• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1988년도 춘계학술대회 논문집
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• pp.17-19
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• 1988

$YBa_2Cu_3O_{7-x}$ oxide superconductors were fabricated by the hot isostatic pressing (HIP). It was shown that their structures were orthorombic and constited of a single (123) phase. While as-sintered compacts had many pores, they were remarkably reduced by Hiping. The on-set and off set temperature of (123) compound sintered at $950^{\circ}C$ in oxygen and hiping at $880^{\circ}C$ were the highest and it showed 0 resistance at $90^{\circ}K$. The critical current density ($J_c$) of the above superconductor was $27A/cm^2$ and it also showed a number of twin structures, which are typical of high $T_c$ superconductor. It seemed that the low current density may be due to the many pores of starting-sintered compacts.

• 동굴
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• 제78호
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• pp.1-8
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• 2007

The combination of mechano-chemical activation (MCA)and Self-propagating High-temperature Synthesis (SHS) has widened the technical possibilities for both methods. For YBCO systems the investigation showed that a short-term MCA of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors (HTS) of YBCO composition with a grain size d <1m is developed using combination of MCA and SHS. The specific feature of the technique is formation of the $YBa_2Cu_3O_7-$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 SMICS 2004 International Symposium on Maritime and Communication Sciences
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• pp.96-99
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• 2004

The combination of mechano-chemical activation and Self-propagating High-temperature Synthesis (SHS) has widened the possibilities for both methods. For YBCO systems the investigation showed that a short-term mechano-chemical activation of initial powders before SHS leads to single-phase and ultra-fine products. A new technique for preparation ultra-fine high-temperature superconductors of YBCO composition with a grain size d ＜1 ${\mu}{\textrm}{m}$ is developed. The specific feature of the technique is formation of the YBa$_2$Cu$_3$O$_{7-{\delta}}$ crystalline lattice directly from an X-ray amorphous state arising as a result of mechanical activation of the original oxide mixture. The technique allows the stage of formation of any intermediate reaction products to be ruled out. X-ray and magnetic studies of ultra-fine high temperature superconductors (HTS) are carried out. Dimension effects associated with the microstructure peculiarities are revealed. A considerable enhancement of inter-grain critical currents is found to take place in the ultra-fine samples.fine samples.

• 수산해양기술연구
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• 제25권3호
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• pp.143-153
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• 1989

산화물 초전도체에 있어서 고천이 임계온도를 갖는 미소영역을 추출하여 이를 분석하기 위하여 La-Ba-Cu-O 계, Y-Ba-Cu-O 계 및 Bi-Pb-Sr-Ca-Cu-O 계의 초전도체를 고상법 및 nitrate solution method로 제조하였다. 제조된 시료들에 대해서 x선회절분석과 저항을 측정하였다. 이들 시료 중에서 고천이온도를 나타내는 미소부분을 Meissner효과를 이용한 추출법으로 분리 해내고 EDAX로 이를 분석하였으며, 이들 결과를 요약하면 다음과 같다. nitrate solution method를 적용하면 YBCO계에 있어서 비교적 단시간에 치밀한 미세조직을 갖는 천이 온도 90K의 초전도체를 제조할 수 있다. Meissner효과를 이용하여 고천이온도에서 추출해낸 미소영역의 EDAX분석 결과는 고상법을 사용한 YBCO-23S와 nitrate solution method으로 제조한 YBCO-23N 및 YBCO-36N 에서는 초기의 조성과 거의 같았으며, 고천이 온도에서 추출된 미소영역은 조성보다는 산소 결함의 차이에 기인한 것으로 생각된다. 공침법으로 제조한 YBCO-23NA 에서는 과도한 Ba의 조성을 보였으며, 천이온도 100K 인 Bi계에서는 약한 반자성효과 때문에 추출이 불가능하였다.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 추계학술대회 논문집
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• pp.150-152
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• 2003

YBa$_2$Cu$_3$O$_{7-{\delta}}$(YBCO) coated conductors were deposited by pulsed laser deposition (PLD) on short buffered substrate in continuous PLD reel-to-reel system. The oxide multilayer buffered substrate of architectures of CeO$_2$/YSZ/Y$_2$O$_3$was fabricated by PLD at steady status. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM) The FWHM of the X-ray $\omega$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current at 77K self-field of 19A, critical temperature of 86K, and current density of 2MA/$\textrm{cm}^2$ were measured. The film also exhibits a homogeneous and dense surface morphology.e morphology.

• Progress in Superconductivity
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• 제6권1호
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• pp.74-78
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• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.