• Progress in Superconductivity
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• 제4권2호
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• pp.162-167
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• 2003

The critical current value of Bi-2223/Ag tape can be influenced by various factors. In particular, it was known that properties of precursor powders could affect the formation of Bi -2223 and grain growth rate of the same. Since, moistures and organic matters can easily contaminate the precursor powders of Bi-2223 tapes and degrade properties of superconductors, the precursor powders should be kept in optimal conditions to minimize contamination. In this study, the effect of moisture and organic matters has been investigated. A Bi-2223/Ag tape contaminated with a large amount of moisture and organic matter has been characterized by low critical current values and bubbling. It has been found that as the quantity of moisture increases, the Bi-2223 phases are formed at lower temperature and the amount of non-superconducting phase increases.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.274-274
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• 2013

We fabricate encapsulation-layer of OLED panel from organic-inorganic hybrid thin film by atomic layer deposition (ALD) molecular layer deposition (MLD) using Al2O3 as ALD process and Adipoyl Chloride (AC) and 1,4-Butanediamine as MLD process. Ellipsometry was employed to verify self-limiting reaction of MLD. Linear relationship between number of cycle and thickness was obtained. By such investigation, we found that desirable organic thin film fabrication is possible by MLD surface reaction in monolayer scale. Purging was carried out after dosing of each precursor to eliminate physically adsorbed precursor with surface. We also confirmed roughness of the organic thin film by atomic force microscopy (AFM). We deposit AC and 1,4-Butanediamine at $70^{\circ}C$ and investigated surface roughness as a function of increasing thickness of organic thin film. We confirmed precursor's functional group by IR spectrum. We calculated WVTR of organic-inorganic hybrid super-lattice epitaxial layer using Ca test. WVTR indicates super-lattice film can be possibly use as encapsulation in flexible devices.

• 한국재료학회지
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• 제26권5호
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• pp.271-280
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• 2016

When a single inorganic precursor is used for the synthesis of a sol-gel coating, there is a problem of cracking on the surface of coating layer. In order to solve this problem of surface cracking, we synthesized inorganic-organic coatings that have hybrid properties of inorganic and organic materials. Sols of various ratios (1:0.07, 0.2, 0.41, 0.82, 1.64, 3.26, 6.54, 13.2) of an inorganic precursor of Tetrabutylorthotitanate ($Ti(OBu)_4$, TBOT) and an organic precursor of ${\gamma}$-Methacryloxy propyltrimethoxysilane (MAPTS) were prepared and coated on stainless steels (SUS316L) by dip coating method. The binding structure and the physical properties of the synthesized coatings were analyzed by FT-IR, FE-SEM, FIB (Focused Ion Beam), and a nano-indenter. Dynamic polarization testing and EIS (electrical impedance spectroscopy) were carried out to evaluate the micro-defects and the corrosion properties of the coatings. The prepared coatings show hybrid properties of inorganic oxides and organic materials. Crack free coatings were prepared when the MAPTS ratio was above a critical value. As the MAPTS ratio increased, the thickness and the corrosion resistance increased, and the hardness decreased.

• Macromolecular Research
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• 제12권3호
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• pp.263-268
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• 2004

We have synthesized a water-soluble polyimide precursor, poly(amic acid) amine salt (PAD), from pyromellitic dianhydride (PMDA), 4,4'-oxydianiline, and N,N -dimethylethanolamine (DMEA) and have investigated in detail its properties with respect to the degree of salt formation (D$\_$sf/). The maximum value of D$\_$sf/ we obtained upon precipitation of the precursor solution into acetone was 79%. We synthesized a PAD having a D$\_$sf/ of 100% (PAD100) by the solid state drying of an organic solution. The precursors showed different solubility depending on the D$\_$sf/ to make up to 4 wt% solutions in water containing a small amount of DMEA. PAD100 is completely soluble in pure water. We investigated the imidization behavior of PAD in aqueous solution using various spectroscopic methods, which revealed that PAD 100 has faster imidization kinetics relative to that of the poly(amic acid)-type precursors. The resulting polyimide films prepared from an aqueous precursor solution possess almost similar physical and thermal properties as those prepared from N-methyl-2-pyrrolidone(NMP) solution. Therefore, we have demonstrated that PAD can be used as a water-based precursor of polyimide; this procedure avoids the use of toxic organic solvents, such as NMP.

• 한국분말재료학회지
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• 제10권2호
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• pp.123-128
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• 2003

$TiO_2$ nanopowder was synthesized by chemical vapor condensation (CVC) process and its photocatalytic property depending on microstructure was considered in terns of decomposition rate of organic compound. In order to control microstructure of $TiO_2$ nanopowder such as particle size and degree of agglomeration, precursor flow rate representing number concentration was changed as a process variable. In TEM observation, spherical $TiO_2$ nanoparticles with average size of 20 nm showed gradual increases in particle size and degree of agglomeration with increase of precursor flow rate. Also decomposition rate of organic compound increased with decreasing precursor flow rate. Thus, it was concluded that photocatalytic property was enhanced by targe surface area of disperse $TiO_2$ nanoparticles synthesized at lower precursor flow rate condition in CVC process.

• 한국전기전자재료학회논문지
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• 제18권10호
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• pp.956-959
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• 2005

High Tc superconducting with a BiSrCaCuO was prepared by the titrate method. The solid precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12 h is not in the amorphous state as expected but in a crystalline state. X-tay diffraction peaks of nearly the same angular position as the peaks of high Tc phase were observed in the precursor.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.395-395
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• 2012

We fabricate organic-inorganic hybrid thin film for the purpose of encapsulation by molecular layer deposition (MLD) using Trimethylaluminium (TMA) and Adipoyl Chloride (AC). Ellipsometry was employed to verify self limiting reaction of ALD. Linear relationship between number of cycle and thickness was obtained. We found that desirable organic thin film fabrication is possible by MLD surface reaction in nanoscale. Purging was carried out after dosing of each precursor to form monolayer in each sequence. We also confirmed roughness of the organic thin film by atomic force microscopy. We deposit TMA and AC at $70^{\circ}C$ and that 1.78A root mean square was obtained which indicates that uniform organic thin film was formed. We confirmed precursor's functional group by IR spectrum. We calculated WVTR of organic-inorganic hybrid super-lattice epitaxial layer using Ca test. WVTR indicates superlattice film can be possibly use as encapsulation in flexible devices.

• 한국미생물·생명공학회지
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• 제20권1호
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• pp.61-67
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• 1992

유기용매 이상계에서의 thermolysin을 사용하여 아스파탐 전구체 합성시 pH, 온도, 기질농도, 그리고 유기용매상에 대한 수용액상의 부비피 ($\alpha$)등의 변화에 따른 기질의 분해 반응, 효소의 안정성, 그리고 Z-APM 합성에 미치는 복합적인 영향을 조사함으로써 반응조건의 최적화를 도모하였다. 유기용매 이상계에서의 L-PM.HCL의 자연분해는 수용액에서보다 훨씬 느리게 일어나며, 또한 $\alpha$가 증가할 수록 분해속도가 감소하는 것을 알 수 있었다.

• 한국결정성장학회지
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• 제15권5호
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• pp.193-197
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• 2005

층상 구조의 유기-무기 복합 소재 $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$를 전구체로 사용하여 CuO를 합성하였다. 외부의 다른 유기화합물 주형이 없이 단순한 $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$의 열분해 방법을 사용하였다 이 방법은 저렴한 가격으로 단일 결정의 CuO 입자를 양산하는 방법을 제공한다 응집된 CuO 입자의 형태는 전구체의 구조에 크게 영향을 받는다.

• Progress in Superconductivity
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• 제7권2호
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• pp.158-161
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• 2006

Superconducting YBCO films were successfully fabricated by MOD process using chemically modified precursor solution. In this study, a chemically modified precursor solution for MOD processing was synthesized using metal-organic salts and organic additives. It was shown that crack-free and uniform precursor films were formed after calcination in humidified Oxygen atmosphere. Less than 3 hours are required to finish the calcination process. XRD measurement shows that $BaF_2,\;CuO,\;Y_2O_3$ are major constituent of precursor films. Furthermore, YBCO films without any secondary phases were successfully fabricated after annealing in wet $Ar/O_2$ atmosphere. The YBCO film prepared on a $LaAlO_3$ single crystal substrate ($10mm{\times}10mm$) gives transport $I_c$ of 10A at 77K. This chemical modification approach is a possible candidate for improving MOD-processing of YBCO coated conductor.