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- 주제어 : YBa2Cu3O7-y (검색결과 6 건)
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용융법에 의한 YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> 초전도체 제작
이상헌 ( Sang Heon Lee ) 한국전기전자재료학회 2022 전기전자재료학회논문지 Vol.35 No.6
YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> bulk as a high temperature oxide superconducting conductor has the high critical temperature of 92 K. YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> bulk superconductors have been fabricated by a seeded melting growth. Magnetic properties were studied by using superconductor of melted YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> oxides. It was demonstrated that Y<sub>2</sub>BaCuO<sub>5</sub> particles acts as a pinning center which plays an important role on the magnetic properties. The thickness of the upper and lower pellets of the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> bulk was formed at 40 mm with 55 g of the composition, and the YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-y</sub> superconductor was manufactured through a heat treatment process. Manufacturing the superconducting bulk, it is possible to improve the pore density of the superconducting bulk by providing a path through which oxygen could be emitted.
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Park, S.D.,Kim, H.J.,Park, B.J.,Han, Y.H.,Jun, B.H.,Lee, J.S.,Kim, C.J. North-Holland 2011 Physica. C, Superconductivity Vol.471 No.21
The effect of calcium doping on the superconducting properties of top seeded melt growth (TSMG) processed Y<SUB>1.5</SUB>Ba<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> superconductors was studied in terms of calcium content (X<SUB>ca</SUB>). YBa<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>7-δ</SUB> (X<SUB>ca</SUB>=0, 0.005, 0.01, 0.02, 0.04, 0.1, 0.3) powders were synthesized by the powder calcination method. YBa<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>7-δ</SUB> powders were mixed with 0.25mole Y<SUB>2</SUB>O<SUB>3</SUB> powder and 1wt.% CeO<SUB>2</SUB> as Y<SUB>2</SUB>BaCuO<SUB>5</SUB> (Y211) refiner, and finally made into Y<SUB>1</SUB>.<SUB>5</SUB>Ba<SUB>2-x</SUB>Ca<SUB>x</SUB>Cu<SUB>3</SUB>O<SUB>y</SUB> (Y1.5)+1wt.% CeO<SUB>2</SUB> composition. The single Y123 growth on the top surface was observed up to X<SUB>ca</SUB>=0.1, while the multiple Y123 growth was observed at X<SUB>ca</SUB>≥0.1. The superconducting transition temperature (T<SUB>c</SUB>) and critical current density (J<SUB>c</SUB>) of TSMG processed Y1.5 samples were inversely proportional to X<SUB>ca</SUB>. The Y211 size increased with increasing X<SUB>ca</SUB> due to the enhancement of Y211 coarsening by calcium doping. No Y211 refining effect by CeO<SUB>2</SUB> was observed in the calcium doped samples. The T<SUB>c</SUB> and J<SUB>c</SUB> decrease by calcium doping are likely to be due to the calcium incorporation with the Y123 lattice and formation of coarse Y211 particles.
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세라믹 초전도체 YBa_(2-X)Ca_(X)Cu_(3)O_(7-Y)의 특성 비교
이종록,정병두,김민경 梨花女子大學校 韓國生活科學硏究院 1993 韓國生活科學硏究院 論叢 Vol.52 No.-
Ceramic superconductors YBa_(2-X)(A)_(S)Cu_(3)O_(7-Y), where A=Ca or Sr, were made for several different values of X X-ray powder diffraction, SEM, magnetigation, and resistivity versus temperature measurements were carried out to study the effects of Ca and Sr substitutions into 1:2:3 type superconductors on the superconducting characteristics. Both ca and Sr substitutions were observed to observed to suppress the critcal temperatuse strongly, but Sr substitution seems to the more effective in the suppression mechanism. The decrease of Tc seems to be due to the change in oxygen concentration induced by the Ca and/or Sr substitution. This implies that the variation of critical temperature has close relation with that of mobile hole concentration in the Cu-O planes.
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Lee, J.H.,Jun, B.H.,Park, S.D.,Park, B.J.,Han, S.C.,Lee, S.H.,Kim, C.J. North-Holland 2011 Physica. C, Superconductivity Vol.471 No.21
To suppress the samarium diffusion from a SmBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-y</SUB> (Sm123) seed into an YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-y</SUB> (Y123) compact during a top seeded melt growth (TSMG) process, Y211 buffer disks of various thicknesses (t) were inserted at the seed/compact interface. The effectiveness of the Y211 buffer insert on the suppression of samarium diffusion was estimated from the susceptibility curve and composition analysis for the three top surface regions (region just below the seed/buffer, intermediate region between the buffer and compact edge and compact edge). The difference in the superconducting temperature (T<SUB>c</SUB>) and the superconducting transition width (ΔT) in the three regions was large, when no buffer or thin buffers (t is smaller than 1mm) were used. As a buffer disk of an appropriate thickness was inserted into the seed/compact interface, the difference in T<SUB>c</SUB> and ΔT in the three regions was much reduced. The composition analysis across the seed/buffer/compact region clearly revealed that the T<SUB>c</SUB> decrease was caused by the samarium diffusion from a seed, which led to the formation of Y<SUB>1-x</SUB>Sm<SUB>x</SUB>Ba<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-y</SUB> in the Y123 compact region. The buffer insert technique was demonstrated to insure the uniform superconducting properties of the top surface of TSMG processed Y123 superconductors.
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이상헌 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.6
A diffusion heat treatment process for YBa2Cu3O7-y bulk superconductor in a Gd2O3 powder was attempted. As a result of measuring the critical temperature of the superconducting bulk, there was no change in the superconducting transition temperature as the Gd particles diffused into the YBa2Cu3O7-y lattice, resulting in dense microstructure. As a result of measuring the critical current, the critical current density (Jc) of the superconducting bulk having treated by the Gd thermal diffusion treatment at 0 T increased to 3104 A/cm2 at 0 T, which was higher than that of the superconducting bulk without thermal diffusion treatment. The surface magnetic force of the superconducting bulk with Gd thermal diffusion treatment was observed at the center of the superconducting bulk with the maximum trapped magnetic force (Hmax) of 1.51 kG. This result means that the Gd thermal diffusion treatment contributes to improving the critical current density Jc of YBa2Cu3O7-y, and it is believed that Gd particles migrating into the superconducting bulk through thermal diffusion either fill the surface pores of YBa2Cu3O7-y superconductors or act as a flux pinning center.
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이상헌 한국전기전자재료학회 2021 전기전자재료학회논문지 Vol.34 No.5
Oxide YBCO bulk superconductors are manufactured using the melt process. Because seed crystal growth method utilizes a slow-spreading layer-by-layer reaction, a long-term heat treatment is required to manufacture a single-crystal specimen of several cm. In this study, the melt process method was applied to compensate for the shortcomings of the seed crystal growth method. The thickness of the upper and lower pellets of the YBCO bulk was molded to 40 mm, and YBCO superconductor was produced by heat treatment. The measurement results of capture magnetism was in line with the literature. This results in a relationship that the higher the growth of Y211 particle in the YBCO, the higher the superconducting properties. We analyzed the YBCO superconductor, focusing on the Y2BaCuO5 particle distribution.
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