• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.111-111
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• 2005

• Journal of the Korean Ceramic Society
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• v.34 no.2
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• pp.188-194
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• 1997

Wet gel with surface modification by TMCS was redispersed in EtOH and redispersed silica sol for coat-ing was prepared. After spin coating of redispersed sol was conducted on silicon substrate, processes of drying(8$0^{\circ}C$) and heat treatment(>25$0^{\circ}C$) were, followed at ambient pressure. The influence of heat treat-ment of properties of film was observed, changing temperature at heat treatment. The optimum redisp-ersion condition for stable silica sol was wet gel:EtOH=1g:110$m\ell$ and the concentration and viscosity of redispersed silica sol with average particle size of 30nm were 0.11 M, 2.0-2.2 cP respectively. Crack-free thin film with the refractive index of 1.14 and thickness of 400 nm was obtained through drying at 8$0^{\circ}C$ and subsequent heat treatment at 45$0^{\circ}C$ for 2 hrs respectively after spin coating of 1500rpm, 10 times.

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.145-151
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• 2014

Solution-based Sb-doped $SnO_2$ (ATO) transparent conductive oxides using a low-temperature process were fabricated by an electrospray technique followed by spin coating. We demonstrated their structural, chemical, morphological, electrical, and optical properties by means of X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, Hall effect measurement system, and UV-Vis spectrophotometry. In order to investigate optimum electrical and optical properties at low-temperature annealing, we systemically coated two layer, four layer, and six layers of ATO sol-solution using spin-coating on the electrosprayed ATO thin films. The resistivity and optical transmittance of the ATO thin films decreased as the thickness of ATO sol-layer increased. Then, the ATO thin films with two sol-layers exhibited superb figure of merit compared to the other samples. The performance improvement in a low temperature process ($300^{\circ}C$) can be explained by the effect of enhanced carrier concentration due to the improved densification of the ATO thin films causing the optimum sol-layer coating. Therefore, the solution-based ATO thin films prepared at $300^{\circ}C$C exhibited the superb electrical (${\sim}7.25{\times}10^{-3}{\Omega}{\cdot}cm$) and optical transmittance (~83.1 %) performances.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.352-358
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• 2019

In recent years, printing paper with a function of information delivery and aesthetic value has attracted a great attention with increasing market demand for coated paper that is capable of high quality printing. The coated paper for inkjet printing with high-quality of photorealistic grades requires the coating layer with a good wettability and porous surface structure in order to improve the printability of ink. In this study, the coated paper was prepared using polyvinyl alcohol (PVA) and surface treated nano silica sol with silane coupling agent. It was confirmed that the coating layer with surface treated nano silica sol showed a uniform pore distribution and flat surface roughness. Glossiness of the prepared printing paper was similar to that of commercial high quality photo paper. Especially, the coated paper with surface treated nano silica sol showed improved printability with excellent roundness of the printed dot of ink. These results indicates that the coating layer with excellent wettability and uniform pore distribution can be formed by using the nano-silica particles with improved dispersibility through the surface treatment of the silane coupling agent.

• Journal of the Korean Ceramic Society
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• v.31 no.7
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• pp.804-812
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• 1994

Stable PZT coating sol was prepared using chelating agent, ethylacetoacetate(EAcAc) by sol-gel processing under ambient atmosphere. Through FT-IR spectrum analysis on solution of each reaction step, formation of metal complex was confirmed and prepared PZT sol was stable over several months. Through TG-DTA, XRD, FT-IR spetrum analysis of PZT gel powder, it was understood that the addition of EAcAc could reduce the transition temperature to ferroelectric phase, due to the increased homogeneity by matching the hydrolysis and condensation rates by chelation. Single perovskite phase was obtained by the heat-treatment at 54$0^{\circ}C$ for 30 min. The film was coated on ITO-coated glass substrate by dip coating method. After heat-treatment, PZT thin film had thickness in the range of 20~130 nm. The maximum dielectric constant of its thin film at room temperature and 1 kHz was 128.

• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1301-1310
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• 1996

Generally it requires high sintering temperatures more than 135$0^{\circ}C$ to make semiconductive BaTiO3 ceramics. Also it is very difficult to achieve a homogeneous mixing in solid-state reaction method. Therefore the liquid phase distributed to non-uniform dilute the characteristics of PTCR. In order to improve the uniformity this study is used the sol-gel coating method. Using this method we studied the new manufacturing process that had a high reproducibility and mass production capability. Tetraethyl orthosilicate (TEOS) was used as a source of Si. The semiconductive BaTiO3 ceramics which was produced by sol-gel method for the SiO2 addition and sintered between 124$0^{\circ}C$ and 130$0^{\circ}C$ showed almost same resistivity at room temperature among 125$0^{\circ}C$ and 130$0^{\circ}C$. As the results We could be sintered the semiconducting BaTiO3 ceramics at lower temperature even at 125$0^{\circ}C$ maintaining the same specific resistivity ratio ($\rho$max/$\rho$min) at 130$0^{\circ}C$. The specific resistivity both below and above the Curie temperature were increased by slow cooling and the steepness of the plots in the reasion of transition from low to high resistance increased as the cooling rate decreased.

• Korean Journal of Materials Research
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• v.30 no.11
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• pp.609-614
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• 2020

3 mol% yttria-doped stabilized zirconia (3YSZ) is synthesized by a solvothermal process, and its characteristics are investigated using various methods. Also, the dispersibility of synthesized 3YSZ nanoparticles is observed with the species of surface modifier. The 3YSZ nano sol prepared with an optimum condition is employed in prism coating and its properties are evaluated. The synthesized 3YSZ nanoparticles show a globular shape with about 10 to 20 nm crystallite size. The mixed phases with the nano sol show a high specific surface of 178 ㎡/g. The prism sheet coated with the 3YSZ nano sol present an excellent refractive index, transmittance, and luminance; refractive index is 1.603, transmittance is 90.2 %, and luminance of coating film is improved by 5.9 % compared to that of the film without 3YSZ nano sol. It is verified that the surface modified 3YSZ is suitable as the prism sheet for optical displays.

• Journal of the Korean Ceramic Society
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• v.29 no.2
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• pp.107-118
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• 1992

Alumina supports for TiO2 ultrafiltration membrane coating were prepared by presintering disk-type preforms at 140$0^{\circ}C$. These supports showed uniform microstructures which had the apparent porosity of 40%, the pore size distribution in the range of 0.1~0.5${\mu}{\textrm}{m}$, and the water flux of 1400ι/$m^2$.h at the pressure difference of 10 atm. The optimum pH and concentration of the TiO2 sol for coating were 0.8 and 1.0 wt%, respectively, and sol particles were identified as rutile forms of 20 nm size. Crack-free alumina-supported rutile TiO2 membranes could be prepared through well controlled drying and heating the gel layer coated by the sol-gel dipping. The pore size of the TiO2 membranes heat-treated at 50$0^{\circ}C$ for 2 hrs was 30~80$\AA$, and their thickness varied from 1.1 to 3.8 ${\mu}{\textrm}{m}$ in accordence with the dipping time (4~40 min). The flux of water through this composite membrane at 10 atm was found to be in the range from 800 to 1100ι/$m^2$.hr depending on the dipping time (10~40 min). The membrane thickness increased linearly with the square root of the dipping time and the slope was 0.62 ${\mu}{\textrm}{m}$/{{{{ SQRT { min} }}.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1491-1496
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• 2005

We fabricated the $Pb_{0.72}La_{0.28}TiO_3$ (PLT(28)) thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of $100\%$ perovskite phase by drying at $350^{\circ}C$ after each coating and final annealing at $650^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the $Pt/Ti/SiO_2/Si$ substrate and its dielectric constant and leakage current density were measured as 936 and $1.1{\mu}A/cm^2$, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.865-868
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• 2005

We fabricated the $Pb_{0.72}La_{0.28}TiO_3 (PLT(28))$ thin film successfully by using the sol-gel method and characterized it to evaluate its potential for being utilized as the capacitor dielectrics of ULSI DRAMs. In our sol-gel process, the acetates were used as the starting materials. Through the TGA-DTA analysis, we established the excellent fabrication conditions of the sol-gel method for the PLT(28) thin film. We obtained the dense and crack-free PLT(28) thin film of 100% perovskite phase by drying at 350$^{\circ}C$ after each coating and final annealing at 650$^{\circ}C$. Electrical properties of PLT(28) thin film were measured through formation on the Pt/Ti/SiO$_2$/Si substrate and its dielectric constant and leakage current density were measured as 936 and 1.1${\mu}$A/cm$^2$, respectively