• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.367-376
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• 1992

The powder characteristics of seeded alumina prepared from alkoxide by sol-gel method were studied. When ${\alpha}$-Al2O3 seeded powders used, these ${\alpha}$ phase transformation temperatures decreased than those of unseeded powders by 110$^{\circ}C$ and fine powders under 0.1 $\mu\textrm{m}$ could be obtained. When Fe-nitrate added powders used, fast transformation rate resulted from ionic effects of Fe3+, but hard aggregated morphology exhibited. When ${\alpha}$-Al2O3 and Fe nitrate simultaneously added, these powders represented lower transformation temperature but resulted in microstructure with aggregated particles.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2461-2465
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• 2013

Pd-$Ce/{\gamma}-Al_2O_3-TiO_2$ catalysts were prepared by combined sol-gel and impregnation methods. Transmission electron microscopy, X-ray diffraction, $H_2$-temperature-programmed reduction, $O_2$-temperature-programmed desorption, and ethanol oxidation experiments were conducted to determine the properties of the catalysts. Addition of an optimal amount of Ce improved the performance of the $Pd/{\gamma}-Al_2O_3-TiO_2$ catalyst in promoting the complete oxidation of ethanol. The catalyst with 1% Ce exhibited the highest activity, and catalyzed complete oxidation of ethanol at $175^{\circ}C$; its selectivity to $CO_2$ reached 87%. Characterization results show that addition of appropriate amount of Ce could enrich the PdO species, and weaken the Pd-O bonds, thus enhancing oxidation ability of the catalyst. Meanwhile, the introduction of $CeO_2$ could make PdO better dispersed on ${\gamma}-Al_2O_3-TiO_2$, which is beneficial for the improvement of the catalytic oxidation activity.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2002.11a
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• pp.69-71
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• 2002

$(Bi, La)Ti_{3}O_{12}(BLT)$ ferroelectric thin films were prepared on $Al_{2}O_{3}/Si$ substrates by the sol-gel method. The as-coated films were post-annealed at the temperature of $650^{\circ}C$ and $700^{\circ}C$ for 30 min. The crystallinty, surface morphologies and electrical properties were affected by the annealing temperatures. The BLT films annealed at above $650^{\circ}C$ exhibited typical bismuth layered perovskite structures with (00$\ell$) preferred orientation. The granular shaped grains with a size of approximately 90nm was formed in the film sample annealed at $700^{\circ}C$. The memory window volatge of the BLT film was 2.5V. The leakage current of BLT films annealed at $650^{\circ}C$ was about $1\times10^{-7}A/\textrm{cm}^2$ at 3V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.489-490
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• 2006

The Ce-doped YAG(Yttrium Aluminum Garnet, $Y_3Al_5O_{12}$) phosphor powders were synthesized by Sol-gel method. The luminescence, formation process and structure of phosphor powders were investigated by means of XRD, SEM and PL. The XRD patterns show that YAG phase can form through sintering at $1000^{\circ}C$ for 2h. This temperature is much lower than that required to synthesize YAG phase via the conventional solid state reaction method. There were no intermediate phases such as YAP(Yttrium Aluminum Perovskite, $YAlO_3$) and YAM(Yttrium Aluminum Monoclinic, $Y_4Al_2O_9$) observed in the sintering process. The powders absorbed excitation energy in the range 410~510nm. Also, the crystalline YAG:Ce showed broad emission peaks in the range 480~600nm and had maximum intensity at 528nm.

• Journal of Powder Materials
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• v.12 no.3
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• pp.220-224
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• 2005

Boehmite (AlOOH) powder with uniform pore size and high specific surface area were synthesized via sol-gel method using metal salts, $Al_2(SO_4)_3$ and $NaAlO_2$. During these synthetic process, the effects of the aging time were investigated to determine the optimal synthetic conditions of boehmite. X-ray diffraction, BET, Raman/IR, and scanning electron microscopy techniques were used for the characterization of the powder. Boehmite gel synthesized at the first stage of the experimental procedure transformed to crystalline boehmite phase after aging for 6 hours. The specific surface area of the crystalline boehmite showed a maximum value, $350m^2/g$, at aging time of 72 hours. The pore size of the boehmite increased with increasing aging time and the boehmite with average pore diameter of 3.6 nm was obtained at aging time of 96 hours.

• Journal of Hydrogen and New Energy
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• v.19 no.6
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• pp.545-551
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• 2008

Fe/$Al_2O_3$ composite granules were prepared by combining sol-gel/oil drop method. The shape of granules were mainly determined by composition and concentration of aluminum precursor. The composite granule with the lowest aluminum concentration was synthesized with 0.75M boehmite solution. The prepared granules were tested as a catalyst in the plug-flow reactor for Fischer-Tropsch synthesis. Before the reaction, catalysts were activated by hydrogen reduction and synthesis gas treatment. The activation conditions and aluminum concentration have affected catalytic performance significantly.

• Journal of the Korean Magnetic Resonance Society
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• v.12 no.1
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• pp.26-32
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• 2008

We report on the ferromagnetic characteristics of $Zn_{1-x}Mn_xO$ films (x = 0.3) prepared by sol-gel method on the silicon and (0001) ${\alpha}-Al_2O_3$ substrates at the annealing temperature of 700$^{\circ}C$. Magnetic measurements show that Curie temperature ($T_C$) and the coercive field ($H_C$) for the film on the silicon are about 32 K and about 275 Oe, while those for that on the sapphire are about 32 K and 425 Oe, respectively. Energy dispersive spectroscopy and transmission electron microscopy measurements suggest that ferromagnetic precipitates originated by manganese oxide compound formed at the interfaces of the both substrates may be responsible for the observed ferromagnetic behavior of the films. Electron paramagnetic resonance study of the powders up to the concentration of x=0.15 supports the result.

• Journal of the Korean Ceramic Society
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• v.30 no.7
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• pp.589-597
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• 1993

The optimum sol solution for making alumina membrane was synthesized by using sol-gel method with aluminium isopropoxide. Two types of supports were made from the $\alpha$-Al2O3 powder. The porosities of supports could be controlled by the forming methods and the heat treatment conditions. After the support was coated with optimum sol solution and heat-treated at 50$0^{\circ}C$ for 1hour, the thickness of crack-free membrane could be controlled reproductively with dipping time.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.135-135
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• 2003

This paper presents the preparation of SnO$_2$ films by Sol-Gel process and using spin coating method, and their sensing properties in CO gas. Experimental procedure consisted of following steps: (1) Tin chloride(SnCl$_4$) and Ammonium hydrogen carbonate (NH$_4$HCO$_3$) were used as precursors; (2) the Sol solution with concentration of about 10wt% SnO$_2$ was prepared from washed Gel-precipitate for spin coating step; (3) thereafter, the coating solution was dropped onto the alumina (Al$_2$O$_3$) substrate that was then spun, the spin coating was carried out with total 10 times; (4) finally, the films were calcined for 3 hours at 50$0^{\circ}C$ or higher temperature (600, 700, 800 or 90$0^{\circ}C$) in order to obtain various gram sizes. The average grain size was calculated by Scherrer's equation using main peaks in XRD spectra; meanwhile the thickness, microstructure and surface morphology of the films were observed by FE-SEM.

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.281-288
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• 1995

to prepare the TiO2 thin films, acetyl-acetone(2.4-pentanedione)(1 : 1 molar ratio) was dissolved in the propanol solution of titanium(IV)isopropoxide(Ti[OCH(CH3)2]4). Al, Cr and Sb in the form of soluble salt and niobium ethoxide were added s dopants, respectively. Thin films were coated by the dip-coating method and characteristics were investigated by XRD, SEM and conductance meter. As a result, viscosity of sol was maintained below 4 centi Poise more than 20 days, and crystal growth and diminution of resistivity occurred as the heat treatment temperature increased. The grains grew over 1${\mu}{\textrm}{m}$ and the lowest resistivity was obtained when Nb was added at 130$0^{\circ}C$.