• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.20 no.5
• /
• pp.227-231
• /
• 2010

Super hydrophilic $TiO_2$ thin films with photocatalytic property were successfully fabricated on a glass substrate by liquid phase deposition (LPD). The $TiO_2$ thin film formed nano particles on a surface at $70^{\circ}C$. As an immersion time in $TiF_4$ solution increased, the thickness of thin films gradually increased. $TiO_2$ thin film showed a water contact angel of below ca. $5^{\circ}$ and the transmittance of ca. 75~90 % in visible range. In addition, $TiO_2$ thin film showed the photocatalytic property to decompose methyl orange solution by the illumination of UV light. The surface morphologies, optical properties and contact angel of prepared thin films with a different immersion time were measured by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), UV-Vis spectrophotometer and contact angle meter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.4
• /
• pp.315-320
• /
• 2012

In general, a photoelectrode in DSSC(dye sensitized solar cell) are fabricated by using the $TiO_2$ (Titanium dioxide) to realize high efficiency and the efficiency of DSSC is affected by the size, the shape and the property of $TiO_2$. We synthesized the crystalline $TiO_2$ by sol-gel method. In spite of many merits, only weakness for the sol-gel method is taking many process times. To solve this problem, we reduced the fabricating processes. The reduced process is the making process that is $TiO_2$ sol to $TiO_2$ powder with including of two heat treatment and two mixing. We could simplify the process by preparing $TiO_2$ sol to $TiO_2$ paste directly. As a result, DSSC fabrication process is simplified and we have obtained the efficiency best result 3.88% with $V_{OC}$=0.71 V, $J_{SC}=8.70\;mA/cm^{-2}$, and FF=62.37%, respectively.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.3
• /
• pp.151-154
• /
• 2001

$TiO_2$ thin film has wide application because of its high capacitanca, reflection, and good transmissivity in visible range. $TiO_2$ thin film can be made by thermal deposition method, reactive evaporation method, activated reactive evaporation(ARE) method. In the case of thermal deposition, the oxygen deficiency can occur because the melting point of Ti is very high. While in the case of reactive evaporation, high density $TiO_2$ can not be made, because reactive gas($O_2$) and evaporated material(Ti) are not fully combined, activated reactive evaporation, $TiO_2$ is easily deposited at lower gas pressure compared with reactive evaporation because the ionized reactive gas is made by plasma. Therefore, activated reactive evaporation is very useful to deposit the material having the high melting point. In this work, we formed $TiO_2$ thin film by activated reactive evaporation method. The surface of $TiO_2$ thin film was analyzed by X-ray photoelectron spectroscopy. The surface morphology which was analyzed by atomic force microscopy(AFM) shows that feature of the film surface is uniform. The dielectric capacitance, withstanding voltage were $600{\mu}F/cm^2$, 0.4V respectively. In further work, we can increase the withstanding voltage by improving the deposition parameter of substrates.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.25 no.7
• /
• pp.537-542
• /
• 2012

DSSCs efficiency by thickness of $TiO_2$ photoelectrode and thickness differences between two substrates studied. DSSCs is made of the doctor blade method and photoelectrode annealing temperature elevated in a different ways. In addition, cells efficiencies of according to the different thickness between $TiO_2$ photoelectrode substrate and Pt counter electrode was measured. Efficiency of DSSCs made with $TiO_2$ photoelectrode of 18 ${\mu}m$ thickness and the gap difference between the substrate 28 ${\mu}m$ shows a highest 4.805% efficiency.

• Journal of Industrial and Engineering Chemistry
• /
• v.68
• /
• pp.325-334
• /
• 2018

Lactose is a reducing disaccharide consisting of two different monosaccharides such as galactose and glucose. The hydrogenation of lactose to lactitol is a formidable challenge because it is a complex process and several side products are formed. In this work, we synthesized Ru-Ni bimetallic nanohybrids as efficient catalysts for selective lactose hydrogenation to give selective lactitol. Ru-Ni bimetallic nanohybrids with $Ru-NiO_x$ (x = 1, 5, and 10 wt%) are prepared by impregnating Ru and Ni salts precursors with $TiO_2$ used as support material. Ru-Ni bimetallic nanohybrids (represented as $5Ru-5NiO/TiO_2$) catalyst is found to exhibit the remarkably high selectivity of lactitol (99.4%) and turnover frequency i.e. ($374h^{-1}$). In contrast, monometallic $Ru/TiO_2$ catalyst shows poor performance with ($TOF=251h^{-1}$). The detailed characterizations confirmed a strong interaction between Ru and NiO species, demonstrating a synergistic effect on the improvement on lactitol selectivity. The impregnation-reduction method for the preparation of bimetallic $Ru-NiO/TiO_2$ catalyst promoted Ru nanoparticles dispersed on NiO and intensified the interaction between Ru and NiO species. $Ru-NiO/TiO_2$ efficiently catalyzed the hydrogenation of lactose to lactitol with high yield/selectivity at almost complete conversion of lactose at $120^{\circ}C$ and 55 bar of hydrogen ($H_2$) pressure. Moreover, $Ru-NiO/TiO_2$ catalyst could also be easily recovered and reused up to four runs without notable change in original activity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.251-251
• /
• 2007

A new type of a lead-free positive temperature coefficient of resistivity(PTCR) material. based on $(Bi_{1/2}Na_{1/2})TiO_3\;-\;BaTiO_3$ solid solution ceramics has been developed. The effect of $Nb_O_5$ and $Y_2O_3$ content on the electrical properties and the microstructure of (1-x) $(Bi_{1/2}Na_{1/2})TiO_3\;-\;x\;BaTiO_3$ (BNBT) ceramics made using a conventional mixed oxide process has been studied. The Curie Temperature was obviously increased with the increasing of $(B_{0.5}Na_{0.5})TiO_3$ content. The Y-doped BNBT ceramics(x=0.02) display low resistivity values of $10^2-10^3$ ohm*cm at room temperature and the Curie Temperature of $Tc=155^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.209-209
• /
• 2010

Multiferroic properties of $BaTiO_3-CuFe_2O_4$ thin films grown on highly-textured Pt(111)/$TiO_2/SiO_2$/Si(100) substrates were studied. $CuFe_2O_4$ ceramic target was synthesized by mixing oxide powders of CuO, $Fe_2O_03$, $BaTiO_3$ ceramic target was also prepared separately. The film structure was of bi-layer type, where $BaTiO_3$ layer lies underneath of $CuFe_2O_4$ layer, where both layers were grown by pulsed laser deposition technique. We will report the ferroelectric and magnetic properties of $BaTiO_3-CuFe_2O_4$ bi-layer films in some detail.

• Korean Journal of Materials Research
• /
• v.7 no.4
• /
• pp.354-360
• /
• 1997

페르브스카이트 구조를 갖는 CaTiO$_{3}$-La(Zn$_{1}$2/Ti$_{1}$2)O$_{3}$계에서 소결 온도와 소결 시간의 증가에 따른 ZnO의 휘발과 이에 따른 고주파 유전 특성에 대하여 조사하였다. 시편 내부를 WDS 분석한 결과 위치에 따른 ZnO의 농도차를 관찰할 수 있었고, 시편의 두께를 달리하여 Qxf$_{o}$ 값을 조사한 결과 ZnO가 많이 휘발된 가장자리에서 더 높은 Qxf$_{o}$ 값을 얻을 수 있었다. 0.535CaTiO$_{3}$-0. 465La(Zn$_{1}$2/Ti$_{1}$2/)O$_{3}$몰비로 155$0^{\circ}C$, 2시간동안 합성한 결과 소결 밀도 5.31g/㎤, 유전율 50, Qxf$_{0}$34,000, 온도계수 +8ppm/$^{\circ}C$의 고주파 유전 특성을 갖는 소결체를 얻을 수 있었다.

• Corrosion Science and Technology
• /
• v.14 no.2
• /
• pp.64-75
• /
• 2015

Single $TiO_2$ coating prepared by sol-gel process usually experiences cracks in coating layer. In order to prevent cracks, an inorganic-organic hybrid $TiO_2-SiO_2$ coating was synthesized by combining precursors with an organic functional group. Five different coatings with various ratios of (1:8, 1:4, 1:1, 1:0.25 and 1:0.125) titanium alkoxide (TBOT, Tetrabutylorthotitanate) to organo-alkoxysilane (MAPTS, ${\gamma}$-Methacryloxy propyltrimethoxysilane) on carbon steel substrate were made by sol-gel dip coating. The prepared coatings were analyzed to study the coating properties (surface crack, thickness, composition) by scanning electron microscope (SEM), focused ion beam (FIB), and Fourier transform infrared spectroscopy (FT-IR). Potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were also performed to evaluate the corrosion characteristics of the coatings. Crack free $TiO_2-SiO_2$ hybrid coatings were prepared with the optimization of the ratio of TBOT to MAPTS. The corrosion rates were significantly decreased in the coatings for the optimized precursor ratio without cracks.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.511-511
• /
• 2007

Low-emissivity (low-e) coatings with visible transparency have attracted increased interest m reducing heat radiation loss through window panes from ecological and sustainable aspects. $TiO_2$-silver transparent thin films for low-e have good properties for UV and IR blocking as well as photocatalyst compared to that with commercial UV blocking films such as fluorine doped oxide (FTO), antimony doped tin oxide (ATO), etc. In this study, transparent $TiO_2$-silver thin films were prepared by successive ink-jet printing of commercial nano silver and $TiO_2$ sol. The $TiO_2$ sol, as ink for ink-jet printing, were synthesized by hydrothermal process in the autoclave externally pressurized with $N_2$ gas of 200 bar at $120^{\circ}C$ for 10 hrs. The synthesized $TiO_2$ sols were all formed with brookite phase and their particle size was several to 30 nm. At first nano sized silver sol was coated on glass substrate, after that $TiO_2$ sol was coated by ink-jet printing. With increasing coating thickness of $TiO_2$-silver multilayer by repeated ink-jet coating, the absorbance of UV region (under 400nm) and IR region (over 700nm) also increase reasonably, compared to that with commercial UV blocking films.