• Proceedings of the Korean Ceranic Society Conference
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• 2003.10a
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• pp.86.2-86
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• 2003

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2624-2630
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• 2002

Organic/inorganic hybrid materials have rapidly become a fascinating research field. In this study, $polyimide/TiO_2$ composites were synthesized from nano-sized anatase $TiO_2$ and two types of polyimide, that is, BPDA-PPD and PMDA-ODA. Nano-sized $TiO_2$ particles were prepared from $TiOEt_4$ solution by the sol-gel method. The synthesized PI/$TiO_2$ composites were characterized by using XRD, TGA, FT-IR, TEM, and Atomic Force Microscope(AFM). $TiO_2$ particles were dispersed well in polyimides and the mechanical and thermal stability of polyimide was improved with $TiO_2$ nano particles.

• Journal of the Korean Chemical Society
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• v.52 no.4
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• pp.387-393
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• 2008

• Journal of the Korean Ceramic Society
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• v.42 no.3 s.274
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• pp.165-170
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• 2005

Sol-gel methods offer many advantages over conventional slip-casting, including the ability to produce ceramic membranes. They are purer, more homogeneous, more reactive and contain a wider variety of compositions. We produced ormosil sol using sol-gel process under various molecular weight of polymer species[polyethylene glycol(PEG)] in total system [Tetraethyl ortho silicate(TEOS)-polyethylene glycol(PEG)]. The properties of as-prepared ormosil sol such as viscosity and gelation time are characterized. Also, the ceramic membrane was prepared by dip-coating with synthetic sol and its microstructure was observed by scanning electron microscopy. The permeability and rejection efficiency of membrane for oil/water emulsion were evaluated as cross­flow apparatus. The ormosil sol coated membrane was easily formed by steric effect of polymer and it improved flux efficiency because infiltration into porous support decreased. Its flux efficiency was elevated about $200\;l/m^2h$ compared with colloidal sol coated membrane at point of five minutes from starting test.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.2084-2086
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• 2006

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.327-331
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• 2009

Nano-porous $TiO_2$ powder was fabricated using Acetylene black, applied photo voltaic device based on the Dye-sensitized Solar Cells (DSCs) was investigated experimentally. $TiO_2$-powder was fabricated using Ti-isopropoxide and 2-propanol by sol-gel combustion method. For cases of variable Acetylene black, characteristic of porosity, size of particle and crystallite of obtained $TiO_2$ nano-powder was investigated. The photovoltaic efficiency of the prepared DSCs was measured using $TiO_2$ film which prepared on each different heat treatment temperature($400^{\circ}C{\sim}700^{\circ}C$) with paste of $TiO_2$ powder. The porosity and size of particle of $TiO_2$ powder made with Acetylene black 0.4g was influenced significantly effect to DSCs characteristic. Heat treatment at $500^{\circ}C$ makes the better photovoltaic efficiency which 5.02%($J_{sc}=11.79mA/cm^2$, $V_{oc}=0.73V$, ff=0.58). The sol-gel combustion method was useful to DSCs fabrication.

• Environmental Engineering Research
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• v.16 no.2
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• pp.81-90
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• 2011

Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.234-235
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• 2007

Transparent nanosized $TiO_2$ sol has been made by sol-gel method, using Titanium(IV) isopropoxide precursor. To promote hydrolysis for titania is needed excess water, Oil bath and temperature about $80^{\circ}C$. $TiO_2$ sol is peptized ranging from pH 1 to 1.5 using hydrochloric acid for the stability of sol during a condensation reaction. The average particle size of $TiO_2$ sol was approximately 20nm. $TiO_2$-sillane sol was synthesized by surface treatment using MTMS to the $TiO_2$ sol. TEM analysis has been used to check the degree of dispersion and FT-IR analysis has been used to see if the sillane has been chemically bonded on the surface of $TiO_2$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.5
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• pp.205-209
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• 2011

Zinc oxide has semi-conductivity and super conductivity characteristics. It can be used optically and is applied on many areas such as gas sensor, solar cell and optical waveguide. In this paper, to improve optical characteristics of ZnO, aluminum was added on zinc oxide. Zinc oxide and aluminum zinc oxide was fabricated as nano fiber form. ZnO solution was created by mixing poly vinyl pyrrolidone, ethyl alcohol, and zinc acetate. An Al doped ZnO was created by adding aluminum solution to ZnO sol. By applying these sols on electro spinning method, nano fibers were fabricated. These fibers are heat treated at 300, 500, and $700^{\circ}C$ degrees and were analyzed with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) to examine the nano structures. TGA and DSC measurement was also used to measure the change of mass and calorie upon temperature change. The absorbance of ZnO and Al-doped ZnO was carried out by UV-vis measurement.

• Journal of Magnetics
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• v.18 no.1
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• pp.21-25
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• 2013

Nickel substituted manganese ferrites, $Mn_{1-x}Ni_xFe_2O_4$ ($0.0{\leq}x{\leq}0.6$), were fabricated by sol-gel method. The effects of sintering and substitution on their crystallographic and magnetic properties were studied. X-ray diffractometry of $Mn_{0.6}Ni_{0.4}Fe_2O_4$ ferrite sintered above 523 K indicated a spinel structure; particles increased in size with hotter sintering. The M$\ddot{o}$ssbauer spectrum of this ferrite sintered at 523 K could be fitted as a single quadrupole doublet, indicative of a superparamagnetic phase. Sintering at 573 K led to spectrum fitted as the superposition of two Zeeman sextets and a single quadrupole doublet, indicating both ferrimagnetic and paramagnetic phase. Sintering at 673 K and at 773 K led to spectra fitted as two Zeeman sextets due to a ferrimagnetic phase. The saturation magnetization and the coercivity of $Mn_{0.6}Ni_{0.4}Fe_2O_4$ ferrite sintered at 773 K were 53.05 emu/g and 142.08 Oe. In $Mn_{1-x}Ni_xFe_2O_4$ ($0.0{\leq}x{\leq}0.6$) ferrites, sintering of any composition at 773 K led to a single spinel structure. Increased Ni substitution decreased the ferrites' lattice constants and increased their particle sizes. The M$\ddot{o}$ssbauer spectra could be fitted as the superposition of two Zeeman sextets due to the tetrahedral and the octahedral sites of the $Fe^{3+}$ ions. The variations of saturation magnetization and coercivity with changing Ni content could be explained using the changes of particle size.