• 한국세라믹학회지
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• 제28권1호
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• pp.37-45
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• 1991

The critical current density, electrical conductivity, critical magnetic field, Meissner effect, apparent density, and microstructure of YBa2Cu3O7-x ceramic superconductor prepared by polymeric precursor, while varing calcining and sintering conditions, were investigated. The best superconducting properties could be obtained from the body sintered at 93$0^{\circ}C$ for 10h after calcining at 90$0^{\circ}C$ for 10h, which gave 383A/$\textrm{cm}^2$ of critical current density(Jc), 96K of onset temperature(Tonset), 94. 8K of zero temperature (Tzero) 225 Oe of critical magnetic field (Hc1), 72.8% of superconducting volume fraction measured by Meissner effect and 6.28g/㎤ of apparent density.

• Journal of Magnetics
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• 제1권2호
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• pp.57-59
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• 1996

The YBa$_2$Cu$_3$O6+xstructures have been fluorinated by a gas phase exchange technique, and 19F NMR was used to identify the structural fluorine. Magnetic susceptibility measurements showed that the fluorination turned a marginally nonsuperconducting sample into a 40 K superconductor, as well as that it raised the onset of the superconducting transition of the 60 K superconductor YBa$_2$Cu$_3$O6.7 to about 100 K.

• 한국세라믹학회지
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• 제26권2호
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• pp.221-227
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• 1989

To investigate the development and densification YBa2Cu3O7-x(1-2-3) superconducting phase, the 1-2-3 phase powders have been prepared by citrate and nitrate processes with changing calcination temperature. Nearly pure 1-2-3 phase peaks have been obtained by calcining the precursor in air at 90$0^{\circ}C$ for 2.5h in citrate process but at 95$0^{\circ}C$ for 2.5h in nitrate process. The sintering density of citrate derived sample calcined at 80$0^{\circ}C$ has been about 4% higher than that calcined at 90$0^{\circ}C$, although the compacting density has been lower at 80$0^{\circ}C$ calcination. This can be explained that the 1-2-3 phase particles formed at 80$0^{\circ}C$ have reactive sub-micron size which has good sinterbililty.

• 한국세라믹학회지
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• 제33권6호
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• pp.718-724
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• 1996

Deformation mechanism map of Langdon-Mohammed type for YBa2Cu3O7-x superconducting ceramic was constructed by considering mechanisms of Nabarro-Herring Coble and powder-law creep and grain boundary sliding (GBS) with an accommodation by grain boundary diffusion. The map was found consistent with experi-mental results not only of the creep the also of the superplastic deformation. It showed the transition from interface reaction-controlled to the grain boundary diffusion-controlled GBS mechanism at about 1 ${\mu}{\textrm}{m}$ grain size and 100 MPa flow stress in agreement with the experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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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.

• 대한화학회지
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• 제36권6호
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• pp.818-823
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• 1992

Y, Er, Yb, Ba 및 Cu를 각각 포함하는 유기금속 화합물인 2-Ethylhexanoate 화합물을 합성하였다. 합성된 유기금속화합물들은 모두 공통용매에 녹아 균일혼합물을 형성하였으며 이들을 원료물질로 하여 고온초전도체 $YBa_2Cu_3O_{7-\delta}(Y_{123})$, $ErBa_2Cu_3O_{7-\delta}(Er_{123})$ 및 $YbBa_2Cu_3O_{7-\delta}(Yb_{123})$를 제조하였다. X-선 회절분석결과 이들은 단일상이 아니었으며 $YBa_2Cu_4O_8(Y_{124})$를 포함한 약간씩의 불순물상을 포함하고 있었고, 이것은 자화율 측정에서도 확인되었다. Ceramic method로 제조한 시료에 비하여 임계온도가 대체로 높았으며, 부피반자성자화율은 큰 변화가 없는 것으로 판단된다.

• E2M - 전기 전자와 첨단 소재
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• 제6권6호
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• pp.514-522
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• 1993

본 연구에서는 Ag/ 첨가에 의한 YB $a_{2}$C $u_{3}$ $O_{7-{\delta}}$산화물의 초전도 특성 변화를 조사하였다. Ag가 첨가된 YB $a_{2}$C $u_{3-x}$A $g_{x}$ $O_{7-{\delta}}$ 산화물 시료를 만들고 이 시료들에 대한 X-ray 회절분석, IR흡수 스펙트럼분석, 임계온도(Tc)측정 및 자화(M-H)특성 측정등을 통하여 제조된 시료의 물리적 성질을 조사하였다. X-ray 회절실험 결과로 부터 x.leq.0.03인 경우에는 YB $a_{2}$C $u_{3-x}$A $g_{x}$ $O_{7-{\delta}}$가 단일상의 물질로 존재하고 x가 증가함에 따라 불순물상( $Y_{2}$ $O_{3}$, 순Ag)이 나타남을 알 수 있었다. IR흡수의 실험결과에서 Cu와 치환되어 들어간 Ag의 Ag-O 결합에 의한 흡수 스펙트럼(670$cm^{-1}$ /)이 관측되었다. 실험 결과로 부터 치환된 Ag의 양 x가 증가함에 따라 Tc가 조금씩 낮아지는 경향이 있었으며 자화의 세기 및 임계자장( $H_{C2}$)은 급격히 감소함을 알 수 있었고 또 M-H특성곡선에는 히스테리시스 특성이 나타났다.났다..났다.다.

• 한국재료학회지
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• 제4권6호
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• pp.681-686
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• 1994

$YBa_{2}Cu_{3}O_{7-x}$결정입계 접합을 이용한 마이크로파 감지소자 $YBa_{2}Cu_{3}O_{7-x}$초전도체 박막을 화학증착법을 이용하여 $LaAIO_{3}$단결정 위에 증착하여 임계온도 90K이상 임계전류밀도 $10^5/A \textrm{cm}^2$(77K) 이상의 우수한 박막을 제작하였다. 이를 포토작업과 이온밀링을 실시하여 수 마이크로미터 크기의 브릿지 형태로 만든 후 이들의 전류전압 특성을 조사하였다. 브릿지에 입사된 마이크로파의 크기에 따라 브릿지 간의 임계전류값의 저하가 관찰되었으며 동시에 샤피로스텝을 관찰할 수 있었다.

• Progress in Superconductivity
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• 제6권2호
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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.

• Journal of Magnetics
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• 제1권1호
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• pp.1-3
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• 1996

The $YBa_2Cu_3O_{7-x}$ structure has been fluorinated by a gas phase exchange technique. The ${^19}F$NMR (nuclear magnetic resonance) spin-lattice relaxation rate (1/T1) measurements on a fluorinated sample gave superconducting energy gap of $2\Delta=4.6kT_c$.