• Journal of the Korean Crystal Growth and Crystal Technology
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• v.4 no.4
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• pp.370-377
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• 1994

DC plasma torch which is a non-transferred type was constructed and silicon nitride powders were produced. Ar gas is used as a plasma gas and gas reactants with the carrier gas are introduced beneath the plasma ignition part. Two slits are attached and a reactive quenching gas is introduced through them. Using $SiCl_4 and NH_3$ as starting materials, silicon nitride powders were produced. As-produced powders were amorphous and crystalline silicon nitrides were obtained by heating at $1420^{\circ}C$ for two hours under nitrogen atmosphere. Silicon nitride phase was identified in the XRD patterns and IR spectrum, and the image of the powders before and after heating was observed from the TEM analysis.

• Corrosion Science and Technology
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• v.14 no.3
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• pp.127-131
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• 2015

Model alloys Fe-9Cr, Fe-20Cr and Fe-20Cr-20Ni (wt. %) with 0.1 and 0.2 % Si were exposed to $Ar-20CO_2-20H_2O$ gas at $818^{\circ}C$. The undoped alloys formed a thick iron-rich oxide scale. The additions of Si reduced scaling rates of Fe-9Cr to some extent but significantly suppressed the formation of iron oxide scales on Fe-20Cr and Fe-20Cr-20Ni. Carburisation also occurred in all undoped alloys, but not in Si-containing Fe-20Cr and Fe-20Cr-20Ni. Protection against carburisation was a result of the formation of an inner scale layer of silica.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1428-1430
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• 1996

Thin Silicon oxynitride(SiON) films have been chemically deposited using 193nm ArF Excimer Laser CVD, with $Si_{2}H_{8}$, $N_{2}O$, and $NH_3$ as the reactive gases and $N_2$ as the carrier gas. Experimental results show that deposition rate and refractive index have a strong dependence on substrate temperature, chamber pressure, gas ratio, laser power and laser beam height. Electrical characterization of oxynitride films demonstrates that for $NH_{3}/N_{2}O$ flow ratios ranging from 0.25 to 1, the leakage currents, the interface trap density and the capacitances (dielect ric constant) increase and the dielectric breakdown fields decrease

• Journal of Powder Materials
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• v.17 no.4
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• pp.295-301
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• 2010

Multi shell graphite coated Ag nano particles with core/shell structure were successfully synthesized by pulsed wire evaporation (PWE) method. Ar and $CH_4$ (10 vol.%) gases were mixed in chamber, which played a role of carrier gas and reaction gas, respectively. Graphite layers on the surface of silver nano particles were coated indiscretely. However, the graphite layers are detached, when the particles are heated up to $250^{\circ}C$ in the air atmosphere. In contrast, the graphite coated layer was stable under Ar and $N_2$ atmosphere, though the core/shell structured particles were heated up to $800^{\circ}C$. The presence of graphite coated layer prevent agglomeration of nanoparticles during heat treatment. The dispersion stability of the carbon coated Ag nanoparticles was higher than those of pure Ag nanoparticles.

• Journal of Surface Science and Engineering
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• v.29 no.5
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• pp.399-406
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• 1996

The orientational cross-over phenomena in an RF sputtering growth of TiN films were studied in an in-situ, real-time synchrotron x-ray scattering experiment. For the films grown with pure Ar sputtering gas, the cross-over from the more strained (002)-oriented grains to the less strained (111)-oriented grains occurred as the film thickness was increased. As the sputtering power was increased, the cross-over thickness, at which the growth orientation changes from the <002> to the <111> direction, was decreased. The addition of $N_2$ besides Ar as sputtering gas suppressed the cross-over, and consequently resulted in the (002) preferred orientation without exhibiting the cross-over. We attribute the observed cross-over phenomena to the competition between the surface and the strain energy. The x-ray powder diffraction, the x-ray reflectivity, and the ex-situ AFM surface topology study consistently suggest that the microscopic growth front was in fact always the (002) planes. In the initial stage of growth, the (002) planes were aligned to the substrate surface to minimize the surface energy. At later stages, however, the (002) growth front tilted away from the surface by about $60^{\circ}$ to relax the strain, which caused the cross-over of the preferred growth direction to the <111> direction.

• Journal of the Korean Magnetics Society
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• v.14 no.2
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• pp.71-75
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• 2004

$\alpha$-LiFe $O_2$ powders have been prepared by a sol-gel method. The crystallographic and magnetic properties were characterized with a x-ray diffractometry, Mossbauer spectroscopy, and vibrating Samples magnetometry. The ${\gamma}$-LiFe $O_2$+LiFe$_{5}$ $O_{8}$ phase is observed in the Samples annealed at $600^{\circ}C$ for 3h in air and $\alpha$-LiFe $O_2$ phase is observed in the Samples annealed at $600^{\circ}C$ for 3 h in $H_2$(5％)/Ar(Bal.) gas atmosphere. The crystal structure of $\alpha$-LiFe $O_2$ is found to be cubic with a lattice a=4.193$\pm$0.0005 $\AA$. The Neel temperature of $\alpha$-LiFe $O_2$ is found to be 130$\pm$3 K.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.24-28
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• 2014

Magnesium diboride superconductor is still of considerable interest because of its appealing characteristics towards application mainly at around 20 K. Unlike Nb-based superconductors, $MgB_2$ can be operated by cryogen-free cooler which provides a cost effective alternative at low field of around 2-5 T. To explore this operating field region considerable efforts are necessary to marginally improve the superconducting properties of $MgB_2$. Under this situation, even the heat treatment environment during the synthesis is considered as an important factor. The addition of $H_2$ gas in small amount with Ar as a mixed gas during annealing has an adverse effect on the superconducting properties of $MgB_2$. It is although interesting to find that the presence of Mg vapor along with hydrogen during heat treatment results in the appreciable improvement in the flux pinning and the overall response of the critical current density for the ex-situ $MgB_2$ samples.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.378-380
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• 2005

Diamond like carbon (DLC) films are known that they show homogeneous alignment property when they are irradiated by Ar ion beam. The DLC films in most of studies were deposited by CVD and contain large mount of hydrogen. In order to identity the hydrogen effect on alignment property, DLC films is deposited by RF magnetron sputter using various ratio of Ar and H2 as reactive gas. DLC films are characterized by FT-IR, Raman and contact angle. Alignment property is estimated by measuring pretilt angle.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.5
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• pp.121-134
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• 1994

Shock tube investigation of ethylene oxide-$0_{2}-N_{2}$ mixture have been performed to reveal detonation characteristics of the mixture in terms of detonation pressure and speed. Theoretical calculation of thermodynamic parameters at the Chapmann-Jouguet detonation of the mixture has been also performed. A comparision of the observed results with the calculated ones can lead us to predict the detonation parameters of ethylene oxide in an artificial air. In addition, we have observed ignition delay times of ethylene oxide mixtures. The best fit of the observed delay times to Arrhenius gas kinetic relation gives : ${\tau}=10^{-144}{e{xp}}(E_a/RT)[C_{2}H_{4}O]^{-4.8}[O_{2}]^{-12.4}[N_{2}]^{-14.1}$ $E_a=3.67kcal/mole$ The observed activation energy is markedly reduced, compared with the case of ethylene oxide diluted in Ar. It could be due to the factor that $N_2$ play a role as detonation promoter yielding very reactive NOx radicals.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.250-251
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• 2009

For the fabrication of a multilevel resist (MLR) based on a very thin amorphous carbon (a-C) layer an $Si_{3}N_{4}$ hard-mask layer, the selective etching of the $Si_{3}N_{4}$ layer using physical-vapor-deposited (PVD) a-C mask was investigated in a dual-frequency superimposed capacitively coupled plasma etcher by varying the following process parameters in $CH_{2}F_{2}/H_{2}/Ar$ plasmas : HF/LF powr ratio ($P_{HF}/P_{LF}$), and $CH_{2}F_{2}$ and $H_2$ flow rates. It was found that infinitely high etch selectivities of the $Si_{3}N_{4}$ layers to the PVD a-C on both the blanket and patterned wafers could be obtained for certain gas flow conditions. The $H_2$ and $CH_{2}F_{2}$ flow ratio was found to play a critical role in determining the process window for infinite $Si_{3}N_{4}$/PVDa-C etch selectivity, due to the change in the degree of polymerization. Etching of ArF PR/BARC/$SiO_x$/PVDa-C/$Si_{3}N_{4}$ MLR structure supported the possibility of using a very thin PVD a-C layer as an etch-mask layer for the $Si_{3}N_{4}$ layer.