oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Nickel hydroxide modified electrodes for urea determination  [cached]
Ricardo Curilazo,Marcelo Rodrigues da Silva,Luiz Henrique Dall′Antonia
Semina : Ciências Exatas e Tecnológicas , 2007,
Abstract: Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO3)2 0,05 mol L ?1 on ITO electrodes (Tin oxide doped with Indium) on PET-like plastic film, applying a current of - 0,1 A cm ?2 during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?1, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II)/Ni(III). A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH)2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?1 and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?1, the behavior is linear and the sensibility found was of 20,3 mA cm?2 (mol L?1)?1, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.
CHEMICAL DISSOLUTION OF NICKEL (II) OXIDE AND HYDROXIDE IN AMINO ACID SOLUTIONS Химическое растворение оксида и гидроксида никеля в растворах аминокислот Х м чне розчинення оксиду та г дроксиду н келю в розчинах ам нокислот  [cached]
S.V. Ivanov
Proceedings of National Aviation University , 2005,
Abstract: Simulation experimenting has been used to analyze thermodynamics of chemical dissolution of nickel (II) oxide and hydroxide in solutions containing various amino acids. Allowance for complexation, protonation and hydrolysis processes has been found to be a must for adequate description of chemical processes. Методом математического моделирования исследован процесс химического растворения оксида и гидроксида никеля ( ) в растворах аминокислот. Показано, что при рН 3–8, когда аминокислоты существуют в форме цвиттер-иона, термодинамическая стабильность соединений никеля линейно зависит от отношения констант / . При рН 8–10 наблюдается минимум энергии Гиббса. Его величина линейно зависит от отношения констант / , а относительное его снижение определяется величиной константы . При рН>10 термодинамическая стабильность соединений никеля линейно уменьшается с ростом константы . В связи с этим для адекватного описания процесса растворения необходим учет процессa комплексообразования, протонирования и гидролиза. Методом математичного моделювання досл джено процеси х м чного розчинення оксиду та г дроксиду н келю ( ) у розчинах ам нокислот. Показано, що при рН 3–8, коли ам нокислоти снують у форм цв ттер- ону, термодинам чна стаб льн сть сполук н келю л н йно залежить в д сп вв дношення констант / . При рН 8–10 спостер га ться м н мум енерг Г ббса. Його величина л н йно залежить в д сп вв дношення констант / , а в дносне зниження визнача ться величиною константи . При рН>10 термодинам чна стаб льн сть сполук н келю л н йно зменшу ться з зб льшенням константи . У зв’язку з цим для адекватного опису процесу розчинення потр бне врахування процесу комплексоутворення, протонування г дрол зу.
Structural and electrochemical studies on the utilization of Cerium (Ce3+) as an additive for nickel hydroxide electrode  [cached]
Marcio Vidotti,Carlos M. Chague,Susana I. Córdoba de Torresi
Semina : Ciências Exatas e Tecnológicas , 2007,
Abstract: This paper describes electrochemical and spectroscopic studies on the utilization of cerium atoms as additives for nickel hydroxide electrodes. Thin films were galvanostatically grown with different amounts of cerium and mixed electrodes were studied by electrochemical measurements and the spectroscopic technique. The electrochromic behavior was investigated by “in situ” experiments , while the amount of species was determined by ICP-OES. The addition of cerium to nickel hydroxide electrodes increases durability, due to modifications in the structural properties, as seen by Raman spectras.
Electronic properties of isolated nickel in diamond
Larico, R.;Justo, J. F.;Machado, W. V. M.;Assali, L. V. C.;
Brazilian Journal of Physics , 2004, DOI: 10.1590/S0103-97332004000400038
Abstract: isolated nickel impurities in diamond have been investigated using the spin-polarized full-potential linearized augmented plane wave total energy method. the electronic and atomic structures, symmetries, transition energies, and formation energies of substitutional and interstitial ni impurities in diamond were computed. the results were discussed in the context of the electrically active centers in synthetic diamond.
A Theoretical Study on a Reaction of Iron(III) Hydroxide with Boron Trichloride by Ab Initio Calculation  [PDF]
Kazuhide Ichikawa,Toshiyuki Myoraku,Akinori Fukushima,Yoshio Ishihara,Ryuichiro Isaki,Toshio Takeguchi,Akitomo Tachibana
Physics , 2009, DOI: 10.1016/j.theochem.2009.08.026
Abstract: We investigate a reaction of boron trichloride (BCl3) with iron(III) hydroxide (Fe(OH)3) by ab initio quantum chemical calculation as a simple model for a reaction of iron impurities in BCl3 gas. We also examine a reaction with water. We find that compounds such as Fe(Cl)(OBCl2)2(OHBCl2) and Fe(Cl)2(OBCl2)(OHBCl2) are formed while producing HCl and reaction paths to them are revealed. We also analyze the stabilization mechanism of these paths using newly-developed interaction energy density derived from electronic stress tensor in the framework of the Regional DFT (Density Functional Theory) and Rigged QED (Quantum ElectroDynamics).
The Structure and Electrochemical Performance of α/β Mutually Embedded Nickel Hydroxide
α/β互嵌氢氧化镍电极活性材料的结构和电化学性能

LI Yanwei LI Yuexiao YAO Jinhuan LIU Changjiu ZHU Wenfeng College of Chemistry,Bioengineering,Guilin University of Technology,Guilin,Key Laboratory of New Processing Technology for Nonferrous Metals,Materials of Ministry of Education,Guilin,
李延伟
,李月晓,姚金环,刘长久,朱文凤

材料研究学报 , 2011,
Abstract: α/β mutually embedded nickel hydroxide has been synthesized by chemical coprecipitation method. The microstructure and surface morphology of the prepared samples were analyzed by X–ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). The electrochemical performance of the prepared sample was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge discharge tests. Compared to the pure β nickel hydroxide, the α/β mutually embedded nickel hydroxide shows a higher electrochemical reaction activity, lower electrochemical reaction impedance, higher discharge capacity, and higher discharge voltage. Moreover, α/β mutually embedded nickel hydroxide has better cyclic performance.
First Principles Study of Electronic Structure, Structural Properties and Superconductivity of Nickel Hydride  [cached]
Shunmugam KANAGAPRABHA,Asvini MEENAATCI,RATNAVELU Rajeswarapalanichamy,Kombiah IYAKUTTI
Walailak Journal of Science and Technology , 2012, DOI: 10.2004/vol10iss1ppaccepted
Abstract: First principles calculation were performed using Tight-binding LMTO method with Local density approximation (LDA) and Atomic sphere approximation (ASA) to understand the electronic properties of Nickel Hydride. The equilibrium geometries, the electronic band structure, the total and partial DOS are obtained under various pressures and are analyzed in comparison with the available experimental and theoretical data. The most stable structure of NiH is NaCl structure, NiH2 is CaF2 structure and NiH3 is AlH3 structure at normal pressure. Our result indicates that the maximum storage capacity achieved was 4.9% for NiH3. In particular there is a non occurrence of superconductivity in NiH. But an increase in Tc is predicted due to the addition of H atoms. The obtained Tc values for NiH2 and NiH3 are 5K and 10K respectively at normal pressure. Also, it is found that the Tc value increases as the pressure increases.
Calculation of electronic properties of amorphous alloys  [PDF]
J. C. Swihart,D. M. C. Nicholson,G. M. Stocks,Y. Wang,W. A. Shelton,H. Yang
Physics , 1995, DOI: 10.1016/S0022-3093(96)00315-8
Abstract: We describe the application of the locally-self-consistent-multiple-scattering (LSMS)[1] method to amorphous alloys. The LSMS algorithm is optimized for the Intel XP/S-150, a multiple-instruction-multiple-data parallel computer with 1024 nodes and 2 compute processors per node. The electron density at each site is determined by solving the multiple scattering equation for atoms within a specified distance of the atom under consideration. Because this method is carried out in real space it is ideal for treating amorphous alloys. We have adapted the code to the calculation of the electronic properties of amorphous alloys. In these calculations we determine the potentials in the atomic sphere approximation self consistently at each site, unlike previous calculations[2] where we determined the potentials self consistently at an average site. With these self-consistent potentials, we then calculate electronic properties of various amorphous alloy systems. We present calculated total electronic densities of states for amorphous Ni$_{80}$P$_{20}$ and Ni$_{40}$Pd$_{40}$P$_{20}$ with 300 atoms in a supercell.
Atomic, electronic and magnetic structure of graphene/iron and nickel interfaces: theory and experiment  [PDF]
D. W. Boukhvalov,Yu. N. Gornostyrev,M. A. Uimin,A. V. Korolev,A. Ye Yermakov
Physics , 2014,
Abstract: First-principles calculations of the effect of carbon coverage on the atomic, electronic and magnetic structure of nickel and iron substrates demonstrate insignificant changes in the interatomic distances and magnetic moments on the atoms of the metallic substrates. The coverage of the iron surface by mono- and few-layer graphene induces significant changes in the orbital occupancies and exchange interactions between the layers in contrast to the case of a nickel substrate for which changes in the orbital ordering and exchange interactions are much smaller. Experimental measurements demonstrate the presence of ferromagnetic fcc-iron in Fe@C nanoparticles and the superparamagnetic behavior of Ni@C nanoparticles.
Magnetism and electronic structure calculation of SmN  [PDF]
C. Morari,F. Beiu?eanu,I. Di Marco,L. Peters,E. Burzo,S Mican,L. Chioncel
Physics , 2014, DOI: 10.1088/0953-8984/27/11/115503
Abstract: The results of the electronic structure calculations performed on SmN by using the LDA+U method with and without including the spin-orbit coupling are presented. Within the LDA+U approach, a N(2$p$) band polarization of $\simeq 0.3\ \mu_B$ is induced by Sm(4$f$)-N(2$p$) hybridization, and a half-metallic ground state is obtained. By including spin-orbit coupling the magnetic structure was shown to be antiferromagnetic of type II, with Sm spin and orbital moments nearly cancelling. This results into a semiconducting ground state, which is in agreement with experimental results.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.