• Title/Summary/Keyword: O2

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Effect of Deposition Temperature and Oxygen on the Growth of $RuO_2$ Thin Films Deposited by Metalorganic Chemical Vapor Deposition (금속유기 화학증착법으로 증착시킨 $RuO_2$박막의 성장에 미치는 증착온도와 산소의 영향)

  • 신웅철;윤순길
    • Journal of the Korean Ceramic Society
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    • v.34 no.3
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    • pp.241-248
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    • 1997
  • RuO2 thin films were deposited on SiO2(1000$\AA$)/Si and MgO(100) single crystal substrates at low tem-peratures by hot-wall metalorganic chemical vapor deposition(MOCVD), and effects of deposition paramet-ers on the properties of the thin films were investigated. RuO2 single phase was obtained at lower de-position temperature of 25$0^{\circ}C$. RuO2 thin films deposited onto SiO2(1000$\AA$)/Si substrates showed a random orientation, and RuO2 films onto MgO(100) single crystals showed the (hk0) orientation. The crystallinity and resistivity of RuO2 thin films increased and decreased with increasing deposition temperature, respec-tively. The resistivity of RuO2 thin films decreased with decreasing the flow rate. The resistivity of the 2600$\AA$-thick RuO2 thin films deposited with O2 flow rate of 50 sccm at 35$0^{\circ}C$ was 52.7$\mu$$\Omega$-cm, and they could be applicable to bottom electrodes of high dielectric materals.

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Dielectric Properties in Na2O-B2O3-SiO2 Glass Containing CoO (CoO를 함유한 Na2O-B2O3-SiO2 계 유리의 유전적 특성)

  • Lee, Chanku;Lee, Sudae;Joung, Maeng-Sig
    • Journal of Korean Ophthalmic Optics Society
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    • v.5 no.1
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    • pp.49-53
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    • 2000
  • Sodium borate silicate glass of composition $10Na_2O-39B_2O_3-50SiO_2-CoO$ and $20Na_2O-14B_2O_3-65SiO_2-CoO$ were prepared by melting oxide mixtures in alumina crucible at $1210^{\circ}C$ in an electric furance in air for 2h, and then quenching in air. The dielectric behavior of the quenched glasses are the subject of the present work. Properties such as dielectric constant and resistivity as a function frequency and temperature are reported. From the dielectric spectra, the glass phase transition temperature has been found to decrease at a rate $Na_2O$ 20 mol% and the dielectric constants increase with increasing $Na_2O$ content. The frequency dependent resistivity response of glass exhibits a non-Debye type relaxation.

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Studies on the Molybdenum Complexes with Tridentate Schiff Base Ligand (I) (세자리 Schiff Base 리간드의 몰리브덴 착물에 관하여 (제1보))

  • Ki Hyung Chjo
    • Journal of the Korean Chemical Society
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    • v.17 no.3
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    • pp.169-173
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    • 1973
  • The tridentate schiff base ligand, salicyliden amino-o-hydroxy benzene, has derived from salicylaldehyde and o-amino phenol. This ligand reacts with a series of Mo (VI), Mo (V), Mo (IV), and Mo (III) oxidated states and forms a new complexes; [Mo O$_2(H_2O)\;(C_{13}H_9O_2N)]$, [MoO Cl$(H_2O)\;(C_{13}H_9O_2N)]$, [Mo(SCN)$_2(H_2O)\;(C_{13}H_9O2_N)]$$[Mo(H_2O)_2\;(C_{13}H_9O_2N)]_2O$. The Mo (VI), Mo(V) and Mo(Ⅳ) ions in these complexes are octahedron, hexa coordinate, and the mole ratio of these ions to the ligand are 1 : 1, but Mo (III) Complex is a Mo-O-Mo oxygen bridge bond and polynuclear, and the mole ratio of Mo (III) to the ligand 1 : 1 above facts are identified from the data of Infrared spectra, visible spectra, and elemental analysis.

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High Temperature Stability for Refractories of the System $Al_2O_3-CaO-Cr_2O_3$ ($Al_2O_3-CaO-Cr_2O_3$ 계 내화물의 고온 안정성)

  • 이홍립
    • Journal of the Korean Ceramic Society
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    • v.17 no.1
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    • pp.8-12
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    • 1980
  • CaO was added to the $MgAlCrO_4$ spinel, a main component of the mag-chro refractroies, by 0, 1, 5 and 10 mol% before sintering at 135$0^{\circ}C$ in air. The X-ray diffraction analysis produced an additional X-ray diffraction pattern of 8CaO.$6Al_2O_3$.$2CrO_3$ besides that of $MgAlCrO_4$. The formation of 8CaO.$6Al_2O_3$.$2CrO_3$ was interpreted as due to the presence of CaO.8CaO.$6Al_2O_3$.$2CrO_3$ was unstable and easily vaporized. It was concluded that formation of the unstable pollutant 8CaO.$6Al_2O_3$.$2CrO_3$ could be prevented in reducing atmospheres. It was found that the basic refractories containing $Al_2 O_3 -CaO-Cr_2 O_3$ system would be more stable and much less toxic in reducing at mospheres than in oxidizing stmosphere.

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Complete Combustion of Benzene over CuO/CeO2 Catalysts Prepared by Various Methods (다양한 방법으로 제조된 CuO/CeO2 촉매에서의 벤젠의 연소반응)

  • Jung, Won Young;Song, Young In;Hong, Seong-Soo
    • Clean Technology
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    • v.19 no.2
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    • pp.128-133
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    • 2013
  • Catalytic combustion of benzene over $CeO_2$-supported copper oxides has been investigated. The supported copper oxides catalysts were prepared using ball mill method and characterized by XRD, FT-IR, TEM and TPR. In the CuO/$CeO_2$ catalysts prepared using ball mill method, highly dispersed copper oxide species were shown at high loading ratio. The CuO/$CeO_2$ prepared using ball mill method showed the higher activity than those prepared using impregnation method. The catalytic activity increased with an increase in the CuO loading ratio, 10 wt% loaded CuO/$CeO_2$ catalyst giving the highest activity. In addition, the promoting of 10 wt% loaded CuO/$CeO_2$ catalyst with $Fe_2O_3$ and CoO enhanced the dispersion of CuO and then increased the catalytic activity.

Corrosion Behavior of Superalloys in Hot Molten Salt under Oxidation Atmosphere (고온용융염계 산화분위기에서 초합금의 부식거동)

  • 조수행;임종호;정준호;이원경;오승철;박성원
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • 2004.06a
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    • pp.285-291
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    • 2004
  • As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of Inconel 718, X-750, Haynes 75 and Haynes 263 alloys in the molten salt of LiCl-Li$_2$O-O$_2$was investigated in the range of temperature; $650^{\circ}C$, time; 24~168h, $Li_2O$; 3wt%, mixed gas; Ar~10%$O_2$. In the molten salt of LiCl-$Li_2O-O_2$, the order corrosion rate was Haynes 263 < Haynes 75 < Inconel X-750 < Inconel 718. Haynes 263 alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of alloys were as fellows: Haynes 75: $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718; $Cr_2O_4$, $NiFe_2O_4$, Haynes 263; $Li(Ni,Co)O_2$, $NiCr_2O_4$, $LiTiO_2$, Inconel X-750; $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$. Haynes 263 showed local corrosion behavior and Haynes 75, Inconel 718 and Inconel X-750 showed uniform corrosion behavior.

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Prediction of the optical properties of $TiO_2$/Ag/$TiO_2$ films using transfer matrix and comparisions with real transmittance measured on the sputter-deposited films (Transfer Matrix를 사용하여 예측한 $TiO_2$/Ag/$TiO_2$ 박막의 광학적 성질 및 스퍼터 증착된 박막과의 특성 비교)

  • Kim, Jin-Il;Kim, Jin-Hyeon;Kim, Yeong-Hwan;O, Tae-Seong
    • Korean Journal of Materials Research
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    • v.5 no.1
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    • pp.140-148
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    • 1995
  • Optical properties of $TiO_{2}$. Ag filrns and $TiO_{2}/Ag/TiO_{2}$ multilayer filrns with different thickness were predicted using the transfer matrix, and these results were compared with real transmittance curves of the sputterdeposited films. With the complex refractive indices, it was possible to predict transmittance characteristics which were close to real data for $TiO_{2}$ and Ag films. Due to the diffusion and agglomeration of Ag during $TiO_{2}$ deposition, optical properties of the sputterdeposited $TiO_{2}/Ag/TiO_{2}$ films were found to be very different from the transmittance curves predicted using the transfer matrix. Using deposition of 4nm-thick or 6nm-thick TI layers as a diffusion barrier, however, the transmittance curves of $TiO_{2}/Ti/Ag/Ti/TiO_{2}$ five-layer films became similar to ones predicted for $TiO_{2}/Ag/TiO_{2}$ threeiayer films.

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The Effect of Vanadium(V) Oxide Content of V2O5-WO3/TiO2 Catalyst on the Nitrogen Oxides Reduction and N2O Formation (질소산화물 환원과 N2O 생성에 있어서 V2O5-WO3/TiO2 촉매의 V2O5 함량 영향)

  • Kim, Jin-Hyung;Choi, Joo-Hong
    • Korean Chemical Engineering Research
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    • v.51 no.3
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    • pp.313-318
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    • 2013
  • In order to investigate the effect of $V_2O_5$ loading of $V_2O_5-WO_3/TiO_2$ catalyst on the NO reduction and the formation of $N_2O$, the experimental study was carried out in a differential reactor using the powder catalyst. The NO reduction and the ammonia oxidation were, respectively, investigated over the catalysts compose of $V_2O_5$ content (1~8 wt%) based on the fixed composition of $WO_3$ (9 wt%) on $TiO_2$ powder. $V_2O_5-WO_3/TiO_2$ catalysts had the NO reduction activity even under the temperature of $200^{\circ}C$. However, the lowest temperature for NO reduction activity more than 99.9% to treat NO concentration of 700 ppm appeared at 340 with very limited temperature window in the case of 1 wt% $V_2O_5$ catalyst. And the temperature shifted to lower one as well as the temperature window was widen as the $V_2O_5$ content of the catalyst increased, and finally reached at the activation temperature ranged $220{\sim}340^{\circ}C$ in the case of 6 wt% $V_2O_5$ catalyst. The catalyst of 8 wt% $V_2O_5$ content presented lower activity than that of 8 wt% $V_2O_5$ content over the full temperature range. NO reduction activity decreased as the $V_2O_5$ content of the catalyst increased above $340^{\circ}C$. The active site for NO reduction over $V_2O_5-WO_3/TiO_2$ catalysts was mainly related with $V_2O_5$ particles sustained as the bare surface with relevant size which should be not so large to stimulate $N_2O$ formation at high temperature over $320^{\circ}C$ according to the ammonia oxidation. Currently, $V_2O_5-WO_3/TiO_2$ catalysts were operated in the temperature ranged $350{\sim}450^{\circ}C$ to treat NOx in the effluent gas of industrial plants. However, in order to save the energy and to reduce the secondary pollutant $N_2O$ in the high temperature process, the using of $V_2O_5-WO_3/TiO_2$ catalyst of content $V_2O_5$ was recommended as the low temperature catalyst which was suitable for low temperature operation ranged $250{\sim}320^{\circ}C$.

Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution (입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화)

  • 이현구
    • Economic and Environmental Geology
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    • v.32 no.3
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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Effect Of $Al_2O_3$on the Crystallization Of MgO-CaO-${SiO_2}-{P_2O_5}$ Bioglass-Ceramic System (I) (MgO-CaO-${SiO_2}-{P_2O_5}$계 Bioglass-Ceramic의 결정화에 미치는 $Al_2O_3$ 첨가의 영향(I))

  • 이민호;배태성
    • Journal of Biomedical Engineering Research
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    • v.15 no.2
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    • pp.189-194
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    • 1994
  • Effects of ${AI_2O_3}/{P_2O_5}$ ratio on the crystallization of a series of glasses with the nominal composition of 41.4wt % $SiO_2$, 35.0wt % CaO, 20.6wt % (${P_2O_5}$+${AI_2O_3}$) and 3.0wt% MgO were investigated with DTA, XRD and SEM. The major crystalline phases are apatite and anorthite. The glass transition temperature ($T_g$) and the softening point ($T_s$) are shifted to the upper temperature by increasing $AI_2O_3$ content. The temperature of apatite crystallization ($T_{p1}$) is increased by $AI_2O_3$ content, but the tempera¬ture of anorthite crystallization ($T_{p2}$) is not affected significantly. With increased of $AI_2O_3$, the apatite crystallization is decreased, but anorthite crystallization is increased.

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