. Lopez; Mendez, U. Ortiz; Yacaman, M. Jose

    2006-01-01

    The elaboration of nanoparticles has become a field of great interest for many scientists. Nanoparticles possess different properties than those ones shown in bulk materials. Shape memory alloys have the exceptional ability to recuperate its original shape by simple heating after being 'plastically' deformed. When this process is originated, important changes in properties, as mechanical and electrical, are developed in bulk material. If there is possible to obtain nanoparticles with shape memory effects, these nanoparticles could be used in the elaboration of nanofluids with the ability to change their electrical and thermal conductivity with temperature changes, i.e., smart nanofluids. In this work, some recent results and discussion of TiNi nanoparticles obtained by ion beam milling directly from a TiNi wire with shape memory are presented. The nanoparticles obtained by this process are about 2 nm of diameter with a composition of Ti-41.0 at.% Ni. Synthesized nanoparticles elaborated by this method have an ordered structure

  13. Cutting NiTi with Femtosecond Laser

    Directory of Open Access Journals (Sweden)

    L. Quintino

    2013-01-01

    Full Text Available Superelastic shape memory alloys are difficult to machine by thermal processes due to the facility for Ti oxidation and by mechanical processes due to their superelastic behavior. In this study, femtosecond lasers were tested to analyze the potential for machining NiTi since femtosecond lasers allow nonthermal processing of materials by ablation. The effect of processing parameters on machining depth was studied, and material removal rates were computed. Surfaces produced were analyzed under SEM which shows a resolidified thin layer with minimal heat affected zones. However, for high cutting speeds, that is, for short interaction times, this layer was not observed. A depletion of Ni was seen which may be beneficial in biomedical applications since Ni is known to produce human tissue reactions in biophysical environments.

  14. La niña proletaria

    Directory of Open Access Journals (Sweden)

    Cartabia, Sabrina A.

    2011-12-01

    Full Text Available El presente trabajo se propone trazar un paralelo entre el cuento de Osvaldo Lamborghini “El niño proletario”, el cual, según la autora del ensayo, introduce al lector en la lucha de clases y el sometimiento de los/as proletarios/as, que sufren las mujeres, en particular a través de la violencia sexual. De esa forma la autora se pregunta si el poder que ciertas clases detentan sobre otras no influye también sobre el sometimiento de la mujer. El ensayo analiza además cómo la violencia sexual es una herramienta que constituye la base de la desigualdad, el sometimiento y la degradación de la mujer, al igual que constituye una herramienta de opresión de otros grupos vulnerables como los niños y niñas.

  15. Effects of phase transformation and interdiffusion on the exchange bias of NiFe/NiMn

    International Nuclear Information System (INIS)

    Lai, Chih-Huang; Lien, W. C.; Chen, F. R.; Kai, J. J.; Mao, S.

    2001-01-01

    The correlation between the exchange field of NiFe/NiMn and the phase transformation of NiMn was investigated. Transmission electron microscopy (TEM) dark-field images, contributed by the order phase of NiMn, were used to identify the location and volume fraction of the order phase. TEM selected area diffraction patterns showed the (110) superlattice diffraction rings of NiMn, verifying the existence of the order phase in the annealed samples. The order volume fraction can be calculated by the dark field image contributed by the (110) diffraction. The exchange field increased almost linearly with increasing order volume fraction. Energy dispersive x-ray spectroscopy attached to TEM indicated that Mn diffused into NiFe for annealing at 280 degreeC, leading to a larger coercivity and small coercivity squareness. Part of the NiMn still maintains the paramagnetic phase even after annealing at 280 degreeC. [copyright] 2001 American Institute of Physics

  16. Ni3Si2 nanowires grown in situ on Ni foam for high-performance supercapacitors

    Science.gov (United States)

    Jiang, Yizhe; Li, Zhihui; Li, Beibei; Zhang, Jinying; Niu, Chunming

    2016-07-01

    Ni3Si2 nanowires and nanoawls have grown in situ on the surface of Ni foams by a controlled low pressure chemical vapor deposition process. Structural characterization shows that the individual Ni3Si2 nanowire is single crystal covered with a thin layer (1-2 nm) of SiO2 with a diameter of ∼20-30 nm and length of ten's micrometers. Individual nanoawl with a circular cone shape is polycrystalline. Both Ni3Si2 nanowire and nanoawl samples are evaluated as potential electrode materials for supercapacitors. The nanowire electrode delivers a very high specific capacitance and excellent rate capability. A specific capacitance of 760 F g-1 is measured at current density of 0.5 A g-1, which decreases to 518 F g-1 when the current density increases to 10 A g-1. The capacitance is dominated by pseudocapacitance with a mechanism similar to that of NiO or Ni(OH)2 widely studied in the literature. An asymmetric supercapacitor fabricated by pairing Ni3Si2 nanowire electrode with an activated carbon electrode exhibits energy densities of 17.5 Wh kg-1 and 8.8 Wh kg-1 at power densites of 301 W kg-1 and 3000 W kg-1.

  17. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    Energy Technology Data Exchange (ETDEWEB)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace, E-mail: jglin@ntu.edu.tw

    2017-02-15

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  18. Radiation damage buildup and dislocation evolution in Ni and equiatomic multicomponent Ni-based alloys

    Energy Technology Data Exchange (ETDEWEB)

    Levo, E. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Granberg, F., E-mail: fredric.granberg@helsinki.fi [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Fridlund, C.; Nordlund, K. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Djurabekova, F. [Department of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland); Helsinki Institute of Physics, P.O. Box 43, FIN-00014, University of Helsinki (Finland)

    2017-07-15

    Single-phase multicomponent alloys of equal atomic concentrations (“equiatomic”) have proven to exhibit promising mechanical and corrosion resistance properties, that are sought after in materials intended for use in hazardous environments like next-generation nuclear reactors. In this article, we investigate the damage production and dislocation mobility by simulating irradiation of elemental Ni and the alloys NiCo, NiCoCr, NiCoFe and NiFe, to assess the effect of elemental composition. We compare the defect production and the evolution of dislocation networks in the simulation cells of two different sizes, for all five studied materials. We find that the trends in defect evolution are in good agreement between the different cell sizes. The damage is generally reduced with increased alloy complexity, and the dislocation evolution is specific to each material, depending on its complexity. We show that increasing complexity of the alloys does not always lead to decreased susceptibility to damage accumulation under irradiation. We show that, for instance, the NiCo alloy behaves very similarly to Ni, while presence of Fe or Cr in the alloy even as a third component reduces the saturated level of damage substantially. Moreover, we linked the defect evolution with the dislocation transformations in the alloys. Sudden drops in defect number and large defect fluctuations from the continuous irradiation can be explained from the dislocation activity.

  19. Corrosion Resistance Of Electroless Ni-P/Cu/Ni-P Multilayer Coatings

    Directory of Open Access Journals (Sweden)

    Zhao G.L.

    2015-06-01

    Full Text Available Ni-P/Cu/Ni-P multilayer coatings were prepared by deposition of Cu layer between two Ni–P layers. The Cu layer was deposited by metal displacement reaction between Cu2+ and Fe atoms. Corrosion behavior of single-layer Ni-P coatings, double-layer Ni-P/Cu coatings, and three-layer Ni-P/Cu/Ni-P coatings were investigated by electrochemical tests in 3.5% NaCl solution. The three-layer coatings exhibited more positive Ecorr and decreased Icorr compared with conventional single-layer Ni-P coatings, which indicated an improved corrosion resistance. The polarization curves of the three-layer coatings were characterized by two passive regions. The improved corrosion resistance was not only attributed to the function of the blocked pores of Cu. The Cu interlayer also acted as a sacrificial layer instead of a barrier in the coatings, which altered the corrosion mechanism and further improved the corrosion resistance of the coatings.

  20. PRECIPITATION HARDENING IN B2-ORDERED NiAl BY Ni2AlTiCOMPOUND

    Institute of Scientific and Technical Information of China (English)

    W.H. Tian; K. Ohishi; M. Nemoto

    2001-01-01

    Microstructural variations and correlated hardness changes in B2-ordered NiAl containing fine precipitation of Ni2AlTi have been investigated by means of transmission electron microscopy (TEM) and hardness tests. The amount of age hardening is not large as compared to the large microstructural variations during aging. TEM observations have revealed that the L21-type Ni2AlTi precipitates keep a lattice coherency with the NiAl matrix at the beginning of aging. By longer periods of aging Ni2AlTi precipitates lose their coherency and change their morphology to the globular ones surrounded by misfit dislocations. The temperature dependence of the yield strength of precipitate-containing B2-ordered NiAl was investigated by compression tests over the temperature range of 873-1273K. The fine precipitation of Ni2AlTi was found to enhance greatly the yield strength and the high-temperature strength is comparison with that of superalloy Mar-M200.``

  1. Development of small-scale electroplating system for Ni-63 electroplating onto Ni foil

    International Nuclear Information System (INIS)

    Kim, Jin Joo; Choi, Sang Mu; Son, Kwang Jae; Hong, Jintae

    2016-01-01

    Betavoltaic battery is a device that converts the decay energy of beta-emitting radioisotopes into electric energy. Ni-63 is pure betaemitter with a low energy spectrum and significantly long half-life of 100.1 years and thus is widely used as the power source of betavoltaic battery. There are several methods for the formation of a Ni deposit onto a semiconductor such as electroplating, electroless plating, and chemical vapor deposition. In this study, small-scale radioisotope electroplating system was designed and fabricated to perform electroplating with a small amount of plating buffer and minimum exposure of radioactive materials. These procedures and the manufactured electroplating device can be applied to radioactive Ni-63 electroplating for the fabrication of a betavoltaic battery. In this study, an electroplating system for small-scale Ni electroplating was designed and manufactured. The process for the fabrication of a Ni-63 foil as the energy source of a betavoltaic battery was developed using the minimum concentration of Ni. These procedures and the manufactured electroplating device can be applied to radioactive Ni-63 electroplating for the fabrication of a betavoltaic battery

  2. Development of small-scale electroplating system for Ni-63 electroplating onto Ni foil

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Joo; Choi, Sang Mu; Son, Kwang Jae; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Betavoltaic battery is a device that converts the decay energy of beta-emitting radioisotopes into electric energy. Ni-63 is pure betaemitter with a low energy spectrum and significantly long half-life of 100.1 years and thus is widely used as the power source of betavoltaic battery. There are several methods for the formation of a Ni deposit onto a semiconductor such as electroplating, electroless plating, and chemical vapor deposition. In this study, small-scale radioisotope electroplating system was designed and fabricated to perform electroplating with a small amount of plating buffer and minimum exposure of radioactive materials. These procedures and the manufactured electroplating device can be applied to radioactive Ni-63 electroplating for the fabrication of a betavoltaic battery. In this study, an electroplating system for small-scale Ni electroplating was designed and manufactured. The process for the fabrication of a Ni-63 foil as the energy source of a betavoltaic battery was developed using the minimum concentration of Ni. These procedures and the manufactured electroplating device can be applied to radioactive Ni-63 electroplating for the fabrication of a betavoltaic battery.

  3. Exchange bias in finite sized NiO nanoparticles with Ni clusters

    International Nuclear Information System (INIS)

    Gandhi, Ashish Chhaganlal; Lin, Jauyn Grace

    2017-01-01

    Structural and magnetic properties of finite sized NiO nanoparticles are investigated with synchrotron X-ray diffraction (XRD), transmission electron microscopy, magnetometer and ferromagnetic resonance (FMR) spectroscopy. A minor Ni phase is detected with synchrotron XRD, attributed to the oxygen defects in the NiO core. A considerable exchange bias of ~100 Oe is observed at 50 K and it drops abruptly and vanishes above 150 K, in association with the reduction of frozen spins. FMR data indicate a strong interaction between ferromagnetic (FM) and antiferromagnetic (AFM) phases below 150 K, consistent with the picture of isolated FM clusters in AFM matrix. - Highlights: • Structural and magnetic properties of finite sized NiO nanoparticles are systematically investigated with several advanced techniques. • A strong interaction between ferromagnetic and antiferromagnetic phases is found below 150 K. • Exchange bias field in finite sized NiO nanoparticles is due to anisotropy energy of Ni clusters over riding the domain wall energy of NiO.

  4. Tipos especiales de niños

    Directory of Open Access Journals (Sweden)

    Mercedes Rodrigo Bellido

    1946-09-01

    Full Text Available En las tres últimas lecciones han sido expuestas algunas consideraciones referentes a niños y adolescentes desde el nacimiento hasta el dintel de la juventud. En todas ellas hemos procurado poner de relieve la necesidad de individualizar el conocimiento de cada niño para obtener mejores resultados en su adaptación a su futura vida de adultos, En todas ellas  nos hemos referido al llamado niño normal. Nos corresponde en la lección de hoy ocuparnos can la superficialidad característica de estas charlas tipo-muestrario, de otras categorías de niños muy dignos de interés.. quienes unas por exceso, otros por defecto, otros por dificultades de adaptación por diferentes causas, se desvían de la línea media de la normalidad. Consideramos que no está fuera del lugar, aquí, el tema de los niños excepcionales y por el contrario que es necesario intensificar el estudio de los trastornos de la vida mental y emocional de los niños en la preparación de los estudiantes de Medicina. Y no es nuestra solo esta opinión; no hace mucho tiempo en la Medical School de Ia Universidad de Minnessota hemos sabido que se ha hecho un intento de considerar y evaluar factores emocionales ambientales sobre las mismas bases que los descubrimientos fisiológicos.

  5. Ni Foam-Ni3 S2 @Ni(OH)2 -Graphene Sandwich Structure Electrode Materials: Facile Synthesis and High Supercapacitor Performance.

    Science.gov (United States)

    Wang, Xiaobing; Hu, Jiangjiang; Su, Yichang; Hao, Jin; Liu, Fanggang; Han, Shuang; An, Jian; Lian, Jianshe

    2017-03-23

    A novel Ni foam-Ni 3 S 2 @Ni(OH) 2 -graphene sandwich-structured electrode (NF-NN-G) with high areal mass loading (8.33 mg cm -2 ) has been developed by sulfidation and hydrolysis reactions. The conductivity of Ni 3 S 2 and Ni(OH) 2 were both improved. The upper layer of Ni(OH) 2 , covered with a thin graphene film, is formed in situ from the surface of the lower layer of Ni 3 S 2 , whereas the Ni 3 S 2 grown on Ni foam substrate mainly acts as a rough support bridging the Ni(OH) 2 and Ni foam. The graphene stabilized the Ni(OH) 2 and the electrochemical properties were effectively enhanced. The as-synthesized NF-NN-G-5mg electrode shows a high specific capacitance (2258 F g -1 at 1 A g -1 or 18.81 F cm -2 at 8.33 mA cm -2 ) and an outstanding rate property (1010 F g -1 at 20 Ag -1 or 8.413 F cm -2 at 166.6 mA cm -2 ). This result is around double the capacitance achieved in previous research on Ni 3 S 2 @Ni(OH) 2 /3DGN composites (3DGN=three-dimensional graphene network). In addition, the as-fabricated NF-NN-G-5mg composite electrode has an excellent cycle life with no capacitance loss after 3000 cycles, indicating a potential application as an efficient electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Salud mental del niño

    OpenAIRE

    Ospina de González, Bernarda

    1987-01-01

    Es ya reconocida por todos las importancia de los primeros años de vida en la estructutración de la personalidad y, por consiguiente, en la salud mental del niño. En este artículo se hace una síntesis de los diferentes aspectos del desarrollo de la personalidad infanltil que seben ser conocidos por el personal de salud para estar en condiciones de brindar una atención integral a la madre y al niño. Con igual propósito se señalan algunos patrones de tipo psicosocial que influyen en la estabili...

  7. Magnetic anisotropy of Ni/Cr multilayers

    International Nuclear Information System (INIS)

    Kang, S.; Xia, H.

    1997-01-01

    The magnetic anisotropy of Ni/Cr multilayers has been investigated by using vibrating sample magnetometer (VSM) and ferromagnetic resonance techniques (FMR). The FMR spectra are obtained as a function of the orientation of the applied magnetic field from in-plane to out-of-plane. The results are fitted theoretically to determine the magnetic anisotropy. From VSM and FMR, a positive value for Ni/Cr interface anisotropy is obtained, which favours a perpendicular easy axis. The possible mechanism for the perpendicular anisotropy has been discussed and it may be attributed to the magnetostriction, caused by intrinsic stress due to lattice mismatch. (orig.). With 005 figs., 001 tabs

  8. Ionizing Radiation Effects in Ni Nanotubes

    Science.gov (United States)

    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.

  9. Linear arrangement of nano-scale magnetic particles formed in Cu-Fe-Ni alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sung, E-mail: k3201s@hotmail.co [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeda, Mahoto [Department of Materials Engineering (SEISAN), Yokohama National University, 79-5 Tokiwadai, Hodogayaku, Yokohama, 240-8501 (Japan); Takeguchi, Masaki [Advanced Electron Microscopy Group, National Institute for Materials Science (NIMS), Sakura 3-13, Tsukuba, 305-0047 (Japan); Bae, Dong-Sik [School of Nano and Advanced Materials Engineering, Changwon National University, Gyeongnam, 641-773 (Korea, Republic of)

    2010-04-30

    The structural evolution of nano-scale magnetic particles formed in Cu-Fe-Ni alloys on isothermal annealing at 878 K has been investigated by means of transmission electron microscopy (TEM), electron dispersive X-ray spectroscopy (EDS), electron energy-loss spectroscopy (EELS) and field-emission scanning electron microscopy (FE-SEM). Phase decomposition of Cu-Fe-Ni occurred after an as-quenched specimen received a short anneal, and nano-scale magnetic particles were formed randomly in the Cu-rich matrix. A striking feature that two or more nano-scale particles with a cubic shape were aligned linearly along <1,0,0> directions was observed, and the trend was more pronounced at later stages of the precipitation. Large numbers of <1,0,0> linear chains of precipitates extended in three dimensions in late stages of annealing.

  10. Molecular dynamics simulation of radiation-induced amorphization of the ordered compound NiZr2

    International Nuclear Information System (INIS)

    Devanathan, R.; Meshii, M.

    1992-12-01

    We have studied the electron irradiation-induced amorphization of the ordered intermetallic compound NiZr 2 by molecular dynamics simulations in conjunction with embedded-atom potentials. Randomly chosen Frenkel pairs and chemical disorder were introduced into the system in separate processes. In both cases, the energy and volume of the system rose above the corresponding levels of a quenched liquid and the calculated diffraction patterns indicated the occurrence of a crystalline-to-amorphous transition. In addition, the average shear elastic constant fell to about 50% of its value in the perfect crystal and the system became elastically isotropic. These results indicate that NiZr 2 can be amorphized by chemical disorder as well as Frenkel pairs and are in good agreement with experimental observations

  11. 'NiNis': Youth in Argentina who Neither Work nor Study. A Social Integration Deficit

    Directory of Open Access Journals (Sweden)

    Lidia de la Torre

    2017-01-01

    Full Text Available This study aims to assess the extent to which vulnerability in household material living conditions affects the institutional integration of young people of Argentina. We worked with a random sample of 4,855 youth aged between 18 and 25. It was observed that 66% of those who neither study nor work live in households having a low or very low socioeconomic status, with 4 out of 10 of these youth residing in shantytowns or slums and with half of them failing to complete high school. Harsh environments create a vicious circle of persistent passivity and isolation. However, the comparison between the NiNis and the working segment allowed us to conclude that similar household levels of socio-economic vulnerability are not necessarily sufficient to explain the situation of social disaffiliation found in these youth NiNis.

  12. Optimization of process parameters for synthesis of silica–Ni ...

    Indian Academy of Sciences (India)

    Optimization of process parameters for synthesis of silica–Ni nanocomposite by design of experiment ... Sol–gel; Ni; design of experiments; nanocomposites. ... Kolkata 700 032, India; Rustech Products Pvt. Ltd., Kolkata 700 045, India ...

  13. Ni hollow spheres as catalysts for methanol and ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Changwei [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Hu, Yonghong; Rong, Jianhua; Liu, Yingliang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2007-08-15

    In this paper, we successfully synthesized Ni hollow spheres consisting of needle-like nickel particles by using silica spheres as template with gold nanoparticles seeding method. The Ni hollow spheres are applied to methanol and ethanol electrooxidation in alkaline media. The results show that the Ni hollow spheres give a very high activity for alcohol electrooxidation at a very low nickel loading of 0.10 mg cm{sup -2}. The current on Ni hollow spheres is much higher than that on Ni particles. The onset potential and peak potential on Ni hollow spheres are more negative than that on Ni particles for methanol and ethanol electrooxidation. The Ni hollow spheres may be of great potential in alcohol sensor and direct alcohol fuel cells. (author)

  14. Separation and preparation of "6"2Ni isotope

    International Nuclear Information System (INIS)

    Ren Xiuyan; Mi Yajing; Zeng Ziqiang; Li Gongliang; Tu Rui

    2014-01-01

    Micro nuclear battery is the perfect power of space craft equipment. "6"3Ni is the core operation material of the "6"3Ni battery. It can produce radioisotope "6"3Ni while high abundance "6"2Ni is irradiated in the reactor. In order to meet the requirements of the abundance and the purity, research of the separation for "6"2Ni isotope was developed. The magnetic field and beam transmission status were simulated. The improvement designs of the ion source and the collector pocket were carried out. The process flow of high abundance "6"2Ni using electromagnetic separation method was established. The experiment of "6"2Ni isotope was developed by using electromagnetism isotope separator. The results show that the enrichment of "6"2Ni isotope is more than 90%. (authors)

  15. X-ray fluorescence analysis of Fe - Ni - Mo systems

    International Nuclear Information System (INIS)

    Belyaev, E.E.; Ershov, A.V.; Mashin, A.I.; Mashin, N.I.; Rudnevskij, N.K.

    1998-01-01

    Procedures for the X-ray fluorescence determination of the composition and thickness of Fe - Ni - Mo thin films and the concentration of elements in thick films of the Fe - Ni - Mo alloy are developed [ru

  16. On a randomly imperfect spherical cap pressurized by a random ...

    African Journals Online (AJOL)

    On a randomly imperfect spherical cap pressurized by a random dynamic load. ... In this paper, we investigate a dynamical system in a random setting of dual ... characterization of the random process for determining the dynamic buckling load ...

  17. Structure characterization of Ni/NiO and Ti/TiO2 interfaces

    International Nuclear Information System (INIS)

    Lamine, Brahim

    1983-01-01

    This research thesis reports the structure characterization of Ni-NiO and Ti-TiO 2 interfaces through an in-situ investigation of thin blade oxidation, of oxide germination and growth, and through a determination of mutual metal/oxide orientation relationships. Thin films of TiO 2 have also been characterized and the study of the influence of vacuum annealing on TiO 2 layer structure and morphology has been attempted. The examination of metal-oxide interface reveals a duplex structure of NiO and TiO 2 layers, and a preferential grain boundary oxidation of the underlying metal [fr

  18. Structure of Ni-rich Ni--Cr--B--Si coating alloys

    International Nuclear Information System (INIS)

    Knotek, O.; Lugscheider, E.; Reimann, H.

    1975-01-01

    The structures of quaternary, nickel-rich Ni--Cr--B--Si alloys were analyzed at a constant boron content of 10 at. percent and a temperature of 850 0 C. The composition range for silicide formation was determined. In these quaternary alloys, known binary nickel silicides, nickel and chromium borides, and the ternary silico-boride Ni 6 Si 2 B were confirmed. A new composition for the W 5 Si 3 -type phase in the Ni--B--Si system was proposed. (U.S.)

  19. Blocked Randomization with Randomly Selected Block Sizes

    Directory of Open Access Journals (Sweden)

    Jimmy Efird

    2010-12-01

    Full Text Available When planning a randomized clinical trial, careful consideration must be given to how participants are selected for various arms of a study. Selection and accidental bias may occur when participants are not assigned to study groups with equal probability. A simple random allocation scheme is a process by which each participant has equal likelihood of being assigned to treatment versus referent groups. However, by chance an unequal number of individuals may be assigned to each arm of the study and thus decrease the power to detect statistically significant differences between groups. Block randomization is a commonly used technique in clinical trial design to reduce bias and achieve balance in the allocation of participants to treatment arms, especially when the sample size is small. This method increases the probability that each arm will contain an equal number of individuals by sequencing participant assignments by block. Yet still, the allocation process may be predictable, for example, when the investigator is not blind and the block size is fixed. This paper provides an overview of blocked randomization and illustrates how to avoid selection bias by using random block sizes.

  20. The study of quasi-projectiles produced in Ni+Ni and Ni+Au collisions: excitation energy and spin

    International Nuclear Information System (INIS)

    Buta, A.

    2003-02-01

    During the collision between the projectile and the target nuclei in the intermediate energy regime (E < 100 MeV/nucleon) two excited nuclei are mainly observed in the exit channel, the quasi projectile (QP) and the quasi target. They disintegrate by particle emission. However, this binary picture is perturbed by the emission of particles and light fragments with velocities intermediate between the projectile velocity and the target one, all along the interaction (midrapidity component). This work aim to determine the excitation energy and the intrinsic angular momentum (or spin) of quasi-projectiles produced in the Ni+Ni and Ni+Au collisions at 52 and 90 MeV/nucleon. The excitation energy is deduced from the kinematical characteristics of particles emitted by the quasi-projectile. They have to be separated from midrapidity particles. Three different scenarios have been used for this purpose. The spin of the quasi-projectile has been extracted from the experimental data by mean of proton and alpha particles multiplicities emitted by the QP in the Ni+Au at 52 MeV/nucleon reaction. The results have been compared to the predictions of a theoretical model based on nucleon transfers. Their evolution is qualitatively reproduced as a function of the violence of the collision. (author)

  1. Low temperature gaseous nitriding of Ni based superalloys

    DEFF Research Database (Denmark)

    Eliasen, K. M.; Christiansen, Thomas Lundin; Somers, Marcel A. J.

    2010-01-01

    In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr......In the present work the nitriding response of selected Ni based superalloys at low temperatures is addressed. The alloys investigated are nimonic series nos. 80, 90, 95 and 100 and nichrome (Ni/Cr...

  2. Elastic Properties of Novel Co- and CoNi-Based Superalloys Determined through Bayesian Inference and Resonant Ultrasound Spectroscopy

    Science.gov (United States)

    Goodlet, Brent R.; Mills, Leah; Bales, Ben; Charpagne, Marie-Agathe; Murray, Sean P.; Lenthe, William C.; Petzold, Linda; Pollock, Tresa M.

    2018-06-01

    Bayesian inference is employed to precisely evaluate single crystal elastic properties of novel γ -γ ' Co- and CoNi-based superalloys from simple and non-destructive resonant ultrasound spectroscopy (RUS) measurements. Nine alloys from three Co-, CoNi-, and Ni-based alloy classes were evaluated in the fully aged condition, with one alloy per class also evaluated in the solution heat-treated condition. Comparisons are made between the elastic properties of the three alloy classes and among the alloys of a single class, with the following trends observed. A monotonic rise in the c_{44} (shear) elastic constant by a total of 12 pct is observed between the three alloy classes as Co is substituted for Ni. Elastic anisotropy ( A) is also increased, with a large majority of the nearly 13 pct increase occurring after Co becomes the dominant constituent. Together the five CoNi alloys, with Co:Ni ratios from 1:1 to 1.5:1, exhibited remarkably similar properties with an average A 1.8 pct greater than the Ni-based alloy CMSX-4. Custom code demonstrating a substantial advance over previously reported methods for RUS inversion is also reported here for the first time. CmdStan-RUS is built upon the open-source probabilistic programing language of Stan and formulates the inverse problem using Bayesian methods. Bayesian posterior distributions are efficiently computed with Hamiltonian Monte Carlo (HMC), while initial parameterization is randomly generated from weakly informative prior distributions. Remarkably robust convergence behavior is demonstrated across multiple independent HMC chains in spite of initial parameterization often very far from actual parameter values. Experimental procedures are substantially simplified by allowing any arbitrary misorientation between the specimen and crystal axes, as elastic properties and misorientation are estimated simultaneously.

  3. Influence of the preparation method on the morphology of templated NiCo{sub 2}O{sub 4} spinel

    Energy Technology Data Exchange (ETDEWEB)

    Cabo, Moises; Pellicer, Eva, E-mail: eva.pellicer.icn@uab.cat; Rossinyol, Emma; Solsona, Pau [Universitat Autonoma de Barcelona, Departament de Fisica, Facultat de Ciencies (Spain); Castell, Onofre [Universitat Autonoma de Barcelona, Servei de Microscopia, Facultat de Ciencies (Spain); Surinach, Santiago; Baro, Maria Dolors [Universitat Autonoma de Barcelona, Departament de Fisica, Facultat de Ciencies (Spain)

    2011-09-15

    The synthesis of NiCo{sub 2}O{sub 4} spinel by several nanocasting strategies (i.e., multi-step nanocasting, one-step nanocasting and soft-templating), in which nickel and cobalt nitrates are used as precursors and Pluronic P123 as surfactant, is explored. First, in the multi-step nanocasting, the effect of the impregnation method (evaporation, solid-liquid and two-solvent) of the SBA-15 silica template on the morphology of NiCo{sub 2}O{sub 4} replica is investigated. The evaporation method seems to be the best choice to obtain mesoporous NiCo{sub 2}O{sub 4} powder which, after calcination at 375 Degree-Sign C and subsequent template removal, displays the highest surface area (93.1 m{sup 2}/g). We have also checked the feasibility of the one-step nanoscating approach for the synthesis of ordered NiCo{sub 2}O{sub 4} arrays, though this methodology entails severe difficulties, mainly related to the different decomposition temperature of the nitrate precursors and the P123 surfactant. Finally, randomly oriented, aggregated NiCo{sub 2}O{sub 4} nanoparticles are obtained by means of P123 surfactant-assisted soft-templating approach.

  4. Ni2+-binding RNA motifs with an asymmetric purine-rich internal loop and a G-A base pair.

    Science.gov (United States)

    Hofmann, H P; Limmer, S; Hornung, V; Sprinzl, M

    1997-01-01

    RNA molecules with high affinity for immobilized Ni2+ were isolated from an RNA pool with 50 randomized positions by in vitro selection-amplification. The selected RNAs preferentially bind Ni2+ and Co2+ over other cations from first series transition metals. Conserved structure motifs, comprising about 15 nt, were identified that are likely to represent the Ni2+ binding sites. Two conserved motifs contain an asymmetric purine-rich internal loop and probably a mismatch G-A base pair. The structure of one of these motifs was studied with proton NMR spectroscopy and formation of the G-A pair at the junction of helix and internal loop was demonstrated. Using Ni2+ as a paramagnetic probe, a divalent metal ion binding site near this G-A base pair was identified. Ni2+ ions bound to this motif exert a specific stabilization effect. We propose that small asymmetric purine-rich loops that contain a G-A interaction may represent a divalent metal ion binding site in RNA. PMID:9409620

  5. Random walks, random fields, and disordered systems

    CERN Document Server

    Černý, Jiří; Kotecký, Roman

    2015-01-01

    Focusing on the mathematics that lies at the intersection of probability theory, statistical physics, combinatorics and computer science, this volume collects together lecture notes on recent developments in the area. The common ground of these subjects is perhaps best described by the three terms in the title: Random Walks, Random Fields and Disordered Systems. The specific topics covered include a study of Branching Brownian Motion from the perspective of disordered (spin-glass) systems, a detailed analysis of weakly self-avoiding random walks in four spatial dimensions via methods of field theory and the renormalization group, a study of phase transitions in disordered discrete structures using a rigorous version of the cavity method, a survey of recent work on interacting polymers in the ballisticity regime and, finally, a treatise on two-dimensional loop-soup models and their connection to conformally invariant systems and the Gaussian Free Field. The notes are aimed at early graduate students with a mod...

  6. Giant magnetocaloric effect in isostructural MnNiGe-CoNiGe system by establishing a Curie-temperature window

    KAUST Repository

    Liu, E. K.; Zhang, H. G.; Xu, G. Z.; Zhang, X. M.; Ma, R. S.; Wang, W. H.; Chen, J. L.; Zhang, H. W.; Wu, G. H.; Feng, L.; Zhang, Xixiang

    2013-01-01

    An effective scheme of isostructural alloying was applied to establish a Curie-temperature window in isostructural MnNiGe-CoNiGe system. With the simultaneous accomplishment of decreasing structural-transition temperature and converting

  7. The large magnetoelectric effect in Ni-lead zirconium titanate-Ni trilayers derived by electroless deposition

    International Nuclear Information System (INIS)

    Bi, K; Wang, Y G; Wu, W; Pan, D A

    2010-01-01

    Magnetoelectric (ME) Ni-lead zirconium titanate-Ni trilayers with neither electrodes nor bonding layers have been derived by electroless deposition. The structure and magnetic properties of the electroless deposited Ni layers with different pH values are characterized by x-ray diffraction and vibrating sample magnetometer. The influence of the bias magnetic field and the magnetic field frequency (f) on ME coupling is discussed. It is seen that α E,31 depends strongly on H dc and f. The value of the ME coefficient increases as the thickness of the Ni layer and the pH of the bath increase. A maximum of the ME voltage coefficient α E,31 = 5.77 V cm -1 Oe -1 at resonance frequency with a deposited Ni layer thickness t Ni = 302 μm is obtained. The large ME coefficient makes these Ni-PZT-Ni trilayers suitable for applications in sensors, actuators and transducers. (fast track communication)

  8. Development of the dentistry alloy Ni-Cr-Nb; Desenvolvimento de ligas odontologicas Ni-Cr-Nb

    Energy Technology Data Exchange (ETDEWEB)

    Souza, M.A.; Ramos, A.S.; Hashimoto, T.M., E-mail: mari_sou@hotmail.co [UNESP/FEG, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia

    2010-07-01

    This work reports on the structural characterization of Ni-Cr-Mo and Ni-Cr-Nb alloys produced by arc melting. Samples were characterized by means of optical microscopy, X-ray diffraction, scanning electron microscopy, and EDS analysis. Results indicated that the arc melting process was efficient to produce homogeneous structures in Ni-Cr-Mo and Ni-Cr-Nb alloys. The nickel dissolved large amounts of Cr, Mo and Nb, which was detected by EDS analysis and X-ray diffraction. The alloy containing molybdenum indicated the presence of structure based on Ni{sub SS}, while that the alloys containing niobium presented primary grains of Ni{sub SS} and precipitates formed by the simultaneous transformation of the Ni and Ni{sub 3}Nb phases. (author)

  9. Microstructure and electrochemical characterization of laser melt-deposited Ti2Ni3Si/NiTi intermetallic alloys

    International Nuclear Information System (INIS)

    Dong Lixin; Wang Huaming

    2008-01-01

    Corrosion and wear resistant Ti 2 Ni 3 Si/NiTi intermetallic alloys with Ti 2 Ni 3 Si as the reinforcing phase and the ductile NiTi as the toughening phase were designed and fabricated by the laser melt-deposition manufacturing process. Electrochemical behavior of the alloys was investigated using potentiodynamic polarization testing and electrochemical impedance spectroscopy in an NaOH solution. The results showed that the alloys have outstanding corrosion resistance due to the formation of a protective passive surface film of Ni(OH) 2 as well as the high chemical stability and strong inter-atomic bonds inherent to Ti 2 Ni 3 Si and NiTi intermetallics. The Ti 2 Ni 3 Si content has a significant influence on the microstructure of the alloys but only a slight effect on electrochemical corrosion properties

  10. Homotopic mapping solution of an oscillator for the El Niño/La Niña-southern oscillation

    International Nuclear Information System (INIS)

    Xian-Chun, Zhou; Yi-Hua, Lin; Wan-Tao, Lin; Jia-Qi, Mo

    2009-01-01

    This paper considers a class of oscillator for the El Niño/La Niña-southern oscillation (ENSO) model. By using the homotopic mapping method, it obtains approximations of the solution for the ENSO model. (general)

  11. Electrochemical reduction of NiO in a composite electrode

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels

    2013-01-01

    a lower overpotential. Microstructures of NiO with different reduction degrees are shown. Electrochemical impedance spectroscopy is carried out during the reduction process. Electrochemical reduction of NiO may need an induction period. When NiO is reduced at a constant voltage the current initially...

  12. Morphological and compositional engineering of Ni/carbon ...

    Indian Academy of Sciences (India)

    Ni/multi-walled carbon nanotubes (MWCNTs) composite films were deposited on the glassy carbon electrode (GCE) by a Ni plating bath containing homogeneously dispersed MWCNTs using polyvinylpyrrolidone (PVP) as dispersion additive. Incorporation of MWCNTs into Ni matrix was greatly enhanced by the application ...

  13. CLASSICAL AREAS OF PHENOMENOLOGY: First-principles calculations for the elastic properties of Ni-base model superalloys: Ni/Ni3Al multilayers

    Science.gov (United States)

    Wang, Yun-Jiang; Wang, Chong-Yu

    2009-10-01

    A model system consisting of Ni[001](100)/Ni3Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2γ'+2γ to 10γ'+10γ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni3Al multilayer with 10γ'+10γ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the γ' phase volume fraction are calculated by varying the proportion of the γ and γ' phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni3Al multilayer can be well predicted by the Voigt-Reuss-Hill rule of mixtures.

  14. Low-field spin dynamics of Cr7Ni and Cr7Ni-Cu -Cr 7Ni molecular rings as detected by μ SR

    Science.gov (United States)

    Sanna, S.; Arosio, P.; Bordonali, L.; Adelnia, F.; Mariani, M.; Garlatti, E.; Baines, C.; Amato, A.; Sabareesh, K. P. V.; Timco, G.; Winpenny, R. E. P.; Blundell, S. J.; Lascialfari, A.

    2017-11-01

    Muon spin rotation measurements were used to investigate the spin dynamics of heterometallic Cr7Ni and Cr7Ni -Cu-Cr7Ni molecular clusters. In Cr7Ni the magnetic ions are arranged in a quasiplanar ring and interact via an antiferromagnetic exchange coupling constant J , while Cr7Ni -Cu-Cr7Ni is composed of two Cr7Ni linked by a bridging moiety containing one Cu ion, that induces an inter-ring ferromagnetic interaction J'≪J . The longitudinal muon relaxation rate λ collected at low magnetic fields μ0H BPP)-like heuristic fitting model that takes into account of a distribution of electronic spin characteristic times for T >5 K, while the shoulder presented by Cr7Ni can be reproduced by a BPP function that incorporates a single electronic characteristic time theoretically predicted to dominate for T <5 K. The flattening of λ (T ) in Cr7Ni -Cu-Cr7Ni occurring at very low temperature can be tentatively attributed to field-dependent quantum effects and/or to an inelastic term in the spectral density of the electronic spin fluctuations.

  15. Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al_3Ni_2@Al nanoparticles as a high microwave absorption material

    International Nuclear Information System (INIS)

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

    2017-01-01

    The Al_3Ni_2@Al nanoparticles (NPs) were prepared from Ni_4_5Al_5_5 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 m"2/g and big pore volume of 0.507 cc/g. The saturation magnetization (M_S) and coercivity (H_C) 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. - Graphical abstract: The microporous Ni/NiO nanoparticles prepared by chemically dealloying Al_3Ni_2@Al NPs exhibit high microwave absorption intensity (−86.9 dB) and wide absorption bandwidth (2.6 GHz for RC≤−10 dB). - Highlights: • Microporous Ni/NiO nanoparticals were prepared by chemically dealloying method. • They possessed micropores of 0.7–1.6 nm with a surface area of 69.5 m"2/g. • They showed high microwave absorption intensity and wide absorption bandwidth. • Microwave absorption mechanism was explained by micropore and core/shell structures.

  16. Microporous Ni@NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al nanoparticles as a high microwave absorption material

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yu; Xie, Xiubo; Li, Da [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China); Chou, Wusheng [School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Liu, Tong, E-mail: tongliu@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing 100191 (China)

    2017-03-15

    The Al{sub 3}Ni{sub 2}@Al nanoparticles (NPs) were prepared from Ni{sub 45}Al{sub 55} 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 m{sup 2}/g and big pore volume of 0.507 cc/g. The saturation magnetization (M{sub S}) and coercivity (H{sub C}) 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. - Graphical abstract: The microporous Ni/NiO nanoparticles prepared by chemically dealloying Al{sub 3}Ni{sub 2}@Al NPs exhibit high microwave absorption intensity (−86.9 dB) and wide absorption bandwidth (2.6 GHz for RC≤−10 dB). - Highlights: • Microporous Ni/NiO nanoparticals were prepared by chemically dealloying method. • They possessed micropores of 0.7–1.6 nm with a surface area of 69.5 m{sup 2}/g. • They showed high microwave absorption intensity and wide absorption bandwidth. • Microwave absorption mechanism was explained by micropore and core/shell structures.

  17. Tracer diffusion of 60Co and 63Ni in amorphous NiZr alloy

    International Nuclear Information System (INIS)

    Hoshino, K.; Averback, R.S.; Hahn, H.; Rothman, S.J.

    1987-01-01

    Tracer diffusion of 60 Co and 63 Ni in equiatomic amorphous NiZr alloy in the temperature range between 486 and 641 0 K can be described by: D/sub Co/sup */ = 3.7 x 10 -7 exp[-(135 +- 14) kJ mole -1 /RT] m 2 /sec and D/sub Ni//sup */ = 1.7 x 10 -7 exp[-(140 +- 9) kJ mole -1 /RT] m 2 /sec. The values of D/sub Ni//sup */ are in reasonable agreement with those measured by the Rutherford backscattering technique. The measured diffusivities were independent of time, indicating that no relaxation took place during diffusion. 27 refs., 2 tabs

  18. Precipitation-induced of partial annealing of Ni-rich NiTi shape memory alloy

    Science.gov (United States)

    Nashrudin, Muhammad Naqib; Mahmud, Abdus Samad; Mohamad, Hishamiakim

    2018-05-01

    NiTi shape memory alloy behavior is very sensitive to alloy composition and heat treatment processes. Thermomechanical behavior of near-equiatomic alloy is normally enhanced by partial anneal of a cold-worked specimen. The shape memory behavior of Ni-rich alloy can be enhanced by ageing precipitation. This work studied the effect of simultaneous partial annealing and ageing precipitation of a Ni-rich cold drawn Ti-50.9at%Ni wire towards martensite phase transformation behavior. Ageing treatment of a non-cold worked specimen was also done for comparison. It was found that the increase of heat treatment temperature caused the forward transformation stress to decrease for the cold worked and non-cold worked specimens. Strain recovery on the reverse transformation of the cold worked wire improved compared to the non-cold worked wire as the temperature increased.

  19. Corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys

    International Nuclear Information System (INIS)

    Sriraman, K.R.; Ganesh Sundara Raman, S.; Seshadri, S.K.

    2007-01-01

    The present work deals with evaluation of corrosion behaviour of electrodeposited nanocrystalline Ni-W and Ni-Fe-W alloys. Corrosion behaviour of the coatings deposited on steel substrates was studied using polarization and electrochemical impedance spectroscopy techniques in 3.5% NaCl solution while their passivation behaviour was studied in 1N sulphuric acid solution. The corrosion resistance of Ni-W alloys increased with tungsten content up to 7.54 at.% and then decreased. In case of Ni-Fe-W alloys it increased with tungsten content up to 9.20 at.% and then decreased. The ternary alloy coatings exhibited poor corrosion resistance compared to binary alloy coatings due to preferential dissolution of iron from the matrix. Regardless of composition all the alloys exhibited passivation behaviour over a wide range of potentials due to the formation of tungsten rich film on the surface

  20. Evolution of collectivity in the 78Ni region: Coulomb excitation of 74Ni at intermediate energies.

    Directory of Open Access Journals (Sweden)

    Marchi T.

    2014-03-01

    Full Text Available The study of the collective properties of nuclear excitations far from stability provides information about the shell structure at extreme conditions. Spectroscopic observables such as the energy or the transition probabilities of the lowest states, in nuclei with large neutron excess, allow to probe the density and isospin dependence of the effective interaction. Indeed, it was recently shown that tensor and three-body forces play an important role in breaking and creating magic numbers. Emblematic is the case of the evolution of the Ni isotopic chain where several features showed up moving from the most neutron rich stable isotope (64Ni towards the 78Ni nucleus where the large neutron excess coincides with a double shell closure. In this framework, we have recently performed an experiment with the goal to extract the B(E2; 0+ → 2+ value for the 74Ni nucleus in an intermediate-energy Coulomb excitation experiment: preliminary results are discussed.

  1. Rate of hydrogen motion in Ni-substituted LaNi5Hx from NMR

    International Nuclear Information System (INIS)

    Mendenhall, Michael P.; Bowman, Robert C.; Ivancic, Timothy M.; Conradi, Mark S.

    2007-01-01

    Partial substitution of Sn, Ge, or Si for Ni in LaNi 5 H x greatly enhances the stability under repeated hydrogen-cycling. Proton NMR relaxation measurements are reported here to determine the rates of H hopping in the substituted metals LaNi 4.6 M 0.4 H x with M = Sn, Ge, and Si, for comparison to bare LaNi 5 H x . The relaxation times T 2 * (FID), T 2 (Hahn echo), T 2 -CPMG, T 1 , and T 1ρ were determined from 130 to 375 K. The three substituents result in only small increases in the average rate of motion at a given temperature but with a broader distribution of rates over the many inequivalent H sites and hopping paths. Evidently, the average energy barriers along the paths for H motion are only little affected by these substituents. Changes of H content x produce only minor changes in the relaxation times

  2. Moessbauer effect measurements on the intermetallic compounds Ni3Al and Ni3Ge

    International Nuclear Information System (INIS)

    Drijver, J.W.; Woude, F. van der

    1975-01-01

    Moessbauer parameters obtained from room temperature emission and absorption spectra of Ni 3 Al and Ni 3 Ga processed by a computer assuming a singlet and a doublet are given. The doublet is due to iron or cobalt atoms at the nickel site. Quadrupole splitting at 57 Fe nuclei in Ni 3 Ga is larger than in Ni 3 Al, viz. 0.52 and 0.37 mm/sec, respectively. Isomer shift at the Al/Ga position is very close to -0.02 mm/sec found in metallic nickel. Also given are the hyperfine magnetic fields at 4.2 K. Considering the preference of 57 Co and 57 Fe atoms in the lattice, the field intensities at the nickel and aluminium sites are found to be 227 +- 1 and 238 +- 1 kOe, respectively. (Z.S.)

  3. Low energy structure of even-even Ni isotopes close to 78Ni

    International Nuclear Information System (INIS)

    Rykaczewski, Krzysztof Piotr; Mazzocchi, C.; Grzywacz, Robert Kazimierz; Batchelder, J.C.; Bingham, Carrol R.; Fong, D.; Hamilton, J.H.; Hwang, J.K.; Karny, M.; Krolas, W.; Liddick, S.N.; Lisetskiy, A. F.; Morton, N.H.; Mantica, P.F.; Mueller, W.F.; Steiner, M.; Stolz, A.; Winger, J.A.

    2005-01-01

    The structure of magic neutron-rich nickel isotopes produced in the fragmentation of a 140 A MeV 86 Kr beam was investigated. For the first time four gamma transitions were assigned to the decay of the I π =8 + , T 1/2 = 590 +180 -110 isomer, thus establishing the 0 + -2 + -4 + -6 + -8 + ground-state band in 76 Ni. The previously unknown 2 + and 4 + levels belonging to the ground-state band in 74 Ni were identified in the β decay of 74 Co (T 1/2 =30(3) ms). The decay properties of 72 Co → 72 Ni were verified and confirmed on the basis of γ-γ coincidence data. The relevance of the measured level properties for the magicity of 78 Ni is analyzed with the help of advanced shell-model predictions

  4. The process of Ni-63 production and measurement of beta radiation of irradiated Ni-63

    International Nuclear Information System (INIS)

    Kim, Jin Joo; Uhma, Young Rang; Kim, Jong Bum; Choi, Sang Mu; Son, Kwang Jae; Hong, Jin Tae; Park, Jong Han

    2016-01-01

    It has the following characteristics: long service lifetime, high energy density, easy small-scale fabrication, and minimum maintenance. For this reasons, betavoltaic batteries are widely used in many low-power applications such as medical applications and power sources for micro electro-mechanical system (MEMS) because they can operate effectively at extreme environments. Proper selection of radioisotope is a critical factor in the design of a betavoltaic battery. The important factors affecting the performance of a betavoltaic battery are specific activity, half-life, and toxicity. In this study, a target for irradiation was produced using 99% Ni-62 metal power concentrate. Ni-62 target of 1 g was irradiated in MARIA reactor operated in Poland for 470 hours, and estimated production of Ni- 63 was calculated. Irradiated Ni-63 pellets were dissolved in HCl solution, and its beta radiation was measured by Liquid Scintillation Counter (LSC).

  5. Synthetic Ni3S2/Ni hybrid architectures as potential contrast agents in MRI

    International Nuclear Information System (INIS)

    Ma, J; Chen, K

    2016-01-01

    Traditional magnetic resonance imaging (MRI) contrast agents mainly include superparamagnetic (SPM) iron oxide nanoparticle as T 2 contrast agent for liver and paramagnetic Gd (III)-chelate as T 1 contrast agent for all organs. In this work, weak ferromagnetic kale-like and SPM cabbage-like Ni 3 S 2 @Ni hybrid architectures were synthesized and evaluated as potential T 1 MRI contrast agents. Their relatively small r 2 /r 1 ratios of 2.59 and 2.38, and high r 1 values of 11.27 and 4.89 mmol −1 L s −1 (for the kale-like and cabbage-like Ni 3 S 2 @Ni, respectively) will shed some light on the development of new-type MRI contrast agents. (paper)

  6. Hierarchical NiCo2 O4 nanosheets grown on Ni nanofoam as high-performance electrodes for supercapacitors.

    Science.gov (United States)

    Gao, Guoxin; Wu, Hao Bin; Ding, Shujiang; Liu, Li-Min; Lou, Xiong Wen David

    2015-02-18

    A high-performance electrode for supercapacitors is designed and synthesized by growing electroactive NiCo2 O4 nanosheets on conductive Ni nanofoam. Because of the structural advantages, the as-prepared Ni@NiCo2 O4 hybrid nanostructure exhibits significantly improved electrochemical performance with high capacitance, excellent rate capability, and good cycling stability. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Ni(II) complexes of dithiophosphonic acids

    Indian Academy of Sciences (India)

    aDepartment of Chemistry, Science and Research Branch, Islamic Azad ... The compounds were characterized by 1H, 13C and 31P NMR, IR spectroscopy and elemental analysis. The ... design and synthesize Ni(II) complexes with new ..... Yield: 86%. ..... 28 65. 18. Greenwood D 1989 Antimicrobial chemotherapy (New.

  8. Ni MINERALIZATION AND PGE CHARACTERIZATION IN THE ...

    African Journals Online (AJOL)

    Mgina

    fractionation, (2) the IPGEs are often associated with chromites as alloys or sulfides in ... Key words: Tanzania, Kabanga, Luhuma, PGE, Ni-Cu sulfides .... massive sulfide based on size of ore zone ... to ≤ 0.1 wt% and Fe2O3T = 80- ≈ 87 wt%.

  9. Modelling of rechargeable NiMH batteries

    NARCIS (Netherlands)

    Ledovskikh, A.; Verbitskiy, E.; Ayeb, A.; Notten, P.H.L.

    2003-01-01

    A new mathematical model has been developed for rechargeable NiMH batteries, which is based on the occurring physical–chemical processes inside. This model enables one to simultaneously simulate the battery voltage, internal gas pressures (both PO2 and PH2) and temperature during battery operation.

  10. Characterisation of a Zn / Ni Plating Bath

    Science.gov (United States)

    2009-09-03

    accelerated corrosion in the first stages which is then slowed down by its own product of corrosion, Zn(OH)212. Zinc hydroxide dehydrates in time to form ZnO ... Electrochemistry , 1991, 21, 642 [5] – Alfantasi, A.M., A study on the synthesis, characterization ans properties of pulse-plated ultrafine- grained Zn-Ni alloy

  11. Evidence for an isomer in 76Ni

    International Nuclear Information System (INIS)

    Sawicka, M.; Pfuetzner, M.; Grzywacz, R.; Daugas, J.M.; Belier, G.; Sauvestre, J.E.; Matea, I.; Lewitowicz, M.; Georgiev, G.; Grawe, H.; Mayet, P.; Becker, F.; Bingham, C.; Borcea, R.; Hammache, F.; Ibrahim, F.; Bouchez, E.; Buta, A.; Dragulescu, E.; Giovinazzo, J.; Meot, V.; Negoita, F.; De Oliveira Santos, F.; Perru, O.; Roig, O.; Rykaczewski, K.P.; Saint-Laurent, M.G.; Sorlin, O.; Stanoiu, M.; Stefan, I.; Stodel, C.; Theisen, C.; Verney, D.

    2004-01-01

    In the experiment performed at the LISE2000 spectrometer at GANIL neutron-rich nickel isotopes were studied by microsecond isomer spectroscopy. Evidence for an isomer in 76 Ni is found, consistently with the shell model prediction of an 8 + state of ν(g 9/2 ) 2 structure. (orig.)

  12. Electroplating condition for Ni nanocrystalline on metal (Ni and Cu) plates

    Energy Technology Data Exchange (ETDEWEB)

    Park, Keun Yung; Uhm, Young Rang; Son, Kwang Jae; Shim, Young Ho; Choi, Sun Ju [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Ni 63, a beta radiation source, is prepared by the electrical deposition of radioactive Ni 63 ions on a thin non radioactive nickel foil or Cu plate. Given a half life of 100 years, a nuclear battery will still produce half of its initial starting power after 100 years. A speck of a radioisotope like nickel 63, for example, contains enough energy to power a nano nuclear battery for decades, and to do so safely. Ni 63 plating is similar to other electroplating processes that employ soluble metal anodes. It requires the passage of a direct current between two electrodes that are immersed in a conductive, aqueous solution of nickel salts. The charged Ni ions are formed by sulfate, sulfamate, chloride, and a Watts bath. However, the charged Ni 63 ions are formed by dissolving metal Ni 63. To established the coating condition of Ni 63, non radioactive metal Ni particles are dissolved an acid solution and electroplated on a Ni sheet. The nickel plating process is used extensively for decorative, engineering and electro forming purposes because the appearance and other properties of electrodeposited nickel can be varied over a wide range by controlling the composition and operating parameters of the plating solution. A continuous increase in the grain size versus current density has also been recognized in the direct current electrodeposition of nickel coating. On the other hand, A runa et al. reported that the current density has no significant effect on the grain size of nickel electro deposits. A review of the literature shows that saccharin has often been added to a nickel plating bath since the 1980s to improve the ductility and brightness, and in later periods as a grain refiner agent. In the present paper, not only the preparation of a Ni plating solution prepared by dissolving metal particles, but also an optimization of the deposition conditions, such as the current density, saccharin concentration in the bath, and different metal substrates were investigated

  13. Electroplating condition for Ni nanocrystalline on metal (Ni and Cu) plates

    International Nuclear Information System (INIS)

    Park, Keun Yung; Uhm, Young Rang; Son, Kwang Jae; Shim, Young Ho; Choi, Sun Ju

    2012-01-01

    Ni 63, a beta radiation source, is prepared by the electrical deposition of radioactive Ni 63 ions on a thin non radioactive nickel foil or Cu plate. Given a half life of 100 years, a nuclear battery will still produce half of its initial starting power after 100 years. A speck of a radioisotope like nickel 63, for example, contains enough energy to power a nano nuclear battery for decades, and to do so safely. Ni 63 plating is similar to other electroplating processes that employ soluble metal anodes. It requires the passage of a direct current between two electrodes that are immersed in a conductive, aqueous solution of nickel salts. The charged Ni ions are formed by sulfate, sulfamate, chloride, and a Watts bath. However, the charged Ni 63 ions are formed by dissolving metal Ni 63. To established the coating condition of Ni 63, non radioactive metal Ni particles are dissolved an acid solution and electroplated on a Ni sheet. The nickel plating process is used extensively for decorative, engineering and electro forming purposes because the appearance and other properties of electrodeposited nickel can be varied over a wide range by controlling the composition and operating parameters of the plating solution. A continuous increase in the grain size versus current density has also been recognized in the direct current electrodeposition of nickel coating. On the other hand, A runa et al. reported that the current density has no significant effect on the grain size of nickel electro deposits. A review of the literature shows that saccharin has often been added to a nickel plating bath since the 1980s to improve the ductility and brightness, and in later periods as a grain refiner agent. In the present paper, not only the preparation of a Ni plating solution prepared by dissolving metal particles, but also an optimization of the deposition conditions, such as the current density, saccharin concentration in the bath, and different metal substrates were investigated

  14. Misuse of randomization

    DEFF Research Database (Denmark)

    Liu, Jianping; Kjaergard, Lise Lotte; Gluud, Christian

    2002-01-01

    The quality of randomization of Chinese randomized trials on herbal medicines for hepatitis B was assessed. Search strategy and inclusion criteria were based on the published protocol. One hundred and seventy-six randomized clinical trials (RCTs) involving 20,452 patients with chronic hepatitis B...... virus (HBV) infection were identified that tested Chinese medicinal herbs. They were published in 49 Chinese journals. Only 10% (18/176) of the studies reported the method by which they randomized patients. Only two reported allocation concealment and were considered as adequate. Twenty percent (30...

  15. Synthesis of microporous Ni/NiO nanoparticles with enhanced microwave absorption properties

    International Nuclear Information System (INIS)

    Liu, Tong; Pang, Yu; Xie, Xiubo; Qi, Wen; Wu, Ying; Kobayashi, Satoru; Zheng, Jie; Li, Xingguo

    2016-01-01

    The fabrication of microporous metal materials with many potential applications is challenging due to their high chemical activities and the difficulty in controlling the pore size. By adjusting the reaction condition and the composition of the Ni–Al nanoparticle precursor, we have successfully produced the microporous Ni nanoparticles (NPs) of 22 nm by chemical dealloying method. During the passivation process, the microporous Ni NPs covered with NiO shell are generated as the result of surface oxidation. The micropores range from 0.6 to 1.2 nm in diameter with a large surface area of 68.9 m"2/g. Due to the elimination of Al atoms during dealloying process, the crystalline size of the microporous Ni NPs is sharply decreased to 2–5 nm. The specific architecture offers the microporous Ni/NiO NPs a small microwave reflection coefficient (RC) and a wide absorption bandwidth (RC ≤ −10 dB) of −49.1 dB and 5.8 GHz, much better than the nonporous counterpart of −24.1 dB and 3.7 GHz. The enhanced microwave absorption performance has been interpreted in terms of the micropore structure, core/shell structure and nanostructure effects. - Highlights: • Microporous Ni/NiO nanoparticles are prepared by chemical dealloying method. • They possess micropores of 0.6–1.2 nm with a surface area of 68.9 m"2/g. • They show minimum microwave reflection coefficient of −49.1 dB and bandwidth of 5.8 GHz. • Microwave absorption mechanism is explained by micropore and core/shell structures.

  16. Synthesis of microporous Ni/NiO nanoparticles with enhanced microwave absorption properties

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tong, E-mail: tongliu@buaa.edu.cn [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing, 100191 (China); Pang, Yu; Xie, Xiubo [Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, No.37 Xueyuan Road, Beijing, 100191 (China); Qi, Wen; Wu, Ying [China Iron & Steel Research Institute Group, Advanced Technology & Materials Co., Ltd, No.76 Xueyuannanlu, Haidian District, Beijing, 100081 (China); Kobayashi, Satoru [Faculty of Engineering, Iwate University, Ueda, Morioka, 020-8551 (Japan); Zheng, Jie; Li, Xingguo [Beijing National Laboratory for Molecular Sciences (BNLMS), The State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871 (China)

    2016-05-15

    The fabrication of microporous metal materials with many potential applications is challenging due to their high chemical activities and the difficulty in controlling the pore size. By adjusting the reaction condition and the composition of the Ni–Al nanoparticle precursor, we have successfully produced the microporous Ni nanoparticles (NPs) of 22 nm by chemical dealloying method. During the passivation process, the microporous Ni NPs covered with NiO shell are generated as the result of surface oxidation. The micropores range from 0.6 to 1.2 nm in diameter with a large surface area of 68.9 m{sup 2}/g. Due to the elimination of Al atoms during dealloying process, the crystalline size of the microporous Ni NPs is sharply decreased to 2–5 nm. The specific architecture offers the microporous Ni/NiO NPs a small microwave reflection coefficient (RC) and a wide absorption bandwidth (RC ≤ −10 dB) of −49.1 dB and 5.8 GHz, much better than the nonporous counterpart of −24.1 dB and 3.7 GHz. The enhanced microwave absorption performance has been interpreted in terms of the micropore structure, core/shell structure and nanostructure effects. - Highlights: • Microporous Ni/NiO nanoparticles are prepared by chemical dealloying method. • They possess micropores of 0.6–1.2 nm with a surface area of 68.9 m{sup 2}/g. • They show minimum microwave reflection coefficient of −49.1 dB and bandwidth of 5.8 GHz. • Microwave absorption mechanism is explained by micropore and core/shell structures.

  17. Geometric structures of thin film: Pt on Pd(110) and NiO on Ni(100)

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Oden L. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    This thesis is divided into 3 papers: dynamical low-energy electron- diffraction investigation of lateral displacements in topmost layer of Pd(110); determination of (1x1) and (1x2) structures of Pt thin films on Pd(110) by dynamical low-energy electron-diffraction analysis; and structural determination of a NiO(111) film on Ni(100) by dynamical low-energy electron-diffraction analysis.

  18. Fabrication and tensile properties of rapidly solidified Cu-10wt. %Ni alloy. [Cu-10Ni

    Energy Technology Data Exchange (ETDEWEB)

    Baril, D; Angers, R; Baril, J [Dept. of Mining and Metallurgy, Laval Univ., Ste-Foy, Quebec (Canada)

    1992-10-15

    Cu-10wt.%Ni ribbons were produced by melt spinning and cut into small particles with a blade cutter mill. The powders were then hot consolidated to full density by hot pressing followed by hot extrusion. Tensile properties of the resulting pieces were measured. Cu-10wt.%Ni cast ingots were also hot extruded and mechanically tested to compare with the rapidly solidified alloy and to evaluate the possible benefits brought by the rapid solidification process.

  19. 59Ni and 63Ni separation from boric acid concentrates produced at NPP

    International Nuclear Information System (INIS)

    Fisera, O.

    2010-01-01

    Procedure for direct separation of radionickel from boric acid concentrate was developed. Quantitative separation from 100 mL of real concentrate on the column filled with 3 mL of PAN-DMG composite material was achieved. PAN-DMG material (dimethylglyoxime in porous beads of polyacrylonitrile) was compared with Ni Resin and DMG-PAN material exhibited higher sorption capacity for nickel than Ni Resin. (author)

  20. Valence electronic structure of Ni in Ni Si alloys from relative K X-ray intensity studies

    Science.gov (United States)

    Kalayci, Y.; Aydinuraz, A.; Tugluoglu, B.; Mutlu, R. H.

    2007-02-01

    The Kβ-to-Kα X-ray intensity ratio of Ni in Ni 3Si, Ni 2Si and NiSi has been determined by energy dispersive X-ray fluorescence technique. It is found that the intensity ratio of Ni decreases from pure Ni to Ni 2Si and then increases from Ni 2Si to NiSi, in good agreement with the electronic structure calculations cited in the literature. We have also performed band structure calculations for pure Ni in various atomic configurations by means of linear muffin-tin orbital method and used this data with the normalized theoretical intensity ratios cited in the literature to estimate the 3d-occupation numbers of Ni in Ni-Si alloys. It is emphasized that investigation of alloying effect in terms of X-ray intensity ratios should be carried out for the stoichiometric alloys in order to make reliable and quantitative comparisons between theory and experiment in transition metal alloys.

  1. La Niña, El Niño, and Atlantic Hurricane Damages in the United States

    Science.gov (United States)

    data discussed below), this definition results in 22 El Niño years, 29 neutral years, and 22 La Niña accounting for the most significant societal changes. To normalize past impacts data to 1997 values, losses , 169 and 186. Trenberth, K. E., 1997: The definition of El Niño. Bull. Amer. Meteor. Soc., 78, 2771

  2. Observations of defect structure evolution in proton and Ni ion irradiated Ni-Cr binary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Briggs, Samuel A., E-mail: sabriggs2@wisc.edu [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Barr, Christopher M. [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Pakarinen, Janne [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); SKC-CEN Belgian Nuclear Research Centre, Boeretang 200, B-2400 Mol (Belgium); Mamivand, Mahmood [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Hattar, Khalid [Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 (United States); Morgan, Dane D. [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States); Taheri, Mitra [Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Sridharan, Kumar [University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States)

    2016-10-15

    Two binary Ni-Cr model alloys with 5 wt% Cr and 18 wt% Cr were irradiated using 2 MeV protons at 400 and 500 °C and 20 MeV Ni{sup 4+} ions at 500 °C to investigate microstructural evolution as a function of composition, irradiation temperature, and irradiating ion species. Transmission electron microscopy (TEM) was applied to study irradiation-induced void and faulted Frank loops microstructures. Irradiations at 500 °C were shown to generate decreased densities of larger defects, likely due to increased barriers to defect nucleation as compared to 400 °C irradiations. Heavy ion irradiation resulted in a larger density of smaller voids when compared to proton irradiations, indicating in-cascade clustering of point defects. Cluster dynamics simulations were in good agreement with the experimental findings, suggesting that increases in Cr content lead to an increase in interstitial binding energy, leading to higher densities of smaller dislocation loops in the Ni-18Cr alloy as compared to the Ni-5Cr alloy. - Highlights: • Binary Ni-Cr alloys were irradiated with protons or Ni ions at 400 and 500 °C. • Higher irradiation temperatures yield increased size, decreased density of defects. • Hypothesize that varying Cr content affects interstitial binding energy. • Fitting CD models for loop nucleation to data supports this hypothesis.

  3. Study of the magnetic anisotropy in Ni/Cu and Ni/glass thin films

    Energy Technology Data Exchange (ETDEWEB)

    Cherif, S.-M. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse, 93340 (France); Layadi, A. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria)]. E-mail: a_layadi@yahoo.fr; Ben Youssef, J. [Laboratoire de Magnetisme de Bretagne, U.B.O., Brest 29238 (France); Nacereddine, C. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Roussigne, Y. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse, 93340 (France)

    2007-01-01

    The magnetic properties of evaporated Ni/Cu and Ni/glass thin films have been investigated by means of the vibrating sample magnetometer (VSM), the Brillouin light scattering (BLS) and magnetic force microscopy (MFM). The Ni thickness, t, ranges from 31 to 165 nm. The second- and fourth-order magnetic anisotropy constants, K {sub 1} and K {sub 2}, have been included; for the Ni/Cu series, K {sub 1} was found to decrease from 1.0x10{sup 6} to 0.18x10{sup 6} erg/cm{sup 3} as t increases from 31 to 165 nm, while K {sub 2} increased from 0.24x10{sup 6} to 0.8x10{sup 6} erg/cm{sup 3}. Over all the thickness range, the magnetization easy axis is in plane. For thinner films, there is a good agreement between anisotropy constant values inferred from VSM and BLS. Stripe domains were observed for t{>=}165 nm in Ni/glass and t{>=}90 nm in Ni/Cu.

  4. Study of the magnetic anisotropy in Ni/Cu and Ni/glass thin films

    International Nuclear Information System (INIS)

    Cherif, S.-M.; Layadi, A.; Ben Youssef, J.; Nacereddine, C.; Roussigne, Y.

    2007-01-01

    The magnetic properties of evaporated Ni/Cu and Ni/glass thin films have been investigated by means of the vibrating sample magnetometer (VSM), the Brillouin light scattering (BLS) and magnetic force microscopy (MFM). The Ni thickness, t, ranges from 31 to 165 nm. The second- and fourth-order magnetic anisotropy constants, K 1 and K 2 , have been included; for the Ni/Cu series, K 1 was found to decrease from 1.0x10 6 to 0.18x10 6 erg/cm 3 as t increases from 31 to 165 nm, while K 2 increased from 0.24x10 6 to 0.8x10 6 erg/cm 3 . Over all the thickness range, the magnetization easy axis is in plane. For thinner films, there is a good agreement between anisotropy constant values inferred from VSM and BLS. Stripe domains were observed for t≥165 nm in Ni/glass and t≥90 nm in Ni/Cu

  5. Effect of Ni4Ti3 precipitation on martensitic transformation in Ti-Ni

    International Nuclear Information System (INIS)

    Zhou, N.; Shen, C.; Wagner, M.F.-X.; Eggeler, G.; Mills, M.J.; Wang, Y.

    2010-01-01

    Precipitation of Ni 4 Ti 3 plays a critical role in determining the martensitic transformation path and temperature in Ni-Ti shape memory alloys. In this study, the equilibrium shape of a coherent Ni 4 Ti 3 precipitate and the concentration and stress fields around it are determined quantitatively using the phase field method. Most recent experimental data on lattice parameters, elastic constants, precipitate-matrix orientation relationship and thermodynamic database are used as model inputs. The effects of the concentration and stress fields on subsequent martensitic transformations are analyzed through interaction energy between a nucleating martensitic particle and the existing microstructure. Results indicate that R-phase formation prior to B19' phase could be attributed to both direct elastic interaction and stress-induced spatial variation in concentration near Ni 4 Ti 3 precipitates. The preferred nucleation sites for the R-phase are close to the broad side of the lenticular-shaped Ni 4 Ti 3 precipitates, where tension normal to the habit plane is highest, and Ni concentration is lowest.

  6. Fabrication of metallic alloy powder (Ni{sub 3}Fe) from Fe–77Ni scrap

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Inseok [ES Materials Research Center, Research Institute of Industrial Science and Technology, Incheon 406-840 (Korea, Republic of); Shin, Shun-Myung [Extractive Metallurgy Department, Korea Institute of Geoscience and Mineral Resources, Deajeon 305-350 (Korea, Republic of); Ha, Sang-An [Department of Environmental Engineering, Silla University, Busan 46958 (Korea, Republic of); Wang, Jei-Pil, E-mail: jpwang@pknu.ac.kr [Department of Metallurgical Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of)

    2016-06-15

    The oxidation behavior of Fe–77Ni alloy scrap was investigated at an oxygen partial pressure of 0.2 atm and temperatures ranging from 400 °C to 900 °C. The corresponding oxidation rate increased with increasing temperature and obeyed the parabolic rate law, as evidenced by its linear proportionality to the temperature. In addition, surface morphologies, cross-sectional views, compositions, structural properties were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Diffusion through either the spinel structure or the NiO layer, which were both present in the alloy during oxidation at elevated temperatures, was deemed the rate-limiting step of the reaction. The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap was obtained using ball-milling and sieving processes. In fact, 15 h of milling yielded a recovery ratio of 97%. Using hydrogen gas, the oxide powder was successfully reduced to an alloy powder of Ni{sub 3}Fe and reduction rates of ∼97% were achieved after 3 h at 1000 °C. - Highlights: • The oxidation behavior of Fe–77Ni alloy scrap was investigated. • The oxide powder less than 10 μm was obtained from Fe–77Ni alloy scrap. • Using hydrogen gas, the oxide powder was successfully reclaimed. • Reduction rates of ∼97% were achieved after 3 h at 1000 °C.

  7. Positron annihilation studies in CeNiIn and LaNiIn

    International Nuclear Information System (INIS)

    Ray, R.; Giri, S.; Sen, M.; Nambissan, P.M.G.; Ghoshray, K.; Ghoshray, A.; Sen, P.

    1997-01-01

    Doppler broadened positron annihilation spectral lineshape (DBPAS) and positron lifetime measurements in the temperature range 18-280 K have been performed in CeNiIn and LaNiIn systems. The nature of the temperature variations of the lifetime in both systems is almost similar in the whole temperature range studied, whereas the nature of the temperature variation of the S parameter in CeNiIn is similar to that in LaNiIn except in the temperature region 18-40 K. For the former system there is a dip around 20 K in the S parameter versus temperature curve. The lifetime versus T curve in both systems could be explained by the thermal expansion of the lattice. The S parameter versus T curve in LaNiIn could also be attributed to the thermal expansion of the lattice, whereas in CeNiIn the above mentioned dip seems an extra feature of the thermal expansion of the lattice. To understand this low temperature behaviour other results on the same system have been discussed. (orig.)

  8. Interfacial reaction of Ni{sub 3}Sn{sub 4} intermetallic compound in Ni/SnAg solder/Ni system under thermomigration

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yi-Shan; Yang, Chia-Jung; Ouyang, Fan-Yi, E-mail: fyouyang@ess.nthu.edu.tw

    2016-07-25

    The growth of Ni{sub 3}Sn{sub 4} intermetallic compound (IMC) between liquid–solid interface in micro-scale Ni/SnAg/Ni system was investigated under a temperature gradient of 160 °C/cm at 260 °C on a hot plate. In contrast to a symmetrical growth of Ni{sub 3}Sn{sub 4} on both interfaces under isothermally annealed at 260 °C, the interfacial Ni{sub 3}Sn{sub 4} IMC exhibited asymmetric growth under a temperature gradient; the growth of Ni{sub 3}Sn{sub 4} at cold interface was faster than that at hot side because of temperature gradient induced mass migration of Ni atoms from the hot end toward the cold end. It was found that two-stage growth behavior of Ni{sub 3}Sn{sub 4} IMC under a temperature gradient. A growth model was established and growth kinetic analysis suggested that the chemical potential gradient controlled the growth of Ni{sub 3}Sn{sub 4} at stage I (0–120 min) whereas the dynamic equilibrium between chemical potential gradient and temperature gradient forces was attained at the hot end at stage II (120–210 min). When dynamic equilibrium was achieved at 260 °C, the critical length-temperature gradient product at the hot end was experimentally estimated to be 489.18 μm × °C/cm and the moving velocity of Ni{sub 3}Sn{sub 4} interface due to Ni consumption was calculated to be 0.134 μm/h. The molar heat of transport (Q*) of Ni atoms in molten SnAg solder was calculated to be +0.76 kJ/mol. - Highlights: • Interfacial reaction in Ni/SnAg solder/Ni system under thermal gradient. • Growth rate of Ni{sub 3}Sn{sub 4} at cold end is faster than that at hot end. • Critical length-temperature gradient product at hot end is 489.2 μm°C/cm at 260 °C. • Velocity of Ni{sub 3}Sn{sub 4} moving interface is 0.134 μm/h during dynamic equilibrium. • Molar heat of transport (Q*) of Ni in molten SnAg was +0.76 kJ/mol.

  9. Exploring the Evidence Base for Acupuncture in the Treatment of Ménière's Syndrome—A Systematic Review

    Directory of Open Access Journals (Sweden)

    Andrew F. Long

    2011-01-01

    Full Text Available Ménière's syndrome is a long-term, progressive disease that damages the balance and hearing parts of the inner ear. To address the paucity of information on which evidence-based treatment decisions should be made, a systematic review of acupuncture for Ménière's syndrome was undertaken. The method used was a systematic review of English and Chinese literature, from six databases for randomized, non-randomized and observational studies. All studies were critically appraised and a narrative approach to data synthesis was adopted. Twenty-seven studies were included in this review (9 in English and 18 in Chinese languages: three randomized controlled trials, three non-randomized controlled studies and four pre-test, post-test designs. All but one of the studies was conducted in China. The studies covered body acupuncture, ear acupuncture, scalp acupuncture, fluid acupuncture point injection and moxibustion. The studies were of varying quality. The weight of evidence, across all study types, is of beneficial effect from acupuncture, for those in an acute phase or those who have had Ménière's syndrome for a number of years. The review reinforces the importance of searching for studies from English and Chinese literature. The transferability of the findings from China to a Western context needs confirmation. Further research is also needed to clarify questions around the appropriate frequency and number of treatment/courses of acupuncture. The weight of evidence suggests a potential benefit of acupuncture for persons with Ménière's disease, including those in an acute phase and reinforces the importance of searching for published studies in the Chinese language.

  10. Evaluation of the Antitumor Activity by Ni Nanoparticles with Verbascoside

    Directory of Open Access Journals (Sweden)

    Mingyue Chen

    2013-01-01

    Full Text Available Verbascoside (VB has attracted a great deal of attention due to ITS pharmacological properties. In our study, we synthesized a multifunctional verbascoside coated Ni nanoparticles (VB-Ni. Transmission electron microscopy (TEM and high performance liquid chromatography (HPLC display the characteristics of VB-Ni nanoparticles. Compared with VB, VB-Ni has been proven to induce apoptosis and resist the growth of doxorubicin-resistant K562 cells in vitro and in vivo. Thus, VB-Ni nanoparticles can be thought of as an ideal mode of cancer treatment.

  11. A Study on Production of Carbon Nanotubes by CH4 Decomposition over LaNiO3, La4Ni3O10, La3Ni2O7 and La2NiO4

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Carbon nanotubes (CNTs) of narrow size distribution can be abundantly produced in the catalytic decomposition of CH4 over pre-reduced LaNiO3, La4Ni3O10, La3Ni2O7 and La2NiO4.The CNTs obtained were characterized by means of transmission electron microscopy (TEM).Thermal oxidation of CNTs in air was monitored thermogravimetrically (TG). The resultsrevealed that a lower La/Ni ratio of the catalysts would lead to a wider diameter distribution and a higher degree of graphitic nature.

  12. Thin NiTi Films Deposited on Graphene Substrates

    Science.gov (United States)

    Hahn, S.; Schulze, A.; Böhme, M.; Hahn, T.; Wagner, M. F.-X.

    2017-03-01

    We present experimental results on the deposition of Nickel Titanium (NiTi) films on graphene substrates using a PVD magnetron sputter process. Characterization of the 2-4 micron thick NiTi films by electron microscopy, electron backscatter diffraction, and transmission electron microscopy shows that grain size and orientation of the thin NiTi films strongly depend on the type of combination of graphene and copper layers below. Our experimental findings are supported by density functional theory calculations: a theoretical estimation of the binding energies of different NiTi-graphene interfaces is in line with the experimentally determined microstructural features of the functional NiTi top layer.

  13. Random surfaces and strings

    International Nuclear Information System (INIS)

    Ambjoern, J.

    1987-08-01

    The theory of strings is the theory of random surfaces. I review the present attempts to regularize the world sheet of the string by triangulation. The corresponding statistical theory of triangulated random surfaces has a surprising rich structure, but the connection to conventional string theory seems non-trivial. (orig.)

  14. Derandomizing from random strings

    NARCIS (Netherlands)

    Buhrman, H.; Fortnow, L.; Koucký, M.; Loff, B.

    2010-01-01

    In this paper we show that BPP is truth-table reducible to the set of Kolmogorov random strings R(K). It was previously known that PSPACE, and hence BPP is Turing-reducible to R(K). The earlier proof relied on the adaptivity of the Turing-reduction to find a Kolmogorov-random string of polynomial

  15. Properties of mechanically alloyed Mg-Ni-Ti ternary hydrogen storage alloys for Ni-MH batteries

    Science.gov (United States)

    Ruggeri, Stéphane; Roué, Lionel; Huot, Jacques; Schulz, Robert; Aymard, Luc; Tarascon, Jean-Marie

    MgNiTi x, Mg 1- xTi xNi and MgNi 1- xTi x (with x varying from 0 to 0.5) alloys have been prepared by high energy ball milling and tested as hydrogen storage electrodes. The initial discharge capacities of the Mg-Ni-Ti ternary alloys are inferior to the MgNi electrode capacity. However, an exception is observed with MgNi 0.95Ti 0.05, which has an initial discharge capacity of 575 mAh/g compared to 522 mAh/g for the MgNi electrode. The Mg-Ni-Ti ternary alloys show improved cycle life compared to Mg-Ni binary alloys with the same Mg/Ni atomic ratio. The best cycle life is observed with Mg 0.5Ti 0.5Ni electrode which retains 75% of initial capacity after 10 cycles in comparison to 39% for MgNi electrodes, in addition to improved high-rate dischargeability (HRD). According to the XPS analysis, the cycle life improvement of the Mg 0.5Ti 0.5Ni electrode can be related to the formation of TiO 2 which limits Mg(OH) 2 formation. The anodic polarization curve of Mg 0.5Ti 0.5Ni electrode shows that the current related to the active/passive transition is much less important and that the passive region is more extended than for the MgNi electrode but the corrosion of the electrode is still significant. This suggests that the cycle life improvement would be also associated with a decrease of the particle pulverization upon cycling.

  16. Densities of molten Ni-(Cr, Co, W) superalloys

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; YANG Ren-hui; FANG Liang; LIU Lan-xiao; ZHAO Hong-kai

    2008-01-01

    In order to obtain more accurate density for molten Ni-(Cr, Co, W) binary alloy, the densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys were measured with a sessile drop method. It is found that the measured densities of molten pure Ni and Ni-Cr, Ni-Co, Ni-W alloys decrease with increasing temperature in the experimental temperature range. The density of alloys increases with increasing W and Co concentrations while it decreases with increasing Cr concentration in the alloy at 1 773-1 873 K. The molar volume of Ni-based alloys increases with increasing W concentration while it decreases with increasing Co concentration. The effect of Cr concentration on the molar volume of the alloy is little in the studied concentration range. The accommodation among atomic species was analyzed. The deviation of molar volume from ideal mixing shows an ideal mixing of Ni-(Cr, Co, W) binary alloys.

  17. Spectroscopic investigation of Ni speciation in hardened cement paste.

    Science.gov (United States)

    Vespa, M; Dähn, R; Grolimund, D; Wieland, E; Scheidegger, A M

    2006-04-01

    Cement-based materials play an important role in multi-barrier concepts developed worldwide for the safe disposal of hazardous and radioactive wastes. Cement is used to condition and stabilize the waste materials and to construct the engineered barrier systems (container, backfill, and liner materials) of repositories for radioactive waste. In this study, Ni uptake by hardened cement paste has been investigated with the aim of improving our understanding of the immobilization process of heavy metals in cement on the molecular level. X-ray absorption spectroscopy (XAS) coupled with diffuse reflectance spectroscopy (DRS) techniques were used to determine the local environment of Ni in cement systems. The Ni-doped samples were prepared at two different water/cement ratios (0.4, 1.3) and different hydration times (1 hour to 1 year) using a sulfate-resisting Portland cement. The metal loadings and the metal salts added to the system were varied (50 up to 5000 mg/kg; NO3(-), SO4(2-), Cl-). The XAS study showed that for all investigated systems Ni(ll) is predominantly immobilized in a layered double hydroxide (LDH) phase, which was corroborated by DRS measurements. Only a minor extent of Ni(ll) precipitates as Ni-hydroxides (alpha-Ni(OH)2 and beta-Ni(OH)2). This finding suggests that Ni-Al LDH, rather than Ni-hydroxides, is the solubility-limiting phase in the Ni-doped cement system.

  18. Design and fabrication of Ni nanowires having periodically hollow nanostructures.

    Science.gov (United States)

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-10-07

    We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag 'barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 ± 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni(2+) for the interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating.

  19. Ductility of Ni3Al doped with substitutional elements

    International Nuclear Information System (INIS)

    Hanada, S.; Chiba, A.; Guo, H.Z.; Watanabe, S.

    1993-01-01

    This paper reports on ductility of B-free Ni 3 Al alloys. Recrystallized Ni 3 Al binary alloys with Ni-rich compositions show appreciable ductility when an environmental effect is eliminated, while the alloys with stoichiometric and Al-rich compositions remain brittle. The ductility in the Ni-rich Ni 3 Al alloys is associated with low ordering energy. The additions of ternary elements, which are classified as γ formers, ductilize ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Pd, Pt, Cu and Co), whereas the additions of γ' formers embrittle ternary Ni 3 Al alloys(Ni-23 at% Al-2 at% X, X = Ta, Mo, Nb, Zr, Hf, V, Ti and Si). The additions of small amounts (less than 1 at%) of γ' formers such as Zr and Hf also ductilize as-cast ternary Ni 3 Al alloys. Ductility of Ni 3 Al alloys doped with substitutional elements is discussed in terms of ordering energy and microstructure

  20. CO2 activation on bimetallic CuNi nanoparticles

    Directory of Open Access Journals (Sweden)

    Natalie Austin

    2016-10-01

    Full Text Available Density functional theory calculations have been performed to investigate the structural, electronic, and CO2 adsorption properties of 55-atom bimetallic CuNi nanoparticles (NPs in core-shell and decorated architectures, as well as of their monometallic counterparts. Our results revealed that with respect to the monometallic Cu55 and Ni55 parents, the formation of decorated Cu12Ni43 and core-shell Cu42Ni13 are energetically favorable. We found that CO2 chemisorbs on monometallic Ni55, core-shell Cu13Ni42, and decorated Cu12Ni43 and Cu43Ni12, whereas, it physisorbs on monometallic Cu55 and core-shell Cu42Ni13. The presence of surface Ni on the NPs is key in strongly adsorbing and activating the CO2 molecule (linear to bent transition and elongation of C˭O bonds. This activation occurs through a charge transfer from the NPs to the CO2 molecule, where the local metal d-orbital density localization on surface Ni plays a pivotal role. This work identifies insightful structure-property relationships for CO2 activation and highlights the importance of keeping a balance between NP stability and CO2 adsorption behavior in designing catalytic bimetallic NPs that activate CO2.

  1. NiCo2S4 nanosheet-decorated 3D, porous Ni film@Ni wire electrode materials for all solid-state asymmetric supercapacitor applications.

    Science.gov (United States)

    Saravanakumar, Balasubramaniam; Jayaseelan, Santhana Sivabalan; Seo, Min-Kang; Kim, Hak-Yong; Kim, Byoung-Suhk

    2017-12-07

    Wire type supercapacitors with high energy and power densities have generated considerable interest in wearable applications. Herein, we report a novel NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire electrode for high performance supercapacitor application. In this work, a facile method is introduced to fabricate a 3D, porous Ni film deposited on a Ni wire as a flexible electrode, followed by decoration with NiCo 2 S 4 as an electroactive material. The fabricated NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire electrode displays a superior performance with an areal and volumetric capacitance of 1.228 F cm -2 and 199.74 F cm -3 , respectively, at a current density of 0.2 mA cm -1 with a maximum volumetric energy and power density (E V : 6.935 mW h cm -3 ; P V : 1.019 W cm -3 ). Finally, the solid state asymmetric wire type supercapacitor is fabricated using the fabricated NiCo 2 S 4 -decorated 3D, porous Ni film@Ni wire as a positive electrode and N-doped reduced graphene oxide (N-rGO) as a negative electrode and this exhibits good areal and volumetric capacitances of C A : 0.12 F cm -2 and C V : 19.57 F cm -2 with a higher rate capability (92%). This asymmetric wire type supercapacitor demonstrates a low leakage current and self-discharge with a maximum volumetric energy (E V : 5.33 mW h cm -3 ) and power (P V : 855.69 mW cm -3 ) density.

  2. Surface morphology and electronic structure of Ni/Ag(100)

    International Nuclear Information System (INIS)

    Hite, D. A.; Kizilkaya, O.; Sprunger, P. T.; Howard, M. M.; Ventrice, C. A. Jr.; Geisler, H.; Zehner, D. M.

    2000-01-01

    The growth morphology and electronic structure of Ni on Ag(100) has been studied with scanning tunneling microscopy (STM) and synchrotron based angle resolved photoemission spectroscopy. At deposition temperatures at or below 300 K, STM reveals Ni cluster growth on the surface along with some subsurface growth. Upon annealing to 420 K, virtually all Ni segregates into the subsurface region forming embedded nanoclusters. The electronic structure of Ni d bands in the unannealed surface shows dispersion only perpendicular to the surface whereas the annealed surface has Ni d bands that exhibit a three-dimensional-like structure. This is a result of the increased Ni d-Ag sp hybridization bonding and increased coordination of the embedded Ni nanoclusters. (c) 2000 American Vacuum Society

  3. Measurement and analyses of molten Ni-Co alloy density

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; K. MUKAI; FANG Liang; FU Ya; YANG Ren-hui

    2006-01-01

    With the advent of powerful mathematical modeling techniques for material phenomena, there is renewed interest in reliable data for the density of the Ni-based superalloys. Up to now, there has been few report on the density of molten Ni-Co alloy.In order to obtain more accurate density data for molten Ni-Co alloy, the density of molten Ni-Co alloy was measured with a modified sessile drop method, and the accommodation of different atoms in molten Ni-Co alloy was analyzed. The density of alloy is found to decrease with increasing temperature and Co concentration in the alloy. The molar volume of molten Ni-Co alloy increases with increasing Co concentration. The molar volume of Ni-Co alloy determined shows a positive deviation from the linear molar volume, and the deviation of molar volume from ideal mixing increases with increasing Co concentration over the experimental concentration range.

  4. In situ NiTi/Nb(Ti) composite

    International Nuclear Information System (INIS)

    Jiang, Daqiang; Cui, Lishan; Jiang, Jiang; Zheng, Yanjun

    2013-01-01

    Graphical abstract: - Highlights: • In situ NiTi/Nb(Ti) composites were fabricated. • The transformation temperature was affected by the mixing Ti:Ni atomic ratios. • The NiTi component became micron-scale lamella after forging and rolling. • The composite exhibited high strength and high damping capacity. - Abstract: This paper reports on the creation of a series of in situ NiTi/Nb(Ti) composites with controllable transformation temperatures based on the pseudo-binary hypereutectic transformation of NiTi–Nb system. The composite constituent morphology was controlled by forging and rolling. It is found that the thickness of the NiTi lamella in the composite reached micron level after the hot-forging and cold-rolling. The NiTi/Nb(Ti) composite exhibited high damping capacity as well as high yield strength

  5. Quantum random number generator

    Science.gov (United States)

    Soubusta, Jan; Haderka, Ondrej; Hendrych, Martin

    2001-03-01

    Since reflection or transmission of a quantum particle on a beamsplitter is inherently random quantum process, a device built on this principle does not suffer from drawbacks of neither pseudo-random computer generators or classical noise sources. Nevertheless, a number of physical conditions necessary for high quality random numbers generation must be satisfied. Luckily, in quantum optics realization they can be well controlled. We present an easy random number generator based on the division of weak light pulses on a beamsplitter. The randomness of the generated bit stream is supported by passing the data through series of 15 statistical test. The device generates at a rate of 109.7 kbit/s.

  6. Quantum random number generator

    Science.gov (United States)

    Pooser, Raphael C.

    2016-05-10

    A quantum random number generator (QRNG) and a photon generator for a QRNG are provided. The photon generator may be operated in a spontaneous mode below a lasing threshold to emit photons. Photons emitted from the photon generator may have at least one random characteristic, which may be monitored by the QRNG to generate a random number. In one embodiment, the photon generator may include a photon emitter and an amplifier coupled to the photon emitter. The amplifier may enable the photon generator to be used in the QRNG without introducing significant bias in the random number and may enable multiplexing of multiple random numbers. The amplifier may also desensitize the photon generator to fluctuations in power supplied thereto while operating in the spontaneous mode. In one embodiment, the photon emitter and amplifier may be a tapered diode amplifier.

  7. Neutron-proton matrix element ratios of 21+ states in 58,60,62,64Ni

    International Nuclear Information System (INIS)

    Antalik, R.

    1989-01-01

    The neutron-proton matrix element ratios (η) for 2 1 + states of even Ni isotopes are investigated within the framework of the shell model quasiparticle random-phase approximation. The special attention is devoted to the dependence of η ratios on the radial neutron and proton ground-state density-distribution differences (Δ np ). This dependence is found to be about 0.5Δ np . The theoretical η ratios are 14-23% greater than the hydrodynamical limit. The theoretical Δ np dependence of η ratios enable us to understand the empirical η ratio results. 20 refs.; 2 figs.; 2 tabs

  8. Electrochemical Noise Chaotic Analysis of NiCoAg Alloy in Hank Solution

    Directory of Open Access Journals (Sweden)

    D. Bahena

    2011-01-01

    Full Text Available The potential and current oscillations during corrosion of NiCoAg alloy in Hank solution were studied. Detailed nonlinear fractal analyses were used to characterize complex time series clearly showing that the irregularity in these time series corresponds to deterministic chaos rather than to random noise. The chaotic oscillations were characterized by power spectral densities, phase space, and Lyapunov exponents. Electrochemical impedance was also applied the fractal dimensions for the corroded surface was obtained, and a corrosion mechanism was proposed.

  9. Highly uniform and reliable resistive switching characteristics of a Ni/WOx/p+-Si memory device

    Science.gov (United States)

    Kim, Tae-Hyeon; Kim, Sungjun; Kim, Hyungjin; Kim, Min-Hwi; Bang, Suhyun; Cho, Seongjae; Park, Byung-Gook

    2018-02-01

    In this paper, we investigate the resistive switching behavior of a bipolar resistive random-access memory (RRAM) in a Ni/WOx/p+-Si RRAM with CMOS compatibility. Highly unifrom and reliable bipolar resistive switching characteristics are observed by a DC voltage sweeping and its switching mechanism can be explained by SCLC model. As a result, the possibility of metal-insulator-silicon (MIS) structural WOx-based RRAM's application to Si-based 1D (diode)-1R (RRAM) or 1T (transistor)-1R (RRAM) structure is demonstrated.

  10. Gamow-Teller strength distributions and electron capture rates for 55Co and 56Ni

    International Nuclear Information System (INIS)

    Nabi, Jameel-Un; Rahman, Muneeb-Ur

    2005-01-01

    The Gamow-Teller strength (GT) distributions and electron capture rates on 55 Co and 56 Ni have been calculated using the proton-neutron quasiparticle random phase approximation theory. We calculate these weak interaction mediated rates over a wide temperature (0.01x10 9 -30x10 9 K) and density (10-10 11 gcm -3 ) domain. Electron capture process is one of the essential ingredients involved in the complex dynamics of supernova explosion. Our calculations of electron capture rates show differences with the reported shell model diagonalization approach calculations and are comparatively enhanced at presupernova temperatures. We note that the GT strength is fragmented over many final states

  11. Autonomous Byte Stream Randomizer

    Science.gov (United States)

    Paloulian, George K.; Woo, Simon S.; Chow, Edward T.

    2013-01-01

    Net-centric networking environments are often faced with limited resources and must utilize bandwidth as efficiently as possible. In networking environments that span wide areas, the data transmission has to be efficient without any redundant or exuberant metadata. The Autonomous Byte Stream Randomizer software provides an extra level of security on top of existing data encryption methods. Randomizing the data s byte stream adds an extra layer to existing data protection methods, thus making it harder for an attacker to decrypt protected data. Based on a generated crypto-graphically secure random seed, a random sequence of numbers is used to intelligently and efficiently swap the organization of bytes in data using the unbiased and memory-efficient in-place Fisher-Yates shuffle method. Swapping bytes and reorganizing the crucial structure of the byte data renders the data file unreadable and leaves the data in a deconstructed state. This deconstruction adds an extra level of security requiring the byte stream to be reconstructed with the random seed in order to be readable. Once the data byte stream has been randomized, the software enables the data to be distributed to N nodes in an environment. Each piece of the data in randomized and distributed form is a separate entity unreadable on its own right, but when combined with all N pieces, is able to be reconstructed back to one. Reconstruction requires possession of the key used for randomizing the bytes, leading to the generation of the same cryptographically secure random sequence of numbers used to randomize the data. This software is a cornerstone capability possessing the ability to generate the same cryptographically secure sequence on different machines and time intervals, thus allowing this software to be used more heavily in net-centric environments where data transfer bandwidth is limited.

  12. Ni3d-Gd4f correlation effects on the magnetic behaviour of GdNi

    Energy Technology Data Exchange (ETDEWEB)

    Paulose, P L [Tata Inst. of Fundamental Research, Bombay (India); Patil, Sujata [Tata Inst. of Fundamental Research, Bombay (India); Mallik, R [Tata Inst. of Fundamental Research, Bombay (India); Sampathkumaran, E V [Tata Inst. of Fundamental Research, Bombay (India); Nagarajan, V [Tata Inst. of Fundamental Research, Bombay (India)

    1996-07-01

    The results of magnetization and heat-capacity measurements on the alloys, Gd{sub 1-x}Y{sub x}Ni (x=0.0, 0.25, 0.5, 0.75 and 0.9) are reported. The data suggest that there is a Gd induced magnetic moment on Ni, which may in turn enhance Gd-Gd exchange interaction strength in GdNi. The induced moment (on Ni) apparently exhibits itinerant ferromagnetism in the magnetically ordered state of GdNi. (orig.).

  13. Effects of Bond Coating on NiCrBSi-Mo Composite Functional Coating Properties in Plasma Spraying NiCrBSi-Mo/Ni Coating

    OpenAIRE

    DU Ji-yu; LI Fang-yi; LU Hai-yang; SHANG Jian-tong; LI Zhen

    2017-01-01

    Nickel-based bond coating and composite functional coating were sprayed on leaf blade steel material FV520B successively by using air plasma spraying system. NiCrBSi-Mo powder deposition rate, coating porosity, bonding strength and surface hardness were tested. The results indicate that, for the NiCrBSi-Mo/Ni coating, bond coating with 180-220μm thickness can improve NiCrBSi-Mo powder deposition rate while the surface coating with lower porosity, higher bonding strength and high hardness is p...

  14. Thermodynamic characterization of Ni3TeO6, Ni2Te3O8 and NiTe2O5

    Science.gov (United States)

    Dawar, Rimpi; Babu, R.; Ananthasivan, K.; Anthonysamy, S.

    2017-09-01

    Measurement of vapour pressure of TeO2(g) over the biphasic mixture Ni3TeO6 (s) + NiO(s) in the temperature range 1143-1272 K was carried out using transpiration-thermogravimetric technique (TTG). Gibbs energy of formation of Ni3TeO6 was obtained from the temperature dependence of vapour pressure of TeO2 (g) generated by the incongruent vapourisation reaction, Ni3TeO6 (s) → NiO(s) + TeO2 (g) + 1/2 O2 in the temperature range 1143-1272 K. An isoperibol type drop calorimeter was used to measure the enthalpy increments of Ni3TeO6, Ni2Te3O8 and NiTe2O5. Thermodynamic functions viz., heat capacity, entropy and Gibbs energy functions of these compounds were derived from the experimentally measured enthalpy increment values. Third-law analysis was carried out to ascertain absence of temperature dependent systematic errors in the measurement of vapour pressure of TeO2 (g). A value of -1265.1 ± 1.5 kJ mol-1 was obtained for Δ Hf,298K o (Ni3TeO6) using third-law analysis.

  15. Structural and magnetic properties of Ni-Zn and Ni-Zn-Co ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Knyazev, A.V., E-mail: knyazevav@gmail.com [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Zakharchuk, I.; Lähderanta, E. [Lappeenranta University of Technology, P.O. Box 20, FI-53851 Lappeenranta (Finland); Baidakov, K.V.; Knyazeva, S.S. [N.I. Lobachevsky State University of Nizhni Novgorod, Gagarin Prospekt 23/2, 603950 Nizhni Novgorod (Russian Federation); Ladenkov, I.V. [Joint-stock Company “Research and Production Company “Salut”, Nizhni Novgorod (Russian Federation)

    2017-08-01

    Highlights: • Ni-Zn and Ni-Zn-Co ferrite powders were prepared by the solid-state reaction at 1073 K. • The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. • The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. • The temperature dependences of magnetization exhibit large spin frustration and spin-glass-like behavior. - Abstract: Ni-Zn and Ni-Zn-Co ferrite powders with nominal compositions Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} were prepared by the solid-state reaction synthesis with periodic regrinding during the calcination at 1073 K. The structure of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4} was refined assuming space group F d-3m. Scanning electron microscopy revealed the average sizes of the crystalline ferrite particles are 130–630 nm for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 140–350 nm for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The room temperature saturation magnetizations are 59.7 emu/g for Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} and 57.1 emu/g for Ni{sub 0.5}Zn{sub 0.3}Co{sub 0.2}Fe{sub 2}O{sub 4}. The coercivity of the samples is found to be much larger than that of bulk ferrites and increases with Co introduction. The Curie temperature tends to increase upon Zn substitution by Co, as well. The temperature dependences of magnetization measured using zero-field cooled and field cooled protocols exhibit large spin frustration and spin-glass-like behavior.

  16. Anti-corrosive and anti-microbial properties of nanocrystalline Ni-Ag coatings

    Energy Technology Data Exchange (ETDEWEB)

    Raghupathy, Y.; Natarajan, K.A.; Srivastava, Chandan, E-mail: csrivastava@materials.iisc.ernet.in

    2016-04-15

    Graphical abstract: - Highlights: • Electrodeposition yielded phase-segregated, nanocrystalline Ni-Ag coatings. • Ni-Ag alloys exhibited smaller Ni crystals compared to pure Ni. • Ultra fine Ni grains of size 12–14 nm favoured Ni-Ag solid solution. • Nanocrystalline Ag resisted bio-fouling by Sulphate Reducing bacteria. • Ni-Ag outperformed pure Ni in corrosion and bio-corrosion tests. - Abstract: Anti-corrosive and anti-bacterial properties of electrodeposited nanocrystalline Ni-Ag coatings are illustrated. Pure Ni, Ni-7 at.% Ag, & Ni-14 at.% Ag coatings were electrodeposited on Cu substrate. Coating consisted of Ni-rich and Ag-rich solid solution phases. With increase in the Ag content, the corrosion resistance of the Ni-Ag coating initially increased and then decreased. The initial increase was due to the Ni-Ag solid solution. The subsequent decrease was due to the increased galvanic coupling between the Ag-rich and Ni-rich phases. For all Ag contents, the corrosion resistance of the Ni-Ag coating was higher than the pure Ni coating. Exposure to Sulphate Reducing Bacteria (SRB) revealed that the extent of bio-fouling decreased with increase in the Ag content. After 2 month exposure to SRB, the Ni-Ag coatings demonstrated less loss in corrosion resistance (58% for Ni-7 at.% Ag and 20% for Ni-14 at.% Ag) when compared pure Ni coating (115%).

  17. Local lattice relaxations in random metallic alloys: Effective tetrahedron model and supercell approach

    DEFF Research Database (Denmark)

    Ruban, Andrei; Simak, S.I.; Shallcross, S.

    2003-01-01

    We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au-ri......-rich CuAu alloys shows that the model yields a quantitatively accurate description of the relaxtion energies in these systems. Finally, we discuss the bond length distribution in random alloys....

  18. Niños y niñas como cuidadores familiares

    Directory of Open Access Journals (Sweden)

    María Rosa Estupiñán Aponte

    2015-01-01

    Full Text Available En el contexto familiar, el cuidado de otra persona por parte de niños y niñas constituye un terreno inexplorado tanto en su significado como en las implicaciones que podrían darse en el proceso. Aunque históricamente se ha asignado el cuidado familiar a las mujeres generando condiciones de inequidad, incrementada con los cambios sociales de los últimos tiempos, es necesario reconocer que en muchos hogares niños y niñas se han visto obligados a desempeñar esta labor sin la preparación ni las destrezas necesarias. Desde una perspectiva de género, el artículo busca evidenciar esta situación mediante la revisión de los abordajes que sobre el tema se han hecho en países de Europa y Norteamérica, así como el análisis de información obtenida a partir de las Encuestas de Hogares y Uso del Tiempo (EUT en algunos países de Latinoamérica. Se establece la forma como las problemáticas sociales inciden en las dinámicas, tipo de tareas y responsabilidades que deben asumir niños y niñas en los hogares, mostrando delgados límites entre la colaboración al interior de las familias, la transmisión cultural de roles y funciones y las actividades que podrían incidir negativamente en su crecimiento y el ejercicio de sus derechos.

  19. Estilos de vida saludables de niños, niñas y adolescentes

    Directory of Open Access Journals (Sweden)

    Lilia Campo-Ternera

    2017-01-01

    Full Text Available Objetivo: Describir los estilos de vida saludables de niños, niñas y adolescentes de Barranquilla. Materiales y métodos: Estudio descriptivo de corte transversal en 991 niños, niñas y ado - lescentes. Se evaluó la actividad física mediante los cuestionarios de Actividad Física para Adolescentes y para niños escolares; se aplicó una encuesta que midió los conocimientos y prácticas de los escolares sobre salud bucal, lavado de manos, consumo de frutas y verduras y cuidado postural; la Lista de Chequeo “Mi Vida en la Escuela”, la cual evalúa los índices de “bullying” y agresión; y la inteligencia emocional a través dela escala TMMS -24. Resultados: El 65,4 % se categoriza como inactivos físicamente. Solo el 14,7% de los estudiantes reconoce que el peso máximo del bolso es el 10 % de su peso corporal; el 34,1 % cambia el cepillo de dientes cada 3 meses, como lo recomiendan los expertos, y 48,4 % se cepilla los dientes entre 2 y 3 veces al día. El 16,6 % no se lava las manos antes y después de ir al baño y 9,4 % no lo hace antes y después de las comidas; el 17,5 % no tiene un buen consumo de verduras y frutas; y se encontró un Índice de “bullying” en el 55,6 % de los participantes. Conclusión: Los anteriores resultados obligan a plantear intervenciones que incrementen las prácticas saludables en niños, niñas y adolescentes.

  20. Electrochemical properties of the ball-milled LaMg10NiMn alloy with Ni powders

    International Nuclear Information System (INIS)

    Wang Yi; Wang Xin; Gao Xueping; Shen Panwen

    2008-01-01

    The electrochemical characteristics of the ball-milled LaMg 10 NiMn alloys with Ni powders were investigated. It was found that the ball-milled LaMg 10 NiMn + 150 wt.% Ni composite exhibited higher first discharge capacity and better cycle performance. By means of the analysis of electrochemical impedance spectra (EIS), it was shown that the existence of manganese in LaMg 10 NiMn alloy increased the electrocatalytic activity due to its catalytic effect, and destabilized metal hydrides, and so reduced the hydrogen diffusion resistance. These contributed to the higher discharge capacity of the ball-milled LaMg 10 NiMn-Ni composite. According to the analytical results of X-ray diffraction (XRD), EIS and steady-state polarization (SSP) experiments, the inhibition of metal corrosion is not the main reason for the better cycle performance. The main reason is that the electrochemical reaction resistance of the ball-milled LaMg 10 NiMn-Ni composite is always lower than that of the ball-milled LaMg 10 Ni 2 -Ni composite because the former one contains manganese, which is a catalyst for the electrode reaction

  1. High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

    International Nuclear Information System (INIS)

    Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

    2008-01-01

    We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

  2. Corrosive sliding wear behavior of laser clad Mo2Ni3Si/NiSi intermetallic coating

    International Nuclear Information System (INIS)

    Lu, X.D.; Wang, H.M.

    2005-01-01

    Many ternary metal silicides such as W 2 Ni 3 Si, Ti 2 Ni 3 Si and Mo 2 Ni 3 Si with the topologically closed-packed (TCP) hP12 MgZn 2 type Laves phase crystal structure are expected to have outstanding wear and corrosion resistance due to their inherent high hardness and sluggish temperature dependence and strong atomic bonds. In this paper, Mo 2 Ni 3 Si/NiSi intermetallic coating was fabricated on substrate of an austenitic stainless steel AISI321 by laser cladding using Ni-Mo-Si elemental alloy powders. Microstructure of the coating was characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDS). Wear resistance of the coating is evaluated under corrosive sliding wear test condition. Influence of corrosion solutions on the wear resistance of the coating was studied and the wear mechanism was discussed based on observations of worn surface morphology. Results showed that the laser clad Mo 2 Ni 3 Si/NiSi composite coating have a fine microstructure of Mo 2 Ni 3 Si primary dendrites and the interdendritic Mo 2 Ni 3 Si/NiSi eutectics. The coating has excellent corrosive wear resistance compared with austenitic stainless steel AISI321 under acid, alkaline and saline corrosive environments

  3. Magnetic properties of two new compounds: Pr2Ni3Si5 and Ho2Ni3Si5

    International Nuclear Information System (INIS)

    Mazumdar, C.; Padalia, B.D.; Godart, C.

    1994-01-01

    Formation of two more new materials, Pr 2 Ni 3 Si 5 and Ho 2 Ni 3 Si 5 , of the series, R 2 Ni 3 Si 5 (R = rare earth and Y) and their magnetic properties are reported here. These materials crystallize in the orthorhombic U 2 Co 3 Si 5 -type structure (space group Ibam). Magnetic susceptibility measurement in the temperature range 5 K--300 K show that the compound Pr 2 Ni 3 Si 5 order antiferromagnetically at T N ∼ 8.5 K and Ho 2 Ni 3 Si 5 at ∼ 6 K. Considering T N (Gd 2 Ni 3 Si 5 ) ∼ 15 K, T N (Pr 2 Ni 3 Si 5 ) ∼ 8.5 K is rather high. The magnetic susceptibility of both of the materials, in the paramagnetic state, follows a Curie-Weiss law with effective moment close to that of the corresponding free trivalent rare earth ion

  4. Effect of Ni Core Structure on the Electrocatalytic Activity of Pt-Ni/C in Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Vladimir Linkov

    2013-07-01

    Full Text Available Methanol oxidation catalysts comprising an outer Pt-shell with an inner Ni-core supported on carbon, (Pt-Ni/C, were prepared with either crystalline or amorphous Ni core structures. Structural comparisons of the two forms of catalyst were made using transmission electron microscopy (TEM, X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS, and methanol oxidation activity compared using CV and chronoamperometry (CA. While both the amorphous Ni core and crystalline Ni core structures were covered by similar Pt shell thickness and structure, the Pt-Ni(amorphous/C catalyst had higher methanol oxidation activity. The amorphous Ni core thus offers improved Pt usage efficiency in direct methanol fuel cells.

  5. Hard X-ray MCD in GdNi/sub 5/ and TbNi/sub 5/ single crystals

    CERN Document Server

    Galera, R M

    1999-01-01

    XMCD experiments have been performed at the R L/sub 2,3/ and Ni K- edges on magnetically saturated single crystals of GdNi/sub 5/ and Tb Ni/sub 5/ ferromagnetic compounds. The spectra present huge and well structured dichroic $9 signals at both the R L/sub 2,3/ and the Ni K- edges. Structures from the quadrupolar (2p to 4f) transitions are clearly observed at the R L/sub 2,3/-edges. Though Ni is not magnetic, large intensities, up to 0.4, are measured at the $9 Ni K- edge. The Ni K-edge XMCD shows a three-peak structure which intensities dependent on the rare earth. (7 refs).

  6. Electrochemically induced transformation of NiS nanoparticles into Ni(OH)2 in KOH aqueous solution toward electrochemical capacitors

    International Nuclear Information System (INIS)

    Hou Linrui; Yuan Changzhou; Li Diankai; Yang Long; Shen Laifa; Zhang Fang; Zhang Xiaogang

    2011-01-01

    Highlights: → NiS is synthesized by means of the H 2 O/CS 2 interface under hydrothermal treatment. → NiS itself owns poor electrochemical capacitance in 2 M KOH solution. → NiS is electrochemically induced and transformed into electroactive Ni(OH) 2 . → Ni(OH) 2 is responsible for good energy storage of the NiS in the KOH solution. → The new formed Ni(OH) 2 delivers large energy density at high rates. - Abstract: Nickel sulfide nanoparticles (NPs) are first synthesized by virtue of a unique H 2 O/CS 2 interface under mild hydrothermal treatment. Electrochemical data reveals that the as-synthesized NiS NPs themselves own poor supercapacitive behavior at initial cyclic voltammetry (CV) cycles in 2 M KOH solution, while a specific capacitance of 893 F g -1 can be surprisingly obtained at a current density of 5 A g -1 just after continuous 320 CV cycles. X-ray diffraction and Fourier transform infrared techniques demonstrate that what is really responsible for the good electrochemical capacitance in the KOH aqueous solution is the new electrochemically formed Ni(OH) 2 phase, rather than NiS NPs themselves. The Ni(OH) 2 is slowly formed during the continuous CV cycling process, in which the electrochemically induced phase transformation from NiS to Ni(OH) 2 phase takes place. Furthermore, the new Ni(OH) 2 phase demonstrates the great ability of delivering large specific capacitance at high rates.

  7. Fe-Ni-bearing serpentines from the saprolite horizon of Caribbean Ni-laterite deposits: new insights from thermodynamic calculations

    Science.gov (United States)

    Villanova-de-Benavent, Cristina; Domènech, Cristina; Tauler, Esperança; Galí, Salvador; Tassara, Santiago; Proenza, Joaquín A.

    2017-10-01

    Fe-Ni-bearing serpentine from the saprolite horizon is the main Ni ores in hydrous silicate-type Ni laterites and formed by chemical weathering of partially serpentinized ultramafic rocks under tropical conditions. During lateritization, Mg, Si, and Ni are leached from the surface and transported downwards. Fe2+ is oxidized to Fe3+ and fixed as insoluble Fe-oxyhydroxides (mostly goethite) that incorporate Ni. This Ni is later leached from goethite and incorporated in secondary serpentine and garnierite. As a result, a serpentine-dominated saprolite horizon forms over the ultramafic protolith, overlapped by a Fe-oxyhydroxide-dominated limonite horizon. The serpentine from the protolith (serpentine I) is of hydrothermal origin and yields similar Ni (0.10-0.62 wt.% NiO) and lower Fe (mostly 1.37-5.81 wt.% FeO) concentrations than the primary olivine. In contrast, Fe-Ni-bearing serpentine from the saprolite (serpentine II) shows significantly higher and variable Fe and Ni contents, typically ranging from 2.23 to 15.59 wt.% Fe2O3 and from 1.30 to 7.67 wt.% NiO, suggesting that serpentine get enriched in Fe and Ni under supergene conditions. This study presents detailed mineralogical, textural, and chemical data on this serpentine II, as well as new insights by thermodynamic calculations assuming ideal solution between Fe-, Ni- and Mg-pure serpentines. The aim is to assess if at atmospheric pressure and temperature Fe-Ni-bearing serpentine can be formed by precipitation. Results indicate that the formation of serpentine II under atmospheric pressure and temperature is thermodynamically supported, and pH, Eh, and the equilibrium constant of the reaction are the parameters that affect the results more significantly.

  8. Random number generation

    International Nuclear Information System (INIS)

    Coveyou, R.R.

    1974-01-01

    The subject of random number generation is currently controversial. Differing opinions on this subject seem to stem from implicit or explicit differences in philosophy; in particular, from differing ideas concerning the role of probability in the real world of physical processes, electronic computers, and Monte Carlo calculations. An attempt is made here to reconcile these views. The role of stochastic ideas in mathematical models is discussed. In illustration of these ideas, a mathematical model of the use of random number generators in Monte Carlo calculations is constructed. This model is used to set up criteria for the comparison and evaluation of random number generators. (U.S.)

  9. Quantum random access memory

    OpenAIRE

    Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo

    2007-01-01

    A random access memory (RAM) uses n bits to randomly address N=2^n distinct memory cells. A quantum random access memory (qRAM) uses n qubits to address any quantum superposition of N memory cells. We present an architecture that exponentially reduces the requirements for a memory call: O(log N) switches need be thrown instead of the N used in conventional (classical or quantum) RAM designs. This yields a more robust qRAM algorithm, as it in general requires entanglement among exponentially l...

  10. Randomization of inspections

    International Nuclear Information System (INIS)

    Markin, J.T.

    1989-01-01

    As the numbers and complexity of nuclear facilities increase, limitations on resources for international safeguards may restrict attainment of safeguards goals. One option for improving the efficiency of limited resources is to expand the current inspection regime to include random allocation of the amount and frequency of inspection effort to material strata or to facilities. This paper identifies the changes in safeguards policy, administrative procedures, and operational procedures that would be necessary to accommodate randomized inspections and identifies those situations where randomization can improve inspection efficiency and those situations where the current nonrandom inspections should be maintained. 9 refs., 1 tab

  11. Random phenomena; Phenomenes aleatoires

    Energy Technology Data Exchange (ETDEWEB)

    Bonnet, G. [Commissariat a l' energie atomique et aux energies alternatives - CEA, C.E.N.G., Service d' Electronique, Section d' Electronique, Grenoble (France)

    1963-07-01

    This document gathers a set of conferences presented in 1962. A first one proposes a mathematical introduction to the analysis of random phenomena. The second one presents an axiomatic of probability calculation. The third one proposes an overview of one-dimensional random variables. The fourth one addresses random pairs, and presents basic theorems regarding the algebra of mathematical expectations. The fifth conference discusses some probability laws: binomial distribution, the Poisson distribution, and the Laplace-Gauss distribution. The last one deals with the issues of stochastic convergence and asymptotic distributions.

  12. Ni{sub 3}Al technology transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Santella, M.L.; Alexander, D.J. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for (1)high-strength castable composition for turbochargers, furnace furniture, and hot-die applications; (2) castability (fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) hot fabricability of cast ingots. All of the issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes work completed to address some of these issues during the fourth quarter of FY 1994.

  13. Ni{sub 3}Al technology transfer

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.; Viswanathan, S.; Santella, M.L. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Ductile Ni{sub 3}Al and Ni{sub 3}Al-based alloys have been identified for a range of applications. These applications require the use of material in a variety of product forms such as sheet, plate, bar, wire, tubing, piping, and castings. Although significant progress has been made in the melting, casting, and near-net-shape forming of nickel aluminides, some issues still remain. These include the need for: (1) high-strength castable composition for many applications that have been identified; (2) castability (mold type, fluidity, hot-shortness, porosity, etc.); (3) weld reparability of castings; and (4) workability of cast or powder metallurgy product to sheet, bar, and wire. The four issues listed above can be {open_quotes}show stoppers{close_quotes} for the commercial application of nickel aluminides. This report describes the work completed to address some of these issues during FY 1996.

  14. Internal chlorination of Ni-Cr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Berztiss, D.; Hennesen, K.; Grabke, H.J. [Max-Planck-Institut fuer Eisenforschung GmbH, Duesseldorf (Germany)

    1998-12-31

    In contrast to internal oxidation, sulfidation and carburization, very little information is available regarding internal chlorination, especially diffusion of chlorine in metallic alloys. This paper describes results of experiments on Ni-Cr alloys (<10 wt% Cr) exposed in an atmosphere containing radioactive HCl. The diffusion of chlorine in the alloy can be determined by measurement of residual {beta}-activity from the sample surface. Successively thin layers (0.5-10 {mu}m) of the alloy were removed by lapping and the surface activity was measured to obtain a depth profile. Both single and polycrystalline materials were tested. Through this work it should be determined if there is in fact solubility and diffusion of chlorine in Ni-based alloys as some authors have proposed or if the ingress of chlorine is mainly a grain boundary phenomenon. (orig.)

  15. Resonant Ni and Fe KLL Auger spectra photoexcited from NiFe alloys

    International Nuclear Information System (INIS)

    Koever, L.; Cserny, I.; Berenyi, Z.; Egri, S.; Novak, M.

    2005-01-01

    Complete text of publication follows. KLL Auger spectra of 3d transition metal atoms in solid environment, measured using high energy resolution, give an insight into the details of the local electronic structure surrounding the particular atoms emitting the signal Auger electrons. Fine tuning the energy of the exciting monochromatic photons across the K-absorption edge, features characteristic to resonant phenomena can be identified in the spectra. The shapes of the resonantly photoexcited KLL Auger spectra induced from 3d transition metals and alloys are well interpreted by the single step model of the Auger process, based on the resonant scattering theory. The peak shapes are strongly influenced by the 4p partial density of unoccupied electronic states around the excited atom. High energy resolution studies of KLL Auger spectra of 3d transition metals using laboratory X-ray sources, however, request very demanding experiments and yield spectra of limited statistical quality making the evaluation of the fine details in the spectra difficult. The Tunable High Energy XPS (THE- XPS) instrument at BW2 offers optimum photon x and energy resolution for spectroscopy of deep core Auger transitions. For the present measurements high purity polycrystalline Ni and Fe sheets as well as NiFe alloy samples of different compositions (Ni 80 Fe 20 , Ni 50 Fe 50 , Ni 20 Fe 80 ) were used. The surfaces of the samples were cleaned by in-situ argon ion sputtering. The measurements of the Ni and Fe KL 23 L 23 Auger spectra of the metal and alloy samples were performed with the THE-XPS instrument using high electron energy resolution (0.2 eV). In Fig.1, the measured Fe KL 23 L 23 spectrum, photoexcited at the Fe K absorption edge from Fe metal, is compared with the respective spectrum excited from a Ni 50 Fe 50 alloy. A significant broadening of the 1 D 2 peak and an enhancement of the spectral intensity at the low energy loss part of this peak observed in the alloy sample, while the

  16. Phase transitions in alloys of the Ni-Mo system

    International Nuclear Information System (INIS)

    Ustinovshikov, Y.; Shabanova, I.

    2011-01-01

    Graphical abstract: The structure of Ni-20 at.% Mo and Ni-25 at.% Mo alloys was studied by methods of TEM and XPS. It is shown that at high temperatures the tendency toward phase separation takes place in the alloys and crystalline bcc Mo particles precipitate in the liquid solution. At 900 deg. C and below, the tendency toward ordering leads to the dissolution of Mo particles and precipitation of the particles of Ni 3 Mo, Ni 2 Mo or Ni 4 Mo chemical compounds. Highlights: → 'Chemical' phase transition 'ordering-phase separation' is first discovered in alloys of the Ni-Mo system. → It is first shown that the phase separation in the alloys studied begins at temperatures above the liquidus one. → The formation of Ni 3 Mo from A1 has gone through the intervening stage of the Ni 4 Mo and Ni 2 Mo coexistence. - Abstract: The structure of Ni-20 at.% Mo and Ni-25 at.% Mo alloys heat treated at different temperatures was studied by the method of transmission electron microscopy. X-ray photoelectron spectroscopy was used to detect the sign of the chemical interaction between Ni and Mo atoms at different temperatures. It is shown that at high temperatures the tendency toward phase separation takes place. The system of additional reflections at positions {1 1/2 0} on the electron diffraction patterns testifies that the precipitation of crystalline bcc Mo particles begins in the liquid solution. At 900 deg. C and below, the tendency toward ordering leads to the precipitation of the particles of the chemical compounds. A body-centered tetragonal phase Ni 4 Mo (D1 a ) is formed in the Ni-20 at.% Mo alloy. In the Ni-25 at.% Mo alloy, the formation of the Ni 3 Mo (D0 22 ) chemical compound from the A1 solid solution has gone through the intervening stage of the Ni 4 Mo (D1 a ) and Ni 2 Mo (Pt 2 Mo) formation.

  17. A FeNiMnC alloy with strain glass transition

    Directory of Open Access Journals (Sweden)

    Hui Ma

    2018-02-01

    Full Text Available Recent experimental and theoretical investigations suggested that doping sufficient point defects into a normal ferroelastic/martensitic alloy systems could lead to a frozen disordered state of local lattice strains (nanomartensite domains, thereby suppressing the long-range strain-ordering martensitic transition. In this study, we attempt to explore the possibility of developing novel ferrous Elinvar alloys by replacing nickel with carbon and manganese as dopant species. A nominal Fe89Ni5Mn4.6C1.4 alloy was prepared by argon arc melting, and XRD, DSC, DMA and TEM techniques were employed to characterize the strain glass transition signatures, such as invariance in average structure, frequency dispersion in dynamic mechanical properties (storage modulus and internal friction and the formation of nanosized strain domains. It is indicated that doping of Ni, Mn and C suppresses γ→α long-range strain-ordering martensitic transformation in Fe89Ni5Mn4.6C1.4 alloy, generating randomly distributed nanosized domains by strain glass transition. Keywords: Strain glass transition, Elinvar alloys, Point defects, Nanosized domains

  18. Magnetic properties of the CrMnFeCoNi high-entropy alloy

    International Nuclear Information System (INIS)

    Schneeweiss, Oldřich; Friák, Martin; Masaryk University, Brno; Dudová, Marie; Holec, David

    2017-01-01

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

  19. Combining Ru, Ni and Ni(OH){sub 2} active sites for improving catalytic performance in benzene hydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Lihua, E-mail: lihuazhu@stu.xmu.edu.cn [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Sun, Hanlei; Zheng, Jinbao [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Yu, Changlin, E-mail: yuchanglinjx@163.com [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Zhang, Nuowei [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Shu, Qing [School of Metallurgy and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiang Xi (China); Chen, Bing H., E-mail: chenbh@xmu.edu.cn [Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2017-05-01

    In this study, the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were successfully prepared by the simple methods of hydrazine-reduction and galvanic replacement, where 0.04/0.96 and T represented the Ru/Ni atomic ratio and reducing temperature of the catalyst in N{sub 2}+10%H{sub 2}, respectively. The nanostructures of the Ru{sub 0.04}Ni{sub 0.96} nanoparticles in the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts were controlled by modulating their annealing temperature in N{sub 2}+10%H{sub 2} and characterized by an array of techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDS) mapping and high-sensitivity low-energy ion scattering (HS-LEIS). The Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, which was composed of Ru clusters or single atoms supported on Ni/Ni(OH){sub 2} nanoparticles, exhibited much better catalytic performance for benzene hydrogenation than the Ru{sub 0.04}Ni{sub 0.96}/C(T) catalysts reduced at above 30 °C, such as Ru{sub 0.04}Ni{sub 0.96}/C(160) with the nanostructure of partial Ru{sub 0.04}Ni{sub 0.9} alloy and Ru{sub 0.04}Ni{sub 0.96}/C(280) with the nanostructure of complete Ru{sub 0.04}Ni{sub 0.9} alloy. The reason was that the synergistic effect of multiple active sites – Ru, Ni and Ni(OH){sub 2} sites was present in the Ru{sub 0.04}Ni{sub 0.96}/C(30) catalyst, where hydrogen was preferentially activated at Ru sites, benzene was probably activated at Ni(OH){sub 2} surface and Ni acted as a “bridge” for transferring activated H{sup ∗} species to activated benzene by hydrogen spillover effect, hydrogenating and forming product – cyclohexane. This study also provided a typical example to illustrate that the synergy effect of multiple active sites can largely improve the catalytic hydrogenation performance. - Highlights: • The Ru

  20. Random oriented hexagonal nickel hydroxide nanoplates grown on graphene as binder free anode for lithium ion battery with high capacity

    Science.gov (United States)

    Du, Yingjie; Ma, Hu; Guo, Mingxuan; Gao, Tie; Li, Haibo

    2018-05-01

    In this work, two-step method has been employed to prepare random oriented hexagonal hydroxide nanoplates on graphene (Ni(OH)2@G) as binder free anode for lithium ion battery (LIB) with high capacity. The morphology, microstructure, crystal phase and elemental bonding have been characterized. When evaluated as anode for LIB, the Ni(OH)2@G exhibited high initial discharge capacity of 1318 mAh/g at the current density of 50 mA/g. After 80 cycles, the capacity was maintained at 834 mAh/g, implying 63.3% remaining. Even the charge rate was increased to 2000 mA/g, an impressive capacity of 141 mAh/g can be obtained, indicating good rate capability. The superior LIB behavior of Ni(OH)2@G is ascribed to the excellent combination between Ni(OH)2 nanoplates and graphene via both covalent chemical bonding and van der Waals interactions.

  1. Imaging magnetic domains in Ni nanostructures

    International Nuclear Information System (INIS)

    Asenjo, A.; Jaafar, M.; Gonzalez, E.M.; Martin, J.I.; Vazquez, M.; Vicent, J.L.

    2007-01-01

    The study of nanomagnets is the subject of increasing scientific effort. The size, the thickness and the geometric shape of the elements determine the magnetic properties and then the domain configuration. In this work, we fabricated by electron-beam lithography the three different arrays of Ni nanostructures keeping the size, the thickness and also the distance constant between the elements but varying the geometry: square, triangular and circular. The domain structure of the nanomagnets is studied by magnetic force microscopy

  2. Determination of 59Ni in radioactive waste

    International Nuclear Information System (INIS)

    Fisera, O.; Sebesta, F.

    2010-01-01

    Composite material PAN-DMG, containing chelating agent dimethylglyoxime (DMG) immobilized in porous matrix of binding polymer polyacrylonitrile (PAN), was used for nickel separation and concentration. Method for preparation of 59 Ni source for low energy photon spectrometry was developed using homogeneous precipitation of nickel with DMG. The proposed method was tested with two types of real radioactive waste (boric acid concentrate from nuclear power plant (NPP) evaporator and spent ion exchanger from NPP). (author)

  3. Structural, electrical and magnetic properties of evaporated Ni/Cu and Ni/glass thin films

    Energy Technology Data Exchange (ETDEWEB)

    Nacereddine, C. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Layadi, A. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria)]. E-mail: A_Layadi@yahoo.fr; Guittoum, A. [Centre de Recherche Nucleaire d' Alger (CRNA), Alger 16000 (Algeria); Cherif, S.-M. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse 93340 (France); Chauveau, T. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse 93340 (France); Billet, D. [Laboratoire PMTM, Institut Galilee, Univeriste Paris 13, Villetaneuse 93340 (France); Youssef, J. Ben [Laboratoire de Magnetisme de Bretagne, U.B.O., Brest 29238 (France); Bourzami, A. [Departement de Physique, Universite Ferhat Abbas, Setif 19000 (Algeria); Bourahli, M.-H. [Departement d' O. M. P., Universite Ferhat Abbas, Setif 19000 (Algeria)

    2007-01-25

    The structural, electrical and magnetic properties of Ni thin films evaporated onto glass and polycrystalline Cu substrates have been investigated. The Ni thickness ranges from 31 to 165 nm. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used to study the structure and morphology of these systems. The Ni/Cu and Ni/glass thin films are found to be polycrystalline with a (1 1 1) texture. There is an overall increase of the grain size with increasing thickness. A negative strain was noted indicating that all the samples are under a compressive stress. Diffusion at the grain boundaries seems to be a major contribution to the electrical resistivity in this thickness range. Study of the hysteresis curves, obtained by vibrating sample magnetometer (VSM), indicates that all samples are characterized by an in-plane magnetization easy axis. Higher in-plane coercive fields seem to be associated with higher grain size, indicating that coercivity may be due to nucleation of reverse domains rather than pinning of domain walls. The saturation field and the squareness have been studied as a function of the Ni thickness.

  4. Participar como niña o niño en el mundo social

    Directory of Open Access Journals (Sweden)

    Silvia Paulina Díaz

    2010-10-01

    Full Text Available En este artículo presento la participación como resultado de un trabajo investigativo realizado durante el año 2007, con niños y niñas escolarizados habitantes de la ciudad de Medellín, Colombia, cuyo objetivo fue analizar las representaciones sociales que ellos y ellas comparten sobre el ejercicio ciudadano. El análisis de la información tiene como ejes fundamentales, la salud colectiva, la sociología de la infancia y la participación en la niñez, en una aproximación que se realiza desde un enfoque cualitativo y etnográfico. En los hallazgos, sobresale cómo las niñas y niños se muestran preparados para ejercer su derecho a la participación como aspecto de sus vidas que se haría posible dentro del marco normativo existente, pero que aún no es asumido en prácticas sociales que los incluyan.

  5. HDO of Methyl Palmitate over Silica-Supported Ni Phosphides: Insight into Ni/P Effect

    Directory of Open Access Journals (Sweden)

    Irina V. Deliy

    2017-10-01

    Full Text Available Two sets of silica-supported nickel phosphide catalysts with a nickel content of about 2.5 and 10 wt % and Ni/P molar ratio 2/1, 1/1 and 1/2 in each set, were prepared by way of a temperature-programmed reduction method using (Ni(CH3COO2 and ((NH42HPO4 as a precursor. The NixPy/SiO2 catalysts were characterized using chemical analysis N2 physisorption, XRD, TEM, 31P MAS NMR. Methyl palmitate hydrodeoxygenation (HDO was performed in a trickle-bed reactor at 3 MPa and 290 °C with LHSV ranging from 0.3 to 16 h−1. The Ni/P ratio was found to affect the nickel phosphide phase composition, POx groups content and catalytic properties in methyl palmitate HDO with the TOF increased along with a decline of Ni/P ratio and a growth of POx groups’ content. Taking into account the possible routes of methyl palmitate conversion (metal-catalyzed hydrogenolysis or acid-catalyzed hydrolysis, we proposed that the enhancement of acid POx groups’ content with the Ni/P ratio decrease provides an enhancement of the rate of methyl palmitate conversion through the acceleration of acid-catalyzed hydrolysis.

  6. Participar como niña o niño en el mundo social

    Directory of Open Access Journals (Sweden)

    Silvia Paulina Díaz

    2010-01-01

    Full Text Available En este artículo presento la participación como resultado de un trabajo investigativo realizado durante el año 2007, con niños y niñas escolarizados habitantes de la ciudad de Medellín, Colombia, cuyo objetivo fue analizar las representaciones sociales que ellos y ellas comparten sobre el ejercicio ciudadano. El análisis de la información tiene como ejes fundamentales, la salud colectiva, la sociología de la infancia y la participación en la niñez, en una aproximación que se realiza desde un enfoque cualitativo y etnográfico. En los hallazgos, sobresale cómo las niñas y niños se muestran preparados para ejercer su derecho a la participación como aspecto de sus vidas que se haría posible dentro del marco normativo existente, pero que aún no es asumido en prácticas sociales que los incluyan.

  7. Tungsten inert gas (TIG) welding of Ni-rich NiTi plates: functional behavior

    Science.gov (United States)

    Oliveira, J. P.; Barbosa, D.; Braz Fernandes, F. M.; Miranda, R. M.

    2016-03-01

    It is often reported that, to successfully join NiTi shape memory alloys, fusion-based processes with reduced thermal affected regions (as in laser welding) are required. This paper describes an experimental study performed on the tungsten inert gas (TIG) welding of 1.5 mm thick plates of Ni-rich NiTi. The functional behavior of the joints was assessed. The superelasticity was analyzed by cycling tests at maximum imposed strains of 4, 8 and 12% and for a total of 600 cycles, without rupture. The superelastic plateau was observed, in the stress-strain curves, 30 MPa below that of the base material. Shape-memory effect was evidenced by bending tests with full recovery of the initial shape of the welded joints. In parallel, uniaxial tensile tests of the joints showed a tensile strength of 700 MPa and an elongation to rupture of 20%. The elongation is the highest reported for fusion-welding of NiTi, including laser welding. These results can be of great interest for the wide-spread inclusion of NiTi in complex shaped components requiring welding, since TIG is not an expensive process and is simple to operate and implement in industrial environments.

  8. High resolution TEM study of Ni4Ti3 precipitates in austenitic Ni51Ti49

    International Nuclear Information System (INIS)

    Tirry, Wim; Schryvers, Dominique

    2003-01-01

    Binary NiTi with a composition of 51 at.% Ni was heat treated to form lens-shaped Ni 4 Ti 3 precipitates that are coherent or semi-coherent with the B2 matrix. High resolution transmission electron microscopy (HRTEM) was used to study the internal structure of the precipitates, precipitate-precipitate and matrix-precipitate interfaces and the deformation of the B2 matrix near a precipitate. Observations were made in the B2 and B2 zones and compared with computer simulated high resolution images. The B2 observations made it possible to study the [0 0 1] H zone orientation of Ni 4 Ti 3 (direction defined according to the hexagonal unit cell of Ni 4 Ti 3 ) which corresponds to the normal of the central plane of the discs. In these images the superperiodicity of the 4:3 ordering is clearly visible confirming the known atomic structure. Close to the precipitate the B2 matrix is deformed, as determined by measuring the interplanar spacing from the HRTEM images. The observed deformations are compared with theoretical models for the stress field

  9. Breakdown of antiferromagnet order in polycrystalline NiFe/NiO bilayers probed with acoustic emission

    Science.gov (United States)

    Lebyodkin, M. A.; Lebedkina, T. A.; Shashkov, I. V.; Gornakov, V. S.

    2017-07-01

    Magnetization reversal of polycrystalline NiFe/NiO bilayers was investigated using magneto-optical indicator film imaging and acoustic emission techniques. Sporadic acoustic signals were detected in a constant magnetic field after the magnetization reversal. It is suggested that they are related to elastic waves excited by sharp shocks in the NiO layer with strong magnetostriction. Their probability depends on the history and number of repetitions of the field cycling, thus testifying the thermal-activation nature of the long-time relaxation of an antiferromagnetic order. These results provide evidence of spontaneous thermally activated switching of the antiferromagnetic order in NiO grains during magnetization reversal in ferromagnet/antiferromagnet (FM/AFM) heterostructures. The respective deformation modes are discussed in terms of the thermal fluctuation aftereffect in the Fulcomer and Charap model which predicts that irreversible breakdown of the original spin orientation can take place in some antiferromagnetic grains with disordered anisotropy axes during magnetization reversal of exchange-coupled FM/AFM structures. The spin reorientation in the saturated state may induce abrupt distortion of isolated metastable grains because of the NiO magnetostriction, leading to excitation of shock waves and formation of plate (or Lamb) waves.

  10. Electric Monopole Transition Strengths in 62Ni

    Directory of Open Access Journals (Sweden)

    Evitts L. J.

    2016-01-01

    Full Text Available Excited states in 62Ni were populated with a (p, p’ reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0, were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77−34+23 × 10−3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0 value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0 values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0 value for the 22+ to 21+ transition.

  11. Electric Monopole Transition Strengths in 62Ni

    Science.gov (United States)

    Evitts, L. J.; Garnsworthy, A. B.; Kibédi, T.; Moukaddam, M.; Alshahrani, B.; Eriksen, T. K.; Holt, J. D.; Hota, S. S.; Lane, G. J.; Lee, B. Q.; McCormick, B. P.; Palalani, N.; Reed, M. W.; Stroberg, S. R.; Stuchbery, A. E.

    2016-09-01

    Excited states in 62Ni were populated with a (p, p') reaction using the 14UD Pelletron accelerator at the Australian National University. Electric monopole transition strengths, ρ2(E0), were measured through simultaneous detection of the internal conversion electrons and γ rays emitted from the de-excitation of populated states, using the Super-e spectrometer coupled with a germanium detector. The strength of the 02+ to 01+ transition has been measured to be 77-34+23 × 10-3 and agrees with previously reported values. Upper limits have been placed on the 03+ to 01+ and 03+ to 02+ transitions. The measured ρ2(E0) value of the 22+ to 21+ transition in 62Ni has been measured for the first time and found to be one of the largest ρ2(E0) values measured to date in nuclei heavier than Ca. The low-lying states of 62Ni have previously been classified as one- and two-phonon vibrational states based on level energies. The measured electric quadrupole transition strengths are consistent with this interpretation. However as electric monopole transitions are forbidden between states which differ by one phonon number, the simple harmonic quadrupole vibrational picture is not suffcient to explain the large ρ2(E0) value for the 22+ to 21+ transition.

  12. Fabrication and magnetic properties of Ni0.5Zn0.5Fe2O4 nanofibres by electrospinning

    International Nuclear Information System (INIS)

    Jun, Xiang; Xiang-Qian, Shen; Fu-Zhan, Song; Ming-Quan, Liu

    2009-01-01

    NiZn ferrite/polyvinylpyrrolidone composite fibres were prepared by sol–gel assisted electrospinning. Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres with a pure cubic spinel structure were obtained subsequently by calcination of the composite fibres at high temperatures. This paper investigates the thermal decomposition process, structures and morphologies of the electrospun composite fibres and the calcined Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres at different temperatures by thermo-gravimetric and differential thermal analysis, x-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The magnetic behaviour of the resultant nanofibres was studied by a vibrating sample magnetometer. It is found that the grain sizes of the nanofibres increase significantly and the nanofibre morphology gradually transforms from a porous structure to a necklace-like nanostructure with the increase of calcination temperature. The Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres obtained at 1000 °C for 2 h are characterized by a necklace-like morphology and diameters of 100–200 nm. The saturation magnetization of the random Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres increases from 46.5 to 90.2 emu/g when the calcination temperature increases from 450 to 1000 °C. The coercivity reaches a maximum value of 11.0 kA/m at a calcination temperature of 600 °C. Due to the shape anisotropy, the aligned Ni 0.5 Zn 0.5 Fe 2 O 4 nanofibres exhibit an obvious magnetic anisotropy and the ease magnetizing direction is parallel to the nanofibre axis. (condensed matter: structure, thermal and mechanical properties)

  13. Muon capture on Ni isotopes, projected QRPA, and CVC hypothesis

    International Nuclear Information System (INIS)

    Samana, Arturo R.; Sande, Danilo; Krmpotic, Francisco; Universidad Nacional de La Plata

    2011-01-01

    In recent years we have developed a novel formalism for the weak interaction processes, obtaining new expressions for the transition rates, which greatly facilitate numerical calculations, for both neutrino-nucleus reactions and muon capture, allowing us to use very large configuration spaces and to evaluate the quasielastic 12 C (ν, μ - ) 12 N cross section at energies of the order of 1 GeV, which are measured in the MiniBooNE experiment. Our formulation includes for the first time the consequences of the explicit violation of the conserved vector current (CVC) hypothesis by the Coulomb field. We have also shown that the particle number projection procedure within the quasiparticle random phase approximation (QRPA) is important in describing the exclusive (ground-state) properties of 12 B and 12 N as well as the muon capture rate and the neutrino nucleus cross section in 56 Fe. In this work, we analyze in a quantitative way the consequences of the CVC violation on the muon capture rates in Ni isotopes (for which are available the experimental data) using both the standard QRPA and the projected QRPA (PQRPA). The last one is the only RPA model that treats the Pauli Principle correctly, and we demonstrate that the number projection procedure is important not only for light nuclei but also for medium heavy ones that were studied here. (author)

  14. Evaluation of Trichogramma spp. for the control of Trichoplusia ni

    International Nuclear Information System (INIS)

    Milanez, Andre Malacarne

    2009-01-01

    The objective of this study was to evaluate the biological characteristics of the parasitoids Trichogramma acacioi, T. atopovirilia, T. marandobai, T. demoraesi, T. exiguum (two lines), and T. pretiosum (six lines), reared on eggs of Trichoplusia ni. The experiment was carried out in a completely randomized design, with 15 replicates. The biological characteristics evaluated were: parasitism, viability, sexual ratio and number of individuals per egg. The parasitism percentage varied between 7.66 and 53%, with highest value observed for Trichogramma pretiosum Tspd line, and the lowest for the T. pretiosum Trecife line. There was no significant difference for the viability, which remained higher than 85%. The sex ratio varied from 0.75 to 1, and Tspd line showed the lowest value. The number of individuals per egg varied between 2.39 for T. marandobai (Tm1 line) and 1.34 for T. exiguum (Te1 line). T. pretiosum (Tspd line) was the species with the best performance in laboratory with the highest values observed in parasitism and in viability. (author)

  15. Tunable random packings

    International Nuclear Information System (INIS)

    Lumay, G; Vandewalle, N

    2007-01-01

    We present an experimental protocol that allows one to tune the packing fraction η of a random pile of ferromagnetic spheres from a value close to the lower limit of random loose packing η RLP ≅0.56 to the upper limit of random close packing η RCP ≅0.64. This broad range of packing fraction values is obtained under normal gravity in air, by adjusting a magnetic cohesion between the grains during the formation of the pile. Attractive and repulsive magnetic interactions are found to affect stongly the internal structure and the stability of sphere packing. After the formation of the pile, the induced cohesion is decreased continuously along a linear decreasing ramp. The controlled collapse of the pile is found to generate various and reproducible values of the random packing fraction η

  16. Random maintenance policies

    CERN Document Server

    Nakagawa, Toshio

    2014-01-01

    Exploring random maintenance models, this book provides an introduction to the implementation of random maintenance, and it is one of the first books to be written on this subject.  It aims to help readers learn new techniques for applying random policies to actual reliability models, and it provides new theoretical analyses of various models including classical replacement, preventive maintenance and inspection policies. These policies are applied to scheduling problems, backup policies of database systems, maintenance policies of cumulative damage models, and reliability of random redundant systems. Reliability theory is a major concern for engineers and managers, and in light of Japan’s recent earthquake, the reliability of large-scale systems has increased in importance. This also highlights the need for a new notion of maintenance and reliability theory, and how this can practically be applied to systems. Providing an essential guide for engineers and managers specializing in reliability maintenance a...

  17. Theory of random sets

    CERN Document Server

    Molchanov, Ilya

    2017-01-01

    This monograph, now in a thoroughly revised second edition, offers the latest research on random sets. It has been extended to include substantial developments achieved since 2005, some of them motivated by applications of random sets to econometrics and finance. The present volume builds on the foundations laid by Matheron and others, including the vast advances in stochastic geometry, probability theory, set-valued analysis, and statistical inference. It shows the various interdisciplinary relationships of random set theory within other parts of mathematics, and at the same time fixes terminology and notation that often vary in the literature, establishing it as a natural part of modern probability theory and providing a platform for future development. It is completely self-contained, systematic and exhaustive, with the full proofs that are necessary to gain insight. Aimed at research level, Theory of Random Sets will be an invaluable reference for probabilists; mathematicians working in convex and integ...

  18. Modified random phase approximation for multipole excitations at finite temperature

    International Nuclear Information System (INIS)

    Nguyen Dinh Dang

    1991-01-01

    The modified finite temperature random phase approximation (modified FT-RPA) has been constructed with taking the influence of thermostat on the structure of quansiparticles into account. The modified FT-RPA linear response for electric quadrupole (λ π = 2 + ) and octupole (λ π = 3 - ) excitations in 5 8Ni has been calculated as a function of the nuclear temperature. As compared to the conventional FT-RPA the modified FT-RPA has given a stronger spreading for the strength distribution of quandrupole excitations at finite temperature T ≤ 3MeV. (author). 22 refs; 4 figs; 2 tabs

  19. Length-dependent corrosion behavior, Ni2+ release, cytocompatibility, and antibacterial ability of Ni-Ti-O nanopores anodically grown on biomedical NiTi alloy.

    Science.gov (United States)

    Hang, Ruiqiang; Liu, Yanlian; Bai, Long; Zhang, Xiangyu; Huang, Xiaobo; Jia, Husheng; Tang, Bin

    2018-08-01

    In the present work, nickel-titanium-oxygen nanopores with different length (0.55-114 μm) were anodically grown on nearly equiatomic nickel-titanium (NiTi) alloy. Length-dependent corrosion behavior, nickel ion (Ni 2+ ) release, cytocompatibility, and antibacterial ability were investigated by electrochemical, analytical chemistry, and biological methods. The results show constructing nanoporous structure on the NiTi alloy improve its corrosion resistance. However, the anodized samples release more Ni 2+ than that of the bare NiTi alloy, suggesting chemical dissolution of the nanopores rather than electrochemical corrosion governs the Ni 2+ release. In addition, the Ni 2+ release amount increases with nanopore length. The anodized samples show good cytocompatibility when the nanopore length is covers the one (1-11 μm) that the nanopores showing favorable antibacterial ability. Consequently, the nanopores with length in the range of 1-11 μm are promising as coatings of biomedical NiTi alloy for anti-infection, drug delivery, and other desirable applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Quantum randomness and unpredictability

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, Gregg [Quantum Communication and Measurement Laboratory, Department of Electrical and Computer Engineering and Division of Natural Science and Mathematics, Boston University, Boston, MA (United States)

    2017-06-15

    Quantum mechanics is a physical theory supplying probabilities corresponding to expectation values for measurement outcomes. Indeed, its formalism can be constructed with measurement as a fundamental process, as was done by Schwinger, provided that individual measurements outcomes occur in a random way. The randomness appearing in quantum mechanics, as with other forms of randomness, has often been considered equivalent to a form of indeterminism. Here, it is argued that quantum randomness should instead be understood as a form of unpredictability because, amongst other things, indeterminism is not a necessary condition for randomness. For concreteness, an explication of the randomness of quantum mechanics as the unpredictability of quantum measurement outcomes is provided. Finally, it is shown how this view can be combined with the recently introduced view that the very appearance of individual quantum measurement outcomes can be grounded in the Plenitude principle of Leibniz, a principle variants of which have been utilized in physics by Dirac and Gell-Mann in relation to the fundamental processes. This move provides further support to Schwinger's ''symbolic'' derivation of quantum mechanics from measurement. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Effects of P/Ni ratio and Ni content on performance of γ-Al_2O_3-supported nickel phosphides for deoxygenation of methyl laurate to hydrocarbons

    International Nuclear Information System (INIS)

    Zhang, Zhena; Tang, Mingxiao; Chen, Jixiang

    2016-01-01

    Graphical abstract: - Highlights: • The formation of AlPO_4 was unfavorable for that of nickel phosphides. • The phase compositions of nickel phosphide depended on the amount of reduced P. • Catalytic activity was determined by surface Ni site density and catalyst acidity. • HDO pathway was promoted by increasing P/Ni ratio and Ni content. • Nickel phosphide gave much higher carbon yield and lower H_2 consumption than Ni. - Abstract: γ-Al_2O_3-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-Al_2O_3 was also studied for comparison. It was found that the formation of AlPO_4 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, Ni_3P, Ni_1_2P_5 and Ni_2P 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-Al_2O_3, the mNi-Pn catalysts showed much lower activities for decarbonylation, C−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

  2. Level structure of 60Ni from the 58Ni(α,2p#betta#) reaction

    International Nuclear Information System (INIS)

    Chan, T.U.; Morand, C.; Azgui, F.

    1982-03-01

    The 60 Ni nucleus has been studied via the 58 Ni (α, 2p#betta#) reaction at Esub(α)=32 MeV using in-beam #betta# spectroscopy techniques. High-spin states up to 10 MeV excitation have been established. Among the 5 branches depopulating the Yrast Jsup(π)=7 - state, has been found an E3 transition down to the 4 + state. Comparison with direct reaction results leads to assign very probably the [#betta#fsub(5/2),#betta#gsub(9/2)] 7 - configuration to the Jsup(π)=7 - Yrast state at 5349 keV. Other high-spin states might be accounted for by the breaking of the 56 Ni core

  3. Atomistic simulation of the pinning of edge dislocations in Ni by Ni3Al precipitates

    International Nuclear Information System (INIS)

    Kohler, Christopher; Kizler, Peter; Schmauder, Siegfried

    2005-01-01

    Classical molecular dynamics simulations of the interaction of edge dislocations in Ni with chains of spherical Ni 3 Al precipitates are performed using EAM potentials. The order hardening is investigated at temperature T=0 -bar K by determining the critical resolved shear stresses (CRSSs) for a superdislocation that is dissociated into four partial dislocations. The CRSS is computed as a function of the radius and the distance of the precipitates. It is found that for precipitates with a diameter smaller than the dissociation width of perfect edge dislocation in Ni, the CRSS of the trailing dislocation of the superdislocation is a fraction of about 0.4 of the CRSS of the leading dislocation

  4. Sorption properties of new composite materials suitable for radioanalytical determination of 59-Ni and 63-Ni

    International Nuclear Information System (INIS)

    Fisera, O.; Sebesta, F.

    2006-01-01

    New composite materials for separation and radioanalytical determination of radionickel ( 59, 63 Ni) were prepared and their sorption properties were examined. Chelating agents dimethylglyoxime (DMG) and diphenylglyoxime (DFG) as active components were immobilized in porous matrix of binding polymer polyacrylonitrile (PAN). Sorption properties of these materials were compared with commercial Ni Resin (Eichrom Technologies, USA). Weight distribution ratios, sorption kinetics and operating capacities were investigated during experiments performed. The highest weight distribution ratios were found for the material DFG-PAN. The sorbent DMG-PAN has the highest operating capacity. The fastest kinetics of nickel sorption was determined for the commercial Ni Resin. Elution of nickel with nitric acid solution allows subsequent and direct determination of radionickel by liquid scintillation counting. (author)

  5. Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

    International Nuclear Information System (INIS)

    Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

    2011-01-01

    Composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 was prepared by mechanical milling starting with nanocrystalline Mg 2 Ni and amorphous Mg 50 Ni 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 50 Ni 50 improved the hydriding and dehydriding kinetics of Mg 2 Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: → First study of the hydriding behavior of composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 . → Microstructural characterization of composite material using XRD and SEM was obtained. → An improved effect of Mg 50 Ni 50 on the Mg 2 Ni hydriding behavior was verified. → The apparent activation energy for the hydrogen desorption of composite was obtained.

  6. When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting.

    Science.gov (United States)

    Wang, Dewen; Li, Qun; Han, Ce; Xing, Zhicai; Yang, Xiurong

    2018-01-24

    The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS 2 nanosheet array on carbon cloth (NiO@Ni/WS 2 /CC) composite. This composite serves as a unique three-dimensional (3D) synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS 2 , but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS 2 . This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO 2 , as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm -2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS 2 . Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

  7. Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn

    Directory of Open Access Journals (Sweden)

    Sonia A. Barczak

    2018-03-01

    Full Text Available TiNiSn is an intensively studied half-Heusler alloy that shows great potential for waste heat recovery. Here, we report on the structures and thermoelectric properties of a series of metal-rich TiNi1+ySn compositions prepared via solid-state reactions and hot pressing. A general relation between the amount of interstitial Ni and lattice parameter is determined from neutron powder diffraction. High-resolution synchrotron X-ray powder diffraction reveals the occurrence of strain broadening upon hot pressing, which is attributed to the metastable arrangement of interstitial Ni. Hall measurements confirm that interstitial Ni causes weak n-type doping and a reduction in carrier mobility, which limits the power factor to 2.5–3 mW m−1 K−2 for these samples. The thermal conductivity was modelled within the Callaway approximation and is quantitively linked to the amount of interstitial Ni, resulting in a predicted value of 12.7 W m−1 K−1 at 323 K for stoichiometric TiNiSn. Interstitial Ni leads to a reduction of the thermal band gap and moves the peak ZT = 0.4 to lower temperatures, thus offering the possibility to engineer a broad ZT plateau. This work adds further insight into the impact of small amounts of interstitial Ni on the thermal and electrical transport of TiNiSn.

  8. Controlled growth of Ni/NiO core–shell nanoparticles: Structure, morphology and tuning of magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    D’Addato, S., E-mail: sergio.daddato@unimore.it [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Spadaro, M.C. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Luches, P. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Grillo, V. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); CNR-IMEM, Parco Area delle Scienze 37/A, 43100 Parma (Italy); Frabboni, S.; Valeri, S. [CNR-NANO, S3, via G. Campi 213/a, Modena (Italy); Dipartimento FIM, Università di Modena e Reggio Emilia, via G. Campi 213/a, Modena (Italy); Ferretti, A.M.; Capetti, E.; Ponti, A. [CNR-ISTM, Laboratorio di Nanotecnologie, via G. Fantoli 16/15, 20138 Milano (Italy)

    2014-07-01

    We performed a detailed study of Ni/NiO core–shell nanoparticles (NP) obtained with a gas aggregation source. The NP oxide shells were produced by oxidizing the NP with different procedures: deposition in oxygen atmosphere, post-annealing in air, sequential deposition of (a) first NiO layer, (b) Ni NP and (c) third NiO Layer. X-ray photoelectron spectroscopy from Ni 2p core-level gave information about the chemical state of Ni in the core and in the oxide shell, while scanning electron microscopy was used for investigation of the NP morphology. High quality scanning transmission electron microscopy in high angle annular dark field mode data demonstrated core–shell structure also for NiO/Ni NP/NiO samples. Field-cooled/zero-field-cooled magnetization curves and field-cooled isothermal hysteresis cycles at T = 5 K were recorded by a SQUID magnetometer. In this way, the relation between magnetic properties and oxide shell structure was assessed, showing the role played by the control of the formation of oxide on the exchange bias and interparticle magnetic interaction.

  9. When NiO@Ni Meets WS2 Nanosheet Array: A Highly Efficient and Ultrastable Electrocatalyst for Overall Water Splitting

    Directory of Open Access Journals (Sweden)

    Dewen Wang

    2017-12-01

    Full Text Available The development of low-cost, high-efficiency, and stable bifunctional electrocatalysts toward the hydrogen evolution reaction (HER and oxygen evolution reaction (OER is of paramount importance for large-scale water splitting. Here, we develop a new strategy for the first design and synthesis of a NiO@Ni decorated WS2 nanosheet array on carbon cloth (NiO@Ni/WS2/CC composite. This composite serves as a unique three-dimensional (3D synergistic electrocatalyst that not only combines the intrinsic properties of individual NiO@Ni and WS2, but also exhibits significantly improved HER and OER activities when compared to that of pure NiO@Ni and WS2. This electrocatalyst possesses Pt-like activity for HER and exhibits better OER performance than that for commercial RuO2, as well as demonstrating superior long-term durability in alkaline media. Furthermore, it enables an alkaline electrolyzer with a current density of 10 mA cm–2 at a cell voltage as 1.42 V, which is the lowest one among all reported values to date. The excellent performance is mainly attributed to the unique 3D configuration and multicomponent synergies among NiO, Ni, and WS2. Our findings provide a new idea to design advanced bifunctional catalysts for water splitting.

  10. Enhanced optical and electrical properties of Ni inserted ITO/Ni/AZO tri-layer structure for photoelectric applications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. Melvin David; Kim, Hyunki [Department of Electrical Engineering, Incheon National University, Incheon 406772 (Korea, Republic of); Park, Yun Chang [Measurement and Analysis Division, National Nanofab Center (NNFC), Daejeon 305-806 (Korea, Republic of); Kim, Joondong, E-mail: joonkim@incheon.ac.kr [Department of Electrical Engineering, Incheon National University, Incheon 406772 (Korea, Republic of)

    2015-05-15

    Highlights: • Ni-embedding transparent conductor effectively reduces the resistivity. • Ni insertion improves the carrier mobility and collection efficiencies. • ITO/Ni/AZO is effective to improve photo-responses compared to ITO/AZO. - Abstract: A thin Ni layer of 5 nm thickness was deposited in between indium-tin-oxide (ITO) and aluminum-doped-zinc oxide (AZO) layers of 50 nm thickness each. The Ni inserting tri-layer structure (ITO/Ni/AZO) showed lower resistivity of 5.51 × 10{sup −4} Ωcm which is nearly 20 times lesser than 97.9 × 10{sup −4} Ωcm of bilayer structure (ITO/AZO). A thin Ni layer in between ITO and AZO enhanced the carrier concentration, mobility and photoresponse behaviors so that figure of merit (FOM) value of ITO/Ni/AZO device was greater than that of ITO/AZO device. ITO/Ni/AZO structure showed improved quantum efficiencies over a broad range of wavelengths (∼350–950 nm) compared to that of ITO/AZO bilayer structure, resulting in enhanced photoresponses. These results show that the optical, electrical and photoresponse properties of ITO/AZO structure could be enhanced by inserting Ni layer of 5 nm thickness in between ITO and AZO layers.

  11. On the Ni-Ion release rate from surfaces of binary NiTi shape memory alloys

    Science.gov (United States)

    Ševčíková, Jana; Bártková, Denisa; Goldbergová, Monika; Kuběnová, Monika; Čermák, Jiří; Frenzel, Jan; Weiser, Adam; Dlouhý, Antonín

    2018-01-01

    The study is focused on Ni-ion release rates from NiTi surfaces exposed in the cell culture media and human vascular endothelial cell (HUVEC) culture environments. The NiTi surface layers situated in the depth of 70 μm below a NiTi oxide scale are affected by interactions between the NiTi alloys and the bio-environments. The finding was proved with use of inductively coupled plasma mass spectrometry and electron microscopy experiments. As the exclusive factor controlling the Ni-ion release rates was not only thicknesses of the oxide scale, but also the passivation depth, which was two-fold larger. Our experimental data strongly suggested that some other factors, in addition to the Ni concentration in the oxide scale, admittedly hydrogen soaking deep below the oxide scale, must be taken into account in order to rationalize the concentrations of Ni-ions released into the bio-environments. The suggested role of hydrogen as the surface passivation agent is also in line with the fact that the Ni-ion release rates considerably decrease in NiTi samples that were annealed in controlled hydrogen atmospheres prior to bio-environmental exposures.

  12. Controlled growth of Ni/NiO core–shell nanoparticles: Structure, morphology and tuning of magnetic properties

    International Nuclear Information System (INIS)

    D’Addato, S.; Spadaro, M.C.; Luches, P.; Grillo, V.; Frabboni, S.; Valeri, S.; Ferretti, A.M.; Capetti, E.; Ponti, A.

    2014-01-01

    We performed a detailed study of Ni/NiO core–shell nanoparticles (NP) obtained with a gas aggregation source. The NP oxide shells were produced by oxidizing the NP with different procedures: deposition in oxygen atmosphere, post-annealing in air, sequential deposition of (a) first NiO layer, (b) Ni NP and (c) third NiO Layer. X-ray photoelectron spectroscopy from Ni 2p core-level gave information about the chemical state of Ni in the core and in the oxide shell, while scanning electron microscopy was used for investigation of the NP morphology. High quality scanning transmission electron microscopy in high angle annular dark field mode data demonstrated core–shell structure also for NiO/Ni NP/NiO samples. Field-cooled/zero-field-cooled magnetization curves and field-cooled isothermal hysteresis cycles at T = 5 K were recorded by a SQUID magnetometer. In this way, the relation between magnetic properties and oxide shell structure was assessed, showing the role played by the control of the formation of oxide on the exchange bias and interparticle magnetic interaction.

  13. Distorted-wave calculations of electron impact ionisation in the Ni isonuclear sequence

    Energy Technology Data Exchange (ETDEWEB)

    Griffin, D C; Pindzola, M S

    1988-10-14

    Electron impact ionisation cross sections for Ni/sup +/, Ni/sup 3+/, Ni/sup 5+/, Ni/sup 6+/, Ni/sup 7+/, Ni/sup 8+/, Ni/sup 12+/, Ni/sup 14+/, and Ni/sup 16+/ are calculated in the distorted-wave approximation. These calculations include contributions from direct ionisation and inner-shell excitation followed by autoionisation. For Ni/sup 12+/, Ni/sup 14+/, and Ni/sup 16+/ we report not only on ionisation cross sections from the ground states but also from the metastable states of these ions. Experimental cross section measurements exist for all ions reported here, except Ni/sup 16+/. The agreement between experiment and theory is reasonably good and improves with ionisation stage.

  14. NiTiCu/AlN/NiTiCu shape memory thin film heterostructures for vibration damping in MEMS

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Navjot; Kaur, Davinder, E-mail: dkaurfph@iitr.ernet.in

    2014-03-25

    Highlights: • Fabrication of NiTiCu/AlN/NiTiCu heterostructure using dc/rf magnetron sputtering. • Exhibits highest hardness (38 GPa) and elastic modulus (187 GPa). • Enhanced dissipation of mechanical energy (E{sub d} = 5.7 N J). • High damping capacity (0.052) and figure of merit (∼0.62). • Can be applied for vibration damping in MEMS. -- Abstract: Shape memory alloy (NiTiCu) thin films coupled with piezoelectric AlN layer produce an intelligent material for vibration damping. In the present study pure NiTiCu, NiTiCu/AlN and NiTiCu/AlN/NiTiCu heterostructures have been deposited on Si substrate using magnetron sputtering technique. By the use of the interfaces and shape memory effect provided by NiTiCu layers, the damping capacity can be increased along with increase in stiffness and mechanical hardness. The heterostructures were characterized in terms of structural, electrical, morphological and mechanical properties by X-ray diffraction (XRD), four probe resistivity method, atomic force microscopy, field emission scanning electron microscopy, and nanoindentation. The NiTiCu/AlN/NiTiCu heterostructure exhibit enhanced mechanical and damping properties as compared to NiTiCu/AlN and pure NiTiCu. This enhancement in hardness and damping of the heterostructure could be attributed to the shape memory effect of NiTiCu, intrinsic piezoelectricity of AlN and increased number of interfaces in heterostructure that help in dissipation of mechanical vibrations. The findings of this work provide additional impetus for the application of these heterostructures in emerging fields of nanotechnology and microelectro mechanical (MEMS) devices.

  15. NiTiCu/AlN/NiTiCu shape memory thin film heterostructures for vibration damping in MEMS

    International Nuclear Information System (INIS)

    Kaur, Navjot; Kaur, Davinder

    2014-01-01

    Highlights: • Fabrication of NiTiCu/AlN/NiTiCu heterostructure using dc/rf magnetron sputtering. • Exhibits highest hardness (38 GPa) and elastic modulus (187 GPa). • Enhanced dissipation of mechanical energy (E d = 5.7 N J). • High damping capacity (0.052) and figure of merit (∼0.62). • Can be applied for vibration damping in MEMS. -- Abstract: Shape memory alloy (NiTiCu) thin films coupled with piezoelectric AlN layer produce an intelligent material for vibration damping. In the present study pure NiTiCu, NiTiCu/AlN and NiTiCu/AlN/NiTiCu heterostructures have been deposited on Si substrate using magnetron sputtering technique. By the use of the interfaces and shape memory effect provided by NiTiCu layers, the damping capacity can be increased along with increase in stiffness and mechanical hardness. The heterostructures were characterized in terms of structural, electrical, morphological and mechanical properties by X-ray diffraction (XRD), four probe resistivity method, atomic force microscopy, field emission scanning electron microscopy, and nanoindentation. The NiTiCu/AlN/NiTiCu heterostructure exhibit enhanced mechanical and damping properties as compared to NiTiCu/AlN and pure NiTiCu. This enhancement in hardness and damping of the heterostructure could be attributed to the shape memory effect of NiTiCu, intrinsic piezoelectricity of AlN and increased number of interfaces in heterostructure that help in dissipation of mechanical vibrations. The findings of this work provide additional impetus for the application of these heterostructures in emerging fields of nanotechnology and microelectro mechanical (MEMS) devices

  16. Gamow-Teller strength and lepton captures rates on 66-71Ni in stellar matter

    Science.gov (United States)

    Nabi, Jameel-Un; Majid, Muhammad

    Charge-changing transitions play a significant role in stellar weak-decay processes. The fate of the massive stars is decided by these weak-decay rates including lepton (positron and electron) captures rates, which play a consequential role in the dynamics of core collapse. As per previous simulation results, weak interaction rates on nickel (Ni) isotopes have significant influence on the stellar core vis-à-vis controlling the lepton content of stellar matter throughout the silicon shell burning phases of high mass stars up to the presupernova stages. In this paper, we perform a microscopic calculation of Gamow-Teller (GT) charge-changing transitions, in the β-decay and electron capture (EC) directions, for neutron-rich Ni isotopes (66-71Ni). We further compute the associated weak-decay rates for these selected Ni isotopes in stellar environment. The computations are accomplished by employing the deformed proton-neutron quasiparticle random phase approximation (pn-QRPA) model. A recent study showed that the deformed pn-QRPA theory is well suited for the estimation of GT transitions. The astral weak-decay rates are determined over densities in the range of 10-1011g/cm3 and temperatures in the range of 0.01 × 109-30 × 109K. The calculated lepton capture rates are compared with the previous calculation of Pruet and Fuller (PF). The overall comparison demonstrates that, at low stellar densities and high temperatures, our EC rates are bigger by as much as two orders of magnitude. Our results show that, at higher temperatures, the lepton capture rates are the dominant mode for the stellar weak rates and the corresponding lepton emission rates may be neglected.

  17. Three-dimensional electrode of Ni/Co layered double hydroxides@NiCo2S4@graphene@Ni foam for supercapacitors with outstanding electrochemical performance

    International Nuclear Information System (INIS)

    Tao, Yan; Ruiyi, Li; Lin, Zhou; Chenyang, Ma; Zaijun, Li

    2015-01-01

    We reported a new strategy for fabricating three-dimensiona electrode of Ni/Co layered double hydroxide@NiCo 2 S 4 @graphene@Ni foam for supercapacitors. The resulting 3D electrode offers a jungle-like architecture. The unique structure creates ultra fast electron transfer and electrolyte transport as well as the maximum utilization rate of the space and the surface. The electrode exhibits a prominent advantage of high specific capacitance, high-current capacitive behaviour and cycle stability. - Highlights: • The study developed a new strategy for fabricating 3D electrode of Ni/Co-LDH@NiCo 2 S 4 @G. • The as-prepared 3D electrode offers a jungle-like architecture. • The unique structure creates an efficient conduction network and high mass loading. • The electrode achieves significantly synergetic effect among different materials. • The electrode exhibits an excellent electrochemical performance for supercapacitors. - ABSTRACT: Great challenge for the fabrication of free-standing three-dimensional electrode still remains to simultaneously achieve high specific capacitance, rate performance and cycle stability. The paper reprted a new three-dimensional (3D) electrode of Ni/Co layered double hydroxide@NiCo 2 S 4 @graphene@Ni foam (Ni/Co-LDH@NiCo 2 S 4 @G) for supercapacitors. The as-prepared 3D electrode offers an unique architecture, which create an efficient conduction network and maximum utilization of space and interface. The graphene acts as well-knit and conductive skin coated on the skeleton of Ni foam for growing NiCo 2 S 4 . The conductive NiCo 2 S 4 array serves as bridge between Ni/Co-LDH and graphene, leading to ultrafast electron transfer and electrolyte transport. A slew of splits and holes existing in the NiCo 2 S 4 array play one role as the ion-reservoir to contain host of electrolyte ions. To evaluate the feasibility of 3D electrode’s application in supercapacitors, the electrochemical performance was investigated by using the three

  18. Energetic Mapping of Ni Catalysts by Detailed Kinetic Modeling

    DEFF Research Database (Denmark)

    Bjørgum, Erlend; Chen, De; Bakken, Mari G.

    2005-01-01

    Temperature-programmed desorption (TPD) of CO has been performed on supported and unsupported nickel catalysts. The unsupported Ni catalyst consists of a Ni(14 13 13) single crystal which has been studied under ultrahigh vacuum conditions. The desorption energy for CO at low CO surface coverage...... was found to be 119 kJ/mol, and the binding energy of C to the Ni(111) surface of the crystal was 703 kJ/mol. The supported catalysts consist of nickel supported on hydrotalcite-like compounds with three different Mg2+/Al3+ ratios. The experimental results show that for the supported Ni catalysts TPD of CO...... precursor seems to result in more steplike sites, kinks, and defects for carbon monoxide dissociation. A detailed kinetic modeling of the TPO results based on elementary reaction steps has been conducted to give an energetic map of supported Ni catalysts. Experimental results from the ideal Ni surface fit...

  19. Synthesis of electroplated {sup 63}Ni source and betavoltaic battery

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Yoo, Kwon Mo; Choi, Sang Mu; Kim, Jin Joo; Son, Kwang Jae [Radioisotope Research Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    Radioisotope (Nuclear) battery using {sup 63}Ni was prepared as beta cell. The electroplated {sup 63}Ni on Ni foil is fabricated, and beta cell and photovoltaic hybrid battery was designed to use at both day and night in space project. A Ni-plating solution is prepared by dissolving metal particles including {sup 62}Ni and {sup 63}Ni from neutron irradiation of (n,γ). Electroplating solution of a chloride bath consists on nickel ions in HCl, H{sub 3}BO{sub 3}, and KOH. The deposition was carried out at current density of 10 mA cm{sup -2}. The prepared beta source was attached on a PN junction and measured I-V properties. The power output at activity of 0.07 mCi and 0.45 mCi were 0.55 pW and 2.69 nW, respectively.

  20. Microstructure and martensitic transformation of Ni-Ti-Pr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Chunwang [Inner Mongolia University of Technology, College of Science, Hohhot (China); Shanghai Maritime University, College of Arts and Sciences, Shanghai (China); Zhao, Shilei; Jin, Yongjun; Hou, Qingyu [Inner Mongolia University of Technology, College of Science, Hohhot (China); Guo, Shaoqiang [Beihang University, Key Laboratory of Micro-nano Measurement, Manipulation and Physics (Ministry of Education), Department of Physics, Beijing (China)

    2017-09-15

    The effect of Pr addition on the microstructure and martensitic transformation behavior of Ni{sub 50}Ti{sub 50-x}Pr{sub x} (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9) alloys were investigated experimentally. Results show that the microstructures of Ni-Ti-Pr alloys consist of the NiTi matrix and the NiPr precipitate with the Ti solute. The martensitic transformation start temperature decreases gradually with the increase in Pr fraction. The stress around NiPr precipitates is responsible for the decrease in martensitic transformation temperature with the increase in Pr fraction in Ni-Ti-Pr alloys. (orig.)

  1. Near-surface segregation in irradiated Ni3Si

    International Nuclear Information System (INIS)

    Wagner, W.; Rehn, L.E.; Wiedersich, H.

    1982-01-01

    The radiation-induced growth of Ni 3 Si films on the surfaces of Ni(Si) alloys containing = 3 Si phase has been observed. Post-irradiation depth profiling by Auger electron spectroscopy, as well as in situ analysis by high-resolution Rutherford backscattering spectrometry, reveals Si-enrichment at the surfaces of Ni(Si) alloys in excess of stoichiometric Ni 3 Si during irradiation. Thin, near-surface layers with silicon concentrations of 28 to 30 at.% are observed, and even higher Si enrichment is found in the first few atom layers. Transmission electron microscopy and selected area-electron diffraction were employed to characterize these Si-enriched layers. A complex, multiple-spot diffraction pattern is observed superposed on the diffraction pattern of ordered Ni 3 Si. The d-spacings obtained from the extra spots are consistent with those of the orthohexagonal intermetallic compound Ni 5 Si 2 . (author)

  2. Crystal growth velocity in deeply undercooled Ni-Si alloys

    Science.gov (United States)

    Lü, Y. J.

    2012-02-01

    The crystal growth velocity of Ni95Si5 and Ni90Si10 alloys as a function of undercooling is investigated using molecular dynamics simulations. The modified imbedded atom method potential yields the equilibrium liquidus temperatures T L ≈ 1505 and 1387 K for Ni95Si5 and Ni90Si10 alloys, respectively. From the liquidus temperatures down to the deeply undercooled region, the crystal growth velocities of both the alloys rise to the maximum with increasing undercooling and then drop slowly, whereas the athermal growth process presented in elemental Ni is not observed in Ni-Si alloys. Instead, the undercooling dependence of the growth velocity can be well-described by the diffusion-limited model, furthermore, the activation energy associated with the diffusion from melt to interface increases as the concentration increases from 5 to 10 at.% Si, resulting in the remarkable decrease of growth velocity.

  3. Diffusion studies in amorphous NiZr alloys

    International Nuclear Information System (INIS)

    Hahn, H.; Averback, R.S.; Hoshino, K.; Rothman, S.J.

    1987-06-01

    Tracer impurity and self diffusion measurements have been made on amorphous (a-) NiZr alloys using radioactive tracer, Secondary Ion Mass Spectrometry and Rutherford backscattering techniques. The temperature dependence of diffusion in a-NiZr can be represented in the form D = D 0 exp(-Q/kT), with no structural relaxation effects being observed. The mobility of an atom in a-NiZr increased dramatically with decreasing atomic radius of the diffusing atom and also with decreasing Ni content for Ni concentrations below ≅40 at. %. These diffusion characteristics in a-NiZr are remarkably similar to those in α-Zr and α-Ti. These mechanisms assume that Zr and Ti provide a close packed structure, either crystalline or amorphous, through which small atoms diffuse by an interstitial mechanism and large atoms diffuse by a vacancy mechanism. 12 refs., 2 figs., 2 tabs

  4. Thermal variation of magnetization in Ni/V multilayers

    International Nuclear Information System (INIS)

    Benkirane, K.; Elkabil, R.; Hamdoun, A.; Lassri, M.; Abid, M.; Lassri, H.; Krishnan, R.

    2004-01-01

    The magnetic properties of Ni/V multilayers, prepared by the RF sputtering method, have been systematically studied by magnetic measurements. The magnetization decreases with a decrease in Ni layer thickness tNi and the analysis of the results at 5K indicates the presence of a dead Ni layer about 12A thick. The effective anisotropy Keff of Ni/V multilayers is obtained using a torque magnetometer. The interface contribution to the magnetic anisotropy is practically negligible. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction Jb, surface exchange interaction JS, and the interlayer coupling strength JI for various Ni layer thicknesses have been obtained

  5. Synthesis of electroplated 63Ni source and betavoltaic battery

    International Nuclear Information System (INIS)

    Uhm, Young Rang; Yoo, Kwon Mo; Choi, Sang Mu; Kim, Jin Joo; Son, Kwang Jae

    2015-01-01

    Radioisotope (Nuclear) battery using 63 Ni was prepared as beta cell. The electroplated 63 Ni on Ni foil is fabricated, and beta cell and photovoltaic hybrid battery was designed to use at both day and night in space project. A Ni-plating solution is prepared by dissolving metal particles including 62 Ni and 63 Ni from neutron irradiation of (n,γ). Electroplating solution of a chloride bath consists on nickel ions in HCl, H 3 BO 3 , and KOH. The deposition was carried out at current density of 10 mA cm -2 . The prepared beta source was attached on a PN junction and measured I-V properties. The power output at activity of 0.07 mCi and 0.45 mCi were 0.55 pW and 2.69 nW, respectively

  6. Equilibrium relationships in the system Ni-U-O

    International Nuclear Information System (INIS)

    Mansour, N.A.L.

    1980-01-01

    Phase relationships were established in air and in oxygen. Mixtures of NiO and U 3 O 8 oxidize to NiUO 4 . The results of analysis of NiUO 4 were identical to those previously published for NiU 3 O 10 . The uranate dissociates to NiO and U 3 O 8 at a temperature higher than that of their oxidation back to the uranate on cooling because of the difficulty of oxygen diffusion and uranate nucleation. Accordingly, dissociation temperature was taken to represent equilibrium and was used to calculate roughly ΔH and ΔS for the reaction of dissociation. In presence of NiO, U 3 O 8 melts partially and does not dissociate to the lower oxide. (orig.) [de

  7. Coercivity scaling in antidot lattices in Fe, Ni, and NiFe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gräfe, Joachim, E-mail: graefe@is.mpg.de; Schütz, Gisela; Goering, Eberhard J., E-mail: goering@is.mpg.de

    2016-12-01

    Antidot lattices can be used to artificially engineer magnetic properties in thin films, however, a conclusive model that describes the coercivity enhancement in this class of magnetic nano-structures has so far not been found. We prepared Fe, Ni, and NiFe thin films and patterned each with 21 square antidot lattices with different geometric parameters and measured their hysteretic behavior. On the basis of this extensive dataset we are able to provide a model that can describe both the coercivity scaling over a wide range of geometric lattice parameters and the influence of different materials.

  8. Sideward flow of K+ in Ru+Ru and Ni+Ni reactions sat SIS energies

    International Nuclear Information System (INIS)

    Crochet, P.; Herrmann, N.; Wisniewski, K.

    2000-01-01

    Experimental data on K + and proton sideward flow measured with the FOPI detector at SIS/GSI in the reactions Ru+Ru at 1.69 A GeV and Ni+Ni at 1.93 A GeV are presented. The K + sideward flow is found to be anti-correlated (correlated) with the one of protons at low (high) transverse momenta. When compared to the predictions of a transport model, the data favour the existence of an in-medium repulsive K + -nucleon potential. (author)

  9. Shape and size effects on layered Ni/PZT/Ni composites magnetoelectric performance

    Energy Technology Data Exchange (ETDEWEB)

    Pan, D A; Zhang, S G; Qiao, L J [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Volinsky, Alex A [Department of Mechanical Engineering, University of South Florida, Tampa FL 33620 (United States)], E-mail: lqiao@ustb.edu.cn

    2008-09-07

    This paper presents the magnetoelectric (ME) effect in trilayered Ni/PZT/Ni composites which is related to their size and shape. The ME composites with the same interfacial areas but different geometrical shapes have different ME voltage coefficients. Longitudinal resonant modes in the rectangular and triangular trilayered ME composites were studied. One should choose optimized size, shape and working frequency of the ME composites in order to gain the maximum ME effect. This study plays a guiding role for trilayered ME composites design for real applications. (fast track communication)

  10. Microstructural evolution of neutron-irradiated Ni-Si and Ni-Al alloys

    Science.gov (United States)

    Takahashi, H.; Garner, F. A.

    1992-10-01

    Additions of silicon and aluminum suppress the neutron-induced swelling of pure nickel but to different degrees. Silicon is much more effective initially when compared to aluminum on a per atom basis but silicon exhibits a nonmonotonic influence on swelling with increasing concentration. Silicon tends to segregate toward grain boundaries while aluminum segregates away from these boundaries. Whereas the formation of the Ni 3Si phase is frequently observed in charged particle irradiation experiments conducted at much higher displacement rates, it did not occur during neutron irradiation in this study. Precipitation also did not occur in Ni-5Al during neutron irradiation, nor has it been reported to occur during ion irradiation.

  11. Strengthening by ordered precipitates in a Ni--Ni4Mo system

    International Nuclear Information System (INIS)

    Goodrum, J.W.; LeFevre, B.G.

    1977-01-01

    The strength characteristics and microstructures of aged Ni-Mo alloys containing ordered (Ni 4 Mo) precipitates were studied as a function of aging time and temperature. It was found that 17 at. percent Mo alloy aged at 750 0 C produced a uniform dispersion of cuboidal β precipitates which coarsened with time producing a gradual increase in flow stress. The flow stress increment was found to vary in qualitative agreement with both order strengthening and coherency strain models. Both these models give over-estimates of the strengthening increment. A negative dependence of flow stress on temperature is attributed to coherency strain contributions

  12. The nature of strong Brønsted acidity of Ni-SMM clay

    NARCIS (Netherlands)

    Yue, C.; Liu, C.; Mezari, B.; Brückner, A.; Pidko, E.A.; Rigutto, M.S.; Hensen, E.J.M.

    2016-01-01

    The origin of the high Brønsted acidity of Ni-SMM (Ni-substituted synthetic mica-montmorillonite; beidellite structure) clays was investigated. Ni-SMM clays with varying F content, SMM with F and Ni-SMM without F in the structure were synthesized under hydrothermal conditions. Ni-SMM clays with

  13. Los niños y los videojuegos

    OpenAIRE

    Orrego Gaviria, Jaime; Fundación Valle de Lili

    2007-01-01

    Los niños y los videojuegos / Efectos perjudiciales de la utilización de los videojuegos por los niños y adolescentes/ Efectos benéficos de la de la utilización de los videojuegos por los niños y adolescentes/ Recomendaciones para favorecer el uso adecuado/ Sistema de clasificación de los videojuegos

  14. Electrochemical Characterization of Ni/(Sc)YSZ Electrodes

    DEFF Research Database (Denmark)

    Ramos, Tania; Thydén, Karl Tor Sune; Mogensen, Mogens Bjerg

    2010-01-01

    Investigations of Ni/(Sc)YSZ cermets for solid oxide cells (SOCs) were performed by electrochemical impedance spectroscopy (EIS), under varying experimental conditions and upon redox cycling, using three different designs of symmetric cells. The deconvolution and fitting of the obtained impedance...... parameters. Initial degradation results for both Ni/ScYSZ and Ni/YSZ based anodes under very high steam content are also reported. ©2010 COPYRIGHT ECS - The Electrochemical Society...

  15. Irradiation-induced precipitation in Ni--Si alloys

    International Nuclear Information System (INIS)

    Barbu, A.; Ardell, A.J.

    1975-07-01

    The microstructures of Ni + ion-irradiated Ni--Si solid-solution alloys, containing 2, 4, 6 and 8 at. percent Si were investigated as a function of dose, dose-rate, and temperature. Results of transmission electron microscopy and other data show the precipitation of γ' (Ni 3 Si) in all samples irradiated at 500 0 C. Characteristics of the precipitates are described and a mechanism for their formation is suggested. (U.S.)

  16. Ni-YSZ graded coatings produced by dipping

    International Nuclear Information System (INIS)

    Ferrari, B.; Moreno, R.

    2004-01-01

    A new colloidal processing route for the shaping of a graded Ni-YSZ composite for applications in SOFC devices is described. A Ni foil is coated by Ni/YSZ layers by dipping in aqueous suspensions with an organic binder. Behind the metal-ceramic layers introduced to improve adhesion, an outer thin layer of nanosized YSZ is formed by electrophoretic deposition. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  17. Low-field spin dynamics of Cr7Ni and Cr7Ni-Cu-Cr7Ni molecular rings as detected by μsR

    OpenAIRE

    Sanna, S.; Arosio, P.; Bordonali, L.; Adelnia, F.; Mariani, M.; Garlatti, E.; Baines, C.; Amato, A.; Sabareesh, K. P.V.; Timco, G.; Winpenny, R. E.P.; Blundell, S. J.; Lascialfari, A.

    2017-01-01

    Muon spin rotation measurements were used to investigate the spin dynamics of heterometallic Cr7Ni and Cr7Ni-Cu-Cr7Ni molecular clusters. In Cr7Ni the magnetic ions are arranged in a quasiplanar ring and interact via an antiferromagnetic exchange coupling constant J, while Cr7Ni-Cu-Cr7Ni is composed of two Cr7Ni linked by a bridging moiety containing one Cu ion, that induces an inter-ring ferromagnetic interaction J ≪ J. The longitudinal muon relaxation rate λ collected at low magnetic fields...

  18. Electronic bipolar resistive switching behavior in Ni/VOx/Al device

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Mengseng [School of Electronic Information Engineering, Hebei University of Technology, Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China); Zhang, Kailiang, E-mail: kailiang_zhang@163.com [School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China); Yang, Ruixia, E-mail: yangrx@hebut.edu.cn [School of Electronic Information Engineering, Hebei University of Technology, Tianjin Key Laboratory of Electronic Materials and Devices, Tianjin 300130 (China); Wang, Fang; Zhang, Zhichao; Wu, Shijian [School of Electronic Information Engineering, Tianjin Key Laboratory of Film Electronic & Communication Devices, Tianjin University of Technology, Tianjin 300384 (China)

    2017-07-15

    Highlights: • The resistive random access memory of Ni/VOx/Al was fabricated. • The device has the electronic bipolar resistive switching characteristic. • The activity energy (Ea) of HRS has been calculated. • The reasons of the degradation of the resistance ratio of HRS/LRS were analyzed. - Abstract: In this paper, the Ni/VOx/Al resistive random access memory (RRAM) device is constructed and it shows bipolar resistive switching behavior, low resistive state (LRS) nonlinearity, and good retention. The set and reset processes are likely induced by the electron trapping and detrapping of trapping centers in the VOx films, respectively. The conduction mechanism in negative/positive region are controlled by space charge limited current mechanism (SCLC)/Schottky emission. The temperature dependence of I–V curves for HRS is measured to confirm the defects trapping and detrapping electrons model. activation energy was calculated to analyze the endurance performance of the device. The detailed analysis of the switching behavior with SCLC mechanism and Schottky emission mechanism could provide useful information for electronic bipolar resistive switching (eBRS) characteristics.

  19. Electronic bipolar resistive switching behavior in Ni/VOx/Al device

    International Nuclear Information System (INIS)

    Xia, Mengseng; Zhang, Kailiang; Yang, Ruixia; Wang, Fang; Zhang, Zhichao; Wu, Shijian

    2017-01-01

    Highlights: • The resistive random access memory of Ni/VOx/Al was fabricated. • The device has the electronic bipolar resistive switching characteristic. • The activity energy (Ea) of HRS has been calculated. • The reasons of the degradation of the resistance ratio of HRS/LRS were analyzed. - Abstract: In this paper, the Ni/VOx/Al resistive random access memory (RRAM) device is constructed and it shows bipolar resistive switching behavior, low resistive state (LRS) nonlinearity, and good retention. The set and reset processes are likely induced by the electron trapping and detrapping of trapping centers in the VOx films, respectively. The conduction mechanism in negative/positive region are controlled by space charge limited current mechanism (SCLC)/Schottky emission. The temperature dependence of I–V curves for HRS is measured to confirm the defects trapping and detrapping electrons model. activation energy was calculated to analyze the endurance performance of the device. The detailed analysis of the switching behavior with SCLC mechanism and Schottky emission mechanism could provide useful information for electronic bipolar resistive switching (eBRS) characteristics.

  20. Assessment of Cr, Ni and Pb Pollution in Rural Agricultural Soils of Tonalite-Trondjhemite Series in Central India.

    Science.gov (United States)

    Shukla, Kriti; Kumar, Bijendra; Agrawal, Rahul; Priyanka, Kumari; Venkatesh, Madavi; Anshumali

    2017-06-01

    Chromium (Cr), nickel (Ni) and lead (Pb) contamination was investigated in wheat cultivated rain-fed and irrigated rural agricultural soils (n = 31) of Tonalite-Trondjhemite Series in Central India. The soil sampling was carried out by using stratified random sampling method. The mean concentrations of Cr, Ni and Pb were 54.8, 38.1 and 68.9 mg/kg, respectively. The average values of enrichment factor (EF), geoaccumulation index (I geo ) and contamination factor (CF) followed the order as: Pb > Ni > Cr. Distribution patterns of soil parent material and weathering processes govern mineral enrichments, irrespective of rainfed or irrigated agricultural practices. Principal component analysis (PCA) showed strong loading of Cr and Ni (PC1) and Pb and clay (PC3). The strong loading on Cr and Ni indicates soils are originating from basic and volcanic rocks in the study area. The strong loading of Pb and clay indicates Pb is strongly adsorbed on clay minerals and Fe-oxides. The cancer risk (CR) index showed negligible carcinogenic risk to the residing population. However, hazard index (HI) values for children exceed the safe limit (HI > 1) for Cr and Pb. Spatial distribution of pollution load index suggest highest pollution in the northeastern part of the district. The study revealed that geogenically enriched soils of the area are suitable for agricultural activities under present conditions.

  1. Comparison of three Ni-Hard I alloys

    Energy Technology Data Exchange (ETDEWEB)

    Dogan, Omer N.; Hawk, Jeffrey A.; Rice, J. (Texaloy Foundry Co., Inc., Floresville, Texas)

    2004-09-01

    This report documents the results of an investigation which was undertaken to reveal the similarities and differences in the mechanical properties and microstructural characteristics of three Ni-Hard I alloys. One alloy (B1) is ASTM A532 class IA Ni-Hard containing 4.2 wt. pct. Ni. The second alloy (B2) is similar to B1 but higher in Cr, Si, and Mo. The third alloy (T1) also falls in the same ASTM specification, but it contains 3.3 wt. pct. Ni. The alloys were evaluated in both as-cast and stress-relieved conditions except for B2, which was evaluated in the stress-relieved condition only. While the matrix of the high Ni alloys is composed of austenite and martensite in both conditions, the matrix of the low Ni alloy consists of a considerable amount of bainite, in addition to the martensite and the retained austenite in as cast condition, and primarily bainite, with some retained austenite, in the stress relieved condition. It was found that the stress relieving treatment does not change the tensile strength of the high Ni alloy. Both the as cast and stress relieved high Ni alloys had a tensile strength of about 350 MPa. On the other hand, the tensile strength of the low Ni alloy increased from 340 MPa to 452 MPa with the stress relieving treatment. There was no significant difference in the wear resistance of these alloys in both as-cast and stressrelieved conditions.

  2. An investigation of the oxidized Ni/InAs interface

    International Nuclear Information System (INIS)

    Venter, A.; Botha, J.R.; Swart, H.C.; Naidoo, S.; Olivier, E.J.

    2009-01-01

    Ni was resistively deposited onto bulk InAs and subsequently oxidized in an O 2 atmosphere. The anneal temperature and time were 450 deg. C and 2.5 h, respectively. X-ray diffraction of the oxidized Ni/InAs sample revealed the formation of In 3 Ni 2 and In 2 O 3 on the front suggesting inter diffusion of In, Ni and O. NiO was not detected by X-ray diffraction. In a preliminary study, using glass as a substrate, NiO readily formed when using these oxidation parameters. Conductivity measurements of the oxidized Ni/InAs surface revealed a conducting front and insulating rear surface while TEM of the Ni/InAs interface revealed an intermediate amorphous diffusion zone between the 'oxidized' Ni layer and the bulk InAs. A closer investigation of the intermediate layer supports the X-ray diffraction results, suggesting compound formation due to diffusion of oxygen and nickel into the substrate, and out-diffusion of In and As from the bulk of the sample. AES was used to further elucidate these results.

  3. An investigation of the oxidized Ni/InAs interface

    Energy Technology Data Exchange (ETDEWEB)

    Venter, A., E-mail: andre.venter@nmmu.ac.z [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, PO Box 339, Bloemfontein 9300 (South Africa); Naidoo, S.; Olivier, E.J. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2009-12-01

    Ni was resistively deposited onto bulk InAs and subsequently oxidized in an O{sub 2} atmosphere. The anneal temperature and time were 450 deg. C and 2.5 h, respectively. X-ray diffraction of the oxidized Ni/InAs sample revealed the formation of In{sub 3}Ni{sub 2} and In{sub 2}O{sub 3} on the front suggesting inter diffusion of In, Ni and O. NiO was not detected by X-ray diffraction. In a preliminary study, using glass as a substrate, NiO readily formed when using these oxidation parameters. Conductivity measurements of the oxidized Ni/InAs surface revealed a conducting front and insulating rear surface while TEM of the Ni/InAs interface revealed an intermediate amorphous diffusion zone between the 'oxidized' Ni layer and the bulk InAs. A closer investigation of the intermediate layer supports the X-ray diffraction results, suggesting compound formation due to diffusion of oxygen and nickel into the substrate, and out-diffusion of In and As from the bulk of the sample. AES was used to further elucidate these results.

  4. Oxidation of hydrogen peroxide by [Ni III (cyclam)

    Indian Academy of Sciences (India)

    The kinetics of oxidation of H2O2 by [NiIII(cyclam)]3+, [NiIIIL1], was studied in aqueous acidic media at 25°C and I = 0.5M (NaClO4). The [NiIIIL1] to [NiIIL1] reduction was found to be fast in the presence of Cu(II) ion than the oxidation of the cyclam ligand by ·OH. The rate constant showed an inverse acid dependence on H+ ...

  5. Level density of radioactive doubly-magic nucleus 56Ni

    International Nuclear Information System (INIS)

    Santhosh Kumar, S.; Rengaiyan, R.; Victor Babu, A.; Preetha, P.

    2012-01-01

    In this work the single particle energies are obtained by diagonalising the Nilsson Hamiltonian in the cylindrical basis and are generated up to N =11 shells for the isotopes of Ni from A = 48-70, emphasizing the three magic nuclei viz, 48 Ni, 56 Ni and 68 Ni. The statistical quantities like excitation energy, level density parameter and nuclear level density which play the important roles in the nuclear structure and nuclear reactions can be calculated theoretically by means of the Statistical or Partition function method. Hence the statistical model approach is followed to probe the dynamical properties of the nucleus in the microscopic level

  6. CVD Graphene/Ni Interface Evolution in Sulfuric Electrolyte

    DEFF Research Database (Denmark)

    Yivlialin, Rossella; Bussetti, Gianlorenzo; Duò, Lamberto

    2018-01-01

    Systems comprising single and multilayer graphene deposited on metals and immersed in acid environments have been investigated, with the aim of elucidating the mechanisms involved, for instance, in hydrogen production or metal protection from corrosion. In this work, a relevant system, namely...... chemical vapor deposited (CVD) multilayer graphene/Ni (MLGr/Ni), is studied when immersed in a diluted sulfuric electrolyte. The MLGr/Ni electrochemical and morphological properties are studied in situ and interpreted in light of the highly oriented pyrolytic graphite (HOPG) electrode behavior, when...... immersed in the same electrolyte. Following this interpretative framework, the dominant role of the Ni substrate in hydrogen production is clarified....

  7. Design and fabrication of Ni nanowires having periodically hollow nanostructures

    Science.gov (United States)

    Sada, Takao; Fujigaya, Tsuyohiko; Nakashima, Naotoshi

    2014-09-01

    We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the interior surfaces of AAO. The Ni shell layer allows the Ni segments to remain even after dissolution of the Ag segments. Because the electroplating conditions can be easily controlled, we could carefully adjust the size and pitch of the periodically hollow nanospaces. We also describe a method for the fabrication of Ni nanorods by forming an Ag shell instead of a Ni shell on the Ni-Ag barcode nanowire, in which the interior of the AAO surfaces was modified with a compound bearing a thiol group prior to electroplating.We propose a concept for the design and fabrication of metal nanowires having periodically hollow nanostructures inside the pores of an anodic aluminum oxide (AAO) membrane using a sacrificial metal. In this study, nickel (Ni) and silver (Ag) were used as the base metal and the sacrificial metal, respectively. Alternating an applied potential between -0.4 and -1.0 V provided alternatively deposited Ni and Ag segments in a Ni-Ag `barcode' nanowire with a diameter of 18 or 35 nm. After etching away the Ag segments, we fabricated Ni nanowires with nanopores of 12 +/- 5.3 nm. Such nanostructure formation is explained by the formation of a Ni shell layer over the surface of the Ag segments due to the strong affinity of Ni2+ for the

  8. Comparative study of NiW, NiMo and MoW prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Gonzalez, G.; Sagarzazu, A.; Villalba, R.; Ochoa, J.

    2007-01-01

    The present work concern the amorphisation process induced by mechanical alloying in the NiW, NiMo and MoW systems. The alloys chosen combine a group of transition elements varying from very similar atomic radius and electronic valences (MoW) to different ones (NiW and NiMo). The three systems achieved an amorphous state after 50 h of milling. The mechanism of amorphisation proposed for NiW and NiMo was the combined effect of an excess concentration of the solute atoms entering into the structure of one of the elements and a critical concentration of defects. Continuous formation of an amorphous phase at the interface of the crystalline phase was observed during the process. MoW seems to amorphize by continuous reduction of grain size down to a critical value where the amorphisation takes place

  9. The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy under Xe26+ ion irradiation

    Science.gov (United States)

    Chen, Huaican; Hai, Yang; Liu, Renduo; Jiang, Li; Ye, Xiang-xi; Li, Jianjian; Xue, Wandong; Wang, Wanxia; Tang, Ming; Yan, Long; Yin, Wen; Zhou, Xingtai

    2018-04-01

    The irradiation hardening of Ni-Mo-Cr and Ni-W-Cr alloy was investigated. 7 MeV Xe26+ ion irradiation was performed at room temperature and 650 °C with peak damage dose from 0.05 to 10 dpa. With the increase of damage dose, the hardness of Ni-Mo-Cr and Ni-W-Cr alloy increases, and reaches saturation at damage dose ≥1 dpa. Moreover, the damage dose dependence of hardness in both alloys can be described by the Makin and Minter's equation, where the effective critical volume of obstacles can be used to represent irradiation hardening resistance of the alloys. Our results also show that Ni-W-Cr alloy has better irradiation hardening resistance than Ni-Mo-Cr alloy. This is ascribed to the fact that the W, instead of Mo in the alloy, can suppress the formation of defects under ion irradiation.

  10. Flexible bottom-emitting white organic light-emitting diodes with semitransparent Ni/Ag/Ni anode.

    Science.gov (United States)

    Koo, Ja-Ryong; Lee, Seok Jae; Lee, Ho Won; Lee, Dong Hyung; Yang, Hyung Jin; Kim, Woo Young; Kim, Young Kwan

    2013-05-06

    We fabricated a flexible bottom-emitting white organic light-emitting diode (BEWOLED) with a structure of PET/Ni/Ag/Ni (3/6/3 nm)/ NPB (50 nm)/mCP (10 nm)/7% FIrpic:mCP (10 nm)/3% Ir(pq)(2) acac:TPBi (5 nm)/7% FIrpic:TPBi (5 nm)/TPBi (10 nm)/Liq (2 nm)/ Al (100 nm). To improve the performance of the BEWOLED, a multilayered metal stack anode of Ni/Ag/Ni treated with oxygen plasma for 60 sec was introduced into the OLED devices. The Ni/Ag/Ni anode effectively enhanced the probability of hole-electron recombination due to an efficient hole injection into and charge balance in an emitting layer. By comparing with a reference WOLED using ITO on glass, it is verified that the flexible BEWOLED showed a similar or better electroluminescence (EL) performance.

  11. Physical simulation of the random failure of implanted braided NiTi stents

    Czech Academy of Sciences Publication Activity Database

    Hiřmanová, Klára; Pilch, Jan; Racek, Jan; Heller, Luděk; Šittner, Petr; Recman, L.; Petrenec, M.; Sedlák, Petr

    2014-01-01

    Roč. 23, č. 7 (2014), s. 2650-2658 ISSN 1059-9495. [International Conference on Shape Memory and Superelastic Technologies (SMST 2013). Praha, 21.05.2013-24.05.2013] R&D Projects: GA ČR GPP108/12/P111; GA ČR GAP107/12/0800; GA MŠk(CZ) 7E11058 EU Projects: European Commission(XE) 262806 - SmartNets Institutional support: RVO:68378271 ; RVO:61388998 Keywords : electron microscopy * failure analysis * mechanical testing Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.998, year: 2014

  12. Hydride Reactivity of Ni-II-X-Ni-II Entities : Mixed-Valent Hydrido Complexes and Reversible Metal Reduction

    NARCIS (Netherlands)

    Gehring, Henrike; Metzinger, Ramona; Herwig, Christian; Intemann, Julia; Harder, Sjoerd; Limberg, Christian

    After the lithiation of PYR-H2 (PYR2-=[{NC(Me)C(H)C(Me)NC6H3(iPr)2}2(C5H3N)]2-), which is the precursor of an expanded beta-diketiminato ligand system with two binding pockets, its reaction with [NiBr2(dme)] led to a dinuclear nickel(II)bromide complex, [(PYR)Ni(mu-Br)NiBr] (1). The bridging bromide

  13. Studies on the valence electronic structure of Fe and Ni in FexNi1−x ...

    Indian Academy of Sciences (India)

    structure of Fe and Ni in various Fex Ni1−x alloys. Since Kβ-to-Kα X-ray intensity ratio has been reported [2–7] to be a sensitive physical parameter to investigate the changes in the valence electronic structure of 3d-transition metals [2], we have undertaken the study of the valence electronic structure of Fe and Ni in the Fex ...

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

    Energy Technology Data Exchange (ETDEWEB)

    Chokprasombat, Komkrich, E-mail: komkrich28@gmail.com [Department of Physics, Faculty of Science, Thaksin University, Phatthalung 93210 Thailand (Thailand); Pinitsoontorn, Supree [Integrated Nanotechnology Research Center, Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 Thailand (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000 Thailand (Thailand)

    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, Fe{sub 50}Co{sub 50−x}Ni{sub x} 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 Fe{sub 50}Ni{sub 50} 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. - Highlights: • We prepared nanocrystalline Fe–Co–Ni alloys by a novel chemical reduction process. • Elemental compositions could be well controlled by the molar ratio of metal sources. • Particle size and magnetic properties clearly depended on the Ni contents. • Fe{sub 50}Co{sub 10}Ni{sub 40} exhibited high saturation magnetization of 126.3 emu/g.

  15. Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

    Science.gov (United States)

    Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

    2016-02-01

    The coarsening of Ni in Ni-yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

  16. Reconstructing random media

    International Nuclear Information System (INIS)

    Yeong, C.L.; Torquato, S.

    1998-01-01

    We formulate a procedure to reconstruct the structure of general random heterogeneous media from limited morphological information by extending the methodology of Rintoul and Torquato [J. Colloid Interface Sci. 186, 467 (1997)] developed for dispersions. The procedure has the advantages that it is simple to implement and generally applicable to multidimensional, multiphase, and anisotropic structures. Furthermore, an extremely useful feature is that it can incorporate any type and number of correlation functions in order to provide as much morphological information as is necessary for accurate reconstruction. We consider a variety of one- and two-dimensional reconstructions, including periodic and random arrays of rods, various distribution of disks, Debye random media, and a Fontainebleau sandstone sample. We also use our algorithm to construct heterogeneous media from specified hypothetical correlation functions, including an exponentially damped, oscillating function as well as physically unrealizable ones. copyright 1998 The American Physical Society

  17. Formation of nickel germanides from Ni layers with thickness below 10 nm

    Energy Technology Data Exchange (ETDEWEB)

    Jablonka, Lukas; Kubart, Tomas; Primetzhofer, Daniel; Abedin, Ahmad; Hellström, Per-Erik; Östling, Mikael; Jordan-Sweet, Jean; Lavoie, Christian; Zhang, Shi-Li; Zhang, Zhen

    2017-03-01

    The authors have studied the reaction between a Ge (100) substrate and thin layers of Ni ranging from 2 to 10 nm in thickness. The formation of metal-rich Ni5Ge3Ni5Ge3 was found to precede that of the monogermanide NiGe by means of real-time in situ x-ray diffraction during ramp-annealing and ex situ x-ray pole figure analyses for phase identification. The observed sequential growth of Ni5Ge3Ni5Ge3 and NiGe with such thin Ni layers is different from the previously reported simultaneous growth with thicker Ni layers. The phase transformation from Ni5Ge3Ni5Ge3 to NiGe was found to be nucleation-controlled for Ni thicknesses <5 nm<5 nm, which is well supported by thermodynamic considerations. Specifically, the temperature for the NiGe formation increased with decreasing Ni (rather Ni5Ge3Ni5Ge3) thickness below 5 nm. In combination with sheet resistance measurement and microscopic surface inspection of samples annealed with a standard rapid thermal processing, the temperature range for achieving morphologically stable NiGe layers was identified for this standard annealing process. As expected, it was found to be strongly dependent on the initial Ni thickness

  18. The Ni-rich Part of the Ni-P-Sn System: Isothermal Sections

    Czech Academy of Sciences Publication Activity Database

    Schmetterer, C.; Vízdal, J.; Kroupa, Aleš; Kodentsov, A.; Ipser, H.

    2009-01-01

    Roč. 38, č. 11 (2009), s. 2275-2300 ISSN 0361-5235 R&D Projects: GA MŠk(CZ) OC08053 Institutional research plan: CEZ:AV0Z20410507 Keywords : lead free solder * phase diagram * Ni-P-Sn Subject RIV: BJ - Thermodynamics Impact factor: 1.428, year: 2009

  19. Fabrication of TiNi/CFRP smart composite using cold drawn TiNi wires

    Science.gov (United States)

    Xu, Ya; Otsuka, Kazuhiro; Toyama, Nobuyuki; Yoshida, Hitoshi; Jang, Byung-Koog; Nagai, Hideki; Oishi, Ryutaro; Kishi, Teruo

    2002-07-01

    In recent years, pre-strained TiNi shape memory alloys (SMA) have been used for fabricating smart structure with carbon fibers reinforced plastics (CFRP) in order to suppress microscopic mechanical damages. However, since the cure temperature of CFRP is higher than the reverse transformation temperatures of TiNi SMA, special fixture jigs have to be used for keeping the pre-strain during fabrication, which restricted its practical application. In order to overcome this difficulty, we developed a new method to fabricate SMA/CFRP smart composites without using special fixture jigs by controlling the transformation temperatures of SMA during fabrication. This method consists of using heavily cold-worked wires to increase the reverse transformation temperatures, and of using flash electrical heating of the wires after fabrication in order to decrease the reverse transformation temperatures to a lower temperature range again without damaging the epoxy resin around SMA wires. By choosing proper cold-working rate and composition of TiNi alloys, the reverse transformation temperatures were well controlled, and the TiNi/CFRP hybrid smart composite was fabricated without using special fixture jigs. The damage suppressing effect of cold drawn wires embedded in CFRP was confirmed.

  20. Transformation dynamics of Ni clusters into NiO rings under electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Knez, Daniel, E-mail: daniel.knez@felmi-zfe.at [Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz (Austria); Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz (Austria); Thaler, Philipp; Volk, Alexander [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria); Kothleitner, Gerald [Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz (Austria); Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz (Austria); Ernst, Wolfgang E. [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz (Austria); Hofer, Ferdinand [Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Steyrergasse 17, 8010 Graz (Austria); Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz (Austria)

    2017-05-15

    We report the transformation of nickel clusters into NiO rings by an electron beam induced nanoscale Kirkendall effect. High-purity nickel clusters consisting of a few thousand atoms have been used as precursors and were synthesized with the superfluid helium droplet technique. Aberration-corrected, analytical scanning transmission electron microscopy was applied to oxidise and simultaneously analyse the nanostructures. The transient dynamics of the oxidation could be documented by time lapse series using high-angle annular dark-field imaging and electron energy-loss spectroscopy. A two-step Cabrera-Mott oxidation mechanism was identified. It was found that water adsorbed adjacent to the clusters acts as oxygen source for the electron beam induced oxidation. The size-dependent oxidation rate was estimated by quantitative EELS measurements combined with molecular dynamics simulations. Our findings could serve to better control sample changes during examination in an electron microscope, and might provide a methodology to generate other metal oxide nanostructures. - Highlights: • Beam induced conversion of Ni clusters into crystalline NiO rings has been observed. • Ni clusters were grown with the superfluid He-droplet technique. • oxidizeSTEM was utilized to investigate and simultaneously oxidize these clusters. • Oxidation dynamics was captured in real-time. • Cluster sizes and the oxidation rate were estimated via EELS and molecular dynamics.

  1. Structural conditions of achieving maximum ductility of two-phase Ni-NiO alloys

    International Nuclear Information System (INIS)

    Grabin, V.V.; Dabizha, E.V.; Movchan, B.A.

    1984-01-01

    A study was made on possibility of increasing ductility of two-phase Ni-NiO alloys, proJuced by traditional technology: ingot smelting, rolling and corresponding annealing for production of grain with certain size. The correlation of mechanical properties of Ni-NiO alloys and pure nickel shows that completion of the structural conJition D--lambda (where D - the average grain diameter, lambda - the value of free path between particles) in two-phase alloys enables: to increase the ultimate strength 1.5 times and preserve the basic level of pure nickel plasticity - at 20 deg C; to increase plasticity 1.4-1.5 times with preserved basic level of pure nickel plasticity - at 800 deg C. The conclusions testify to possibility of controlling mechanical properties of two-phase alloys using structural D and lambda parameters It is proposed that creation of structures with more unifor m particle distribution with respect to sizes will the accompanied by further increase of plasticity under D=lambda condition

  2. Experimental study of the $^{66}$Ni$(d,p)^{67}$Ni one-neutron transfer reaction

    CERN Document Server

    Diriken, J.; Andreyev, A.N.; Antalic, S.; Bildstein, V.; Blazhev, A.; Darby, I.G.; De Witte, H.; Eberth, J.; Elseviers, J.; Fedosseev, V.N.; Flavigny, F.; Fransen, Ch.; Georgiev, G.; Gernhauser, R.; Hess, H.; Huyse, M.; Jolie, J.; Kröll, Th.; Krücken, R.; Lutter, R.; Marsh, B.A.; Mertzimekis, T.; Muecher, D.; Orlandi, R.; Pakou, A.; Raabe, R.; Randisi, G.; Reiter, P.; Roger, T.; Seidlitz, M.; Seliverstov, M.; Sotty, C.; Tornqvist, H.; Van De Walle, J.; Van Duppen, P.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

    2015-01-01

    The quasi-SU(3) sequence of the positive parity $νg_{9/2}, d_{5/2}, s_{1/2}$ orbitals above the N=40 shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe (Z=26) and Cr (Z=24) isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of $^{68}$Ni (Z=28,N=40) through the $^{66}$Ni($d,p$)$^{67}$Ni one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball $\\gamma$-array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-$\\mu$s isomer at 1007 keV in $^{67}$Ni. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the $νg_{9/2}$ (1007 keV) and $νd_{5/2}$ (2207 keV and 3277 keV) positive-parity neutron states and negative parity ($νpf$) states have been observed at low excitation energy. The extracted relativ...

  3. Energies of Electronic States of Ni (II) Ion in NiO-Al2O3 Catalyst Prepared by Impregnation

    International Nuclear Information System (INIS)

    Obadovic, D. Z.; Kiurski, J.; Marinkovic-Neducin, R. P.

    2007-01-01

    The behavior of NiO-Al2O3 catalysts is strongly dependent on the preparation method, as well as on pretreatment conditions. In the present work we investigated the influences of Ni(II) ion on NiO-Al2O3 catalysts properties due to the preparation by impregnation method. Based on experimental diffuse reflectance spectroscopy (DRS) data of electronic d-d transitions of Ni (II) promoter ion the energies of electronic states in spinel-like structure were calculated, and the most probable scheme of molecular orbital have been proposed

  4. Interacción familiar y desarrollo emocional en niños y niñas

    Directory of Open Access Journals (Sweden)

    Gloria Cecilia Henao López

    2009-01-01

    Full Text Available En la presente investigación se tuvo como objetivo principal abordar los estilos de interacción de padres y madres de niños y niñas preescolares y su relación con el desarrollo emocional de sus hijos e hijas (235 niños y 169 niñas entre cinco y seis años de edad. Las dimensiones que se consideraron para evaluar el nivel emocional de los niños y niñas fueron: autorregulación, comprensión emocional, y empatía. Como primer aspecto describimos los tipos de interacción con sus hijos e hijas y el desarrollo emocional de los niños y niñas evaluados. Un segundo aspecto que se abordó, es el de explorar las asociaciones entre el estilo de interacción familiar y el desarrollo emocional infantil. El instrumento utilizado dirigido a los padres y madres fue la Escala de Identificación de Prácticas Educativas Familiares (PEF, versión española realizada por Alonso y Román; a los niños y niñas les aplicamos la evaluación del desempeño emocional (EDEI, que se construye como parte de esta investigación. Se trabajó con una muestra de 404 niños y niñas, y sus respectivos padres y madres. Los resultados obtenidos en esta investigación resaltan el estilo equilibrado como generador de conductas adecuadas y adaptativas en el niño o niña, al igual que rescata este estilo como el que más posibilita el nivel de comprensión emocional en los niños y niñas de nuestro estudio.

  5. Enhanced photocatalytic efficiency in zirconia buffered n-NiO/p-NiO single crystalline heterostructures by nanosecond laser treatment

    Energy Technology Data Exchange (ETDEWEB)

    Molaei, R.; Bayati, M. R.; Alipour, H. M.; Nori, S.; Narayan, J. [Department of Materials Science and Engineering, NC State University, EB-1, Raleigh, North Carolina 27695-7907 (United States)

    2013-06-21

    We report the formation of NiO based single crystalline p-n junctions with enhanced photocatalytic activity induced by pulsed laser irradiation. The NiO epilayers were grown on Si(001) substrates buffered with cubic yttria-stabilized zirconia (c-YSZ) by using pulsed laser deposition. The NiO/c-YSZ/Si heterostructures were subsequently laser treated by 5 pulses of KrF excimer laser (pulse duration = 25 Multiplication-Sign 10{sup -9} s) at lower energies. Microstructural studies, conducted by X-ray diffraction ({theta}-2{theta} and {phi} techniques) and high resolution transmission electron microscope, showed a cube-on-cube epitaxial relationship at the c-YSZ/Si interface; the epitaxial relationship across the NiO/c-YSZ interface was established as NiO<111 > Double-Vertical-Line Double-Vertical-Line c-YSZ<001> and in-plane NiO<110> Double-Vertical-Line Double-Vertical-Line c-YSZ<100>. Electron microscopy studies showed that the interface between the laser annealed and the pristine region as well as the NiO/c-YSZ interface was atomically sharp and crystallographically continuous. The formation of point defects, namely oxygen vacancies and NiO, due to the coupling of the laser photons with the NiO epilayers was confirmed by XPS. The p-type electrical characteristics of the pristine NiO epilayers turned to an n-type behavior and the electrical conductivity was increased by one order of magnitude after laser treatment. Photocatalytic activity of the pristine (p-NiO/c-YSZ/Si) and the laser-annealed (n-NiO/p-NiO/c-YSZ/Si) heterostructures were assessed by measuring the decomposition rate of 4-chlorophenol under UV light. The photocatalytic reaction rate constants were determined to be 0.0059 and 0.0092 min{sup -1} for the as-deposited and the laser-treated samples, respectively. The enhanced photocatalytic efficiency was attributed to the suppressed charge carrier recombination in the NiO based p-n junctions and higher electrical conductivity. Besides, the oxygen vacancies

  6. Tritium-tracer study of catalytic hydrogenation reaction of ethylene on Ni, Pt and Ni-Pt

    International Nuclear Information System (INIS)

    Matsuyama, M.; Yasuda, Y.; Takeuchi, T.

    1978-01-01

    The influence of the pressure of tritiated hydrogen on the rate of the formation of tritiated ethylene, X, and that of tritiated ethane, Z, in the hydrogenation reaction of ethylene on Ni, Pt and Ni-Pt (1:1) alloy catalysts was investigated. The ratio of the rate of the exchange to that of the hydrogenation, selectivity X/Z, decreased markedly with the increase in the pressure of the tritiated hydrogen and the order of X/Z was Ni>Ni-Pt>Pt. These results were interpreted in terms of the difference in the amount of chemisorbed tritium on each metal catalyst. (orig.) [de

  7. Lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite for electrochemical supercapacitor materials

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qingnan [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wen, Ming, E-mail: m_wen@tongji.edu.cn [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China); Chen, Shipei [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Wu, Qingsheng [Department of Chemistry, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shanghai 200092 (China); Shanghai Key Lab of Chemical Assessment and Sustainability, Tongji University, Shanghai 200092 (China)

    2015-10-15

    Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure with a single lamellar spacing of ∼5 nm was effectively constructed through two-phase-interface reaction process followed by the CNTs crossed among the lamellar-nanostructured Ni(OH){sub 2}. The resultant nanocomposite can offer large active surface areas and short diffusion paths for electrons and ions, and is investigated as a potential pseudocapacitor electrode material for electrochemical energy storage applications. Electrochemical data demonstrate that the as-prepared nanocomposite exhibits a high specific capacitance of ∼1600 F g{sup −1} at the scan rate of 1 mV s{sup −1} in 6 M KOH solution at normal pressure and temperature, which is great higher than Ni(OH){sub 2} (∼1200 F g{sup −1}). Furthermore, Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposite shows a higher energy density (∼125 Wh kg{sup −1}, 2 A g{sup −1}) and has a slightly decrease of 5% in specific capacitance after 1000 continuous charge/discharge cycles. - Graphical abstract: As-constructed Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructure exhibits remarkable enhancement in electrochemical stability and high specific capacity of ∼1600 F g{sup −1} at a scan rate of 1 mV s{sup −1}, suggesting promising potential for supercapacitor applications. - Highlights: • New designed lamellar-crossing-structured Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have been firstly reported in this work. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} lamellar-crossing-nanostructures show firm nanostructure and excellent electrochemical stability. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites exhibit excellent specific capacitance. • Ni(OH){sub 2}/CNTs/Ni(OH){sub 2} nanocomposites have the potential application in electrochemical energy storage applications.

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

    KAUST Repository

    Liang, Hanfeng

    2017-04-11

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

  9. Photoelectrochemical Water Splitting Properties of Ti-Ni-Si-O Nanostructures on Ti-Ni-Si Alloy

    Directory of Open Access Journals (Sweden)

    Ting Li

    2017-10-01

    Full Text Available Ti-Ni-Si-O nanostructures were successfully prepared on Ti-1Ni-5Si alloy foils via electrochemical anodization in ethylene glycol/glycerol solutions containing a small amount of water. The Ti-Ni-Si-O nanostructures were characterized by field-emission scanning electron microscopy (FE-SEM, energy dispersive spectroscopy (EDS, X-ray diffraction (XRD, and diffuse reflectance absorption spectra. Furthermore, the photoelectrochemical water splitting properties of the Ti-Ni-Si-O nanostructure films were investigated. It was found that, after anodization, three different kinds of Ti-Ni-Si-O nanostructures formed in the α-Ti phase region, Ti2Ni phase region, and Ti5Si3 phase region of the alloy surface. Both the anatase and rutile phases of Ti-Ni-Si-O oxide appeared after annealing at 500 °C for 2 h. The photocurrent density obtained from the Ti-Ni-Si-O nanostructure photoanodes was 0.45 mA/cm2 at 0 V (vs. Ag/AgCl in 1 M KOH solution. The above findings make it feasible to further explore excellent photoelectrochemical properties of the nanostructure-modified surface of Ti-Ni-Si ternary alloys.

  10. Photoelectrochemical Water Splitting Properties of Ti-Ni-Si-O Nanostructures on Ti-Ni-Si Alloy.

    Science.gov (United States)

    Li, Ting; Ding, Dongyan; Dong, Zhenbiao; Ning, Congqin

    2017-10-31

    Ti-Ni-Si-O nanostructures were successfully prepared on Ti-1Ni-5Si alloy foils via electrochemical anodization in ethylene glycol/glycerol solutions containing a small amount of water. The Ti-Ni-Si-O nanostructures were characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and diffuse reflectance absorption spectra. Furthermore, the photoelectrochemical water splitting properties of the Ti-Ni-Si-O nanostructure films were investigated. It was found that, after anodization, three different kinds of Ti-Ni-Si-O nanostructures formed in the α-Ti phase region, Ti₂Ni phase region, and Ti₅Si₃ phase region of the alloy surface. Both the anatase and rutile phases of Ti-Ni-Si-O oxide appeared after annealing at 500 °C for 2 h. The photocurrent density obtained from the Ti-Ni-Si-O nanostructure photoanodes was 0.45 mA/cm² at 0 V (vs. Ag/AgCl) in 1 M KOH solution. The above findings make it feasible to further explore excellent photoelectrochemical properties of the nanostructure-modified surface of Ti-Ni-Si ternary alloys.

  11. Characterization and electrochemical properties of Ni(Si)/Ni5Si2 multiphase coatings prepared by HVOF spraying

    Science.gov (United States)

    Verdian, M. M.; Raeissi, K.; Salehi, M.

    2012-11-01

    Ni(Si)/Ni5Si2 powders were produced by mechanical alloying (MA) of Ni-25 at.% Si powder mixture. Then, the as-milled powders were sprayed onto copper substrate using high velocity oxy-fuel (HVOF) process. The phase composition and microstructure of the coatings were examined by X-ray diffractometry and scanning electron microscopy. Polarization tests and electrochemical impedance spectroscopy (EIS) measurements were also employed to study corrosion performance of the coatings in 3.5% NaCl solution. The results showed that although single phase Ni3Si was formed during annealing of Ni(Si)/Ni5Si2 powders, but, only Ni(Si) and Ni5Si2 are present in HVOF coatings and no new phase has been formed during spraying. The coatings had microhardness up to 746 HV0.05. Further investigations showed the corrosion performance of multiphase coatings in 3.5% NaCl solution was better than that of copper substrate. The phase transitions during MA, HVOF and annealing processes were discussed in association with Ni-Si phase diagram and nature of each process.

  12. Viviendo con VIH/SIDA: Las voces ocultas de los niños y niñas afectados

    OpenAIRE

    Luz Adriana Aristizábal Becerra

    2015-01-01

    El VIH/SIDA no es solamente un problema de salud, sino también un problema social. Los primeros casos de VIH/SIDA en niños se describen en 1982 en Estados Unidos, y desde entonces el número de niños infectados y afectados continúa incrementándose, hasta convertirse en lo que en la actualidad se denota como una pandemia. Objetivo. Posibilitar un espacio para que los niños y niñas afectados por el VIH/SIDA, puedan expresar sus vivencias en torno al padecimiento propio y/o de sus padres. Metodol...

  13. Influence of Ni/Co molar ratio on electromagnetic properties and microwave absorption performances for Ni/Co paraffin composites

    Energy Technology Data Exchange (ETDEWEB)

    Yan, S.J., E-mail: shaojiuyan@126.com [Department of Structural Steel, Functional Materials and Heat Treatment Processing, AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Aviation Key Laboratory of Science and Technology on Stealth Materials, Beijing 100095 (China); Dai, S.L. [The Office of AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Ding, H.Y.; Wang, Z.Y. [Aviation Key Laboratory of Science and Technology on Stealth Materials, Beijing 100095 (China); Liu, D.B [Department of Structural Steel, Functional Materials and Heat Treatment Processing, AVIC Beijing Institute of Aeronautical Materials, Beijing 100095 (China)

    2014-05-01

    Ni and Co metallic microparticles with submicron size were synthesized with a simple wet chemical reduction method at a relatively low temperature. Then their morphologies and structures were characterized by SEM and XRD. Ni metallic microparticles have spherical-shape morphology with fcc crystalline structure, however, Co has a distinct leaf-like morphology with the fcc and hcp mixed phases crystalline structures. For the characterization of their electromagnetic properties, paraffin matrix composites containing different molar ratio Ni and Co mixture powder as fillers were prepared. It was found that both the electromagnetic properties and electromagnetic microwave absorption performances of absorber layer were remarkably influenced by Ni/Co molar ratio. The electromagnetic microwave absorption performances were significantly improved by blending Ni and Co metallic microparticles into paraffin matrix with changing Ni/Co molar ratio, and enhanced mechanism were discussed. - Highlights: • Ni and Co microparticles were synthesized by a wet chemical reduction method. • EM properties of absorber were remarkably influenced by Ni/Co molar ratio. • EMA performances can be adjusted by artificially changing Co/Ni molar ratio. • Enhanced EMA performances result from multiple EM attenuation mechanisms.

  14. Synergetic interface between NiO/Ni3S2 nanosheets and carbon nanofiber as binder-free anode for highly reversible lithium storage

    Science.gov (United States)

    Jiang, Jialin; Ma, Chao; Yang, Yinbo; Ding, Jingjing; Ji, Hongmei; Shi, Shaojun; Yang, Gang

    2018-05-01

    A novel heterostructure of NiO/Ni3S2 nanoflake is synthesized and composited with carbon nanofibers (CNF) membrane. NiO/Ni3S2 nanoflakes are homogeneously dispersed in CNF network, herein, NiO/Ni3S2 like leaf and CNF like branch. Carbon nanofibers network efficiently prevents the pulverization and buffers the volume changes of NiO/Ni3S2, meanwhile, NiO/Ni3S2 nanoflakes through the conductive channels of carbon nanofibers own improved Li+ diffusion ability and structural stability. The capacity of NiO/Ni3S2/CNF reaches to 519.2 mA g-1 after 200 cycles at the current density of 0.5 A g-1 while NiO/Ni3S2 fades to 71 mAh g-1 after 40 cycles. Owing to the synergetic structure, the resultant binder-free electrode NiO/Ni3S2/carbon nanofibers shows an excellent reversible lithium storage capability.

  15. Vacuum-Free, Maskless Patterning of Ni Electrodes by Laser Reductive Sintering of NiO Nanoparticle Ink and Its Application to Transparent Conductors

    KAUST Repository

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

    2014-01-01

    © 2014 American Chemical Society. 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

  16. Residual stress in Ni-W electrodeposits

    DEFF Research Database (Denmark)

    Mizushima, Io; Tang, Peter Torben; Hansen, Hans Nørgaard

    2006-01-01

    In the present work, the residual stress in Ni–W layers electrodeposited from electrolytes based on NiSO4 and Na2WO4, is investigated. Citrate, glycine and triethanolamine were used as complexing agents, enabling complex formation between the nickel ion and tungstate. The results show that the type...... of complexing agent and the current efficiency have an influence on the residual stress. In all cases, an increase in tensile stress in the deposit with time after deposition was observed. Pulse plating could improve the stress level for the electrolyte containing equal amounts of citrate...

  17. Anomalous Hall effect in polycrystalline Ni films

    KAUST Repository

    Guo, Zaibing

    2012-02-01

    We systematically studied the anomalous Hall effect in a series of polycrystalline Ni films with thickness ranging from 4 to 200 nm. It is found that both the longitudinal and anomalous Hall resistivity increased greatly as film thickness decreased. This enhancement should be related to the surface scattering. In the ultrathin films (46 nm thick), weak localization corrections to anomalous Hall conductivity were studied. The granular model, taking into account the dominated intergranular tunneling, has been employed to explain this phenomenon, which can explain the weak dependence of anomalous Hall resistivity on longitudinal resistivity as well. © 2011 Elsevier Ltd. All rights reserved.

  18. Intermittency and random matrices

    Science.gov (United States)

    Sokoloff, Dmitry; Illarionov, E. A.

    2015-08-01

    A spectacular phenomenon of intermittency, i.e. a progressive growth of higher statistical moments of a physical field excited by an instability in a random medium, attracted the attention of Zeldovich in the last years of his life. At that time, the mathematical aspects underlying the physical description of this phenomenon were still under development and relations between various findings in the field remained obscure. Contemporary results from the theory of the product of independent random matrices (the Furstenberg theory) allowed the elaboration of the phenomenon of intermittency in a systematic way. We consider applications of the Furstenberg theory to some problems in cosmology and dynamo theory.

  19. Random quantum operations

    International Nuclear Information System (INIS)

    Bruzda, Wojciech; Cappellini, Valerio; Sommers, Hans-Juergen; Zyczkowski, Karol

    2009-01-01

    We define a natural ensemble of trace preserving, completely positive quantum maps and present algorithms to generate them at random. Spectral properties of the superoperator Φ associated with a given quantum map are investigated and a quantum analogue of the Frobenius-Perron theorem is proved. We derive a general formula for the density of eigenvalues of Φ and show the connection with the Ginibre ensemble of real non-symmetric random matrices. Numerical investigations of the spectral gap imply that a generic state of the system iterated several times by a fixed generic map converges exponentially to an invariant state

  20. Random a-adic groups and random net fractals

    Energy Technology Data Exchange (ETDEWEB)

    Li Yin [Department of Mathematics, Nanjing University, Nanjing 210093 (China)], E-mail: Lyjerry7788@hotmail.com; Su Weiyi [Department of Mathematics, Nanjing University, Nanjing 210093 (China)], E-mail: suqiu@nju.edu.cn

    2008-08-15

    Based on random a-adic groups, this paper investigates the relationship between the existence conditions of a positive flow in a random network and the estimation of the Hausdorff dimension of a proper random net fractal. Subsequently we describe some particular random fractals for which our results can be applied. Finally the Mauldin and Williams theorem is shown to be very important example for a random Cantor set with application in physics as shown in E-infinity theory.

  1. Comparison of Corrosion Behavior of Electrochemically Deposited Nano-Cobalt-Coated Ni Sheet

    Directory of Open Access Journals (Sweden)

    Nasser Al-Aqeeli

    2013-01-01

    Full Text Available Corrosion behavior of nano-coblat-coated Ni sheet was compared with pure Ni and 20% Fe-Ni alloy sheet using potentiodynamic polarization and linear polarization technique in 0.1 M NaCl solution at room temperature. Results showed that corrosion resistance properties of nano-Co-coated Ni sheet were almost same as that of pure Ni sheet, however corrosion resistance of 20% Fe-Ni sheet was decreased significantly. Pitting potential of 20% Fe-Ni sheet was subsequently decreased as compared to pure Ni sheet as well as nano-cobalt-coated Ni sheet. SEM/EDS analysis of the corroded surfaces showed that both pure Ni and nano-coblat-coated Ni sheet did not show any appreciable corrosion however significant corrosion was observed in the case of 20% Fe-Ni sheet.

  2. [Intel random number generator-based true random number generator].

    Science.gov (United States)

    Huang, Feng; Shen, Hong

    2004-09-01

    To establish a true random number generator on the basis of certain Intel chips. The random numbers were acquired by programming using Microsoft Visual C++ 6.0 via register reading from the random number generator (RNG) unit of an Intel 815 chipset-based computer with Intel Security Driver (ISD). We tested the generator with 500 random numbers in NIST FIPS 140-1 and X(2) R-Squared test, and the result showed that the random number it generated satisfied the demand of independence and uniform distribution. We also compared the random numbers generated by Intel RNG-based true random number generator and those from the random number table statistically, by using the same amount of 7500 random numbers in the same value domain, which showed that the SD, SE and CV of Intel RNG-based random number generator were less than those of the random number table. The result of u test of two CVs revealed no significant difference between the two methods. Intel RNG-based random number generator can produce high-quality random numbers with good independence and uniform distribution, and solves some problems with random number table in acquisition of the random numbers.

  3. On Random Numbers and Design

    Science.gov (United States)

    Ben-Ari, Morechai

    2004-01-01

    The term "random" is frequently used in discussion of the theory of evolution, even though the mathematical concept of randomness is problematic and of little relevance in the theory. Therefore, since the core concept of the theory of evolution is the non-random process of natural selection, the term random should not be used in teaching the…

  4. Structure determination of the ordered (2 × 1) phase of NiSi surface alloy on Ni(111) using low-energy electron diffraction

    Science.gov (United States)

    Sazzadur Rahman, Md.; Amirul Islam, Md.; Saha, Bidyut Baran; Nakagawa, Takeshi; Mizuno, Seigi

    2015-12-01

    The (2 × 1) structure of the two-dimensional nickel silicide surface alloy on Ni(111) was investigated using quantitative low-energy electron diffraction analysis. The unit cell of the determined silicide structure contains one Si and one Ni atom, corresponding to a chemical formula of NiSi. The Si atoms adopt substitutional face-centered cubic hollow sites on the Ni(111) substrate. The Ni-Si bond lengths were determined to be 2.37 and 2.34 Å. Both the alloy surface and the underlying first layers of Ni atoms exhibit slight corrugation. The Ni-Si interlayer distance is smaller than the Ni-Ni interlayer distance, which indicates that Si atoms and underlying Ni atoms strongly interact.

  5. Fragmentation of neutron-hole strengths in 59Ni observed in the 60Ni(p, d) 59Ni reaction at 65 MeV

    International Nuclear Information System (INIS)

    Matoba, M.; Ohgaki, H.; Kugimiya, H.; Ijiri, H.; Maki, T.; Nakano, M.

    1995-01-01

    The 60 Ni(p, d) 59 Ni reaction has been studied with 65 MeV polarized protons. Angular distributions of the differential cross section and analyzing power have been measured for neutron hole states in 59 Ni up to the excitation energies of 7 MeV. The data analysis with a standard distorted-wave Born approximation theory provides transferred angular momenta l, j and spectroscopic factors for thirty-nine transitions. The nuclear damping mechanism of the single hole states is discussed. ((orig.))

  6. Uniform random number generators

    Science.gov (United States)

    Farr, W. R.

    1971-01-01

    Methods are presented for the generation of random numbers with uniform and normal distributions. Subprogram listings of Fortran generators for the Univac 1108, SDS 930, and CDC 3200 digital computers are also included. The generators are of the mixed multiplicative type, and the mathematical method employed is that of Marsaglia and Bray.

  7. On randomly interrupted diffusion

    International Nuclear Information System (INIS)

    Luczka, J.

    1993-01-01

    Processes driven by randomly interrupted Gaussian white noise are considered. An evolution equation for single-event probability distributions in presented. Stationary states are considered as a solution of a second-order ordinary differential equation with two imposed conditions. A linear model is analyzed and its stationary distributions are explicitly given. (author). 10 refs

  8. Coded Random Access

    DEFF Research Database (Denmark)

    Paolini, Enrico; Stefanovic, Cedomir; Liva, Gianluigi

    2015-01-01

    The rise of machine-to-machine communications has rekindled the interest in random access protocols as a support for a massive number of uncoordinatedly transmitting devices. The legacy ALOHA approach is developed under a collision model, where slots containing collided packets are considered as ...

  9. Random eigenvalue problems revisited

    Indian Academy of Sciences (India)

    statistical distributions; linear stochastic systems. 1. ... dimensional multivariate Gaussian random vector with mean µ ∈ Rm and covariance ... 5, the proposed analytical methods are applied to a three degree-of-freedom system and the ...... The joint pdf ofω1 andω3 is however close to a bivariate Gaussian density function.

  10. Mössbauer emission study on 57Co doped carbon-supported Ni and Ni-Mo sulfide hydrotreating catalysts : the influence of phosphorus on the structure

    NARCIS (Netherlands)

    Crajé, M.W.J.; Beer, de V.H.J.; Kraan, van der A.M.

    1991-01-01

    In the present study it is demonstrated that Mössbauer emission spectroscopy (MES) can generate information on the various Ni phases present in sulfided Ni containing catalysts when a small amount of 57Co is used as a probe for Ni.Application of MES to 57Co:Ni(4.5)Mo(8.0)/C and 57Co:Ni(5.6)/C

  11. Characterization of Sputtered Nickel-Titanium (NiTi) Stress and Thermally Actuated Cantilever Bimorphs Based on NiTi Shape Memory Alloy (SMA)

    Science.gov (United States)

    2015-11-01

    necessary anneal . Following this, a thin film of NiTi was blanket sputtered at 600 °C. This NiTi blanket layer was then wet -etch patterned using a...varying the sputter parameters during NiTi deposition, such as thickness, substrate temperature during deposition and anneal , and argon pressure during...6 Fig. 4 Surface texture comparison between NiTi sputtered at RT, then annealed at 600 °C, and NiTi

  12. Using DR52c/Ni2+ mimotope tetramers to detect Ni2+ reactive CD4+ T cells in patients with joint replacement failure.

    Science.gov (United States)

    Zhang, Yan; Wang, Yang; Anderson, Kirsten; Novikov, Andrey; Liu, Zikou; Pacheco, Karin; Dai, Shaodong

    2017-09-15

    T cell mediated hypersensitivity to nickel (Ni 2+ ) is one of the most common causes of allergic contact dermatitis. Ni 2+ sensitization may also contribute to the failure of Ni 2+ containing joint implants, and revision to non-Ni 2+ containing hardware can be costly and debilitating. Previously, we identified Ni 2+ mimotope peptides, which are reactive to a CD4 + T cell clone, ANi2.3 (Vα1, Vβ17), isolated from a Ni 2+ hypersensitive patient with contact dermatitis. This T cell is restricted to the major histocompatibility complex class II (MHCII) molecule, Human Leukocyte Antigen (HLA)-DR52c (DRA, DRB3*0301). However, it is not known if Ni 2+ induced T cell responses in sensitized joint replacement failure patients are similar to subjects with Ni 2+ induced contact dermatitis. Here, we generated DR52c/Ni 2+ mimotope tetramers, and used them to test if the same Ni 2+ T cell activation mechanism could be generalized to Ni 2+ sensitized patients with associated joint implant failure. We confirmed the specificity of these tetramers by staining of ANi2.3T cell transfectomas. The DR52c/Ni 2+ mimotope tetramer detected Ni 2+ reactive CD4 + T cells in the peripheral blood mononuclear cells (PBMC) of patients identified as Ni 2+ sensitized by patch testing and a positive Ni 2+ LPT. When HLA-typed by a DR52 specific antibody, three out of four patients were DR52 positive. In one patient, Ni 2+ stimulation induced the expansion of Vβ17 positive CD4 + T cells from 0.8% to 13.3%. We found that the percentage of DR52 positivity and Vβ17 usage in Ni 2+ sensitized joint failure patients are similar to Ni sensitized skin allergy patients. Ni 2+ independent mimotope tetramers may be a useful tool to identify the Ni 2+ reactive CD4 + T cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Rapid synthesis of binary α-NiS–β-NiS by microwave autoclave for rechargeable lithium batteries

    International Nuclear Information System (INIS)

    Idris, Nurul Hayati; Rahman, Md Mokhlesur; Chou, Shu-Lei; Wang Jiazhao; Wexler, David; Liu, Hua-Kun

    2011-01-01

    Highlights: ► NiS has been synthesized by a rapid, one-pot, hydrothermal microwave autoclave method. ► The α-NiS–β-NiS sample synthesized at 160 °C yielded good electrochemical performance in terms of high reversible capacity (320 mAh g −1 at 0.1C up to 100 cycles). ► At high rates, the sample operated at a good fraction of its capacity. - Abstract: To reduce the reaction time, electrical energy consumption, and cost, binary α-NiS–β-NiS has been synthesized by a rapid, one-pot, hydrothermal autoclave microwave method within 15 min at temperatures of 160–180 °C. The microstructure and morphology of the α-NiS–β-NiS products were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). At 140 °C, pure hexagonal NiAs-type α-NiS phase was identified from the XRD patterns. With increasing reaction temperature (160–180 °C), the XRD evidence indicates that an increasing fraction of rhombohedral millerite-like β-NiS is formed as a secondary phase. The α-NiS–β-NiS sample synthesized at 160 °C yielded good electrochemical performance in term of high reversible capacity (320 mAh g −1 at 0.1C up to 100 cycles). Even at high rates, the sample operated at a good fraction of its capacity. The likely contributing factor to the superior electrochemical performance of the α-NiS–β-NiS sample could be related to the improved morphology. TEM imaging confirmed that needle-like protrusions connect the clusters of α-NiS particles, and the individual protrusions indicated a very high surface area including folded sheet morphology, which helps to dissipate the surface accumulation of Li + ions and facilitate rapid mobility. These factors help to enhance the amount of lithium intercalated within the material.

  14. Coarsening of Ni-Ge solid-solution precipitates in 'inverse' Ni{sub 3}Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ardell, Alan J., E-mail: alan.ardell@gmail.com [National Science Foundation, 4201 Wilson Boulevard, Arlington, VA 22230 (United States); Ma Yong [Aquatic Sensor Network Technology LLC, Storrs, CT 06268 (United States)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer We report microstructural evolution of disordered Ni-Ge precipitates in Ni{sub 3}Ge alloys. Black-Right-Pointing-Pointer Coarsening kinetics and particle size distributions are presented. Black-Right-Pointing-Pointer Data are analyzed quantitatively using the MSLW theory, but agreement is only fair. Black-Right-Pointing-Pointer The shapes of large precipitates are unusual, with discus or boomerang cross-sections. Black-Right-Pointing-Pointer Results are compared with morphology, kinetics of Ni-Al in inverse Ni{sub 3}Al alloys. - Abstract: The morphological evolution and coarsening kinetics of Ni-Ge solid solution precipitates from supersaturated solutions of hypostoichiometric Ni{sub 3}Ge were investigated in alloys containing from 22.48 to 23.50 at.% Ge at 600, 650 and 700 Degree-Sign C. The particles evolve from spheres to cuboids, though the flat portions of the interfaces are small. At larger sizes the precipitates coalesce into discus shapes, and are sometimes boomerang-shaped in cross section after intersection. The rate constant for coarsening increases strongly with equilibrium volume fraction, much more so than predicted by current theories; this is very different from the coarsening behavior of Ni{sub 3}Ge precipitates in normal Ni-Ge alloys and of Ni-Al precipitates in inverse Ni{sub 3}Al alloys. The activation energy for coarsening, 275.86 {+-} 24.17 kJ/mol, is somewhat larger than the result from conventional diffusion experiments, though within the limits of experimental error. Quantitative agreement between theory and experiment, estimated using available data on tracer diffusion coefficients in Ni{sub 3}Ge, is fair, the calculated rate constants exceeding measured ones by a factor of about 15. The particle size distributions are not in very good agreement with the predictions of any theory. These results are discussed in the context of recent theories and observations.

  15. Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

    2016-02-22

    The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

  16. Microemulsion prepared Ni88Pt12 for methane cracking

    KAUST Repository

    Zhou, Lu

    2017-01-16

    Monodispersed NiPt nanoparticles of 10 nm were synthesized by water-in-oil microemulsion. The Ni-Pt alloy structure was stable during the thermal treatment between 330 and 1037 °C, whereas the relatively low temperature range of 600-700 °C was favorable for methane cracking to produce hydrogen and carbon nanotubes.

  17. Solubility of sulfur in Fe-Cr-Ni alloys

    International Nuclear Information System (INIS)

    Bogolyubskij, S.D.; Petrova, E.F.; Rogov, A.I.; Shvartsman, L.A.

    1979-01-01

    The solubility of 35 S was determined in Fe-Cr-Ni alloys in the range of temperatures between 910 and 1050 deg C by the method of radiometric analysis. It was found that the solubility of sulfur increases with the concentration of chromium in alloys with 20% Ni

  18. Stabilization of Reactive MgO Surfaces by Ni Doping

    Science.gov (United States)

    Mazheika, Aliaksei; Levchenko, Sergey V.

    Ni-MgO solid solutions are promising materials for catalytic reduction of CO2 and dry reforming of CH4. To explain the catalytic activity, an ab initio study of Ni-substitutional defects in MgO (NiMg) has been performed. At first, the validation of the theory level was done. We compared results of CCSD(T) embedded-cluster calculations of NiMg formation energies and adsorption energies of CO, CO2 and H2 on them to the HSE(α) hybrid DFT functional with the fraction of the exact exchange α varied between 0 and 1. HSE(0.3) was found to be the best compromise in this study. Our periodic HSE(0.3) calculations show that NiMg defects are most stable at corner sites, followed by steps, and are least stable at (001) terraces. Thus, Ni-doping stabilizes stepped MgO surfaces. The dissociative adsorption of H2 on the terrace is found to be endothermic (+ 1 . 1 eV), whereas on (110) surface with NiMg it is highly exothermic (- 1 . 6 eV). Adsorbed CO2 is also significantly stabilized (- 0 . 6 vs. - 2 . 2 eV). These findings explain recent microcalorimetry measurements of H2 and CO2 adsorption at doped Ni-MgO samples. partially supported by UniCat (Deutsche Forschungsgemeinschaft).

  19. More active and sulfur resistant bimetallic Pd-Ni catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Betti, Carolina; Carrara, Nicolás; Badano, Juan; Lederhos, Cecilia; Vera, Carlos; Quiroga, Mónica, E-mail: mquiroga@fiq.unl.edu.ar [Instituto de Investigaciones en Catálisis y Petroquímica, INCAPE (FIQ-UNL, CONICET), Santa Fe (Argentina)

    2018-02-15

    The influence of the kind of metal precursor and the sequence of impregnation on the properties of Pd-Ni catalysts was evaluated during the test reaction of selective hydrogenation of styrene to ethylbenzene by means of physicochemical characterization. The focus was put on the final hydrogenating activity and the resistance to deactivation by sulfide compounds (thiophene). The used techniques of characterization were ICP, XPS, XDR, TPR, CO chemisorption and TEM. XPS results indicated the presence of different Pd species: Pd{sup δ-}, Pd{sup 0} and Pd{sup δ+}. In the case of the Ni containing catalysts, Ni{sup 0} and NiO species were also detected. These palladium and nickel species would be responsible of the variation of activity and sulfur resistance of the catalysts. NiClPd catalysts had a higher resistance to deactivation by sulfur poisoning. This was associated to a higher concentration of Pd{sup η+}Cl{sub x}O{sub y} species that would prevent the adsorption of thiophene by both steric and electronic effects. It could also be due to the lower concentration of Pd{sup 0} and Ni{sup 0} on these catalysts, as compared to those shown by the PdNiCl catalysts. Both the Pd{sup 0} and Ni{sup 0} species are more prone to poisoning because of their higher electronic availability. (author)

  20. NOVEL RU-NI-S ELECTRODE CATALYST FOR PEMFC

    Science.gov (United States)

    The expected results from this project include: a new formula and preparation procedures for Ru-Ni-S catalyst; demonstration of CO and S tolerance of the new catalyst; a small size PEMFC with Ru-Ni-S catalyst and good performance; an...

  1. Microemulsion prepared Ni88Pt12 for methane cracking

    KAUST Repository

    Zhou, Lu; Harb, Moussab; Hedhili, Mohamed N.; Mana, Noor Al; Basset, Jean-Marie

    2017-01-01

    Monodispersed NiPt nanoparticles of 10 nm were synthesized by water-in-oil microemulsion. The Ni-Pt alloy structure was stable during the thermal treatment between 330 and 1037 °C, whereas the relatively low temperature range of 600-700 °C was favorable for methane cracking to produce hydrogen and carbon nanotubes.

  2. Varying the exchange interaction between NiO nanoparticles

    DEFF Research Database (Denmark)

    Bahl, Christian Robert Haffenden; Mørup, Steen

    2006-01-01

    We demonstrate that exchange interactions between antiferromagnetic nanoparticles of 57Fe-doped NiO can be varied by simple macroscopic treatments. Mössbauer spectroscopy studies of the superparamagnetic relaxation behaviour show that grinding or suspension in water of nanoparticles of NiO can...

  3. Large scale synthesis and characterization of Ni nanoparticles by ...

    Indian Academy of Sciences (India)

    WINTEC

    Ni nanoparticles were mass synthesized by solution reduction process successfully. The influence of the parameters on the particle size of Ni nanoparticles were studied and the ... with a weight % of 0⋅2. .... Hou Y L and Gao S 2004 J. Alloy.

  4. Muon spin rotation measurements on LaNiSn

    International Nuclear Information System (INIS)

    Drew, A.J.; Lee, S.L.; Ogrin, F.Y.; Charalambous, D.; Bancroft, N.; Paul, D. McK.; Takabatake, T.; Baines, C.

    2006-01-01

    The first microscopic investigation of superconductivity in LaNiSn is reported using muon spin rotation. LaNiSn is found to be mainly a type I superconductor in an intermediate state with some evidence for type II behaviour at low temperatures, possibly due to a temperature dependent Ginzburg Landau parameter κ

  5. Violencia sexual contra hombres y niños

    OpenAIRE

    Russell, Wynne

    2007-01-01

    Es bien sabido que los conflictos armados y la violencia sexual contra las mujeres y las niñas suelen ir de la mano. Lo que no se conoce tanto es que los conflictos armados y sus secuelas también suponen un peligro sexual para los hombres y los niños.

  6. Facile synthesis of monodisperse thermally immiscible Ag–Ni alloy ...

    Indian Academy of Sciences (India)

    Administrator

    In the presence of different ligands such as sodium citrate, polyvinyl alcohol and potassium carbonate a mixture of silver oxide and Ag–Ni. ANPs was ... demonstrate antibacterial effects against these germs due to their ... 100 mL deionized water was prepared. .... Heat stability of the Ag–Ni ANPs was tested by annealing.

  7. Electrolytic deposition and corrosion resistance of Zn–Ni coatings

    Indian Academy of Sciences (India)

    Zn–Ni coatings were deposited under galvanostatic conditions on steel substrate (OH18N9). The influence of current density of deposition on the surface morphology, chemical and phase composition was investigated. The corrosion resistance of Zn–Ni coatings obtained at current density 10–25 mA cm-2 are measured, ...

  8. Cd, Zn, Ni and Cu in the Indian Ocean

    NARCIS (Netherlands)

    Saager, Paul M.; Baar, Hein J.W. de; Howland, Robin J.

    1992-01-01

    Vertical profiles of dissolved Cd, Zn, Ni and Cu in the Northwest Indian Ocean (Arabian Sea) exhibit a nutrient type distribution also observed in other oceans. The area is characterized by strong seasonal upwelling and a broad oxygen minimum zone in intermediate waters. However, neither Cd, Zn, Ni

  9. Preliminary screening of Ni(II metal tolerance and dye-decolorizing by Nocardiopsis sp. SD8

    Directory of Open Access Journals (Sweden)

    Ramasamy Thangaraj

    2016-04-01

    Full Text Available Objective: To reveal the screening of metal tolerance and dye-decolorizing of Nocardiopsis sp. Methods: NiSO4 and Congo red dye were used for evaluating the metal tolerance and dyedecolorizing of the randomly selected actinobacterial isolates. Results: Nocardiopsis sp. SD8 showed a better efficiency in Ni(II tolerance, though a longer lag phase was observed for this microorganism grown for 7 days in integrated mismatch negativity. Interestingly, we also found that Nocardiopsis sp. SD8 had dye-decolorizing, hemolytic, lipase and protease activity. Conclusions: The present results revealed the bioremediation of metal resistant and diverse properties of Nocardiopsis sp. SD8 and further investigations are needed to extract and identify the potent molecule.

  10. Alzheimer random walk

    Science.gov (United States)

    Odagaki, Takashi; Kasuya, Keisuke

    2017-09-01

    Using the Monte Carlo simulation, we investigate a memory-impaired self-avoiding walk on a square lattice in which a random walker marks each of sites visited with a given probability p and makes a random walk avoiding the marked sites. Namely, p = 0 and p = 1 correspond to the simple random walk and the self-avoiding walk, respectively. When p> 0, there is a finite probability that the walker is trapped. We show that the trap time distribution can well be fitted by Stacy's Weibull distribution b(a/b){a+1}/{b}[Γ({a+1}/{b})]-1x^a\\exp(-a/bx^b)} where a and b are fitting parameters depending on p. We also find that the mean trap time diverges at p = 0 as p- α with α = 1.89. In order to produce sufficient number of long walks, we exploit the pivot algorithm and obtain the mean square displacement and its Flory exponent ν(p) as functions of p. We find that the exponent determined for 1000 step walks interpolates both limits ν(0) for the simple random walk and ν(1) for the self-avoiding walk as [ ν(p) - ν(0) ] / [ ν(1) - ν(0) ] = pβ with β = 0.388 when p ≪ 0.1 and β = 0.0822 when p ≫ 0.1. Contribution to the Topical Issue "Continuous Time Random Walk Still Trendy: Fifty-year History, Current State and Outlook", edited by Ryszard Kutner and Jaume Masoliver.

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

    Science.gov (United States)

    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.

  12. Influence of Plant Growth Regulators and Humic Substance on the Phytoremediation of Nickel in a Ni-Polluted Soil

    Directory of Open Access Journals (Sweden)

    Mahshid Shafigh

    2017-06-01

    Full Text Available Introduction: Plants can uptake, bioaccumulate and immobilize different metals in their tissues. Phytoremediation technique has been used to remove hazardous substances including heavy metals from the environment. Assisted phytoremediation is usually the process of applying a chemical additive to heavy metal contaminated soils to enhance the metal uptake by plants. The main objective of present study was to investigate the effectiveness of plant growth regulators (PGRs and a humic substance (HS on Ni phytoremediation by maize in a Ni-pollutrd calcareous soil. Materials and Methods: The experiment designed as a 5×3 factorial trial arranged in a completely randomized design with three replicates. Three kilograms of soil was placed in plastic pots and pots were watered with distilled water to field capacity and maintained at this moisture level throughout the experiment by watering the pots to a constant weight. The soils were polluted with 250 mg Ni Kg-1 as Ni-nitrate Ni (NO32. Six maize (Zea mays L. seeds were planted 2 cm deep in soil and thinned to three uniform stands 1 week after emergence. Treatments consisted of three levels of soil application of commercially humic substance, HS, (0, 3, and 6 mg kg as Humax 95-WSG containing about 80% humic acid, and about 15% fulvic acid and five levels of PGRs (0 or 10 µM GA3, IAA, BAP and SA. The HS was applied as split doses in three times at 15 day intervals along with irrigation water. The seedlings were exposed to aqueous solutions of HS 16 days after sowing for the first time. Prepared solutions of PGRs were sprayed three times at 15 day intervals from emergence. Seven weeks after planting, shoots were harvested and roots were separated from soil carefully, both parts were rinsed with distilled water and dried at 65°C for 72 h, weighed, ground, and dry meshed at 550°C. Root and shoot dry matter and Ni concentration and uptake and phytoremediation criteria were considered as plant responses

  13. Mixed conductor anodes: Ni as electrocatalyst for hydrogen conversion

    DEFF Research Database (Denmark)

    Primdahl, S.; Mogensen, Mogens Bjerg

    2002-01-01

    Five types of anodes for solid oxide fuel cells (SOFC) are examined on an yttria-stabilised zirconia (YSZ) electrolyte by impedance spectroscopy at 850 degreesC in hydrogen. The examined porous anodes are a Ni/Zr(0.92)Y(0.16)O(2.08) (Ni/YSZ) cermet, a Ni/Ce(0.9)Gd(0.1)O(1.95) (Ni/CGI) cermet, a Ce......(0.6)Gd(0.4)O(1.8) (CG4) ceramic, a La(0.75)Sr(0.25)Cr(0.97)V(0.03)O(3) (LSCV) ceramic and a Ti(0.22) Y(0.16)Zr(0.92)O(2.52) (TiYSZ) ceramic, Addition of small amounts ( approximate to I w/o) of Ni to the electrode surface is found to improve electrode performance on mixed electronic and ionic...

  14. Defects in codoped NiO with gigantic dielectric response

    Science.gov (United States)

    Wu, Ping; Ligatchev, Valeri; Yu, Zhi Gen; Zheng, Jianwei; Sullivan, Michael B.; Zeng, Yingzhi

    2009-06-01

    We combine first-principles, statistical, and phenomenological methods to investigate the electronic and dielectric properties of NiO and clarify the nature of the gigantic dielectric response in codoped NiO. Unlike previous models which are dependent on grain-boundary effects, our model based on small polaron hopping in homogeneous material predicts the dielectric permittivity (104-5) for heavily Li- and MD -codoped NiO (MD=Ti,Al,Si) . Furthermore, we reproduce the experimental trends in dielectric properties as a function of the dopants nature and their concentrations, as well as the reported activation energies for the relaxation in Li- and Ti-codoped NiO (0.308 eV or 0.153 eV depending on the Fermi-level position). In this study, we demonstrate that small polaron hopping on dopant levels is the dominant mechanism for the gigantic dielectric response in these codoped NiO.

  15. Microstructure and mechanical properties of Cu-Ni-Si alloys

    International Nuclear Information System (INIS)

    Monzen, Ryoichi; Watanabe, Chihiro

    2008-01-01

    The microstructure and mechanical properties of 0.1 wt.% Mg-added and Mg-free Cu-2.0 wt.% Ni-0.5 wt.% Si alloys aged at 400 deg. C have been examined. The addition of Mg promotes the formation of disk-shaped Ni 2 Si precipitates. The Cu-Ni-Si-Mg alloy exhibits higher strength and resistance to stress relaxation than the Cu-Ni-Si alloy. The higher strength or stress relaxation resistance is attributable to the reduction in inter-precipitate spacing by the Mg addition or the drag effect of Mg atoms on dislocation motion. The Cu-Ni-Si alloy with a large grain size of 150 μm shows higher stress relaxation resistance than the alloy with a small grain size of 10 μm because of a lower density of mobile dislocations in the former alloy

  16. Microstructure and mechanical properties of Cu-Ni-Si alloys

    Energy Technology Data Exchange (ETDEWEB)

    Monzen, Ryoichi [Division of Innovative Technology and Science, Graduate School of Natural Science and Technology, Kanzawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)], E-mail: monzen@t.kanazawa-u.ac.jp; Watanabe, Chihiro [Division of Innovative Technology and Science, Graduate School of Natural Science and Technology, Kanzawa University, Kakuma-machi, Kanazawa 920-1192 (Japan)

    2008-06-15

    The microstructure and mechanical properties of 0.1 wt.% Mg-added and Mg-free Cu-2.0 wt.% Ni-0.5 wt.% Si alloys aged at 400 deg. C have been examined. The addition of Mg promotes the formation of disk-shaped Ni{sub 2}Si precipitates. The Cu-Ni-Si-Mg alloy exhibits higher strength and resistance to stress relaxation than the Cu-Ni-Si alloy. The higher strength or stress relaxation resistance is attributable to the reduction in inter-precipitate spacing by the Mg addition or the drag effect of Mg atoms on dislocation motion. The Cu-Ni-Si alloy with a large grain size of 150 {mu}m shows higher stress relaxation resistance than the alloy with a small grain size of 10 {mu}m because of a lower density of mobile dislocations in the former alloy.

  17. Physical and mechanical metallurgy of NiAl

    Science.gov (United States)

    Noebe, Ronald D.; Bowman, Randy R.; Nathal, Michael V.

    1994-01-01

    Considerable research has been performed on NiAl over the last decade, with an exponential increase in effort occurring over the last few years. This is due to interest in this material for electronic, catalytic, coating and especially high-temperature structural applications. This report uses this wealth of new information to develop a complete description of the properties and processing of NiAl and NiAl-based materials. Emphasis is placed on the controlling fracture and deformation mechanisms of single and polycrystalline NiAl and its alloys over the entire range of temperatures for which data are available. Creep, fatigue, and environmental resistance of this material are discussed. In addition, issues surrounding alloy design, development of NiAl-based composites, and materials processing are addressed.

  18. Natural Ni speciation in the Callovo-Oxfordian clay rocks: implications for potential 63Ni isotopic exchange and retention mechanisms

    International Nuclear Information System (INIS)

    Grangeon, S.; Tournassat, C.; Schaefer, T.; Lerouge, C.; Wille, G.; Giffaut, E.

    2010-01-01

    Document available in extended abstract form only. In the perspective of deep underground long-term nuclear waste storage, 63 Ni is considered as a priority radio-element to be studied. 63 Ni behaviour prediction is made difficult mainly because its geochemical behaviour is still subject to debate. For instance, the solubility of Ni simple compounds at high pH is ill-defined, and the knowledge on solubility control phases is still pending. Clay rocks such as Callovo-Oxfordian (COx) contain non negligible amounts of natural and stable isotopes of Ni. As a consequence, a good understanding of the natural speciation of Ni in the formation could help to understand 63 Ni controls in this environment, including long term isotopic exchange with naturally present Ni. We focused our study on the COx formation, where the Bure (France) ANDRA underground research laboratory is located. Speciation of naturally occurring Ni was studied by combining chemical, microscopic and spectrometric methods. Chemical methods consisted of total rock analyses and sequential extractions on various COx samples representative of the variability of the formation (from carbonate rich samples to clay rich samples). This method enabled quantifying the main Ni reservoirs. Physical methods were used to get a closer look at the Ni-bearing phases. Optical and scanning electron microscopy techniques were used to identify and isolate minerals from thin rock sections, originating from different geological horizons. Chemical results indicate that the mean Ni concentration in the Callovo-Oxfordian clay rock is of ∼30 ppm (10 -6 g/g). Identified Ni-bearing minerals were mainly primary minerals (biotite, chlorite, muscovite), calcite and pyrite; organic matter being also observed. Electron microprobe and X-ray fluorescence analyses were performed in order to quantify the amounts and variability of Ni contents in these different Callovo-Oxfordian components. Ni is occasionally present in primary minerals with

  19. 4.0-nm-thick amorphous Nb–Ni film as a conducting diffusion barrier layer for integrating ferroelectric capacitor on Si

    Energy Technology Data Exchange (ETDEWEB)

    Dai, X.H. [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China); College of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401 (China); Guo, J.X.; Zhang, L.; Jia, D.M.; Qi, C.G.; Zhou, Y.; Li, X.H.; Shi, J.B.; Fu, Y.J.; Wang, Y.L.; Lou, J.Z. [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China); Ma, L.X. [Department of Physics, Blinn College, Bryan, TX 77805 (United States); Zhao, H.D. [College of Electronic and Information Engineering, Hebei University of Technology, Tianjin 300401 (China); Liu, B.T., E-mail: btliu@hbu.cn [Hebei Key Lab of Optic-electronic Information and Materials, College of Physics Science & Technology, Hebei University, Hebei 071002 (China)

    2015-10-05

    Highlights: • 4-nm-thick amorphous Nb–Ni film is first used as the conducting barrier layer. • No obvious interdiffusion/reaction can be found from the LSCO/PZT/LSCO/Nb–Ni/Si. • The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties. • Ultrathin amorphous Nb–Ni film is ideal to fabricate silicon-based FRAM. - Abstract: We have successfully integrated La{sub 0.5}Sr{sub 0.5}CoO{sub 3}/PbZr{sub 0.4}Ti{sub 0.6}O{sub 3}/La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO/PZT/LSCO) capacitors on silicon substrate using a ∼4.0-nm-thick amorphous Nb–Ni film as the conducting diffusion barrier layer. Transmission electron microscopy technique confirms that the Nb–Ni film is still amorphous after fabrication of the capacitors, and the interfaces related to Nb–Ni are clean and sharp without any findable interdiffusion/reaction. The LSCO/PZT/LSCO capacitor, measured at 5 V, possesses very good properties, such as large remanent polarization of ∼22.1 μC/cm{sup 2}, small coercive voltage of ∼1.27 V, good fatigue-resistance, and small pulse width dependence, implying that ultrathin amorphous Nb–Ni film is ideal as the conducting diffusion barrier layer to fabricate high-density silicon-based ferroelectric random access memories.

  20. Wear behavioral study of as cast and 7 hr homogenized Al25Mg2Si2Cu4Ni alloy at constant load

    Science.gov (United States)

    Harlapur, M. D.; Sondur, D. G.; Akkimardi, V. G.; Mallapur, D. G.

    2018-04-01

    In the current study, the wear behavior of as cast and 7 hr homogenized Al25Mg2Si2Cu4Ni alloy has been investigated. Microstructure, SEM and EDS results confirm the presence of different intermetallic and their effects on wear properties of Al25Mg2Si2Cu4Ni alloy in as cast as well as aged condition. Alloying main elements like Si, Cu, Mg and Ni partly dissolve in the primary α-Al matrix and to some amount present in the form of intermetallic phases. SEM structure of as cast alloy shows blocks of Mg2Si which is at random distributed in the aluminium matrix. Precipitates of Al2Cu in the form of Chinese script are also observed. Also `Q' phase (Al-Si-Cu-Mg) be distributed uniformly into the aluminium matrix. Few coarsened platelets of Ni are seen. In case of 7 hr homogenized samples blocks of Mg2Si get rounded at the corners, Platelets of Ni get fragmented and distributed uniformly in the aluminium matrix. Results show improved volumetric wear resistance and reduced coefficient of friction after homogenizing heat treatment.