• Title, Summary, Keyword: sol-gel process

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A Study on Preparation and Characterization of Mullite Coated Film by Sol-Gel Process (졸-겔법에 의한 Mullite 코팅막의 제조 및 특성에 관한 연구)

  • 이용택;최영우;양중식
    • Journal of the Korean Ceramic Society
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    • v.34 no.6
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    • pp.611-619
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    • 1997
  • Optimal Mullite sol was synthesized by sol-gel process using Aluminium sec-butoxide(ASB), Tetraethoxysilane(TEOS) and then, Mullite films were dip-coated with various holding time in sol bath and heat-treated at 130$0^{\circ}C$ above for crystallization. The thickness of coated film increased linearly with holding time in sol bath and average pore size was controllable within 20~30$\AA$.

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Effects of β-SiC Particle Seeds on Morphology and Size of High Purity β-SiC Powder Synthesized using Sol-Gel Process (β-SiC 분말 Seeds가 Sol-gel 공정으로 합성된 고순도 β-SiC 분말 형상 및 크기에 미치는 영향)

  • Kim, Gyu-Mi;Cho, Gyoung-Sun;Park, Sang-Whan
    • Journal of the Korean Ceramic Society
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    • v.46 no.5
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    • pp.528-533
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    • 2009
  • High purity $\beta$-SiC powders were synthesized using sol-gel processing. TEOS and phenol resin were used as the starting material for the silicon source and carbon source, respectively. The process turned out to be capable of producing high purity SiC powder purity degree with 99.98 %. However, it was difficult to control the shape and size of $\beta$-SiC powders synthesized by sol-gel process. In this study, $\beta$-SiC powder with size of $1{\sim}5$ um an 30 nm were used as the seeds for $\beta$-SiC to control the $\beta$-SiC powder morphology. It was found that $\beta$-SiC powder seeds was effective to increase the powder average size of synthesized $\beta$-SiC using sol-gel process by acting as the preferred growing sites for $\beta$-SiC.

Preparation and Properties of Inorganic-organic Hybrid $Li^+$ Ion Conductor by Sol-gel Process

  • Nishio, Keishi;Miyazawa, Tsutomu;Watanabe, Yuichi;Tsuchiya, Toshio
    • The Korean Journal of Ceramics
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    • v.7 no.1
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    • pp.1-5
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    • 2001
  • Inorganic-organic hybrid Li$^+$ ion conductors were prepared by the sol-gel process. Tetramethyl orthosilicate (TMOS), polyethylene glycol 200 (PEG$_200$) and lithium bis (trifluoro-methylsulfony) imide were used as raw materials and $H_2O$ was used as a solvent. Hybrid Li$^+$ ion conductor prepared by the sol-gel process showed very high ion conductivities of log${\sigma}_R.T$(S/cm)=-3.73, log${\sigma}_60$(S/cm)=-3.00 at room temperature and $60^{\circ}C$, respectivery. Decomposition voltage was 3.1 V.

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Comparative Study and Electrochemical Properties of LiFePO4F Synthesized by Different Routes

  • Huang, Bin;Liu, Suqin;Li, Hongliang;Zhuang, Shuxin;Fang, Dong
    • Bulletin of the Korean Chemical Society
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    • v.33 no.7
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    • pp.2315-2319
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    • 2012
  • To improve the performance of $LiFePO_4F$, a novel sol-gel process is developed. For comparison, ceramic process is also implemented. From X-ray diffraction results we know that each sample adopts a triclinic $P{\bar{1}}$ space group, and they are isostructural with amblygonite and tavorite. The scanning electron microscope images show that the homogeneous grains with the dimension of 300-500 nm is obtained by the sol-gel process; meanwhile the sample particles obtained by ceramic process are as big as 1000-3000 nm. By galvanostatic tests and at electrochemical impedance spectroscopy method, the sample obtained by sol-gel process presents better electrochemical properties than the one obtained by ceramic process.

Improved Immobilized Enzyme Systems Using Spherical Micro Silica Sol-Gel Enzyme Beads

  • Lee, Chang-Won;Yi, Song-Se;Kim, Ju-Han;Lee, Yoon-Sik;Kim, Byung-Gee
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.11 no.4
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    • pp.277-281
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    • 2006
  • Spherical micro silica sol-gel immobilized enzyme beads were prepared in an emulsion system using cyclohexanone and Triton-X 114. The beads were used for the in situ immobilization of transaminase, trypsin, and lipase. Immobilization during the sol to gel phase transition was investigated to determine the effect of the emulsifying solvents, surfactants, and mixing process on the formation of spherical micro sol-gel enzyme beads and their catalytic activity. The different combinations of sol-gel precursors affected both activity and the stability of the enzymes, which suggests that each enzyme has a unique preference for the silica gel matrix dependent upon the characteristics of the precursors. The resulting enzyme-entrapped micronsized beads were characterized and utilized for several enzyme reaction cycles. These results indicated improved stability compared to the conventional crushed form silica sol-gel immobilized enzyme systems.

Development of fabrication process of Planar Light-wave Circuit (PLC) : Optimization of the fabrication process of planar light-wave circuit by Hybrid Sol-Gel methods

  • Jang, Won-Gun;Kim, Chung-Ryeol;Kim, Jae-Pil;Park, Young-Sik
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.484-485
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    • 2003
  • We report on the optimization of the fabrication process of hybrid sol-gel thin film deposition to produce low cost $1 {\times} 16$ splitters for optical communications. We learn that sol-gel film thickness is dependent upon the spinning speeds and viscosity of the sol-gel solutions and refractive index upon the dopant concentrations of Al and Zr in the sol solutions. We could find the optimized physical conditions to achieve the desired thickness of core and cladding layers. We will further carry out the fabrication and measurements of insertion loss, polarization dependent loss (PDL), etc. for the performance of fabricated splitter devices.

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Properties of Nano-Hybrid Coating Films Synthesized from Colloidal Silica-Silane (콜로이달 실리카와 실란으로부터 합성된 나노하이브리드 코팅 박막의 특성)

  • Na, Moon-Kyong;Ahn, Myeong-Sang;Kang, Dong-Pil
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.232-233
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    • 2006
  • In recent years the interest in organic/inorganic hybrid materials has increased at a fast rate. Nano organic-inorganic hybrid composites have shown advantages for preparing hard coating layers. Especially, nano hybrid composite has low environmental pollution. It has high transparency, hardness, toughness, thermal dissociation temperature, hydrophobicity by using nano sized inorganic material. There are many ways in which these materials may be synthesized, a typical one being the use of silica and silanes using the sol-gel process. The structure of sol-gel silica evolves as a result of these successive hydrolysis and condensation reactions and the subsequent drying and curing. The sol-gel reactions are catalyzed by acids and produce silica sol solutions. The silica sol grows until they reach a size where a gel transition occurs and a solid-like gel is formed. Colloidal silica(CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. From all sol-gel solutions, seasoning effect of sol-gel coating layer on glass was observed.

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Immobilization of Phospholipase C by sol-gel method

  • Sohn, Ok-Jae;Yim, Yong-Sik;Jung, Jin-Su;Lee, Yong-Jun;Lee, Hye-Na;Rhee, Jong-Il
    • 한국생물공학회:학술대회논문집
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    • pp.120-122
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    • 2005
  • Phospholipases C (PLCs) from B. cereus 318 and recombinant Pichia pastoris were immobilized on sol-gel coated glass beads. The pH and temperature on immobilized PLC activity were investigated. Operational and storage stability of the immobilized PLCs was measured by spectro- photometric assay. The PLCs immobilized on sol-gel coated glass beads were photographed by scanning electron microscope (SEM).

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Electrochemical Characteristics of TiO2 Photoelectrode for DSSC Prepared by Sol-gel Method (졸겔법에 의한 DSSC 광전극의 전기화학적 특성)

  • Park, A-Reum;Jin, En Mei;Gu, Hal-Bon
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.4
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    • pp.315-320
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    • 2012
  • In general, a photoelectrode in DSSC(dye sensitized solar cell) are fabricated by using the $TiO_2$ (Titanium dioxide) to realize high efficiency and the efficiency of DSSC is affected by the size, the shape and the property of $TiO_2$. We synthesized the crystalline $TiO_2$ by sol-gel method. In spite of many merits, only weakness for the sol-gel method is taking many process times. To solve this problem, we reduced the fabricating processes. The reduced process is the making process that is $TiO_2$ sol to $TiO_2$ powder with including of two heat treatment and two mixing. We could simplify the process by preparing $TiO_2$ sol to $TiO_2$ paste directly. As a result, DSSC fabrication process is simplified and we have obtained the efficiency best result 3.88% with $V_{OC}$=0.71 V, $J_{SC}=8.70\;mA/cm^{-2}$, and FF=62.37%, respectively.

Microwave Dielectric Properties of Low-temperature Sintered $MgCo_2(VO_4)_2$ Ceramics Synthesized by Sol-Gel process (졸-겔 공정에 의해 제조된 저온소결 $MgCo_2(VO_4)_2$ 세라믹스의 마이크로파 유전특성)

  • Lee, Ji-Hun;Bang, Jae-Cheol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.288-289
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    • 2006
  • We studied the effect of sol-gel processing and sintering temperature on the microwave properties of $MgCo_2(VO_4)_2$ system(MCV) which is applicable to LTCC(low-temperature cofired ceramics). The MCV was synthesized by sol-gel process using solution that contains precursor molecules for Mg, Co, and V. SEM analysis shows that the average particle size is ${\sim}1{\mu}m$ and size distribution is very uniform compared to the one prepared by conventional solid-state reaction process. Highly dense samples were obtained at the sintering temperature range of $750^{\circ}C{\sim}930^{\circ}C$. The maximum $Q{\times}f_0$ value of 55,700GHz, dielectric constant(${\varepsilon}_r$) of 10.41 and temperature coefficient(${\tau}_f$) of $-85ppm/^{\circ}C$ was obtained at the sintering temperature of $930^{\circ}C$. The superior microwave properties of sol-gel processed MCV relative to conventional solid-state reaction processed one is remarkable especially at lower sintering temperatures such as $750^{\circ}C$ and $800^{\circ}C$.

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