• 한국재료학회지
• /
• 제24권2호
• /
• pp.116-122
• /
• 2014

$Bi_2Sr_2CaCu_2O_x$(Bi-2212) and $Bi_2Sr_2Ca_2Cu_3O_y$(Bi-2223) high-Tc superconductors(HTS) have been manufactured by plasma spraying, partial melt process(PMP) and annealing treatment(AT). A Bi-2212/2223 HTS coating layer was synthesized through the peritectic reaction between a 0212 oxide coating layer and 2001 oxide coating layer by the PMP-AT process. The 2212 HTS layer consists of whiskers grown in the diffusion direction. The Bi-2223 phase and secondary phase in the Bi-2212 layer were observed. The secondary phase was distributed uniformly over the whole layer. As annealing time goes on, the Bi-2212 phase decreases with mis-orientation and irregular shape, but the Bi-2223 phase increases because a new Bi-2223 phase is formed inside the pre-existing Bi-2212 crystals, and because of the nucleation of a Bi-2223 phase at the edge of Bi-2212 crystals by diffusion of Ca and Cu-O bilayers. In this study the spray coated layer showed superconducting transitions with an onset Tc of about both 115 K, and 50 K. There were two steps. Step 1 at 115 K is due to the diamagnetism of the Bi-2223 phase and step 2 at 50 K is due to the diamagnetism of the Bi-2212 phase.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2009년도 춘계학술발표대회
• /
• pp.56.1-56.1
• /
• 2009

The intermediate operating temperature of solid oxide fuel cells (IT-SOFCs) have achieved considerable importance in the area of power fabrication. This is because to improve materials compatibility, their long-term stability and cost saving potential. However, to conserve rational cell performance at reduced-temperature regime, cathode performance should be obtained without negotiating the internal resistance and the electrode kinetics of the cell. Recently, double perovskite structure cathodes have been studied with great attention as a potential material for IT-SOFCs. In this study, double-perovskite structured cathodes of $GdBaCoCuO_{5+\delta}$, $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ compositions and $(1-x)GdBaCo_2O_{5+\delta}+xCe_{0.9}Gd_{0.1}O_{1.95}$ (x = 10, 20, 30 and 40 wt.%) composites were evaluated as the cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). Electrical conductivity of the cathodes were measured by DC 4-probe method, and the thermal expansion coefficient of each sample was measured up to $900^{\circ}C$ by a dilatometer study. Area specific resistances(ASR) of the $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ cathode and 70 wt.% $GdBaCo_2O5+\delta$ + 30wt.% Ce0.9Gd0.1O1.95 composite cathode on CGO electrolyte substrate were analyzed using AC 3-probe impedance study. The obtained results demonstrate that double perovskite-based compositions are promising cathode materials for IT-SOFCs.

• 공업화학
• /
• 제26권4호
• /
• pp.394-399
• /
• 2015

본 연구에서는 Cu 촉매가 도입된 활성탄소섬유를 제조하여 고효율 $SO_2$ 흡착재를 제조하였다. 라이오셀 섬유를 내염화 및 탄화공정을 통해 탄소섬유를 얻었으며, $SO_2$ 흡착능을 향상시키기 위해 KOH 활성화를 사용하여 높은 비표면적 및 균일한 미세기공구조를 부여하였다. 활성탄소섬유에 Cu 촉매를 도입하기 위하여 $Cu(NO_3)_2{\cdot}3H_2O$ 수용액을 사용하였으며, 공정 시 i) 탄소섬유 내 산소 관능기의 분해반응을 촉진하고, ii) 산화구리 및 질산염의 분해로 oxygen radical이 생성되어 탄소섬유의 활성화 반응을 촉진시켰다. 이로 인해 활성탄소섬유의 미세공과 중기공 형성효과 및 탄소섬유 표면에 고르게 분산된 Cu 촉매를 확인하였다. Cu 촉매 도입 후, 활성탄소섬유에 비해 비표면적 및 미세공의 비율이 약 10% 이상 증가되었고, $SO_2$ 흡착능이 149% 이상 향상된 결과를 얻을 수 있었다. Cu 촉매도입공정 시, 전이금속 촉매효과에 의하여 발달된 미세공, 중기공 및 비표면적에 의한 물리적 흡착과 도입된 Cu 촉매에 의한 $SO_2$ 가스의 화학적 흡착반응의 시너지 효과에 기인하여 $SO_2$ 흡착능이 향상된 것으로 사료된다.

• 한국재료학회지
• /
• 제33권4호
• /
• pp.142-150
• /
• 2023

AZO/Cu/AZO thin films were deposited on glass by RF magnetron sputtering. The specimens showed the preferred orientation of (0002) AZO and (111) Cu. The Cu crystal sizes increased from about 3.7 nm to about 8.5 nm with increasing Cu thickness, and from about 6.3 nm to about 9.5 nm with increasing heat treatment temperatures. The sizes of AZO crystals were almost independent of the Cu thickness, and increased slightly with heat treatment temperature. The residual stress of AZO after heat treatment also increased compressively from -4.6 GPa to -5.6 GPa with increasing heat treatment temperature. The increase in crystal size resulted from grain growth, and the increase in stress resulted from the decrease in defects that accompanied grain growth, and the thermal stress during cooling from heat treatment temperature to room temperature. From the PL spectra, the decrease in defects during heat treatment resulted in the increased intensity. The electrical resistivities of the 4 nm Cu film were 5.9×10^-4 Ω·cm and about 1.0×10^-4 Ω·cm for thicker Cu films. The resistivity decreased as the temperature of heat treatment increased. As the Cu thickness increased, an increase in carrier concentration resulted, as the fraction of AZO/Cu/AZO metal film increased. And the increase in carrier concentration with increasing heat treatment temperature might result from the diffusion of Cu ions into AZO. Transmittance decreased with increasing Cu thicknesses, and reached a maximum near the 500 nm wavelength after being heat treated at 200 ℃.

• 한국재료학회지
• /
• 제21권5호
• /
• pp.283-287
• /
• 2011

As the performance of microelectronic devices is improved, the use of copper as a heat dissipation member is increasing due to its good thermal conductivity. The high thermal conductivity of copper, however, leads to difficulties in the joining process. Satisfactory bonding with copper is known to be difficult, especially if high shear and peel strengths are desired. The primary reason is that a copper oxide layer develops rapidly and is weakly attached to the base metal under typical conditions. Thus, when a clean copper substrate is bonded, the initial strength of the joint is high, but upon environmental exposure, an oxide layer may develop, which will reduce the durability of the joint. In this study, an epoxy adhesive formulation was investigated to improve the strength and reliability of a copper to copper joint. Epoxy hardeners such as anhydride, dihydrazide, and dicyandiamide and catalysts such as triphenylphosphine and imidazole were added to an epoxy resin mixture of DGEBA and DGEBF. Differential scanning calorimetry (DSC) analyses revealed that the curing temperatures were dependent on the type of hardener rather than on the catalyst, and higher heat of curing resulted in a higher Tg. The reliability of the copper joint against a high temperature and high humidity environment was found to be the lowest in the case of dihydrazide addition. This is attributed to its high water permeability, which led to the formation of a weak boundary layer of copper oxide. It was also found that dicyandiamide provided the highest initial joint strength and reliability while anhydride yielded intermediate performance between dicyandiamide and dihydrazide.

• 한국응용과학기술학회지
• /
• 제17권1호
• /
• pp.1-5
• /
• 2000

The selective catalytic reduction(SCR) of nitric oxide by ethane in the presence of oxygen was investigated on Cu-ZSM-5, Co-ZSM-5 and Ga-ZSM-5 catalysts over a range of 400, 450 and $500^{\circ}C$. The catalysts were prepared by ion-exchange method. The composition of the reactant gases were 1000 ppm of NO, 1000 ppm of $C_{2}H_{6}$ and 2.5% of $O_{2}$, and the reaction was conducted in a fixed-bed reactor at 1 atm. For the 20wt% Co-ZSM-5(50) catalyst, the NO conversion reached up to 100%, while the $C_2H_6$ conversion and the CO selectivity were about 50% and 25%, respectively, at $450^{\circ}C$. For the 20wt% Cu-ZSM-5(50) catalyst, the NO conversion and the C2H6 conversion were about 80% and 100%, respectively, but there was no CO produced. The metal ion-exchanged ZSM-5 catalysts exhibited a tendency to increase the NO conversion with the Si/Al ratio of the ZSM-5, that is, NO conversion was inversely proportional to the acidity of the catalysts. But, the effect of the acidity on NO conversion was not so large. From the XRD results of the catalysts before and after SCR reaction it was found that there was no structural change.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.257.1-257.1
• /
• 2014

We investigated characteristics of ITO/Ag-Pd-Cu (APC)/ITO multilayer electrodes prepared by direct current magnetron sputtering for use as an anode in organic solar cells (OSCs). To optimize electrical properties of ITO/APC/ITO multilayer, we fabricated the ITO/APC/ITO multilayer at a fixed ITO thickness of 30 nm as a function of APC thickness. Compare to the surface of Ag layer on ITO, the APC had a smooth surface morphology. At optimized APC thickness of 12 nm, the ITO/APC/ITO multilayer exhibited a sheet resistance of $6{\Omega}/square$ and optical transmittance of 84.15% at a wavelength of 550 nm which is comparable to conventional ITO/Ag/ITO multilayer. However, the APC-based ITO multilayer showed a higher average transmittance in a visible region than the Ag-based ITO multilayer. The higher average transmittance of ITO/APC/ITO multilayer indicated the multilayer is suitable anode for organic solar cells with P3HT:PCBM active layer. OSCs fabricated on the optimized ITO/ACP/ITO multilayer exhibited a better performance with a fill factor of 64.815%, a short circuit current of $8.107mA/cm^2$, an open circuit voltage of 0.59 V, and power conversion efficiency (3.101%) than OSC with ITO/Ag/ITO multilayer (2.8%).

• 한국광물학회지
• /
• 제17권3호
• /
• pp.209-220
• /
• 2004

구리 흡착 실험과 MINTEQA2 및 FITEQL3.2 컴퓨터 프로그램을 이용하여 고성군 판곡리에서 산출되는 황토 현탁액의 구리 흡착 특성을 연구하였다 구리 흡착 실험은 pH, 구리 용액의 양, 전해질의 이온 세기를 변화시키면서 실시하였고, 구리의 농도는 유도결합플라즈마분광분석기를 사용하여 분석하였다. 첨가하는 구리 이온의 양과 pH가 증가할수록 흡착되는 구리 이온의 양도 증가한다. 특히 pH가 5.5에서 6.5로 변할 경우 급격한 흡착률의 증가가 있으며, pH 7.5에서 거의 100% 흡착된다. 배경 전해질의 이온 세기에 영향을 받지 않는 것으로 보아 구리 이온은 황토 표면과 내부권 복합체(inner-sphere complex)로써 아주 강한 화학적 결합을 하고 있는 것으로 판단할 수 있다. MINTEQA2 프로그램을 이용하여 구리의 화학종 분포를 계산한 결과, pH가 증가함에 따라 $Cu^{2+}$ 의 농도는 점점 감소하고 $Cu(OH)_2$ 농도는 점점 증가한다. FITEQL3.2 프로그램을 이용하여 황토의 표면을 규산염 광물 자리와 산화염 광물 자리로 나눈 two sites-three pKas 모델을 적용하여 흡착 양상을 모델링한 결과, 구리 용액의 부피가 2～6 mL인 경우 구리 흡착 평형 상수 값을 도출할 수 있었다. 철산화염 광물 반응 자리에 흡착되는 구리의 앙은 pH 4.5～6.5 범위에서 급격한 흡착 양상을 보이다가 그 이상 pH에서는 흡착되는 양이 조금씩 밖에 증가하지 않는다. 규산염 광물 반응 자리에 흡착되는 구리의 양은 구리 용액의 양이 적을 때는 미약하다가 구리 용액의 양이 커질 경우 그 양이 많아진다. 침전에 의하여 제거되는 구리의 양은 광물 표면 자리에 흡착되는 양과 비교하면 아주 적다. 구리 이온에 대한 흡착 친화도는 규산염 광물보다는 철산화염 광물이 더 큰 것으로 판단된다.

• 한국재료학회지
• /
• 제17권6호
• /
• pp.308-312
• /
• 2007

Chromium oxide thin films have been deposited on silicon substrates using a tabletop 9kJ mathertyped plasma focus (PF) device. Before deposition, pinch behavior with gas pressure was observed. Strength of pinches was increased with increasing working pressure. Deposition was performed at room temperature as a function of working pressure between 50 and 1000 mTorr. Composition and surface morphology of the films were analyzed by Auger Electron Spectroscopy and Scanning Electron Microscope, respectively. Growth rates of the films were decreased with pressure. The oxide films were polycrystalline containing some impurities, Cu, Fe, C and revealed finer grain structure at lower pressure.

• Transactions on Electrical and Electronic Materials
• /
• 제7권4호
• /
• pp.167-172
• /
• 2006

Submicron colloidal silica coated with ceria were prepared by mixing of silica and nano ceria particles and modified by hydrothermal reaction. The polishing efficiency of the ceria coated silica slurry was tested over oxide film on silicon wafer. By changing the polishing pressure in the range of $140{\sim}420g/cm^2$ with the ceria coated silica slurries in $100{\sim}300nm$, rates, WIWNU and friction force were measured. The removal rate was in the order of 200, 100, and 300 nm size silica coated with ceria. It was known that the smaller particle size gives the higher removal rate with higher contact area in Cu slurry. In the case of oxide film, the indentation volume as well as contact area gives effect on the removal rate depending on the size of abrasives. The indentation volume increase with the size of abrasive particles, which results to higher removal rate. The highest removal rate in 200 nm silica core coated with ceria is discussed as proper combination of indentation and contact area effect.