• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.3
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• pp.83-89
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• 2004

In this work, HA/$TiO_2$ biocomposite to get high mechanical properties with biocompatibility were prepared. HA/$TiO_2$ biocomposite powders were prepared by mixing $TiO_2$ and HA powders which were synthesized through sol-gel, precipitation and hydrothermal methods. The mixing ratio was fixed at 1:1 ratio (HA/$TiO_2$, wt%). HA/$TiO_2$ biocomposite powders showed different microstructures depending on their particle size and shape. The smaller particles were coated on the surface of larger particles, whereas they were well mixed and dispersed when both $TiO_2$ and HA were nanocrystallites. HA/$TiO_2$ biocomposite powders with homogeneous microstructure showed high sintered density and good mechanical properties.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.60-68
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• 2011

[ $ZrO_2-TiO_2$ ]binary oxides with various Zr:Ti molar ratios were prepared by sol-gel method and Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were fabricated for proton exchange membrane fuel cells (PEMFCs) at high temperature and low humidity. Water uptake, Ion exchange capacity (IEC), and proton conductivity of Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membranes were characterized and these composite membranes were tested in a single cell at $120^{\circ}C$ with various relative humidity (R.H.) conditions. The obtained results were compared with the unmodified membranes (Nafion$^{(R)}$ 112 and Recast Nafion$^{(R)}$). A Nafion$^{(R)}$/$ZrO_2-TiO_2$ composite membrane with 1:3 of Zr:Ti molar ratio showed the highest performance. The performance showed 500 mW/$cm^2$ (0.499V) at $120^{\circ}C$, 50% R. H., and 2 atm.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.66-66
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• 2011

Anodic titanium dioxide (TiO2) nanotubes are very attractive materials for gas sensors due to its large surface to volume ratios. The most widely known method for fabrication of TiO2 nanotubes is anodic oxidation of metallic Ti foil. Since the remaining Ti substrate is a metallic conductor, TiO2 nanotube arrays on Ti are not appropriate for gas sensor applications. Detachment of the TiO2 nanotube arrays from the Ti Substrate or the formation of electrodes onto the TiO2 nanotube arrays have been used to demonstrate gas sensors based on TiO2 nanotubes. But the sensitivity was much lower than those of TiO2 gas sensors based on conventional TiO2 nanoparticle films. In this study, Ti thin films were deposited onto a SiO2/Si substrate by electron beam evaporation. Samples were anodized in ethylene glycol solution and ammonium fluoride (NH4F) with 0.1wt%, 0.2wt%, 0.3wt% and potentials ranging from 30 to 60V respectively. After anodization, the samples were annealed at $600^{\circ}C$ in air for 1 hours, leading to porous TiO2 films with TiO2 nanotubes. With changing temperature and CO concentration, gas sensor performance of the TiO2 nanotube gas sensors were measured, demonstrating the potential advantages of the porous TiO2 films for gas sensor applications. The details on the fabrication and gas sensing performance of TiO2 nanotube sensors will be presented.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.4 s.33
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• pp.55-59
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• 2004

We fabricates the $TiO_2$ thin film from anatase phase $TiO_2$ powder having good photocatalytic property using aerosol deposition method at room temperature. Aerosol deposition method, which sprays an aerosol powder with ultrasonic velocity and deposits a thin film on substrate at low temperature, has the advantages of low thermal stress and low cost. To fabricate the $TiO_2$ thin film, the aerosol bath pressure and chamber pressure were 500 torr and 0.4 torr, respectively. The difference of aerosol bath pressure and chamber pressure accelerated the $TiO_2$ nano powder to ultrasonic velocity through the nozzle of $0.4 mm{\times}10 mm$ and $TiO_2$ thin film was finally formed. SS mesh with diameter of 50 mm was used as a substrate to apply the $TiO_2$ thin film to water quality purification. The raw powder was dehydrated for the good dispersion of $TiO_2$ powder. To suppress the formation of second particle, the powder was dispersed for 90 min in alcohol bath by ultrasonic treatment and desiccated. The grain size of $1 {\mu}m$ was observed in $TiO_2$ thin film deposited on SUS mesh by scanning electron microscopy (SEM). The anatase phase of $TiO_2$ thin film was also observed by X-ray diffraction (XRD) and the anatase phase of raw powder was nicely maintained after aerosol deposition. The results are applicable to water treatment filter having photocatalytic reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.400-403
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• 2004

The dielectric properties of $BaTiO_3/SrTiO_3$ multilayered thick films with printing times were investigated. $BaTiO_3/SrTiO_3$ thick films were deposited by Screen-printing method on alumina substrates. The obtained films were sintered at $1400^{\circ}C$ with bottom electrode(Pt) for 2hours. The structural and the dielectric properties were investigated for various printing times. The BST phase appeared in all of the $BaTiO_3/SrTiO_3$ mutilayered thick films. The $BaTiO_3/SrTiO_3$ multilayered thick film thickness, obtained by one printings, was $50{\mu}m$. The dielectric constant and dielectric loss of the $BaTiO_3/SrTiO_3$ multilayered thick film, obtained by five printings, were about 266, 0.8% at 1Mhz, respectively.

• Journal of the Korean Ceramic Society
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• v.28 no.10
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• pp.831-837
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• 1991

Spherical TiO2 particles are prepared from TiCl4 aqueous solution by the spray pyrolysis method using ultrasonic atomization technique. The formation mechanism of TiO2 particles from atomized droplets it studied by varying the concentration of the source solution, reaction temperature, and the solvent. spherical TiO2 powders with almost the same normalized particle size distribution can be made reproducibly by changing the concentration of the source solution, and their mean sizes are in the range of 0.2~1.4${\mu}{\textrm}{m}$.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.302-308
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• 2009

This study investigated the production of hydrogen over Ga (1.0, 2.0, and 5.0 mol%)-$TiO_2$ photocatalysts prepared by a solvothermal method. The absorption band was slightly blue-shifted upon the incorporation of the gallium ions, but the intensity of the photoluminescence (PL) curves of Ga-incorporated $TiO_2$s was distinguishably smaller, with the smallest case being the 2.0 mol% Ga-$TiO_2$, which was related to the recombination between the excited electrons and holes. $H_2$ evolution from photo splitting of water over Ga-incorporated $TiO_2$ in the liquid system was enhanced, compared to that over pure $TiO_2$; particularly, the production of 5.6 mL of $H_2$ gas after 8 h when 1.5 g of the 2.0 mol% Ga-incorporated $TiO_2$ was used.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1097-1098
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• 2006

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. Silica coated $BaTiO_3$ powders were prepared by sol-gel method. The particle size of the $BaTiO_3$ powders were $\sim35$ nm and the thickness of the $SiO_2$ coating layer was $\sim5$ nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion. The Zeta potential of $SiO_2$ coated $BaTiO_3$ was getting close to that of pure silica with a more negative charge, compared with that of the uncoated $BaTiO_3$. The onset temperature of shrinkage curves shifted to higher temperatures with increasing $SiO_2$ contents

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.111-117
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• 1995

TiO2 thin films were prepared on a (100)silicon wafer using a chemical vapor deposition(CVD) method. The deposition experiments were performed using the TTIP in the deposition temperature ransing from 200 content. The deposition rate of TiO2 was increased with the substrate temperature and the oxygen content. The thickness of the deposited thin film and the compositional analysis of this thin films with theoxygen content were measured using Ellipsometry, SEM and ESCA, respectively. The deposited thin film was composed of a bilayer, external TiO2 and internal Ti. Carbon as a residual impurity was found to remain when zero sccm O2 was purged into a reaction chamber and the composition of the deposited thin film was found to change Ti into TiO in a deeper layer. However, when 600sccm O2 was supplied to a reaction chamber, it has been found to reside less carbon content than without O2. Finally, in the condition of 1200sccm O2, no impurity level of carbon was observed and a deeper layer consisted of the Ti composite, even though the deposited surface was composed of TiO2.

• Analytical Science and Technology
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• v.19 no.4
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• pp.301-308
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• 2006

Pitch-coated anatase $TiO_2$ typed was prepared by $CCl_4$ solvent mixing method with different mixing ratios. Since the carbon layers derived from pitch on the $TiO_2$ particles were porous, the pitch-coated $TiO_2$ sample series showed a good adsorptivity and photo decomposition activity. The BET surface area depends on the pitch contents, which was made by changing the mixing ratios of the pitch with the raw $TiO_2$. The SEM results present to the characterization of porous texture on the pitch-coated $TiO_2$ sample and pitch distributions on the surfaces for all the materials used. From XRD data, a weak and broad carbon peak of graphene with pristine anatase peaks were observed in the X-ray diffraction patterns for the pitch-coated $TiO_2$. The EDX spectra show the presence of C, O and S with strong Ti peaks. Most of these samples are richer in carbon and major Ti metal than any other elements. Finally, the excellent photocatalytic activity of pitchcoated $TiO_2$ with Uv/Vis spectra between absorbance and time could be attributed to the homogeneous coated pitch on the external surface by $CCl_4$ solvent method.