• 한국표면공학회지
• /
• 제56권6호
• /
• pp.451-456
• /
• 2023

Transparent conducting films having a three layered structure of ZnO/Cu/ZnO (ZCZ) were deposited onto the glass substrates by using RF and DC magnetron sputtering at room temperature. The emissivity and opto-electrical properties of the films were investigated with a varying thickness(5, 10, 15 nm) of the Cu interlayer. With increasing the Cu thickness to 15 nm, the films showed a enhanced electrical properties. Although ZnO 30/Cu 15/ZnO 30 nm film shows a lower resistivity of 5.2×10^-5 Ωcm, it's visible transmittance is deteriorated by increased optical absorbtion of the films. In addition, X-ray diffraction patterns indicated that the insertion of Cu interlayer improve the grain size of ZnO films, which is favor for the electrical and optical properties of transparent conducting films. From the observed low emissivity of the films, it is concluded that the ZCZ thin films with optimal thickness of Cu interlayer can be applied effectively for the car's window coating materials.

• Korean Journal of Chemical Engineering
• /
• 제36권2호
• /
• pp.191-196
• /
• 2019

The phase of Cu,Zn,Al precursors strongly affects the activity of their final catalysts. Herein, the Cu,Zn,Al precursor was prepared by precipitation of $Al^{3+}$ onto primitive, amorphous Cu,Zn precipitate. This precursor turned out to be a phase mixture of zincian malachite and hydrotalcite in which the latter phase was less abundant compared to the co-precipitated precursor. The final catalyst derived from this precursor exhibited a little higher copper surface area and methanol synthesis activity than the co-precipitated counterpart. Therefore, the two precursor phases need to be mixed in an adequate proportion for the preparation of active $Cu/ZnO/Al_2O_3$ catalyst.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
• /
• pp.359-359
• /
• 2011

This study reports the H2S gas sensing properties of CuO / ZnO nano-hetero structure bundle and the investigation of gas sensing mechanism. The 1-Dimensional ZnO nano-structure was synthesized by hydrothermal method and CuO / ZnO nano-heterostructures were prepared by photo chemical reaction. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) spectra confirmed a well-crystalline ZnO of hexagonal structure. In order to improve the H2S gas sensing properties, simple type of gas sensor was fabricated with ZnO nano-heterostructures, which were prepared by photo-chemical deposition of CuO on the ZnO nanorods bundle. The furnace type gas sensing system was used to characterize sensing properties with diluted H2S gas (50 ppm) balanced air at various operating temperature up to 500$^{\circ}C$. The H2S gas response of ZnO nanorods bundle sensor increased with increasing temperature, which is thought to be due to chemical reaction of nanorods with gas molecules. Through analysis of X-ray photoelectron spectroscopy (XPS), the sensing mechanism of ZnO nanorods bundle sensor was explained by well-known surface reaction between ZnO surface atoms and hydrogen sulfide. However at high sensing temperature, chemical conversion of ZnO nanorods becomes a dominant sensing mechanism in current system. Photo-chemically fabricated CuO/ZnO heteronanostructures show higher gas response and higher current level than ZnO nanorods bundle. The gas sensing mechanism of the heteronanostructure can be explained by the chemical conversion of sensing material through the reaction with H2S gas.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 C
• /
• pp.1488-1490
• /
• 2000

ZnO:Cu thin films are deposited by using an RF magnetron co-sputtering system with Cu chips attached on ZnO target. Structural and electrical properties are analyzed as a function of deposition conditions, such as Cu chip areas, $O_2/(Ar+O_2)$ ratios, and working pressures, The results show that a higher electrical resistivity above $10^{10}$ ${\Omega}cm$ along with an excellent c-axial growth can be easily achieved by Cu-doping. SAW filters based on the ZnO:Cu films are also fabricated to estimate the electric-mechanical coupling coefficient($K^{2}_{eff}$). Higher $K^{2}_{eff}$ and lower insertion losses are observed for ZnO:Cu films, compared with those for ZnO films.

• 한국재료학회지
• /
• 제28권1호
• /
• pp.32-37
• /
• 2018

We report on the efficient detection of NO gas by an all-oxide semiconductor p-n heterojunction diode structure comprised of n-type zinc oxide (ZnO) nanorods embedded in p-type copper oxide (CuO) thin film. The CuO thin film/ZnO nanorod heterostructure was fabricated by directly sputtering CuO thin film onto a vertically aligned ZnO nanorod array synthesized via a hydrothemal method. The transport behavior and NO gas sensing properties of the fabricated CuO thin film/ZnO nanorod heterostructure were charcterized and revealed that the oxide semiconductor heterojunction exhibited a definite rectifying diode-like behavior at various temperatures ranging from room temperature to $250^{\circ}C$. The NO gas sensing experiment indicated that the CuO thin film/ZnO nanorod heterostructure had a good sensing performance for the efficient detection of NO gas in the range of 2-14 ppm under the conditions of an applied bias of 2 V and a comparatively low operating temperature of $150^{\circ}C$. The NO gas sensing process in the CuO/ZnO p-n heterostructure is discussed in terms of the electronic band structure.

• 자원리싸이클링
• /
• 제12권6호
• /
• pp.8-12
• /
• 2003

본 논문에서는 최근 고품위 TV 및 고정세도 디스플레이용으로 화상의 정세도를 향상시키기 위해 수평주파수를 높이려는 움직임이 있어, 편향 요크용 페라이트 코아에는 고주파수 영역에 있어서도 코아로스가 낮은 재료가 요구되고 있는 실정이다. Mg-Zn 페라이트에 있어서 화학조성 및 프로세스가 미세구조에 미치는 영향에 착안하여 저온 소결화를 하였다. 저손실인 Mg-Zn계 Ferrite에 Cu를 첨가하였다. MgO, ZnO, $Fe_2$$O_3$, CuO를 선택한 후 조성비의 변화를 두며 CuO를 MgO로 치환하였다. 이 시료를 $980∼1350^{\circ}C$까지 3시간 소결하였다. 측정은 투자율, 전력손실, 수축율, 코아로스를 측정하였다. 시료의 수축율을 개시하는 온도는 $900^{\circ}C$부근이며 Cu치환에 따라 수축율이 증가하였으며, Cu 치환에 따라 소성온도가 약 $-50∼-75^{\circ}C$ 낮아졌다.

• 공업화학
• /
• 제21권3호
• /
• pp.328-332
• /
• 2010

본 연구에서는 다이에틸렌글리콜 용매 상에서 공침법을 이용하여 기공성 아연 구형 산화물과 구리-아연 복합 산화물을 합성하였다. 합성된 물질들의 물리화학적 특성은 전자현미경, X-선 회절분석, $N_2$ 흡착, $H_2$-TPR 방법을 통하여 분석되었고, 다양한 Cu 함량(0, 6.6, 21.3 36.4, 54.6, 77.8 wt%)을 포함한 Cu-ZnO 복합 산화물을 고정층 반응 장치에서 일산화탄소 산화 반응성을 고찰하였다. 합성된 산화물 중에서 Cu 함량이 증가할수록 Cu-ZnO의 비표면적과 미세 기공 부피는 감소하였으며, Cu (36.4 wt%)-ZnO이 가장 좋은 일산화탄소 산화 반응성을 나타내었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.169-169
• /
• 2012

The high-temperature superconductor YBa2Cu3O7-x (YBCO) have attached attentions because of a high superconducting transition temperature, low surface resistance, high superconducting critical current density (Jc), and superior superconducting capability under magnetic field. Moreover, the Jc of YBCO superconductors can be enhanced by adding impurities to the YBCO films for vortex-pinning. Understanding and controlling pinning centers are key factors to realize high Jc superconductors. We synthesized vertically-aligned ZnO nanorods on SrTiO3 (STO) substrates by catalyst-free metal-organic chemical vapor deposition (MOCVD), and subsequently, deposited YBCO films on the ZnO nanorods/STO templates using pulsed laser deposition (PLD). The various techniques were used to analyze the structural and interfacial properties of the YBCO/ZnO nanorods/STO hybrid structures. SEM, TEM, and XRD measurements demonstrated that YBCO films on ZnO nanorods/STO were well crystallized with the (001) orientation. EXAFS measurements from YBCO/ZnO nanorods/STO at Cu K edge demonstrated that the local structural properties around Cu atoms in YBCO were quite similar to those of YBCO/STO.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.103-103
• /
• 2011

The epitaxial Cu-doped ZnO and pure ZnO thin films were grown on Al2O3 (0001) substrates by RF sputtering method. The structures and crystallographic orientations were investigated using X-ray diffraction (XRD) and X-ray absorption spectroscopy. From the XRD pattern, it is observed that peak positions shift towards higher $2{\theta}$ value with Cu doping. The ${\omega}$-scan measurements at the (0002) diffraction peak for these samples reveal that the full-widths at half-maxima (FWHMs) are about $0.017-0.019^{\circ}$, which indicate a good c-axis orientation of the Zn1-xCuxO films. From phi-scan, all of the Zn1-xCuxO films were epitaxially grown. EXAFS measurements also demonstrated that Cu incorporated into a Zn-atom position substitutionally. All the results confirmed that copper ion were well incorporated into the ZnO lattices by substituting Zn sites without changing the wurtzite structure and no secondary phase existed in Cu-doped ZnO thin films.

• Molecules and Cells
• /
• 제21권1호
• /
• pp.161-165
• /
• 2006

Dichlorodihydrofluorescein ($DCFH_2$) is a widely used probe for intracellular $H_2O_2$. However, $H_2O_2$ can oxidize $DCFH_2$ only in the presence of a catalyst, whose identity in cells has not been clearly defined. We compared the peroxidase activity of Cu,Zn-superoxide dismutase (CuZnSOD), cytochrome c, horseradish peroxidase (HRP), $Cu^{2+}$, and $Fe^{3+}$ under various conditions to identify an intracellular catalyst. Enormous increase by bicarbonate in the rate of $DCFH_2$ oxidation distinguished CuZnSOD from cytochrome c and HRP. Cyanide inhibited the reaction catalyzed by CuZnSOD but accelerated that by $Cu^{2+}$ and $Fe^{3+}$. Oxidation of $DCFH_2$ by $H_2O_2$ in the presence of a cell lysate was also enhanced by bicarbonate and inhibited by cyanide. Confocal microscopy of $H_2O_2$-treated cells showed enhanced DCF fluorescence in the presence of bicarbonate and attenuated fluorescence for the cells pre-incubated with KCN. Moreover, DCF fluorescence was intensified in CuZnSOD-transfected HaCaT and RAW 264.7 cells. We propose that CuZnSOD is a potential intracellular catalyst for the $H_2O_2$-dependent oxidation of $DCFH_2$.