• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.177-181
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• 1997

Epitaxial films of cubic silicon carbide (3C-SiC, $\beta$-SiC) have been grown on Si(001) and Si(111) substrates by high vacuum chemical vapor deposition using the single precursor 1,3-disilabutane, $H_3SiCH_2SiH_2CH_3$, at temperatures 900~$100^{\circ}C$. The advantage of using the single precursor over the covnentional chemical vapor deposition is evident in that the source chemical is safe to handle, carbonization of the substrates is not necessary, accurate stoichiometry of the silicon carbide films is easily achieved, and the deposition temperature is much lowered. The films were characterized by XPS, XRD, SEM, RHEED, RBS, AES, and TED.

• Journal of Environmental Science International
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• v.21 no.3
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• pp.305-312
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• 2012

This work is to study the variations of adsorption characteristics of binary vapor according to packing system of double-layer bed by fixed bed experiment. Breakthrough curves of single and binary vapor composed of acetone and benzene on single-layer and double-layer adsorption bed composed of activated carbon (AC) and silica-aluminar (SA) were compared. Adsorptions of binary vapor on double-layer bed were influenced by the differences of surface area between adsorbents as well as the polarity difference between adsorbent and adsorbate. The roll-up phenomenon of acetone vapor was happened by replacement with competing adsorption between acetone vapor and benzene vapor on AC bed, but it was not happened on SA bed because acetone vapor and benzene vapor had less difference in affinity with SA bed. The breakthrough times of acetone vapor and benzene vapor on AC/SA double-layer bed were three times and 1.4 times larger respectively than on SA/AC double-layer bed, the differences of breakthrough times were relatively larger than the equilibrium adsorption capacities according to packing system of double-layer bed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.4
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• pp.481-488
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• 2004

Laser chemical vapor deposition can be used as a new approach for a rapid prototyping technique. The purpose of the study is to fabricate several 3-dimensional objects that are relatively simple as well as to find the characteristics of SiC rod growth that is the first step in developing a new rapid prototyping technique with laser chemical vapor deposition. In the study, SiC rods were generated with varying precursor pressure for 5 minutes. Deposition rates with varying precursor pressure, shapes of rods, surface roughness and component organization were investigated, in particular. Finally, several simple objects like a branch or a propeller were successfully fabricated using laser chemical vapor deposition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.14-21
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• 2005

Laser chemical vapor deposition can be an effective technique for a rapid prototyping with ceramic materials, in particular. The objective of the study is to fabricate several 3-dimensional objects by stacking multi-layers as well as to find out some basic aspects of a rapid prototyping with laser chemical vapor deposition such as deposition characteristics with traversing speed of the laser, possible problems in stacking multi-layers etc. The limit speed of the laser that can grow a tilted SiC rod was found in this study, and laser directing writing that occurs over the limit speed was also investigated. Finally, a zigzag-shaped rod, a spiral-shaped rod, a wall and a square duct were successfully fabricated with laser chemical vapor deposition of tetramethylsilane

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2245-2248
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• 2009

This paper demonstrates room temperature chemical vapor deposition (RTCVD) for fabricating titania inverse opals. The colloidal crystals of monodisperse polymer latex spheres were used as a sacrificial template. Titania was deposited into the interstices between the colloidal spheres by altermate exposures to water and titanium tetrachloride (Ti$Cl_4$) vapors. The deposition was achieved under atmospheric pressure and at room temperature. Titania inverse opals were obtained by burning out the colloidal template at high temperatures. The filling fraction of titania was controlled by the number of deposition of Ti$Cl_4$ vapor. The morphology of inverse opals of titania were investigated. The optical reflection spectra revealed a photonic band gap and was used to estimate the refractive index of titania.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.9
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• pp.1226-1233
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• 2002

The purpose of the present study was to examine some basic aspects of laser chemical vapor deposition that will be ultimately utilized for solid freeform fabrication of three dimensional objects. Specifically, deposition of silicon carbide (SiC) using tetramethylsilane (TMS) as precursor was studied for a rod grown by $CO_2$laser-assisted chemical vapor deposition. First, temperature distribution for substrate was analyzed to select proper substrate where temperature was high enough for SiC to be deposited. Then, calculations of chemical equilibrium and heat and mass flow with chemical reactions were performed to predict deposition rates, deposit profiles, and deposit components. Finally, several rods were experimentally grown with varying chamber pressure and compared with the theoretical results.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.839-842
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• 2012

We report for the first time the synthesis of niobium dioxide nanowires on a sapphire substrate by chemical vapor transport method. We identified single crystalline nature of as-synthesized nanowires by scanning electron microscopy and transmission electron microscopy. Niobium dioxide nanowires with their large surface-to-volume ratio and high activities can be employed for electrochemical catalysts and immunosensors. The Raman spectrum of niobium dioxide nanowires also confirmed their identity.

• Bulletin of the Korean Chemical Society
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• v.13 no.2
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• pp.148-155
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• 1992

Computerized interpretation of vapor phase infrared spectra using a novel expert system approach for spectra/structure correlation for vapor phase spectra is introduced. Rapid identification of aromatic functional groups of components in gaseous mixture can be achieved using this expert system.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.381-381
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• 2011

The influence of the water vapor on the growth of single-walled carbon nanotubes (SWCNTs) was investigated. SWCNTs were synthesized by catalytic chemical vapor deposition of acetylene over Fe-Mo/MgO catalyst with injection of water vapor. The morphologies and structures of the water-assisted SWCNTs were investigated according to the growth conditions such as water vapor concentrations, flow rate of the gas, furnace temperature, and growth time. Water-assisted SWCNTs exhibited large bundle morphological features with well-alignment of each CNT, while SWCNTs synthesized in the absence of water vapor showed entangled CNT with the random orientation. We also found that the diameter of the SWCNT bundle could be controlled by the growth condition. In our optimal growth condition, the product yield and the purity were 300 wt. % and 75%, which were 7.5 and 2.5 times higher than those of SWCNTs synthesized without water vapor, respectively. More detail discussion will be offered at the poster presentation.

• Bulletin of the Korean Chemical Society
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• v.25 no.4
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• pp.480-484
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• 2004

$LiGaO_2$ films have been grown on Si (100) substrates using a new single precursor $[Li(OCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ under high vacuum conditions $(5{\times}10^{-6}Torr)$. The $[Li(OCH_2CH_2OCH_3)_2Ga(CH_3)_2]_2$ was synthe-sized and characterized by using spectroscopic methods and single-crystal X-ray diffraction analysis. The chemical composition, crystalline structure, and morphology of the deposited films were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, and scanning electron microscopy. The results show that polycrystalline $LiGaO_2$ films preferentially oriented in the [010] direction can be deposited on Si (100) at 500-550$^{\circ}C$ by metal organic chemical vapor deposition (MOCVD). The single precursor $[LiOCH_2CH_2OCH_3)_2-Ga(CH_3)_2]_2$ has been found suitable for chemical vapor deposition of $LiGaO_2$ thin films on Si substrates.