• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.137-138
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• 2012

ZnO 박막을 Sol-gel용액을 이용한 스핀코팅 방법으로 석영기판 위에 성장하였고 Sol-gel 용액의 온도 변화에 따른 구조적, 광학적 특성을 분석하였다. ZnO 박막의 구조적, 광학적 특성을 조사하기 위해 field-emission scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), 그리고 ultraviolet-visible (UV) spectroscopy을 사용하였다. PL 분석에서 ZnO 박막은 orange 계열의 발광을 하였으며, PL spectra는 3.3 eV 부근의 near-band edge emission (NBE) 피크와 2.0 eV 부근의 deep-level emission (DLE) 피크로 이루어져있다. 모든 sol-gel 용액 온도에서, DLE 피크가 NBE 피크보다 더 우세하고 이 DLE 피크는 sol-gel 용액의 온도가 증가함에 따라 점점 증가하다가 감소하는 것을 알 수 있다. 이런 DLE 피크는 산소 공공, 아연 공공, 침입형 산소, 침입형 아연 등과 같은 결함에 의한 것이며, ZnO 박막은 sol-gel 용액의 온도에 따라 결함의 특성이 변화하였다.

• 한국결정성장학회지
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• 제9권1호
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• pp.101-106
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• 1999

Pb$(Zr_{0.5},Ti_{0.5})O_3$ 박막을 $Pt/Ti/SiO_2/Si$ 기판 위에 spin-coating법으로 제조하였다. 제조된 sol을 초음파 bath 내에서 초음파 처리하여 균일화를 촉진시킨 다음, 박막을 제조하여 초음파 처리되지 않은 sol로 제조된 박막과의 비교를 통해 초음파의 영향을 고찰하였다. 초음파 처리된 sol로 제조된 박막의 경우, $550^{\circ}C$에서 perovskite 단일상을 얻을 수 있었고, "rosette" 구조가 사라졌음을 관찰할 수 있엇따. 초음파 처리되지 않은 sol로 제조된 박막의 유전상수(10kHz), 잔류분극(Pr) 및 항전계(Ec) 값은 335, 12.3$\mu$C/$\textrm{cm}^2$, 168.4 kV/cm 였고, 초음파 처리된 sol로 제조된 박막은 각각 443, 172$\mu$C/$\textrm{cm}^2$, 153,5kVcm 로 전기적 특성이 개선되어 졌음을 알 수 있었다.

• 한국세라믹학회지
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• 제32권4호
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• pp.482-488
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• 1995

The phase transformation temperature from $\theta$- to $\alpha$-alumina was lowered from 1214$^{\circ}C$ to 114$0^{\circ}C$ in DSC by treating ${\gamma}$-alumina obtained by calcination of boehmite at $700^{\circ}C$ for 2hrswith $\alpha$-Al2O3 seeds (d50=0.36${\mu}{\textrm}{m}$) and 3wt% of the alumina sol. $\alpha$-Al2O3 seeds seemed to lower to the transformation temperature and the alumina sol suppressed the high temperature agglormeration. The effect was increased as the amount of the sol was increased, which was supported by TEM and particle size distribution. For an example, spherical ${\gamma}$-alumina powder with d50=0.54${\mu}{\textrm}{m}$ was prepared by treating the ${\gamma}$-alumina with 9 wt% of the alumina sol and 3wt% of the $\alpha$-Al2O3. It sintered to 99% of the theoretical density at 150$0^{\circ}C$ for 2hrs. and it had relatively homogeneous microstructure with 2~3${\mu}{\textrm}{m}$ sized grains.

• 한국세라믹학회지
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• 제32권1호
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• pp.17-24
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• 1995

The TEA complex polymeric sol was prepared by the alkoxide sol-gel method. The purpsoe of this experiment was to vefity the particle shape in the sol from the investigation of the rheological properties. TEA retarded hydrolysis rate by the reaction with alkoxide enough to make a stable transparent sol in the wide range of composition. From the results of the viscosity change with time, the optimum mole ratio for spinning was selected as 0.5 mole of TEA, 3 mole of H2O and the optimum viscosity was 104 cPs. The rheological behavior of the sol showed that the particle shape in the sol was linear, which was adequate for fiber drawing.

• E2M - 전기 전자와 첨단 소재
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• 제7권6호
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• pp.496-503
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• 1994

In recent years Sol-Gel processing provides an interesting alternative method for the fabrication of ferroelectric thin layers and powder. PZT powder was prepared from an alkoxide-based solution by a Sol-Gel method. Gelation of synthesized complex solutions, microstructure, thermal analysis and crystallization behaviors of the calcined powder were studied in accordance with a water content and a catalyst. Especially gelation and crystallization behavior were analysed with the change of pH. The gelation time decreased as the pH of the mixed solution increased. For PZT powder with 650.deg. C heat treatment, 100% perovskite phase was formed by using either acidic or basic catalyst. By using either acidic or basic catalyst, we were able to get very fine powders of uniform shape with an average particle size of 0.8-1.mu.m.

• 한국세라믹학회지
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• 제28권9호
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• pp.705-711
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• 1991

Alumina precursor sol was obtained by the reaction of Al(OC4H9)3 and acetylacetone in the solvent followed by the partial hydrolysis. This sol was measured by viscosity and the effect of pH. The powders obtained from this sol were calcined at the various temperatures. The transition of crystals and crystal state were investigated at the various temperatures. The powders dried at 90$^{\circ}C$ showed amorphous and ${\gamma}$-Al2O3 at 900$^{\circ}C$, ${\alpha}$-Al2O3 mono-phase at 1050$^{\circ}C$ respectively. As a result of Al27-MASNMR analysis, amorphous and ${\alpha}$-Al2O3 powders showed 6-coordinated Al, ${\gamma}$-Al2O3 4-coordinated Al respectively.

• 한국세라믹학회지
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• 제28권5호
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• pp.365-372
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• 1991

LAS (lithium aluminosilicate) sol was synthesized using the hydrolysis-condensation reaction of TEOS, chelated Al(OBus)3 and Li-salt with H2O in alcohol (EtOH+2-Propanol) medium. Effects of important reaction parameters on the properties of sol and gel-derived LAS were examined. The crystallization of the sol-gel derived LAS with ${\beta}$-spodumene composition began at ∼600$^{\circ}C$, and a series of polymorphic transformations occurred as temperature was increased to 1100$^{\circ}C$: amorphous LAS\longrightarrowhexagonal LiAl(SiO3)2\longrightarrow${\beta}$-spodumene. Lowering Li content in the gel enhanced densification and retarded the crystallization significantly. Optimum reaction conditions of LAS sol formation for thin coating applications were derived from rheological measurements, and these can be summarized as: H2O/total alkoxides molar ratio=4, pH=∼2.5, and aging time of ∼250h.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.111-111
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• 2005

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.158-162
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• 1996

The steady-state emission and fluorescence lifetimes of 1,3-dipyrenylpropane were measured in silicate sol-gel and xerogel matrices. In sol solution, the fluorescence emission spectra of monomer and excimer resemble those in hydrocarbon solvents. In gel and xerogel condition, however, the fluorescence spectra exhibit significant change, largely confirming the intramolecular motions in gel pores are influenced by microviscosity. The rate constants for intramolecular excimer formation were obtained from the measured fluorescence lifetimes and the rate processes for excimer forming in silicate sol-gel are described by a simple kinetic scheme.

• 한국세라믹학회지
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• 제32권9호
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• pp.995-1002
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• 1995

The alumina fiber was obtained by extruding the TEA complexed polymeric sol, synthesized by the alkoxide sol-gel method, through nozzle. The purpose of this study was to investigate the properties of fiber spun by TEA complexed sol. The analysis of sol indicated that TEA was bonded at alkoxide precursor and the optimum molar ratio for spinning was 0.5 mole of TEA, 3 mole of H2O. The cross section of the fiber from circular nozzle was not circular but oval, which indicated that the shape of nozzle did not affect the shape of fiber. The diameter of the fiber was about 100 ${\mu}{\textrm}{m}$ in the state of dried gel fiber, 60${\mu}{\textrm}{m}$ in calcined fiber, and the tensile strength of the fiber calcined at 90$0^{\circ}C$ was 2.1$\times$108 Pa.