• Bulletin of the Korean Chemical Society
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• 제28권9호
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• pp.1457-1462
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• 2007

A simple and facile sonochemical route was described for the fabrication of diameter-controlled ZnO nanorod arrays on Si wafers. The diameter of ZnO nanorods was controlled by the concentration of zinc cations and hydroxyl anions in aqueous precursor solution. At high concentration of the precursor solution, thick ZnO nanorod arrays were formed. On the contrary, thin ZnO nanorod arrays were formed at low concentration of the precursor solution. The average diameter of ZnO nanorods varies from 40 to 200 nm. ZnO nanorod arrays with sharp tip were also fabricated by the step-by-step decrease in precursor solution concentration. The crystal structure and optical characteristics of ZnO nanorods were investigated by transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. Growth mechanism of ZnO nanorod arrays was also proposed.

• Current Applied Physics
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• 제18권11호
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• pp.1300-1305
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• 2018

The tunable electronic performance of the solution-processed semiconductor metal oxide is of great significance for the printing electronics. In current work, transparent thin-film transistors (TFTs) with indium-zinc oxide (IZO) were fabricated as active layer by a simple eco-friendly aqueous route. The aqueous precursor solution is composed of water without any other organic additives and the IZO films are amorphous revealed by the X-ray diffraction (XRD). With systematic studies of atomic force microscopy (AFM), X-ray photoemission spectroscopy (XPS) and the semiconductor property characterizations, it was revealed that the electrical performance of the IZO TFTs is dependent on the concentration of precursor solution. As well, the optimum preparation process was obtained. The concentrations induced the regulation of the electronic performance was clearly demonstrated with a proposed mechanism. The results are expected to be beneficial for development of solution-processed metal oxide TFTs.

• 한국세라믹학회지
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• 제40권4호
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• pp.380-384
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• 2003

The effects of the mole concentrations of precursor solution on the microstructure and dielectric properties of sol-gel deposited $Ba_{0.85}$S $r_{0.15}$Ti $O_3$(BST) thin films have been investigated. The films were of single perovskite phase with strong (100) preferred orientation when grown on LaNi0$_3$ buffered Pt/Ti/ $SiO_2$Si substrates using a diluted precursor solution. Variation of the precursor solution concentration resulted in a different microstructure and, in turn, affected the tunability of the sol-gel deposited films. It was observed that leakage currents increased asymmetrically for the negative and positive bias voltage with decreasing thickness. Overall results suggest that those BST films have acceptable properties f3r applications as room-temperature tunable elements.

• 한국초전도ㆍ저온공학회논문지
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• 제5권3호
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• pp.23-25
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• 2003

Effect of chemically modified precursor solution on YBCO coated conductor prepared by MOD-TFA method was investigated. YBCO thin films were deposited on (l00)-oriented single crystalline LaAlO$_3$ substrates by conventional MOD-TFA process. The microstructures of YBCO thin films contain maze-like patterns. The origin of this microstructure was delineated by compositional inhomogeneity during the pyrolysis process and it was shown that addition of diethanolamine (DEA) improve the microstructure of grown YBCO films. In addition, it was demonstrated that the chemical modification of precursor solution makes no harmful effect on biaxial texture of YBCO thin films.

• 한국분말재료학회지
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• 제18권1호
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• pp.35-40
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• 2011

LAS-system ceramic powder, spodumene ($Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$-spodumene powder having a specific surface area of $7.57\;m^2/g$. The agglomerated $\beta$-spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.

• Journal of Magnetics
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• 제16권2호
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• pp.186-191
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• 2011

[ $YBa_2C_3O_{7-x}$ ]films were fabricated on a $SrTiO_3$ (100) substrate using a trimethylaceate propionic acid (TMAP)-based MOD process by controlling the precursor solution viscosity, firing temperature, and by using various coatings. The viscosity of the precursor solution was controlled by the addition of Xylenes. The films were heat treated with different temperatures from 750 to $800^{\circ}C$. c-axis oriented films were obtained. After adding 9 ml of Xylene into the precursor solution, the $T_c$ of the YBCO film, which was coated 2 times and heat treated at $800^{\circ}C$, was 86 K and the measured $J_c$ was above 2.5 MA/$cm^2$ at 77 K in a zero-field.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.438-439
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• 2006

Pure and stable YAG $(Y_3Al_5O_{12})$ powders were synthesized by a PVA (polyvinyl alcohol) polymer solution technique. PVA was used as an organic carrier for the precursor ceramic gel. The precursor gels were crystallized to YAG at relatively a low temperature of $900\;^{\circ}C$. The synthesized powders, which have nano-sized primary particles, were soft and porous, and the porous powders were ground to sub-micron size by a simple ball milling process. The ball-milled powders were densified to 94% relative density at $1500\;^{\circ}C$ for 1h. In this study, the characteristics of the synthesized YAG powders were examined.

• Bulletin of the Korean Chemical Society
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• 제21권8호
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• pp.817-822
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• 2000

Crack-free hard coating siIica films were prepared by sol-gel processfrom twokinds of silicon alkoxide (tetra-ethoxysilane and methyltrimethoxysilane) and two kinds of alcohol (methanol and isopropyl alcohol) with an acid catalyst,acetic acid. A silicate framework of the precursor solution was investigated by infrared spectros-copy (IR) in the process of hydrolysis and condensation. Theextent of the condensation in the intermediates was elucidated by gel permeation chromatography (GPC) and 29Si-NMR spectroscopy. The hard coating films werecharacterized by IR,scanning electron microscope (SEM), thermo gravimetric analyzer (TGA) and dif-ferential scanning calroimeter (DSC). The synthetic condition for the crack-free and transparent silica film for-mation was optimized interms of starting materials for the precursor solution as well as preparation method of the silica film.

• 한국초전도ㆍ저온공학회논문지
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• 제10권2호
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• pp.20-23
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• 2008

[ $La_2Zr_2O_7$] (LZO) buffer layers were deposited on biaxially textured Ni-W substrates by chemical solution deposition method (CSD). In this study, the effect of $B_2O_3$ addition on texture and surface roughness of LZO films was investigated. The alkoxide-based precursor solution was employed to synthesize the precursor solution of LZO and the solution was coated on biaxially textured Ni-W substrates and subsequently annealed at $900^{\circ}C$ for crystallization. The pure LZO film without $B_2O_3$ addition showed a (222) reflection in the X-ray diffraction (XRD) profile. The intensity of (222) reflection was enhanced and more rough surface was obtained after further repetition of coating. Contrary to this, the LZO film prepared by $B_2O_3$ added precursor solution shows well-developed (400) reflection peak in the XRD profile and excellent biaxial texture (${\Delta}{\theta}=4.3^{\circ}$, ${\Delta}{\phi}=6.8^{\circ}$). The surface roughness of LZO films were also improved by addition of $B_2O_3$ even after multicoating ($R_{rms}{\sim}3.1nm$). It was shown that the LZO film with smooth surface and biaxial texture was grown on the biaxially textured Ni-W substrates with addition of $B_2O_3$ in the precursor solution.

• 한국표면공학회지
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• 제46권6호
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• pp.277-282
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• 2013

This study is an experimental attempt to confirm the binder effect of zeolite coating on glass plate by heat treatment. As a result, zeolite was successfully formed with low concentratios of pressure, whose concentration was effective in 10% or more for thin film zeolite coating. And as the content of the binder (TEOS) in mixed coating solution was higher, the zeolite was fastened better on the surface. Above 5% content of the binder in the coating solution, TEOS hindered zeolite synthesis of the precursor and brought to zeolite capacity decrease. Furthermore, when the concentration of the precursor, sedimentation rate of the precursor was higher and the coating efficiency is reduced thereby. Therefore, the most effective concentrations of the precursor and TEOS in the coating solution was 10% and 5%, respectively. It was concluded that zeolite coating is produced by heat treatment method after dipping without hydrothermal synthesis.