• Current Photovoltaic Research
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• 제5권1호
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• pp.15-19
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• 2017

The fossil fuel power consumption generates $CO_2$, which causes the problems such as global warming. Also, the increase in energy consumption has accelerated the depletion of the fossil fuels, and renewable energy is attracting attention. Among the renewable energies, the solar energy gets a lot of attention as the infinite clean energy source. But, the supply level of solar cell is insignificant due to high cost of generation of electric power in comparison with fossil fuels. Thus several researchers are recently doing the research on ultra-low-cost solar cells. Also, $Cu_2O$ is one of the applied materials as an absorption layer in ultra-low-cost solar cells. Cuprous oxide ($Cu_2O$) is highly desirable semiconductor oxide for use in solar energy conversion due to its direct band gap ($E_g={\sim}2.1eV$) and a high absorption coefficient that absorbs visible light of wavelengths up to 650 nm. In addition, $Cu_2O$ has several advantages such as non-toxicity, low cost and can be prepared with simple and cheap methods on large scale. In this work, we fabricated the $Cu_2O$ thin films by reactive sputtering method. The films were deposited with a Cu target with variable parameters such as substrate temperature, rf-power, and annealing condition. Finally, we confirmed the structural properties of thin films by XRD and SEM.

• 한국재료학회지
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• 제13권8호
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• pp.503-508
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• 2003

The purpose of this study is to investigate the effect of $V_2$$O_{5}$ addition on the Ag and Cu precipitation in the NiCuZn ferrite layers of 7.7${\times}$4.5${\times}$1.0 mm sized multi-layer chip inductors prepared by the screen printing method using 0∼0.5 wt% $V_2$$O_{5}$ -doped ferrite pastes. With increasing the $V_2$$O_{5}$ content and sintering temperature, Ag and Cu oxide coprecipitated more and more at the polished surface of ferrite layers during re-annealing at $840^{\circ}C$. It was thought that during the sintering process, V dissolved in the NiCuZn ferrite lattice and the Ag-Cu liquid phase of low melting point was formed in the ferrite layers due to the Cu segregation from the ferrite lattice and Ag diffusion from the internal electrode. During re-annealing at $840^{\circ}C$, the Ag-Cu liquid phase came out the polished surface of ferrite layers, and was decomposed into the isolated Ag particles and the Cu oxide phase during the cooling process.

• 한국자기학회지
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• 제17권2호
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• pp.99-102
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• 2007

The Cu oxide nano powders were synthesized by levitational gas condensation (LGC) method and their high heterogeneous catalytic effects of oxidation of 2,3,5-trimethyl-1,4-hydroquinone (TMHQ) and catalase activity were studied. The nano powders consist of mainly $Cu_2O$. The catalytic effect which was clarified by the oxidation of TMHQ and the activity of catalase, was found to depend on the amount of $Cu_2O$ phase and the particle size.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2519-2522
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• 2014

Recently, the observation of the electrocatalytic behavior of individual nanoparticles (NPs) by electrochemical amplification method has been reported. For example, the Iridium oxide ($IrO_x$) NP collision on the Pt UME was observed via electrocatalytic water oxidation. However, the bare Pt UME had poor reproducibility for the observation of NP collision signal and required an inconvenient surface pre-treatment for the usage. In this manuscript, we has been investigated other metal electrode such as Cu UME for the reproducible data analysis and convenient use. The $IrO_x$ NP collision was successively observed on the bare Cu UME and the reproducibility in collision frequency was improved comparing with previous case using the $NaBH_4$ pre-treated Pt UME. Also, the adhesion coefficient between NP and the Cu UME was studied for better understanding of the single NP collision system.

• 한국세라믹학회지
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• 제31권4호
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• pp.381-388
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• 1994

A new process which co-fires the low-firing-substrate and copper conductor was studied to achieve good bond strength and low sheet resistance of conductor. Cupric oxide is used as the precursor of conductive material in the new method and the firing atmosphere of the new process is changed sequently in air H2N2. The addition of cupric oxide and variations of firing atmosphere permited complete binder-burnout in comparison with the conventional method and contributed to the improvement of resistance and bonding behaviors. The potimum conditions of this experiment to obtain the satisfactory resistance and bond strength are as follows (binder-burnout temperature in air; 55$0^{\circ}C$, reducing temperature in H2; 40$0^{\circ}C$ for 30 min, ratio of copper and cupric oxide; 60:40~30:70 wt%). The bonding mechanism between the substrate and metal was explained by metal diffusion layer in the interface and the bond strength mainly depended on the stress caused by the difference of shrinkage and thermal expansion coefficient between the substrate and metal.

• Transactions on Electrical and Electronic Materials
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• 제13권6호
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• pp.305-309
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• 2012

In this study, ZnO nanorods and $SnO_2$-CuO heterogeneous oxide were grown on membrane-type gas sensor platforms and the sensing characteristics for carbon monoxide (CO) were studied. Diaphragm-type gas sensor platforms with built-in Pt micro-heaters were made using a conventional bulk micromachining method. ZnO nanorods were grown from ZnO seed layers using the hydrothermal method, and the average diameter and length of the nanorods were adjusted by changing the concentration of the precursor. Thereafter, $SnO_2$-CuO heterogeneous oxide thin films were grown from evaporated Sn and Cu thin films. The average diameters of the ZnO nanorods obtained by changing the concentration of the precursor were between 30 and 200 nm and the ZnO nanorods showed a sensitivity value of 21% at a working temperature of $350^{\circ}C$ and a carbon monoxide concentration of 100 ppm. The $SnO_2$-CuO heterogeneous oxide thin films showed a sensitivity value of 18% at a working temperature of $200^{\circ}C$ and a carbon monoxide concentration of 100 ppm.

• 한국응용과학기술학회지
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• 제33권1호
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• pp.129-135
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• 2016

Cu-Mn과 Cu-Zn 촉매를 침전제로 다르게 하거나, 금속의 몰비율, 소성온도를 다르게 하여 공침법으로 제조하였고 CO산화반응을 수행하여 혼합산화물 촉매에서 Cu, Mn 과 Zn의 영향 및 소성온도가 미치는 영향을 조사하였다. 촉매의 물리 화학적 특성을 알아보기 위하여 XRD, $N_2$ 흡착 및 SEM의 분석을 수행하였다. $Na_2CO_3$로 침전시켜 $270^{\circ}C$로 소성하여 제조한 2Cu-1Mn 산화물 촉매가 저온에서 CO 산화반응 활성이 가장 좋았으며 2Cu-1Mn 산화물 촉매는 $43m^2/g$으로 가장 높은 비표면적과 촉매 활성을 나타내었다. XRD로 촉매의 결정구조를 분석하였을 때 $Cu_{0.5}Mn_{2.5}O_4$의 결정구조를 갖는 촉매는 낮은 활성을 보였다. $270^{\circ}C$에서 소성한 촉매가 좋은 활성을 나타냈으며 Pt 촉매와 비교하여도 저온에서 CO산화반응이 더욱 우수함을 알 수 있었다.

• 한국분말재료학회지
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• 제7권4호
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• pp.218-227
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• 2000

It is well known that the Cu-Cr alloys are very difficult to be made by conventional sintering methods. This difficulty originates both from limited solubility of Cr in the Cu matrix and from limited sintering temperature due to high vapor pressures of Cr and Cu components at the high temperature. Densification of Cu-50%Cr Powder compacts by conventional Powder metallurgy Process has been studied. Three kinds of sintering methods were tested in order to obtain high-density sintered compacts. Completely densified Cu-Cr compacts could be obtained neither by solid state sintering method nor by liquid phase sintering method. Both low degree of shrinkage and evolution of large pores in the Cu matrix during the solid state sintering are attributed to the anchoring effect of large Cr particles, which inhibits homogeneous densification of Cu matrix and induces pore generation in the Cu matrix. In addition, the effect of undiffusible gas coming from the reduction of Cu-oxide and Cr-oxide was observed during liquid phase sintering. A two-step sintering method, solid state sintering followed by liquid phase sintering, was proved to have beneficial effect on the fabrication of high-dendsity Cu-Cr sintered compacts. The sintered compacts have properties similar to those of commercial products.

• 한국재료학회지
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• 제23권1호
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• pp.1-6
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• 2013

A simple thermal oxidation of Cu thin films deposited on planar substrates established a growth of vertically aligned copper oxide (CuO) nanorods. DC sputter-deposited Cu thin films with various thicknesses were oxidized in environments of various oxygen partial pressures to control the kinetics of oxidation. This is a method to synthesize vertically aligned CuO nanorods in a relatively shorter time and at a lower cost than those of other methods such as the popular hydrothermal synthesis. Also, this is a method that does not require a catalyst to synthesize CuO nanorods. The grown CuO nanorods had diameters of ~100 nm and lengths of $1{\sim}25{\mu}m$. We examined the morphology of the synthesized CuO nanorods as a function of the thickness of the Cu films, the gas environment, the oxidation time, the oxidation temperature, the oxygen gas flow rate, etc. The parameters all influence the kinetics of the oxidation, and consequently, the volume expansion in the films. Patterned growth was also carried out to confirm the hypothesis of the CuO nanorod protrusion and growth mechanism. It was found that the compressive stress built up in the Cu film while oxygen molecules incorporated into the film drove CuO nanorods out of the film.

• 한국대기환경학회지
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• 제22권3호
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• pp.373-381
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• 2006

The catalytic combustion of toluene was investigated on the Cu-Mn oxide catalysts prepared by the deposition-precipitation method. Experiment of toluene combustion was performed with a fixed bed flow reactor in the temperature range of $100{\sim}280^{\circ}C$. Among the catalysts, 1.29Cu/Mn showed the most activity at $260^{\circ}C$. The deposition-precipitation method may be showed the potential to enhance the activity of catalysts. The catalysts were characterized by BET, scanning electron microscopy (SEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. On the basis of catalyst characterization data, the results showed that the surface of catalysts by deposition-precipitation method had uniform distribution and smaller particle size, which enhanced the reduction capability of catalysts. The XRD results showed that $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase was made by deposition-precipitation method, and increased catalyst activity and redox characteristic. It was assumed that the reduction step of $Cu_{1.5}Mn_{1.5}O_{4}$ spinel phase progressed $Cu_{1.5}Mn_{1.5}O_{4}\;to\;CuMnO_{2},\;and\;Cu_{2}O\;to\;CuMn_{2}O_{4}\;and\;Cu$.