• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.26-29
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• 1999

Superconducting $YBa_{2}$$Cu_{3}$ $O_{7-x}$(YBCO) thin films were deposited on MgO(100) substrates using a hollow cathode discharge sputtering system. Influence of the sputtering conditions such as substrate temperature and discharge sputtering gas pressure on electrical and structural properties were investigated. It was found that YBCO thin films with zero resistance temperature higher than 85 K were obtained to the pressure 200 mToorr(Ar/O2=0.9), substrate temperature of $760^{\circ}C$, and target-substrate distance of 10 mm during film deposition. Homogeneous large area YBCO films with 2 inch diameter were also sucessfully fabricated by this method.

• Journal of the Korean Ceramic Society
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• v.29 no.2
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• pp.152-160
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• 1992

High-Tc superconductor thick films of YBa2Cu$\chi$O7-y (X=3, 3.5, 4) of which thickness varies from 100 $\mu\textrm{m}$ to 200 $\mu\textrm{m}$ were successfully prepared by plasma spraying method, and the characteristics of thick film depending on copper content and heat treatment conditions were investigated. Regardless of heat-treated temperature, the specimens with X=3 were composed of YBa2Cu$\chi$O7-y, Y2BaCuO5 and BaCuO3 phases. The specimens with X=4, however, were composed of YBa2Cu$\chi$O7-y phase at all heat treatment conditions. The specimens with X=4 composition showed the best superconducting characteristics after heat treatment at 925$^{\circ}C$, and the superconducting transition temperature with zero resistivity (Tc,zero) was 87K. The thick film lost superconductivity when the specimens were heat-treated at 950$^{\circ}C$ because of interdiffusion between superconductor elements and bond coating elements and Y2BaCuO5 phase was found was found to be main phase at the interface.

• Journal of the Speleological Society of Korea
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• no.76
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• pp.49-55
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• 2006

The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to 1.0 ${\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)_2$ and CuO. When pH values were adjusted to 6.4-6.7, $Ba(NO_3)_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. Acetone is used as electrophoreticsolution, in which some water and iodine (0.2 g/1) and polyethylene glycol (2 vol. %) are added. The concentrations of $YBa_2Cu_3O_x$ powders is 20g/l. The thickness of deposited film could be more than 50 ${\mu}m$ in 3 minutes of depositing time. The most EPD films could be 90K zero resistance and the Jc values were over 1000A/cm2 (0 H, 77 K).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.351-354
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• 1998

The formation of the $YBa_2Cu_30_{7_\delta}$(Y123) thick films has been investigated by a surface diffusion Imcess between $3BaCu0_2$+2CuO composite coating powder and a $Y_2BaCuO_5$(Y211). This reaction has been studied in the temperature of $930^{\circ}C$ and $940^{\circ}C$ for 2h to 10h in an oxygen atmosphere. The Y211 substrates becomes covered by co-precipitation of Y123 grains and CuO inclusions. X-ray diflractotnctn. revealed that the lager consisted of an orthorhombic crystal structure. The maximum Jc of $400A/\textrm{cm}^2$ is abtained when the specimen was heat-treated at $930^{\circ}C$ for 6h on the Y211 substrate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.470-473
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• 2002

In order to get proper original suspension for the electrophoresis process of making YBaCuO films, YBaCuO superconductor powder was prepared with the Sol-gel method. The composition of the powder was analyzed by X-ray diffraction, which was identified as YBa$_2$Cu$_3$O$\sub$7-x/(Yl23) phase. The form of YBaCuO single particle was showed to be spherical by scanning electronic microscope and its size was among 0.2-1 $\mu\textrm{m}$. The critical transition temperature (T$\sub$c/) and the critical current density (J$\sub$c/) were measured with the four-probe, method. The T$\sub$c/ was about 91 K, and the J$\sub$c/ was 5-30 A/$\textrm{cm}^2$.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.169-169
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• 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.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1137-1139
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• 1993

The superconducting thin films of $YBa_2Cu_3O_{7-x}$ were deposited on (100) sapphire substrates at low temperature by rf magnetron sputtering and annealed at $895^{\circ}C$ for 60 sec. using rapid-thermal-annealing(RTA) technique. The films were characterized by SEM, four-point probe resistivity measurement, XRD, and AES. The RTA processed HTS films had a preferential structure with c-axis normal to the substrate surface.

• Electrical & Electronic Materials
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• v.6 no.4
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• pp.318-323
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• 1993

본 연구에서는 rf magnetron 스퍼터링으로 (100) 사파이어 기판에 퇴적시킨 YBa$_{2}$Cu$_{3}$$O_{7-x}$박막을 열처리하기 위하여 급속 열처리 방법을 사용하였다. XRD, AES, 그리고 4단자 비저항 측정법을 사용하여 급속 열처리로 형성시킨 초전도체 박막과 기판사이의 상호확산을 조사하였다. 제조된 박막은 91K에서 Tc(onset)를 80K에서 Tc(zero)를 나타내었다. AES 분석 결과, 급속 열처리 방법의 경우 YBa$_{2}$Cu$_{3}$$O_{7-x}$ HTS 박막과 기판사이의 계면에서 항호확산이 감소되는 것을 확인하였다. XRD 분석 결과, 급속 열처리에 의해 형성된 HTS 박막은 주로 c-축이 기판의 표면에 수직인 구조를 가지고 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.557-560
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• 2003

The submicron $YBa_2Cu_3O_x$ powder was prepared by the sol-gel method. The particle size is distributed from 0.2 to $1.0\;{\mu}m$, which benefits to eliminate the micro-cracks formed in the $YBa_2Cu_3O_x$ films deposited by electrophoresis. The powder was single phase of $YBa_2Cu_3O_x$ examined by X-ray diffraction. In the sol-gel process the citrate gel was formed from citric acid and nitrate solution of $Y_2O_3$, $Ba(NO_3)O_2$ and CuO. When pH values were adjusted to $6.4{\sim}6.7,\;Ba(NO_3)O_2$ could be dissolved in the citrate solution completely. Appropriate evaporative temperature of the sol-gel formation is discussed. After the heat treatment the transition temperature($T_c$) and critical current density($J_c$) of the $YBa_2Cu_3O_x$ samples made of the submicron powder were measured.

• Progress in Superconductivity
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• v.6 no.2
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• pp.129-132
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• 2005

The formation behavior of $YBa_2Cu_3O_{7-x}$(Y123) and CuO phases in the heat-treated Cu-sheathed YBCO thick films was studied. The thick films were prepared by screen-printing method using $BaCO_3$ and Y211 powders on Cu tapes. The screen-printed thick films were placed at the center of the tube furnace, heated to $930^{\circ}C$ in air atmosphere and then maintained at the temperature for 60 sec - 300 sec. The microstructure and phases formed in the thick films were investigated by using optical microscope, X-ray diffraction (XRD) and SEM image analysis. During the heat treatment, partial melting occurred rapidly in the printed layers by peritectic reaction between CuO and precursor powders, and then YBCO superconducting phases nucleated from the Cu tapes and grew in a form of thick films.