• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.96-99
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• 2004

A new proton conductive inorganic-organic hybrid membrane doped with $H_3PO_4$ was fabricated via sol-gel process wit 3- glycidoxypropyltrimethoxysilane(GPTMS), 3-aminopropyltriethoxysilane(APTES) and tetraethoxysilane(TEOS) asprecursors. Theproto conductivity of about 3.0$\times10^{-3}S/cm$ was obtained at $120^{\circ}C$ under $50\%$ relative humidity (R.H). DTA curves showed that the thermal stability of the membrane is significantly enhanced by the presence of $SiO_2$ framework up to $250^{\circ}C$. SEM and XRD revealed that the gel is microporou and amorphous. The addition of APTES improved the conductivity of the membranes and the effect of the APTES on the conductivity was also discussed in this paper.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.42-45
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• 2003

Inorganic polymer based hybrid membranes consisting of zirconium oxide and polydimethylsiloxane (PDMS) have been synthesized by sol-gel processes. The hybrid membranes showed thermal stability and flexibility up to $300^{\circ}C$. The membrane becomes proton conducting polymer electrolyte when added with 12-phosphotungstic acid (PWA). The conductivity of the membranes was measured in the temperature range from room temperature to $150^{\circ}C$ under saturated humidity and a maximum conductivity of $5{\times}10^{-5}\;Sm^{-1}$ was obtained at $150^{\circ}C$.

• Macromolecular Research
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• 제17권11호
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• pp.907-911
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• 2009

To improve the moisture stability of the $CaS:Eu^{2+}$ red phosphor, surface coatings with silica nanoparticles were performed using five different methods, i.e., $P_1$, $P_2$, $P_3$, $P_4$, and $P_5$. The phosphors were coated with silica nanoparticles using a dip coating method ($P_1$) and sol-gel method ($P_2$). The phosphors were coated using a solution containing silica nanoparticles and poly(1-vinyl-2-pyrrolidone), PVP, $(P_3$). The phosphors were also coated with silica nanoparticles by reacting with the 1-vinyl-2-pyrrolidone (VP) monomer ($P_4$) or by reacting with mixtures containing VP and tetraethylorthosilicate ($P_5$). A decrease in the photoluminescence (PL) intensity was observed regardless of the coating methods. However, the moisture stability of the phosphors was enhanced by the coating when aged in a temperature-controlled humidity chamber. Among these methods, the $P_4$ (or $P_5$) method exhibited the greatest increase in moisture stability of the phosphors. The coated phosphors showed a relatively constant intensity with aging time, whereas the uncoated phosphor showed a decrease.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.622-627
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• 2013

콜로이달 실리카는 실리콘과 사파이어 웨이퍼의 정밀연마슬러리, 유-무기 하이브리드 코팅제, 정밀주조의 바인더 등 다양한 제품으로 사용되는 물질이다. 이러한 실리카 졸의 입자크기 및 분산 안정성은 웨이퍼의 표면, 코팅 막 혹은 벌크의 기계적, 화학적, 광학적 특성에 영향을 주기 때문에 정확한 측정값이 요구된다. 본 연구에서는 제조사에서 제시한 입자 크기 및 표면 특성이 다른 8종류 실리카 졸의 부피 분율에 따라 입자 크기, 졸 점도 및 입자 전기영동이동도의 측정결과에 미치는 영향을 논의하였다. 높은 표면활성을 지닌 실리카 입자의 특성 및 실리카 졸의 희석에 의한 안정화 이온 농도의 변화로 인해 실리카의 측정 입자 크기와 이동도는 졸의 부피 분율 혹은 입자 크기에 따라 변한다. 60 nm 보다 작은 입자는 부피 분율이 증가함에 따라 측정된 입자 크기가 증가한 반면에, 그 보다 큰 입자에서는 측정된 입자 크기가 감소하였다. 12 nm와 같이 작은 입자는 부피 분율이 증가함에 따라 점도가 상승하면서 측정 입자의 이동도가 감소한 반면에 100 nm의 큰 입자는 0.048의 낮은 부피 분율까지 이동도가 증가하다가 그보다 높은 부피 분율부터 감소하였다.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.394-401
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• 2019

The unique study of TiO₂ sol-gel modified carbon paste electrode (CPE) nanocomposites have been developed for electrochemical sensor detecting fipronil pesticide compound. We develop the easy synthesized TiO₂ via a sol-gel method and modified in CPE which applied electrochemical system as cyclic voltammetry (CV) because the concentration is proportional with current peaks. We discover the TiO₂ optimal mass used of 0.1 g which is compared with 0.7 g carbon and 0.3 mL paraffin. It has high-current anodic (Ip_a) of 1.13×10³ μA and high-current cathodic (Ip_c) -0.96×10³ μA in scan rate of 0.5 V/s. The limit of detection (LOD) of fipronil has been determined of 34.0×10^-5 μM in percent recovery of 0.8%. Its high-stability for lifetime TiO₂-CPE nanocomposites was expressed for 13 days which mean that can be used for detecting fipronil pesticide.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.500-506
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• 2010

The metal monolith catalyst coated with 15wt% Ni/$MgAl_2O_4$ is applied to the natural gas steam reforming for hydrogen production. To address the improvement of adherence between metal monolith and catalyst coating layer, the pre-calcination temperature as well as the coating conditions of $Al_2O_3$ sol are optimized. When the Fe-Cr alloy monolith is pre-calcined at $900^{\circ}C$ for 6 h, $Al_2O_3$ layer was formed uniformly on the entire surface of the metal substrate. It is seen that the formation of $Al_2O_3$ layer on the monolith surface is essential for the uniform coating of $Al_2O_3$ sol onto the monolith substrate. The monolith catalyst coated with 10wt% $Al_2O_3$ sol shows high $CH_4$ conversion and good thermal stability as compared with the monolith catalyst without $Al_2O_3$ sol coating under severe reaction conditions with high GHSV of 30,000 $h^{-1}$ at $700^{\circ}C$. In addition, the metal monolith catalyst shows higher catalytic activity and better thermal conductivity than 15wt% Ni/$MgAl_2O_4$ pellet catalyst.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.288-293
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• 2017

$Fe_2O_3$ is one of the most important metal oxides for gas sensing applications because of its low cost and high stability. It is well-known that the shape, size, and phase of $Fe_2O_3$ have a significant influence on its sensing properties. Many reports are available in the literature on the use of $Fe_2O_3$-based sensors for detecting gases, such as $NO_2$, $NH_3$, $H_2S$, $H_2$, and CO. In this paper, we investigated the gas-sensing performance of a Pt-doped ${\varepsilon}$-phase $Fe_2O_3$ gas sensor. Pt-doped $Fe_2O_3$ nanoparticles were synthesized by a Sol-Gel method. Platinum, known as a catalytic material, was used for improving gas-sensing performance in this research. The gas-response measurement at $300^{\circ}C$ showed that $Fe_2O_3$ gas sensors doped with 3%Pt are selective for $NO_2$ gas and exhibita maximum response of 21.23%. The gas-sensing properties proved that $Fe_2O_3$ could be used as a gas sensor for nitrogen dioxide.

• Journal of Pharmaceutical Investigation
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• 제22권1호
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• pp.41-48
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• 1992

Six common tablet disintegrants (corn starch, Avicel PH102, calcium carboxymethylcellulose, Primojel, Kollidon CL and Ac-Di-Sol) were used at the concentration of 0, 2, 4 and 6% (w/w) in salicylamide tablets made with wet granulation method. Certain physical parameters of the disintegrants (moisture sorption, hydration capacity and bulk density) were determined to evaluate their relative efficiency. The disintegration time and dissolution rate of the tablets were correlated well with the ranks of initial rate of moisture sorption for each disintegrant as follows; Ac-Di-Sol, Kollidon CL, primojel, calcium CMC, corn starch and Avicel PH102. The initial rate of moisture sorption was important for the disintegration capacity as well as hydration capacity. The effect of storage at different temperatures and relative humidity upon the tablets containing various disintegrants was evaluated in terms of tablet hardness and disintegration time. Storage at high temperature reduced the hardness substantially and retarded the disintegration of the all tablets studied. Especially, the hardness of tablets containing Kollidon CL was significantly reduced. Although the tablet hardness was decreased and the disintegration time was increased under a moderate humid condition, both of them were decreased under the severely high humid condition of 80 or 90% RH, which was due to the breakrupture of tablet matrix bonds by the excessive uptake of moisture. Therefore, the stability caused by moisture sorption should be considered, when disintegrants having high moisture sorption such as Kollidon CL, Ac-Di-Sol and Primojel were employed in the tablets containing water-labile or hygroscopic drugs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.353-353
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• 2011

Titanium dioxide is a suitable material for industrial use at present and in the future because titanium dioxide has efficient photoactivity, good stability and low cost [1]. Among the three phases (anatase, rutile, brookite) of titanium dioxide, the anatase form is particularly photocatalytically active under ultraviolet (UV) light. In fabrication of photocatalytic devices based on catalytic nanodiodes [2], it is challenging to obtain a photocatalytically active TiO2 thin film that can be prepared at low temperature (< 200$^{\circ}C$). Here, we present the synthesis of a titanium dioxide film using TiO2 nanoparticles and sol-gel methods. Titanium tetra-isopropoxide was used as the precursor and alcohol as the solvent. Titanium dioxide thin films were made using spin coating. The change of atomic structure was monitored after heating the thin film at 200$^{\circ}C$ and at 350$^{\circ}C$. The prepared samples have been characterized by X-ray diffraction (XRD), scanning electron microcopy, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy (UV-vis), and ellipsometry. XRD spectra show an anatase phase at low temperature, 200$^{\circ}C$. UV-vis confirms the anatase phase band gap energy (3.2 eV) when using the photocatalyst. TEM images reveal crystallization of the titanium dioxide at 200$^{\circ}C$. We will discuss the switching behavior of the Pt /sol-gel TiO2 /Pt layers that can be a new type of resistive random-access memory.

• 한국분말재료학회지
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• 제30권5호
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• pp.394-401
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• 2023

Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) is considered to be one of the promising solid-state electrolytes owing to its excellent chemical and thermal stability, wide potential range (~5.0 V), and high ionic conductivity (~10^-4 S/cm). LATP powders are typically prepared via the sol-gel method by adding and mixing nitrate or alkoxide precursors with chelating agents. Here, the thermal properties, crystallinity, density, particle size, and distribution of LATP powders based on chelating agents (citric acid, acetylacetone, EDTA) are compared to find the optimal conditions for densely sintered LATP with high purity. In addition, the three types of LATP powders are utilized to prepare sintered solid electrolytes and observe the microstructure changes during the sintering process. The pyrolysis onset temperature and crystallization temperature of the powder samples are in the order AC-LATP > CA-LATP > ED-LATP, and the LATP powder utilizing citric acid exhibits the highest purity, as no secondary phase other than LiTi₂PO₄ phase is observed. LATP with citric acid and acetylacetone has a value close to the theoretical density (2.8 g/cm³) after sintering. In comparison, LATP with EDTA has a low sintered density (2.2 g/cm³) because of the generation of many pores after sintering.