• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.157-157
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• 2000

The adsorption processes of methyl chloride on Si(100)-2$\times$1 have been studied by low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and semiempirical PM3 calculations. The dissociative adsorption of the methyl chloride on Si(100) takes place without breaking of the silicon dimer with high efficiency. For adsorption at the room temperature, the existence of a precursor state is confirmed by the behavior of the sticking probability depending on the coverage and temperature. From AES measurements, the determined activation barrier of adsorption ($\Delta$ Hads) is -28.4 kj/mol. This results indicate that the dissociative process is nonactivated. The optimized precursor state of CH3Cl on the Si(100)-2$\times$1 surface was determined by PM3 calculations based on a cluster model.

• Journal of environmental and Sanitary engineering
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• v.6 no.1
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• pp.47-62
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• 1991

Yellow Sand Phenomena was observed from April 8 th to 10 th in 1990. During this period particle was collected to investigate the chacteristics of chemical composition of particulate by High Volume Air Sampler and Andersen Air Sa~npler in Seoul. During this period the particle concentration was 350 yg/$m^3$ and the anions, cations, and metal concentrations were increased and the orders of these were $S0_4\;^{-2}>N0_3\;^->Cl^->F^-, Na^+>Ca^{+2}>NH_4\;^+>Mg^{2+}>K^+$, and Fe>Al>Si>Zn>Pb respectively. The principal source of Yellow Sand were identified soil and sea salt. Mn used by the trace element of soil, the persentage of contribution from soil was calculated to be about 81.3% for the particle increased by Yellow Sand Phenomena. Also the principal chemical compounds of particle were estimate metals(Fe, Al, Si, Zn) oxides, $CaSO_4, NaSO_4, MgSO_4, NaC1, MgCl_2$ and $(NH_4)_2SO_4$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.101-101
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• 2003

• Korean Journal of Materials Research
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• v.28 no.1
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• pp.6-11
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• 2018

There are various manufacturing processes for pure $SiO_2$ that is used as abrasives, chemicals, filters, and glasses, and in metallurgy and optical industries. In the optical fiber industry, to produce $SiO_2$ preform, $SiCl_4$ is utilized as a raw material. However, the combustion reaction of $SiCl_4$ has caused critical environmental issues, such as ozone deficiency by chlorine compounds, the greenhouse effect by carbon dioxide and corrosive gas such as hydrochloric acid. Thus, finding an alternative source that does not have those environmental issues is important for the future. Octamethylcyclotetrasiloxane (OMCTS or D4) as a chlorine free source is recently promising candidate for the $SiO_2$ preform formation. In this study, we first conducted a vaporizer design to vaporize the OMCTS. The vaporizer for the OMCTS vaporization was produced on the basis of the results of the vaporizer design. The size of the primary particle of the $SiO_2$ formed by OMCTS was less than 100 nm. X-ray diffraction patterns of the $SiO_2$ indicated an amorphous phase. Fourier-transform infrared spectroscopy analysis revealed the Si-O-Si bond without the -OH group.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.115-121
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• 2002

In this research we have investigated the characteristics of ultra thin $HfO_2 /SiON$stack structure films using several analytical techniques. SiON layer was thermally grown on standard SCI cleaned silicon wafer at $825^{\circ}C$ for 12sec under $N_2$O ambient. $HfO_2 /SiON$$_4$/$H_2O$ as precursors and $N_2$as a carrier/purge gas. Solid HfCl$_4$was volatilized in a canister kept at $200^{\circ}C$ and carried into the reaction chamber with pure $N_2$carrier gas. $H_2O$ canister was kept at $12^{\circ}C$ and carrier gas was not used. The films were grown on 8-inch (100) p-type Silicon wafer at the $300^{\circ}C$ temperature after standard SCI cleaning, Spectroscopic ellipsometer and TEM were used to investigate the initial growth mechanism, microstructure and thickness. The electrical properties of the film were measured and compared with the physical/chemical properties. The effects of heat treatment was discussed.

• Polymer(Korea)
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• v.25 no.4
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• pp.468-475
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• 2001

For copolymerization of ethylene and norbornene initiated by various metallocene catalysts such as $rac-Et(Ind)_2ZrCl_2,\;rac-Me_2Si(Ind)_2ZrCl_2,\;rac-Me_2Si(Cp)_2ZrCl_2,\;and\;(n-BuCp)_2ZrCl_2$ with modified methylaluminoxane(MMAO) cocatalyst, the ${\alpha}$-olefins such as 1-hexene(H), 1-octene and 1-decene were added as a 3rd monomer. In this situation, the effects of the polymerization condition, the catalyst structure as well as the structure and the amount of added ${\alpha}$-olefin on the catalyst activity as well as the properties and structure of polymer were examined. As results, it was found that the catalyst activity and thermal property of polymer depended on not only catalyst structure but also ${\alpha}$-olefin structure. For $rac-Et(Ind)_2ZrCl_2/MMAO$ catalyst system, it was possible to get high activity and controllable $T_g$ of polymer. Among ${\alpha}$-olefins, H as a 3rd monomer exhibited the maximum enhancement in catalyst activity.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.46-53
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• 1998

A new method to form the double structured active layers of a-Si/a-SiN$_{x}$ of polycrystalline thin film transistor is proposed and poly-Si TFTs employed double structure active film are fabricated. Nitrogen ions were added to bottom amorphous silicon active film(a-SiN$_{x}$ ) and pure a-Si film deposition on a-SiN$_{x}$ was followed. The XeCl excimer laser was irradiated to crystallize double structure active film. The grain growth of upper a-Si film was also promoted in the double structured active layers of a-Si/a-SiN$_{x}$ due to the mitigation of solidification process of lower a-SiN$_{x}$ layer. Our experimental results show that the ratio of NH$_3$/SiH$_4$ is required to maintain below 0.11 for the reduction of contact resistance of n$^{+}$ poly-SiN$_{x}$ layer.r.

• Corrosion Science and Technology
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• v.21 no.2
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• pp.111-120
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• 2022

To solve the corrosion problem of industrial equipment and other constructions containing metals, corrosion protection can be performed by using coating which provides a barrier between the metal and its environment. Coatings play a significant role in protecting irons and steels in harsh marine and acid environments. This study was conducted to identify an anti-corrosive epoxy coating for carbon steel composite with 0.1, 0.3, and 0.5 wt% concentrations of nanoparticles of SiO₂ using the dip-coating method. The electrochemical behavior was analyzed with open circuit potential (OCP) technics and polarization curves (Tafle) in 3.5 wt% NaCl and 5 vol% H₂SO₄ media. The structure, composition, and morphology were characterized using different analytical techniques such as X-ray Diffraction (XRD), Fourier Transform Infrared spectrum (FT-IR), and Scanning Electron Microscopy (SEM). Results revealed that epoxynano SiO₂ coating demonstrated a lower corrosion rate of 2.51 × 10^-4 mm/year and the efficiency of corrosion protection was as high as 99.77%. The electrochemical measurement showed that the nano-SiO₂ / epoxy coating enhanced the anti-corrosive performance in both NaCl and H₂SO₄ media.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1529-1530
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• 2007

The manganese co-doped $Ca_8Mg_1(SiO_4)_4Cl_2:Eu^{2+}$,$Mn^{2+}$ phosphor was synthesized by solid-state reaction and its photoluminescence characteristics were investigated. The synthesized phosphor show two emission spetrums: green band of 512nm and yellow band of 550nm. White light-emitting diodes (LEDs) were fabricated through combination of a 405nm-emitting InGaN chip and a synthesis phosphor in a single package. Under 20mA current, its CIE chromaticity coordinates are x=0.40 and y=0.45 and a color temperature of 4053K.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.1
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• pp.45-53
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• 2012

The metal chloride wastes from a pyrochemical process to recover uranium and transuranic elements has been considered as a problematic waste difficult to apply to a conventional solidification method due to the high volatility and low compatibility with silicate glass. In this study, a dechlorination approach to treat LiCl-KCl waste for final disposal was adapted. In this study, a $SiO_2-Al_2O_3-P_2O_5$ (SAP) inorganic composite as a dechlorination agent was prepared by a conventional sol-gel process. By using a series of SAPs, the dechlorination behavior and consolidation of reaction products were investigated. Different from LiCl waste, the dechlorination reaction occurred mainly at two temperature ranges. The thermogravimetric test indicated that the first reaction range was about $400^{\circ}C$ for LiCl and the second was about $700^{\circ}C$ for KCl. The SAP 1071 (Si/Al/P=1/0.75/1 in molar) was found to be the most favorable SAP as a dechlorination agent under given conditions. The consolidation test revealed that the bulk shape and the densification of consolidated forms depended on the SAP/Salt ratios. The leaching test by PCT-A method was performed to evaluate the durability of consolidated forms. This study provided the basic information on the dechlorination approach. Based on the experimental results, the dechlorination method using a $SiO_2-Al_2O_3-P_2O_5$ (SAP) could be considered as one of alternatives for the immobilization of waste salt.