• 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.31 no.11
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• pp.1271-1282
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• 1994

The surface of commercial alumina fibers used for reinforcing the MCFC matrix has been coated with ${\gamma}$-LiAlO2 being the same material as the matrix, by the sol-gel method in order to enhance the corrosion resistivity of alumina fibers. Stable LiAlO2 complex polymeric sols for coating was synthesized by mixing aluminum alkoxide polymeric sols with LiNO3 solution. It was found that the LiAlO2 polymeric sol prepared by adding the mixed chelate of acethylacetone and triethanolamine (the mole ratio of AA/TEA = 0.125/0.75) to the 1 mole of the aluminum alkoxide had the excellent stability and coating behavior. The crystalline structure of the dried gel from the ${\gamma}$-LiAlO2 sol was completely transformed into the ${\gamma}$-LiAlO2 at $600^{\circ}C$. The optimum viscosity of the sol for coating the alumina long fibers was 30~40 cP, while it was 12~20 cP in case of the short fiber coating. The ${\gamma}$-LiAlO2 coated alumina fibers without defects fully densified when heat-treated at 120$0^{\circ}C$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.641-643
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• 2003

The ferroelectric properties of PZT(53/47) thin film was investigated by methoxy enthanol solution based on sol-gel method. The thickness of each layer by spincoating 0.25M sol at one time was $0.1{\mu}m$ and crack-free film was formed. $LaNiO_3/Si(100)$ electrode and $Pt/Ti/SiO_2/Si(100)$ electrode was coated by PZT sol at several times. PZT orientation was confirmed as a method of XRD and coercive field(Ec) as well as remnant polarization(Pr) was investigated from hysterisis curve. As a result of XRD analysis, we can know that the orientation of on PZT/LNO/Si(100) is better than on $Pt/Ti/SiO_2/Si(100)$. The remnant polarization(Pr) in LNO electrode was $87.5{\mu}C/cm^2$ and $39.8{\mu}C/cm^2$ in Pt. From this figures, it is investigated that the Pr in LNO electrode was better than in Pt.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.35-36
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• 2006

The influence of the concentration of precursor solution and the number of solution coatings on the densification of the Pb($Zr_xTi_{1-x}$)$O_3$(PZT) thick films was studied. PZT powder and PZT precursor solution were prepared by sol-gel method and PZT thick films were fabricated by the screen-printing method on the alumina substrates. The powder and solution of composition were PZT(70/30) and PZT(30/70), respectively. The coating and drying procedure was repeated 4 times. And then the PZT precursor solution was spin-coated on the PZT thick films. A concentration of a coating solution was 0.5 to 2.0 mol/L[M] and the number of coating was repeated from 0 to 6. The relative dielectric constant of the PZT thick film was increased with increasing the number of solution coatings and the thick films with 15M, 6-time coated showed the 698. The remanent polarization of the 1.5M, 6-time coated PZT thick films was 38.3 ${\mu}C/cm^2$.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.506-511
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• 2008

In this study sol-gel and combustion process was surveyed for the preparation of the red $Y_2O_3$: Eu phosphor, and the properties of phosphor was considered. Chelation and hydrolysis in amorphous citrate sol-gel process were completed in initial reaction stage, and water-forming condensation was superior to organic acid-forming condensation. The mole ratio of citric acid to metal ion had to be above to for the progress of sol-gel process. The dried gel powders are mostly amorphous, and crystallize completely at $700^{\circ}C$, and the crystallinity increases with increasing calcining temperature. The luminescence property of the phosphor was analyzed by measuring the emission spectra. The luminescence intensity increases when the calcination temperature and concentration of metal ions in solution increase.

• Journal of the Korean Ceramic Society
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• v.39 no.11
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• pp.1063-1068
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• 2002

Polyimide/silica(PI/silica) hybrid materials having physical or chemical bonds between the PI and silica network were prepared using sol-gel process through hydrolysis and polycondensation of tetraethoxysilane with the polyamic Acid(PAA) or end-capped PAA solution. PAA solution was synthesized by ring opening reaction of pyromellitic dianhydride and oxydianiline monomers in dimethyl acetamide solution. End-capped PAA solution was synthesized by the addition of 3-aminopropyltriethoxysilane in PAA solution. PI/silica hybrid samples were characterized by infrared spectroscopy, differential thermogravimetry, X-ray diffractometry, scanning electron microscopy, and tensile tester. It has been demonstrated that the properties of hybrid samples were affected by the silica content and the bond type between PI and silica.

• Korean Journal of Materials Research
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• v.24 no.12
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• pp.689-693
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• 2014

Anti-reflection coating films have used to increase the transmittance of displays and enhance the efficiency of solar cells. Hydrophobic anti-reflection coating films were fabricated on a glass substrate by sol-gel method. To fabricate an anti-reflection film with a high transmittance, poly ethylene glycol (PEG) was added to tetraethyl orthosilicate (TEOS) solution. The content of PEG was changed from 1 to 4 wt% in order to control the morphology, thickness, and refractive index of the $SiO_2$ thin films. The reflectance and transmittance of both sides of the coated thin film fabricated with PEG 4 wt% solution were 0.3% and 99.4% at 500 nm wavelength. The refractive index and thickness of the thin film were n = 1.29 and d = 105 nm. Fluoro alkyl silane (FAS) was used for hydrophobic treatment on the surface of the anti-reflection thin film. The contact angle was increased from $13.2^{\circ}$ to $113.7^{\circ}$ after hydrophobic treatment.

• Polymer(Korea)
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• v.31 no.6
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• pp.485-490
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• 2007

Hard coating was made on a polycarbonate plate using a sol-gel process with a melamine derivative and silicates, and examined as potential substitutes for automobile glass. Methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and phenyltriethoxysilane were used to form a coating solution. The coatings on the polycarbonate plate were deposited using a sol-gel process. Poly(methyl methacrylate) was coated on the surface of polycarbonate in order to improve adhesion property. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Adding the melamine derivative to the coating solution, the pencil hardness of the coating was improved. The hardness of a 3H class pencil, excellent abrasion resistance, and surface uniformity were found in the coated polycarbonate surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.2
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• pp.307-314
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• 1998

PZT thin films were fabricated by the Sol-gel method. Starting materials used for the preparation of the stock solution were Pb-acetate trihydrate, Zr-normal propoxide and Ti-isopropoxide. 2-Methoxyethanol and iso-propanol were used for solution. For studying the diffusion of Pb ion into the substrates. We used bare Si substrate, $SiO_2/Si$ substrates which was produced by thermal oxidation and $TiO_2/SiO_2/Si$ which was mad by Sol-gel method. Densification and adhesion of thin films were observed by SEM. Phase formation of thin films and diffusion of Pb ion into the substrate were examined by XRD and ESCA, respectively. In the case of bare Si and $SiO_2/Si$ substrate, we obtained the perovskite phase at $700^{\circ}C$ and restricted a little the diffusion of Si ion into the film with $SiO_2$ buffer layer. In the case of $TiO_2/SiO_2/Si$, perovskite phase were obtained at $500^{\circ}C$ and the diffusion of Pb ion and Si ion were restriced.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.220-224
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• 2016

Anti-reflection (AR) thin films were fabricated on a glass substrate by using an ultrasonic spray. Glycidoxypropyl trimethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) were used to synthesize a sol-gel hybrid coating solution. The moving speed of spray nozzle was changed from 15~25 mm/s to control the coating thickness of AR thin film. As the moving speed of spray nozzle increased, the thickness of AR thin film decreased from 138 nm to 86 nm. When the AR thin film was fabricated by nozzle moving speed of 20 mm/s, the refractive index and thickness of AR thin film was measured to be 1.31 and 104 nm, respectively. The average reflectance and transmittance of AR thin film coating glass was measured to be 0.75 % and 94 %, respectively into the visible light range of 380~780 nm.