• Polymer Science and Technology
• /
• v.8 no.3
• /
• pp.248-260
• /
• 1997

• Polymer Science and Technology
• /
• v.8 no.3
• /
• pp.261-268
• /
• 1997

• Journal of the Korean Chemical Society
• /
• v.46 no.3
• /
• pp.242-251
• /
• 2002

We report the synthesis and characterization of the perovskite nanotubes made by sol-gel template syn-thesis.Both lead titanate (PbTiO3 : PT), lead zirconate (PbZrO3 : PZ) and lead zirconium titanate (PbZrO3 -PbTiO3 : PZT) solid solution nanotubes were prepared with a chelate sol-gel of titanium isopropoxide (Ti(OPri)4 ), zirconium tet-rabutoxide (Zr(OBu)4 ) and the respective lead acetate (Pb(OAc)2 -3H2O). WhatmanRanodisc membranes, with a 200nm pore size, served as the template. After the removal of the template in the 6M-NaOH, scanning electron microscopy shows that the shapes formed are 200 nm outer diameter tubes with 50mm lengths. Transmission electron microscopy and electron diffraction reveal that the tubes are polycrystalline. The PT nanotubes so far have shown an anomalous transition temperature, 234.4$^{\circ}C$ as measured by DSC with a small particle size, 15.4 nm determined by X-ray analysis with the aid of Scherrer's equation.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.224-224
• /
• 2003

광통신을 위한 구성 요소는 빛을 발생시키는 발광소자, 빛을 검출하는 수광소자 그리고 광신호를 처리하는 광신호처리 소자로 구성된다. 이때 각 소자간 광전송과 광소자에 의한 광 신호 처리 과정에서 광전송 손실이 심각하게 일어나 광정보를 상실하게 되므로 각 요소별로 광신호 증폭이 반드시 필요하다. 뿐만 아니라 완전 광화에 의한 초고속/대용량 광통신망의 구축에는 저가이며, 광집적화가 가능한 광도파로형 광증폭기가 요구되고 있다. 짧은 거리에 높은 증폭 효율을 얻기 위한 광도파로형 광증폭기를 구현하기 위해서는 광통신 파장대인 1.55$\mu\textrm{m}$ 대역의 증폭이 가능한 Er 이온을 고농도로 도핑 할 필요가 있다. 그러나 Er 이온을 단순히 고농도로 첨가하면 Er-Er 간 뭉침 현상에 의해 더 이상의 증폭이 어렵게 된다. 본 연구에서는 이러한 문제를 해결하면서 스핀 코팅이 가능하여 저가 공정이 가능한 유/무기 졸-겔 재료 내에 Er 이온을 제어된 방법으로 첨가하고 그 결합 환경을 FT-IR 및 $^{17}$ O-NMR로 분석하였다. 유/무기 졸겔 재료 제조를 위하여 먼저 MPTS(MethAcryoxyPropylTrimethoxySilane)를 부분 가수분해한 후 ZrOCl$_2$.8$_2$O (Zirconyl Chloride Octahydrate) 와 ErCl$_3$. 6$H_2O$ (Erbium(III) Chloride Hexahydrate)를 순차적으로 결합시키고, Zr/MPTS 및 Zr/Er의 첨가비에 따른 발광 특성을 PL(photoluminescence) 스팩트럼으로 분석하여 Er 이온의 주위 결합 환경이 PL에 미치는 영향을 조사하였다. 또한 Si 기판에 코팅한 Er이 도핑된 유/무기 하이브리드 졸-겔 코팅막의 굴절율 등 광도파로 재료로서의 특성도 프리즘 커플러 등을 이용하여 조사하였다.

• Polymer(Korea)
• /
• v.31 no.6
• /
• pp.485-490
• /
• 2007

Hard coating was made on a polycarbonate plate using a sol-gel process with a melamine derivative and silicates, and examined as potential substitutes for automobile glass. Methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and phenyltriethoxysilane were used to form a coating solution. The coatings on the polycarbonate plate were deposited using a sol-gel process. Poly(methyl methacrylate) was coated on the surface of polycarbonate in order to improve adhesion property. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Adding the melamine derivative to the coating solution, the pencil hardness of the coating was improved. The hardness of a 3H class pencil, excellent abrasion resistance, and surface uniformity were found in the coated polycarbonate surface.

• Journal of Adhesion and Interface
• /
• v.6 no.3
• /
• pp.10-18
• /
• 2005

The hard coatings on the polycarbonate plate were performed with the object of substitution the glass in the car to the polycarbonate plate. In this research, tetraethyl orthosilicate (TEOS), methyltriethoxysilane (MTES) were used to prepare the coatings by sol-gel process. The optimum conditions and formulation to get the excellent physical properties were determined. The pretreatment condition of polycarbonate plate, the mole ratio of TEOS and MTES, selection of the solvent, the aging time, the amount of acid catalyst, and the number of folds of coating were characterized. Pretreatment with poly(methyl methacrylate) was very effective to increase the adhesion strength. The smooth coating which got the 2 H class in pencil hardness was formed in this research by sol-gel process.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.55-55
• /
• 2003

Recently, with the rapid development of the waveguide division multiplexing (WDM) systems for large capacity and flexibility of information network, the broad band 1.5$\mu\textrm{m}$ erbium-doped waveguide amplifier (EDWA) become important. The main factors affecting the performance of sol-gel-based waveguides are non-radiative relaxation channels due to rare-earth concentration quenching and to vibration of the OH groups Therefore, the sol-gel process has to be carefully controlled in order to minimize the residual OH content.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2003.03a
• /
• pp.206-206
• /
• 2003

현재, 메탈의 내부식성 코팅막 제조에 사용되고 있는 크로메이트 기반 코팅제는 유독성 물질에 대한 환경 규제에 따라 조만간 사용이 금지 될 예정이다. 본 연구에서는 이러한 유독성 금속 내부식성 코팅제를 대체할 새로운 코팅 재료로 부식 억제제가 결합된 수용성 졸을 제조하고 그 특성을 보고하고자 한다 부식 억제제가 결합된 수용성 졸은 부분 가수 분해된 GPS((3-glycidoxypropyltriethoxysilane)에 Zirconiumoxychlorideoctahydrate 혹은 cerium nitrate를 일정 양 첨가하고 이온 교환수에 희석하여 제조하였다. 이 코팅 졸을 아연 도금 강판에 딥 코팅법으로 코팅한 후 상온에서 건조하고, 80~15$0^{\circ}C$에서 열처리하여 염수 분무 시험으로 백청 발생 정도를 관찰하여 내 부식성을 조사하였다. 코팅막의 두께는 수직으로 절단한 면을 전자 현미경으로 관찰하여 측정하였으며, 표면의 경도는 연필 경도계로 조사하였다. 또한 코팅막의 부식 전위는 전기화학적인 방법으로 분석되어 부식억제제의 종류에 따른 효과도 정량적으로 비교되었다.

• Membrane Journal
• /
• v.18 no.2
• /
• pp.176-184
• /
• 2008

Nano-porous ceramic membranes was synthesized by the sol-gel method. Gas permeation of hydrogen and nitrogen was determined by single composition gas. Pore size $0.1{\mu}m$ and porosity 32% of flat type ${\alpha}-Al_2O_3$ substrate was manufactured. An intermediate ${\gamma}-Al_2O_3$ layer with pore size of 4 nm was formed by dip-coating. Polymeric silica sol was synthesized by acid catalyzed hydrolysis and condensation of tetra-ethyl-ortho-silicate. Supported membranes on alumina were prepared by dipping and calcining. He, $N_2$ permeation experiments with nanoporous sol-gel modified supported ceramic membranes were peformed to determine the gas transport characteristics. $He/N_2$ permselectivity around $100{\sim}160$ and helium permeation in the order of $10^{-7}mol/m^2{\cdot}s{\cdot}Pa$ were measured in the temperature range of $303{\sim}363K$.

• Analytical Science and Technology
• /
• v.11 no.3
• /
• pp.156-160
• /
• 1998

SiC is synthesized by sol-gel and carbothermal reaction method from various carbon sources and Si source and characterized through the results of DSC and XRD. More SiC has been formed in carbothermal reaction than sol-gel method. From the XRD results, the degree of formation of SiC increases in the order of petroleum cokes, activated carbon, artificial graphite all in two introduced methods. Based on the DSC data, the enthalpy values for the exothermic reaction decrease in the order of activated carbon, petroleum cokes, artificial graphite in carbothermal reaction methods, while those for the endothermic reactions increase in the reverse order. But, the enthalpy values for the exothermic reactions decrease in the order of petroleum cokes, activated carbon, artificial graphite in sol-gel methods.