• Journal of the Korean Ceramic Society
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• v.34 no.1
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• pp.37-44
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• 1997

Barium ferrite thin films on the thermal oxidized Si substrate were prepared by using sol-gel method (dip coating) from the sol of composition ratio of 5.25, designated by mole ratio 2Fe/Ba. The gelation process was largely divided into 4 step, and the sol prepared by reaction for 90 minutes at 8$0^{\circ}C$ was the suit-able for coating. Needle shaped particles formed on the coating layer were placed parallel to substrate and the inclination was increased with film thickness. The easy-direction of magnetization of needle shaped par-ticles was long-axis direction.

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

• Journal of the Korean Society of Safety
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• v.13 no.1
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• pp.85-91
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• 1998

Sol-gel derived silica films were prepared by dip-coating onto polymethylmethacylate with Tetraethoxysilane(TEOS) as starting materials. Film properties such as viscosity and thickness were investigated as a function of dip speed, waterprecursor ratio, sol aging time. IR spectra of the gel films prepared from TEOS at various R are given. At small values of R the absorption peaks assignable to C-H vibration in $-OC_2H_5$ groups are observed around 3000 and 1500-1300 $cm^{-1}$. These bands indicate that the -$-OC_2H_5$ groups are retained in the gel at small values of R because of incomplete hydrolysis of TEOS. Film behaviour was interpreted in terms of the dependence of hydrolysis and condensation rates on the interplay between sol pH and waterprecursor ratio. Film thickness was found to increase by approximately a factor of two as waterprecursor ratio increased from two to six. Film thickness also increased with sol prepolymerization time. Surface quality was correlated with processing conditions.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.163-167
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• 2013

Aluminum doped zinc oxide (AZO) thin films have been prepared on the glass substrates (Corning 1737) by sol-gel dip-coating method employing zinc acetate and aluminum chloride hexahydrate for the transparent conducting oxide (TCO) applications. 1 at% Al was doped to the ZnO thin films. The effects of post-heating temperature on the crystallization, optical and electrical properties of the AZO films have been investigated. Experimental results showed that post-heating temperature affected the microstructure, electrical resistance, and optical transmittance of the AZO films. From the X-ray diffraction analysis, all films have hexagonal wurtzite crystal structure. Optical transmittance spectra of the AZO films exhibited transmittance higher than about 80% within the visible wavelength region and the optical direct band gap ($E_g$) of these films was increased with increasing post-heating temperature. A minimum resistivity of $2.5{\times}10^{-3}{\Omega}cm$ was observed at $650^{\circ}C$.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.233-233
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• 2006

[ $Y_{2}O_{2}S:Eu$ ], a red phosphor, coated with silica nanoparticles or nanocomposites composed of silica nanoparticles and polymeric materials such as PMMA and PVP was prepared via sol-gel process. Samples were prepared from four different methods coded P1, P2, P3, and P4. P1 includes a conventional sol-gel process and a dip-coating method while P2 has the same procedure with P1 except that nanocomposites containing both silica nanoparticles and polymer prepared by sol-gel process were used as coating materials. In P3 method, phosphors were dispersed in a solution containing silica precursor, i.e., TEOS and then polymerization was performed to coat onto the phosphors surface while P4 followed the same procedure with P3 except that a solution containing both TEOS and organic monomer were used in preparing coating materials. Among various coating methods examined in this study, uniform coating of phosphor could be achieved by using method P4, i.e., phosphor surface coating in a solution containing hydrophobic monomer and TEOS. Furthermore, $Y_{2}O_{2}S:Eu$ red phosphor coated with nanocomposite composed of PMMA matrix and silica nanoparticles exhibited enhanced PL intensity and long-term stability.

• Journal of the Korean Ceramic Society
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• v.33 no.11
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• pp.1195-1202
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• 1996

To prepare the dielectric thin films of (Pb1-xSrx)TiO3 (x=0.1, 0.2, 0.3, 0.35, 0.5) by the sol-gel process titanium (IV) isopropoxide (Ti[OCH(CH3)2]4) and Pb Sr, acetate were used therefore the thin films were fabricated by dip-coating method. Stability of the sol decreased with addition of Sr content thin films could be fabricated up to 35mol% Over this range precipitation of sol occured thin films couldn't be obtained. Transmittance of thin films at visible range decreased with the increase of heat-treatment temperature but exhibited transmit-tance above 60% in all case. Moreover transmittance of thin films at visible range slightly increased with of addition of Sr,. When thin film containing 30 mol% srontium was heated at 600℃ the best perovskite phase was obtained. The dielectric constant (ε) was 280 and dielectric loss factor (tan δ) was 0.021 and curie tempera-ture (Tc) decreased with the increase of addition of Sr.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1060-1068
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• 1994

Stable zirconia sol was prepared from zirconium butoxide Zr(OC4O9)4 as a precursor and ethylacetoacetate(EAcAc) or diethylene glycol(DEG) as a chelating agent under ambient agent under ambient atmosphere by Sol-Gel process. The sythesized sol was coated on 304 stainless steel substrate by dip coating, thereafter zirconia film could be obtained by heat-treatment at $600^{\circ}C$. The characteristics of coating film were determined by FT-IR, XRD, and ellipsometion peak represented Zr-O-Zr bonding of tetragonal phase was shown at 470cm-1. Crystallization of zirconia gel and film from amorphous state to tetragonal phase started at 40$0^{\circ}C$, and then transformed into monoclinic phase around $700^{\circ}C$. Zirconia film coated on 304 stainless steel substrate showed relatively low porosity of 16% when it was coated with 0.4M zirconia sol and thereafter heat-treated at 80$0^{\circ}C$ and the film was densified continuously up to 90$0^{\circ}C$. The zirconia film of 10 nm thick acted as a protective layer against oxidation up to $700^{\circ}C$.

• The Korean Journal of Ceramics
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• v.2 no.1
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• pp.1-10
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• 1996

Transparent conducting $SnO_2$-based thin films have been coated on float substrates such as fused quartz, and ceramic fiber cloths such as the Nexel and E-glass cloth from tin alkoxides by the sol-gel technique. Also, thin films of alternating layers of $SnO_2$ and $SiO_2$ have been fabricated by dip coating. The sheet resistance and average visible transmittance of the films were investigated in the aspect of the applications as transparent electrodes such as liquid crystal displays, photo-detectors and solar cells. The Nextel and E-glass cloths coated with antimony-doped tin oxide (ATO) had sheet resistance of as low as $20 \;ohm/{\Box}$ and $120ohm/\;{\Box}$, respectively. The promotion effects of additives as $La_2O_3$ and Pt on the ethanol gas sensing properties of the films were investigated in the aspects of the applications as an alcohol sensor and a breath alcohol checker. Possible evidence of quantum well effects in the oxide multilayers of $SnO_2$ and $SiO_2$ was investigated.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.839-847
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• 1996

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.456-460
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• 1999

Transparent conducting tin (IV) oxide thin films have been studies and developed for the electrode materials of solar cell substrate. Fabrication of tin oxide thin films by sol-gel method is process development of lower cost photovoltaic solar cell system. The research is focused on the establishment of process condition and development of precursor. The precursor solution was made of tin isopropoxide dissolved in isopropyl alcohol. The hydrolysis rate was controlled by addition of triethanolamine. Dip and spin coating technique were applied to coat tin oxide on borosilicate glass. The resistivity of the thin film was lower than 0.1Ω-cm and the transmittance is higher than 90% in a visible range.