• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.574-582
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• 1991

The CO molecules adsorbed on Ni(111) surface is studied in the cluster approximation employing EH method with self-consistent charge iteration. The effect of CO coverage is simulated by allowing the variation of valence state ionization potentials of each Ni atom in model cluster according to the self-consistent charge iteration method. The CO coverage dependent C-O stretching frequency shift, adsorption site conversion, and metal work function change are attributed to the charge transfer between metal surface and adsorbate. For CO/Ni(111) system, net charge transfer from Ni surface to chemisorbed CO molecules makes surface Ni atoms be more positive with increasing coverage, and lowers Ni surface valence band. This leads to a weaker interaction between metal surface valence band and Co $2{\pi}^{\ast}$ MO, less charge transfer to a single CO molecule, and the bule shift of C-O stretching frequency. Further increase of coverage induces the conversion of 3-fold site CO to lower coordination site CO as well as the blue shift of C-O stretching frequency. This whole process is accompanied by the continuous increase of metal work function.

• Bulletin of the Korean Chemical Society
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• v.24 no.8
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• pp.1150-1154
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• 2003

The reactions of [Ni(L)(H₂O)₂]Cl₂ (L = 2,5,9,12-tetramethyl-1,4,8,11-tetraazacyclotetradecane) with terephtalate (tp) and 2,5-pyridinedicarboxylate (pdc) generate one-dimensional nickel(II) complexes, [Ni(L)(H₂O)₂](tp) · ₄H₂O (1) and [Ni(L)(H₂O)₂](pdc)·₄H₂O (2). The structures have been characterized by X-ray crystallography, magnetic susceptibility and spectroscopy. The crystal structures of 1 and 2 show a distorted octahedral coordination geometry around the Ni(II) ion, with secondary amines of the macrocycle and two water molecules at the trans position. Complexes 1 and 2 display the one-dimensional hydrogen-bonded infinite chains. The magnetic behavior of all compounds exhibits weak interchain antiferromagnetic interactions with J values of -1.09(3) for 1 and -1.14(2) cm-1 for 2.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.2
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• pp.82-86
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• 2002

A series of $Ni_xZn_yFe_{3-x-y}O_4$ films were prepared by spin-spray ferrite plating on glass substrates from aqueous solution at $90[^{\circ}C]$. The magnetic properties in terms of contents of Ni and Zn in the plated films are presented. All the films are polycrystalline with spinel structure. At x+y=0.58, the film presents preferential orientation. As composition of y in the films increases grain size and void in the films increases, while saturation magnetization and coercive force of the films decrease.

• Journal of Korean Society for Atmospheric Environment
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• v.5 no.1
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• pp.52-61
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• 1989

The hydrodenitrogenation of quinoline dissolved in n-heptane was studied over sulfided Ni-Mo/$\gamma-Al_2O_3$ catalyst at the range of the temperature between 553 K and 673 and the total pressure between $20 \times 10^5$ Pa and $60 \times 10^5$ Pa in a fixed bed flow reactor. Quinoline conversion was very high at relatively low temperature and total pressure, and decreased with quinoline partial pressure. The thermodynamic equilibrium between quinoline and Py-THQ existed in wide ranges of experimental conditions and shifted in favor of quinoline at higher temperature. At the range of the temperature betwwen 553 K and 673 K and at the total pressure $60 \times 10^5$ Pa, the quinoline reaction rate was 1st order with respect to the concentr4ation of quinoline and its apparent activation energy was 7.15 Kcal/mole.

• Journal of the Korean Magnetics Society
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• v.16 no.6
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• pp.279-282
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• 2006

Magnetic tunnel junctions (MTJs), which consisted of amorphous ferromagnetic NiFeSiB free layers, were investigated. The NiFeSiB layers were used to substitute for the traditionally used CoFe and/or NiFe layers with the emphasis being given to obtaining an understanding of the effect of the amorphous free layer on the switching characteristics of the MTJs. $Ni_{16}Fe_{62}Si_{8}B_{14}$ has a lower saturation magnetization ($M_{s}:\;800\;emu/cm^{3}$) than $Co_{90}Fe_{10}$ and a higher anisotropy constant ($K_{u}:\;2700\;erg/cm^{3}$) than $Ni_{80}Fe_{20}$. The $Si/SiO_{2}/Ta$ 45/Ru 9.5/IrMn 10/CoFe $7/AlO_{x}/CoFeSiB\;(t)/Ru\;60\;(in\;nanometers)$structure was found to be beneficial for the switching characteristics of the MTJ, leading to a reduction in the coercivity ($H_{c}$) and an increase in the sensitivity resulted from its lower saturation magnetization and higher uniaxial anisotropy. Furthermore, by inserting a very thin CoFe layer at the tunnel barrier/NiFeSiB interface, the TMR ratio and switching squareness were improved more with the increase of NiFeSiB layer thickness up to 11 nm.

• Journal of Powder Materials
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• v.24 no.2
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• pp.87-95
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• 2017

Lithium silicate, a lithium-ion conducting ceramic, is coated on a layer-structured lithium nickel manganese oxide ($LiNi_{0.7}Mn_{0.3}O_2$). Residual lithium compounds ($Li_2CO_3$ and LiOH) on the surface of the cathode material and $SiO_2$ derived from tetraethylorthosilicate are used as lithium and silicon sources, respectively. Powder X-ray diffraction and scanning electron microscopy with energy-dispersive spectroscopy analyses show that lithium silicate is coated uniformly on the cathode particles. Charge and discharge tests of the samples show that the coating can enhance the rate capability and cycle life performance. The improvements are attributed to the reduced interfacial resistance originating from suppression of solid-electrolyte interface (SEI) formation and dissolution of Ni and Mn due to the coating. An X-ray photoelectron spectroscopy study of the cycled electrodes shows that nickel oxide and manganese oxide particles are formed on the surface of the electrode and that greater decomposition of the electrolyte occurs for the bare sample, which confirms the assumption that SEI formation and Ni and Mn dissolution can be reduced using the coating process.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.1
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• pp.49-58
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• 2000

Thermal spraying is one of the most common surface coating techniques to be used for many applications and flame spraying covers a wide range of different materials which can be coated onto various substrates. The purpose of this study is to investigate the effects of mixed ratio in composite coatings on the mechanical and anti-corrosion properties. The five different types of composite coatings were made with $Al_2O_3$ ceramic and Ni-alloy powder on the mild steel substrate by flame spraying method. The mechanical properties such as microhardness, adhesive strength and erosion resistance and corrosion resistance were tested for the sprayed coating specimens. The results obtained are summarized as follows; 1. The composite coating layers greatly improve the microstructure, erosion resistance and adhesive strength by increasing the content of Ni-Al alloy. 2. Microhardness of the compsite coating layer is decreased by increasing the content of Ni-Al alloy. 3. The anti-corrosion properties is considerably improved by increasing the compsite rate of Ni-Al alloy.

• Journal of Surface Science and Engineering
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• v.51 no.4
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• pp.231-236
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• 2018

We report p-type electrical characteristics of the amorphous $La_2NiO_{4+{\delta}}$ thin films which were sputtered on the glass substrates using an RF sputtering system. As-deposited thin films at room temperature and $300^{\circ}C$ were amorphous in nature. Post-annealing of the thin film samples over $400^{\circ}C$ resulted in the nano-crystallization of the $La_2NiO_{4+{\delta}}$. The electrical properties of the films were much dependent on the oxygen partial pressure, temperature of the post-annealing and sputtering ambient. The as-deposited samples at room temperature show a hole concentration of $7.82{\times}10^{13}cm^{-3}$, and it could be increased as high as $3.51{\times}10^{22}cm^{-3}$ when the films were post-annealed in an oxygen atmosphere at $500^{\circ}C$. Such p-type conductivity behavior of the $La_2NiO_{4+{\delta}}$ films suggests that the amorphous and nano-crystallized $La_2NiO_{4+{\delta}}$ films have potential for the application as p-type semiconductive or conductive materials at low temperatures where material diffusion is limited.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.183-183
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• 2011

Multiferroic materials have been widely studied in recent years, because of their abundant physics and potential applications in the sensors, data storage, and spintronics. $BiFeO_3$ is one of the well-known single-phase multiferroic materials with $ABO_3$ structure and G-type antiferromagnetic behavior below the Neel temperature $T_N$ ~ 643 K, but the ferroelectric behavior below the Curie temperature $T_c$~1,103 K. In this study, the $BiFe_{1-x}Ni_xO_3$ (x=0 and 0.05) bulk ceramics were prepared by solid-state reaction and rapid sintering with high-purity $Bi_2O_32$, $Fe_3O_4$ and NiO powders. The powders of stoichiometric proportions were mixed, as in the previous investigations, and calcined at 450$^{\circ}C$ for $BiFe_{1-x}Ni_xO_3$ for 24 h. The obtained powders were grinded, and pressed into 5-mm-thick disks of 1/2-inch diameter. The disks were directly put into the oven, which has been heated up to 800$^{\circ}C$ and sintered in air for 20 min. The sintered disks were taken out from the oven and cooled to room temperature within several min. The phase of samples was checked at room temperature by powder x-ray diffraction using a Rigaku Miniflex diffractometer with Cu K${\alpha}$ radiation. The Raman measurements were carried out by employing a hand-made Raman spectrometer with 514.5-nm-excitation $Ar^+$ laser source under air ambient condition on a focused area of 1-${\mu}m$ diameter. The field-dependent magnetization measurements were performed with a superconducting quantum-interference-device magnetometer.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.435-441
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• 1994

The inclusion compound constituted with three-dimensional metal-complex $Cd(pn)Ni(CN)_4$ has been prepared and determined the crystal structure from single crystal X-ray diffraction data. Crystal data are as follows: $[Cd(pn)Ni(CN)_4]{\cdot}0.5(CH_3COCH_3{\cdot}H_2O)$, Fw = 387.35, Orthorhombic, $Pn2_1a$, a = 13.950(3) $\AA$, b = 26.713(7) $\AA$, c = 7.628(1) $\AA$, V = 2843(1) $\AA^3$, Z = 4, $D_x=1.81 gcm^{-3}$, $\mu(MoK{\alpha})$ = $28.153 cm^{-1}$, T = 297K, final R = 0.0418 for 3521($F_0>3{\sigma}(F_0)$). The metal-complex host provides tunnel cavity, similar to thiourea inclusion compounds, accommodated guest molecules $(=CH_3COCH_3\;and\;$H_2O).$ The stoichiometric host: guest ratio is 0.5. The title inclusion compound reveals another evidence for the host-selectivity, that is, the branched aliphatic guest molecule leads T-type host structure.