• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
• /
• pp.121-121
• /
• 2003

NiO thin films are very attractive for use as an antiferromagnetic layer, p-type transparent conducting films, in electrochromic devices and functional sensor layer for chemical sensors, due to their excellent chemical stability, as well as optical, electrical and magnetic properties. In addition, (100)- and (111)-oriented NiO films can be used as buffer layers on which to deposit other oriented oxide films, such as c-axis-oriented perovskite-type ferromagnetic films and superconducting films, because of the similarity in symmetry of oxygen ion lattice and lattice constants between the NiO films and the oriented oxide films. Thus, controlling the crystallographic orientation and surface roughness of the NiO films for a buffer layer are very important.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2007년도 추계학술대회 논문집
• /
• pp.63-66
• /
• 2007

Reformers which produce hydrogen from natural gas are essential for the operation of residential PEM fuel cells. For this purpose, steam-methane reforming reactions with Ni catalysts is primarily utilized. Commercial Ni catalysts are generally made to have porous pellet shapes in which Ni catalyst particles are uniformly dispersed over Alumina support structures. This study numerically investigates the reduction of catalyst effectiveness due to the mass transport resistances posed by porous structures of spherical catalyst pellets. The multi-component diffusion through porous media and the accurate kinetics of reforming reaction is fully considered in the numerical model. The preliminary results on the variation of the effectiveness factor according to different operation conditions are presented, which is planned to be used to develop correlations in future studies.

• 한국전기전자재료학회논문지
• /
• 제12권1호
• /
• pp.94-102
• /
• 1999

Ni/CGO cermets were fabricated as the anode for SOFC which uses CGO as the electrolyte. And their electrical conductivity, electrochemical reactivity, and thermal expansion coefficient were optimized through the variation of NiO/CGO particle size ration and their composition. The electrical conductivity of the cermet was increased abruptly at a certain Ni content and the percolation concentration was decreased with the decreasing particle size ratio. Anodic overpotential was also decreased with the decreasing particle size ratio. For a fixed ratio it showed a minimum value at 50 wt.%. Thermal expansion coefficient was increased monotonically with increasing Ni contents, however it did not depend on the size ratio. With three properties taken into account, the cermet of particle size ration of 0.03 and composition of 50 wt.% was judged to be optimal as the anode.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.185-188
• /
• 2000

Crystal orientation of Ni$_{18}$ $Fe_{19}$ thin films prepared by facing targets sputtering system was investigated. FTS system can deposit a high quality thin film and control deposition conditions in wide range. T he crystallographic characteristics of Ni$_{18}$ $Fe_{19}$ thin films on variation of thickness and substrate tempera ture was investigated by XRD and AFM. As a result, we obtained Ni$_{18}$ $Fe_{19}$ thin films prepared at subst rate temperature room temperature, thickness 160nm and over revealed good crystal orientation to [111] direction.irection.

• Bulletin of the Korean Chemical Society
• /
• 제12권5호
• /
• pp.574-582
• /
• 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.

• 한국전기전자재료학회논문지
• /
• 제17권1호
• /
• pp.46-51
• /
• 2004

The cause for the variation of the initial permeability according to the Co substitution of Ni-Zn ferrite used in the LC resonance filter for the power line communication is studied. The initial permeability decreases as the quantity of Co diminishes, and the saturation magnetization increases as the quantity increases. Because the sintering density and the microstructure of ferrite show little change, the variation of the initial permeability can't be explained by the density, microstructure nor the saturation magnetization factor. The magnetocrystalline anisotropy increases, similar with the saturation magnetization, as the quantity of Co increases. The increase of magnetocrystalline anisotropy value makes the domain wall energy grow, which leads to the decrease of the initial permeability, because there's linear law between the magnetocrystalline anisotropy and the domain wall energy. The resonance frequency to Co substitution moved to high frequency band, due to the close relationship with domain wall energy, Initial permeability decreaed a little with an increase of Co contents, but resonace frequency moved to high frequency band. as a result of that, when Co was added 0.05 mol, initial permeability and resonace frequency was 75 and 25 MHz respectively.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
• /
• pp.764-767
• /
• 2004

This study was to measure the minuteness structure, dielectric properties of (0.3-x)PMN - XPSS-0.7PZT+0.5wt%NiO+0.5wt%$MnO_2$(x=0.05, 0.10, 0.15, 0.20, 0.25)ceramics according to sintering temperature and PSS moi percentage after manufacturing the specimens with a general method. the results of this study were gotten such as follows. The crystal structure of ceramic has the rombohedral structure in XRD. it appeared that addition of Ni, Mn additive was helpful to the formation of stable structure. Dielectric constant at $20^{\circ}C$ showed its maximum value 890.001 in specimens sintered at $1000^{\circ}C$, x=0.15mol. and dielectric loss showed its minimum value 6.95[%] in specimens sintered at $1000^{\circ}$, x=0.05mol. The variation rate of dielectric constant according to the change of frequency was decreased by increasing frequency, The variation rate of dielectric constant according to the change of temperature was increased by increasing temperature.

• 한국환경보건학회지
• /
• 제26권2호
• /
• pp.41-48
• /
• 2000

This study has been carried out to determine the seasonal characteristics of concentration of various ionic (CI-, NO3-, SO42-, Na+, NH+, K+, Ca2+) and heavy metallic (Pb, Mn, Cu, Ni) species in Pusan from August 1997 to April 1998. The concentrations of CI-, Na+, K+ were higher during summer with 2.98 ${\mu}{\textrm}{m}$/㎥. Seasonal variation of total concentration of but the concentration of NH4+ was higher during winter with 2.46${\mu}{\textrm}{m}$/㎥. Seasonal variation of total concentration of heavy metals(Pb, Cu, Mn, Ni) were 186.0 ng/㎥ in summer, 222.6 ng/㎥ in autumn, and 135.83 ng/㎥ in winter. Over the seasons inspected, the concentration of Mn was higher in coarse particles than fine particles and concentration of Ni was higher in fine particles than coarse particles. during yellow sand period, the concentration of TSP was increased about two times than that of other period. SO42-, Ca2+ concentrations were higher than other ionic components because of soil particles. The concentration of Ni showed 94.62ng/㎥ was increased about 4~5 times than other period. Principal component of the yellow sand, SO42-, Ca2+ could be discreased by rainfall and washout effect of atmospheric aerosol was higher in coarse particles than fine particles. Results from PCA(principal component analysis) showed that major pollutant was NaCl by seasalt particulate and (NH4)2SO4.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
• /
• pp.259-259
• /
• 2015

Single crystalline indium-tin-oxide (ITO) nanowires (NWs) were grown by sputtering method. A thin Ni film of 5 nm was deposited before ITO sputtering. Thermal treatment forms Ni nanoparticles, which act as templates to diffuse Ni into the sputtered ITO layer to grow single crystalline ITO NWs. This Ni diffusion through an ITO NW was investigated by transmission electron microscope to observe the Ni-tip sitting on a single crystalline ITO NW. Meanwhile, a single crystalline ITO structure was found at bottom and body part of a single ITO NW without remaining of Ni atoms. This indicates the Ni atoms diffuse through the oxygen vacancies of ITO structure. Rapid thermal process (RTP) applied to generate an initial stage of a formation of Ni nanoparticles with variation in time periods to demonstrate the existence of an optimum condition to initiate ITO NW growth. Modulation in ITO sputtering condition was applied to verify the ITO NW growth or the ITO film growth. The Ni-assisted grown ITO layer has an improved electrical conductivity while maintaining a similar transmittance value to that of a single ITO layer. Electrically conductive and optically transparent nanowire-coated surface morphology would provide a great opportunity for various photoelectric devices.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.493-496
• /
• 1999

Ni/3C-SiC 옴믹 접합에 대한 미세구조적-접합 특성과의 상관관계를 규명하였다. 3C-SiC 웨이퍼 위에 저저항 전면 옴믹 적합층을 형성하기 위하여 Ni(t=300$\AA$)을 thermal evaporator를 사용하여 증착하고, 50$0^{\circ}C$, 80$0^{\circ}C$, 103$0^{\circ}C$ 온도에서 30분간(Ar 분위기) 열처리 한 후, scratch test를 실행하여 Ni/3C-SiC의 접착력 특성을 조사하였다. 여러 다른 온도에 따른 Ni/3C-SiC 층의 표면과 계면의 미세구조는 X-ray scattering 법을 사용하였다. 50$0^{\circ}C$ 에서 열처리된 Ni/3C-SiC 층은 가장 낮은 계면 평활도와 가장 높은 표면 평활도를 나타내었다. Ni/3C-SiC 접착력 분석에서 500 $^{\circ}C$ 열처리된 시편의 측정된 임계하중 값은 As-deposited 시편(12 N~ 13 N)보다 훨씬 낮은 2 N~3 N 범위의 값을 보였으나, 열처리 온도가 증가함에 따라 다시 높아지는 경향을 보였다. 미세구조 특성에서는 열처리 온도가 500 $^{\circ}C$ 이상에서는 NiSi$_2$silicides의 domain size는 결정성의 향상에 따라 증가되었다. 결정성 향상이 3C-SiC와 silicides 사이의 격자상수의 낮은 불일치를 완화시키는데 기여 하였 다.