• Bulletin of the Korean Chemical Society
• /
• 제30권1호
• /
• pp.219-223
• /
• 2009

$TiO_2$ doped with $Er^{3+\;and\;Yb^{3+}$ was used for fabricating a scattering layer and a nano-crystalline $TiO_2$ electrode layer to be used in dye-sensitized solar cells. The material was prepared using a new sol-gel combustion hybrid method with acetylene black as fuel. The $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide powder synthesized at 700oC had embossed structure morphology with a size between 27 to 54 nm that agglomerated to produce micron size particles, as observed by the scanning electron micrographs. The XRD patterns showed that the $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide had an amorphous structure, while using the same method without doping $Er^{3+}\;or\;Yb^{3+},\;TiO_2$ was obtained in the crystallite form with thea dominance of rutile phase. Fabricating a bilayer structure consisting of nano-crystalline $TiO_2$ and the synthesized $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide showed better scattering property, with an overall increase of 15.6% in efficiency of the solar cell with respect to a single nano-crystalline $TiO_2$ layer.

• 한국전기전자재료학회논문지
• /
• 제29권10호
• /
• pp.665-670
• /
• 2016

Prevailing dissemination of machine tools and cutting technology have caused drastic developments of high speed dry machining with work materials of high hardness, and demands on the high-hardness-materials with high efficiency have become increasingly important in terms of productivity, cost reduction, as well as environment-friendly issue. Addition of Si to TiAlN has been known to form nano-composite coating with higher hardness of over 30 GPa and oxidation temperature over $1,000^{\circ}C$. However, it is not easy to add Si to TiAlN by using conventional PVD technologies. Therefore, Ti-Al-Si-N have been prepared by hybrid process of PVD with multiple target sources or PVD combined with PECVD of Si source gas. In this study, a single composite target of Ti-Al-Si was prepared by powder metallurgy of MA (mechanical alloying) and SPS (spark plasma sintering). Properties of he resulting alloying targets were examined. They revealed a microstructure with micro-sized grain of about $1{\sim}5{\mu}m$, and all the elements were distributed homogeneously in the alloying target. Hardness of the Ti-Al-Si-N target was about 1,127 Hv. Thin films of Ti-Al-Si-N were prepared by unbalanced magnetron sputtering method by using the home-made Ti-Al-Si alloying target. Composition of the resulting thin film of Ti-Al-Si-N was almost the same with that of the target. The thin film of Ti-Al-Si-N showed a hardness of 35 GPa and friction coefficient of 0.66.

• 공업화학
• /
• 제23권3호
• /
• pp.271-278
• /
• 2012

본 연구에서는 마이카와 산화 아연을 이용하여 복합 재료를 제조하고, 이를 자외선 차단 크림에 응용하는 연구를 수행하였다. 먼저 마이카와 산화 아연을 각각 3-aminopropyltrimethoxysilane (APTMS)으로 처리하여 표면에 아민기를 생성시켰다. 아민기가 붙은 마이카를 1,4-phenylenediisothiocyanate (PDC)와 반응시켜 표면에 -N=C=S 작용기를 활성화시킨 후, 아민기가 붙어있는 산화 아연과 결합시켜 산화 아연으로 덮인 마이카 복합 재료를 합성하였다. 원소 분석, EDS 분석, 열 중량 분석, SEM 이미지 분석, 형광 이미지 분석, 제타 전위 측정, X-선 회절 분석, DRS UV/Vis 분석을 통하여 고체 생성물의 특성을 규명하였다. 최종적으로 표준 프로토콜로 제조된 자외선 차단 크림의 파장에 따른 투과도를 280~400 nm 범위에서 측정하여 자외선 차단 효과를 확인하였다.

• 대한금속재료학회지
• /
• 제49권8호
• /
• pp.596-600
• /
• 2011

Thermal degradation behavior of a $WO_3-TiO_2$ monolithic catalyst was investigated in terms of structural, morphological, and physico-chemical analyses. The catalyst with 4 wt.% $WO_3$ contents were prepared by a wet-impregnation method, and a durability test of the catalysts were performed in a temperature range between $400^{\circ}C$ and $800^{\circ}C$ for 3 h. An increase of thermal stress decreased the specific surface area, which was caused by grain growth and agglomeration of the catalyst particles. The phase transition from anatase to rutile occurred at around $800^{\circ}C$ and a decrease in the Brønsted acid sites was confirmed by structural analysis and physico-chemical analysis. A change in Brønsted acidity can affect to the catalytic efficiency; therefore, the thermal degradation behavior of the $WO_3-TiO_2$ catalyst could be explained by the transition to a stable rutile phase of $TiO_2$ and the decrease of specific surface area in the SCR catalyst.