• Bulletin of the Korean Chemical Society
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• 제5권4호
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• pp.149-153
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• 1984

Reactions of $MoOCl_5^{2-}$ with ${\alpha}_2-[P_2W_{17}O_{61}]^{10-}$ have been studied spectrophotometrically and several complexes have been identified. The transient species initially formed is probably $[Mo_2O_4(P_2W_{17}O_{6l})_2]^{18-}$. At $pH {\le} 3$the visible spectrum changes gradually, indicating formation of a transient isomer of $[P-2Mo^VW_{17}O_{62}]^{7-}$, which again transforms into the stable isomer. The transient isomer absorbs light much more strongly than the stable isomer in the visible range. At $pH > 3 [P_2W^VW_{16}O_{61}]^{11-}$ is formed probably via the transient isomer of $[P_2Mo^VW_{17}O_{61}]^{7-}$.

• 한국세라믹학회지
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• 제26권2호
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• pp.210-220
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• 1989

The properties of the powder of Al2O3-15v/o ZrO2(＋3m/o Y2O3) system prepared by co-precipitation method at the pH values of 7, 9, 10 and 11 were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Zirconium hydroxide decreased the specific surface area of aluminum hydroxide of AlOOH type, while increased the specific surface area of aluminum hydroxide of Al(OH)3 type, and formed co-network structure of Al-O-Zr type with the aluminum hydroxides. The rate of transition to $\alpha$-Al2O3 from co-precipitated materials occurred in the order of 7≒10, 9 and 11 of pH values. Al2O3 and ZrO2 interacted to bring about coupled grain growth, and the growth of ZrO2 crystallite size rapidly occurred within $\theta$-Al2O3 matrix. Segregation did not occur in the system Al2O3-15v/o ZrO2(＋3m/o Y2O3) and Y2O3 acted as a stabilizer to ZrO2. The lattice strain of tetragonal ZrO2 was increased by the constraint effect of Al2O3 matrix.

• 한국환경과학회지
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• 제12권10호
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• pp.1071-1077
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• 2003

The aim of this study is, firstly, to find out what kinds of inorganic species are produced in the photocatalytic oxidation of ammonium-nitrogen containing water and, secondly, to seek the influence of anion for the photocatalytic oxidation of ammonium contained compounds. The photoenergy above 3 eV(λ <415 nm) was effectively absorbed by TiO$_2$ and TiO$_2$/polymer was used to be oxidized NH$_4$-N in wastewater to NO$_3$-N. Existing the anion as Cl$\^$-/, the rate of photocatalytic oxidation decreased regardless of other condition. This result showed that the chloride ions reduced the rate of oxidation by scavenging oxidizing radical species as OH$\^$-/ and OCl$\^$-/. Some of the added ion might have blocked the active sites of the catalyst surface, thus deactivated the catalyst.

• 한국세라믹학회지
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• 제25권2호
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• pp.117-124
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• 1988

The properties of the powders of the system Al2O3-ZrO2-Y2O3 prepared by precipitation method were investigated. Al2(SO4)3$.$18H2O3, ZrOCl2$.$8H2O and YCl3$.$6H2O were used as starting materials. Amorphous aluminum hydrate prepared by precipitation method was completely transformed to alpha Al2O3 as a result of calcining at 1100$^{\circ}C$ for 1 hr and gamma, delta and theta phases appeared as transition phases. In ZrO2-Y2O3 system prepared by co-precipitation method, the crystallization temperature of ZrO2 was increase with Y2O3 contents. The coupled crystallization occured in coprecipitated Al2O3-ZrO2-Y2O3 system, therefore the formation temperature of alpha Al2O3 and ZrO2-Y2O3 system. In this ternary system, the powder morphology showed a particular shape which was composed of large Al2O3 grains having small spherical ZrO2 particles within large Al2O3 grain and relatively large ZrO2 particles along the grian boundaries.

• 공업화학
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• 제34권6호
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• pp.584-589
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• 2023

지지체 TiO₂가 다른 VOx/TiO₂ 촉매들에 대해 특성 분석과 SCR 반응을 수행하였다. Sigma Aldrich 사의 anatase TiO₂와 TiOCl₂와 TTIP를 출발 원료로 제조한 TiO₂를 사용하여 VOx/TiO₂ 촉매를 제조하고, 이를 각각 VS, VC, VP로 표시하였다. VS 시료의 비표면적은 VC 및 VP 시료 대비 1/10 이하로서 바나듐 산화물의 분산성은 상대적으로 낮았다. XPS 분석 결과, 촉매 표면의 흡착 산소의 비는 Ti³⁺가 존재하는 VS와 VP 시료가 VC 시료에 비해 높았다. 또한 VC와 VP시료에서 바나듐은 바나듐 산화물의 분산성과 관련하여 주로 V⁴⁺와 V³⁺ 상태로 존재하였다. 250 ℃ 이하 NH₃-SCR 활성에는 바나듐 산화물의 분산성보다는 흡착 산소 양이 더 기여한 반면, 300 ℃ 이상 활성에는 바나듐 산화물의 분산성이 더 기여하는 것으로 판단되었다. 촉매들의 fast SCR 활성은 3 시료 모두 NO₂/NOx = 0.5에서 가장 높았으며, VS < VC < VP 시료 순으로 나타났다. 빠른 NH₃-SCR 촉매 활성에는 촉매의 바나듐 산화물의 분산성이 영향을 크게 미친다고 판단되었다.

• 한국세라믹학회지
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• 제25권4호
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• pp.364-372
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• 1988

The mechanical properties and microstructure of ceramics of the system Al2O3-ZrO2-Y2O3 sintered at 1$650^{\circ}C$ for 2h after powder preparation by the precipitation method from Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were investigated. The Al2O3-ZrO2-Y2O3 ceramics sintered at 1$650^{\circ}C$ for 2h after mixing alpha-Al2O3 and ZrO2-Y2O3 powders, both were separately precipitated and calcined, were found to have the relative density higher than 97.5% so that the strengthening and toughening mechanisms could be explained mainly as the stress-induced phase transformation. On the other hand, the sintered bodies prepared by co-precipitating the three starting materials were measured to have the relative density lower than 85% so that the degradation of strength were observed above 15 vol% ZrO2 contents due to the high porosity by which the effect of stress-induced phase transformation was assumed to be depressed.

• 한국세라믹학회지
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• 제23권4호
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• pp.78-84
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• 1986

Zirconium acetate solution which was obtained from $ZrOCl_2$.$8H_2O$ was condensed polymerized and drawn to fibers by pulling method. Drawn gel fibers fired at 130$0^{\circ}C$ were short porous and mechanically weak. But addition of CaO about 13m/o caused the fibers to have the cubic structure and relatively dense microstructure. In order to clarify the condition for the synthesis of zirconia fibers viscosity measurement DTA-TG analysis X-ray diffraction infrared spectroscopy, SEM and specific surface area were studied.

• Bulletin of the Korean Chemical Society
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• 제5권4호
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• pp.167-169
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• 1984

Analyses of $_1$H-NMR, infrared and electronic spectral data for $[Ir(CH_2 = CHCN)(CO)(P(C_6H_5)_3)_2]ClO_4 (1)$prepared by the reaction of $Ir(OClO_3)(CO)(P(C_6H_5)_3)_2$ with $CH_2 = CHCN$, agree with the suggestion that 1 is a mixture of the nitrogen-bonded acrylonitrile complex, $[(CO)(P(C_6H_5)_3)_2Ir-NCCH = CH_2]ClO_4$ and other compound which may be the C = C ${\Pi}$ -system-bonded acrylonitrile complex, "[(CO)(P(C6H5)3)2Ir-CHCN = CH2]ClO4.

• 대한화학회지
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• 제34권5호
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• pp.452-459
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• 1990

일련의 산소 및 황 가교결합의 이핵 몰리브덴(V) 착물, Mo$_2$O$_4$L$_2$, Mo$_2$O$_3$L$_4$, Mo$_2$O$_2$S$_2$L$_2$, 그리고 Mo$_2$OS$_3$L$_2$, L = bis(hydroxyethyl)dithiocarbamate을 합성하였다. 말단과 가교의 산소결합 착물은 수용액에서 (PyH)$_2$MoOCl$_5$ 혹은 MoCl$_5$와 리간드의 반응으로부터 합성되었고, Mo$_2$O$_4^{2+}$핵에서 산소가 황으로 치환된 착물, Mo$_2$O$_2$S$_2$L$_2$은 Mo$_2$OS$_3$L$_2$의 클로로포름 용액에 트리페닐포스핀을 가하므로 합성되었다. 한편, Mo$_2$OS$_3$L$_2$착물은 sodium dithionite 존재하에서 (NH$_4$)$_2$MoS$_4$와 리간드의 수용액으로부터 얻어졌다. 합성한 착물에 대한 원소분석과 ir, uv-vis, nmr, 그리고 mass 스펙트라에 의한 착물의 분광학적 성질을 조사하였다. 또한 디메틸술폭시드 용액에서 이들 착물의 전기화학적 성질을 순환전압-전류법으로 조사하였다.

• Bulletin of the Korean Chemical Society
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• 제31권8호
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• pp.2242-2246
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• 2010

New 3,7-diphenylthieno[3,2-e]bis[1,2,4]triazolo[4,3-a:4',3'-c]pyrimidine derivatives were easily synthesized at room temperature in good yield by the oxidative cyclization of thienopyrimidinyl hydrazones with alumina-supported calcium hypochlorite ($Ca(OCl)_2/Al_2O_3$).