• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.766-772
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• 1992

Bi-Sr-Ca-Cu-O superconducting system has both the low and high Tc phases. We added Pb and sintered for 200hrs. in OS12T atmosphere in order to get the superconductor above critical temperature 100K. Superconducting properties of the Bi(Pb)SrCaCuO system doped Sb were also investigated. When Sb of 0.1mol is added, the sintering time becomes shorter than that doped Pb only. We could get the critical temperature 102K at the samples sintered for 24hrs. and 109K for 210hrs.

• Progress in Superconductivity
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• v.9 no.1
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• pp.1-4
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• 2007

The most common technique to fabricate $MgB_2$ superconducting wire is by powder-in-tube (PIT) technique. Therefore, the starting powder for the processing of $MgB_2$ superconductors is an important factor influencing the superconducting properties and performance of the conductors. In this study, the influence of magnesium precursor powders and annealing temperatures on the transition temperatures ($T_c$) and critical current densities ($J_c$) of $MgB_2/Fe$ wires was investigated. All the $MgB_2/Fe$ wires were fabricated by in situ PIT process. It was found that higher $J_c$ was obtained for $MgB_2$ wires with smaller particle size of magnesium precursor powders. The $J_c$ also increases with decreasing annealing temperatures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.269-274
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• 2002

(Sm/Y)-Ba-Cu-O system high Tc composite superconductors with/without $CeO_2$ additive were directionally grown by zone-melting process, haying large temperature gradient, In air atmosphere. Cylindrical green rods of $({Sm/y})_{1.8}Ba_{2.4}Cu_{3.4}O_x$ [(Sm/Y)1.8] composite oxides by cold isostatic pressing(CIP) method using rubber mold were fabricated. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The size of nonsuperconducting $({Sm/y})_2BaCuO_5$ inclusions of the melt-textured (Sm/Y)1.8 sample with CeO$_2$ additive were remarkably reduced and uniformly distributed within the superconducting (Sm/Y)1.8 matrix. Both samples, with/without $CeO_2$ additive, showed an onset Tc $\geq$ 90 K and sharp superconducting transition. The critical current density Jc value of the $CeO_2$ addictive were $1{\times}10^5A/\textrm{cm}^2$ in 77 K, 0 Tesla.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.231-237
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• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.4
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• pp.336-342
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• 2003

(Sm/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(Sm/Y)1.8] high $T_{c}$ superconductors were directionally grown by Rod-type Seed Melt Growth(RSMG) process in air atmosphere. The sintered polycrystalline N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$(Nd1.8) of rod-type seed crystal grown by extrusion mold process were used for achieving the ab-plane alignment haying large grains perpendicular to the center of (Sm/Y)1.8 samples. The observations using TEM micrographs of the melt-textured (Sm/Y)1.8 samples revealed that the nonsuperconducting (Sm/Y)211 inclusions are uniformly distributed in the superconducting (Sm/Y)123 matrix. The microstructure and superconducting properties were investigated by XRD, TEM and SQUID magnetometer. The RSMG (Sm/Y)1.8 samples showed an onset $T_{c}$ $\geq$ 90 K and sharp superconducting transition.nsition.ion.nsition.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.24-28
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• 2018

To understand the effects of Cd substitution for Cu, $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ (x = 0 ~ 0.5) compounds were synthesized and the structural and superconducting properties of the compounds were characterized. Resistivity data revealed that superconducting transition temperature rises initially up to x = 0.25 and then decreases as the Cd doping content increases. Room-temperature thermoelectric power decreases at first up to x = 0.25 and then increases with higher Cd doping content, indicating that the change in $T_c$ is mainly caused by the change in the hole concentration on the superconducting planes by the Cd doping. The non-monotonic dependence of the lattice parameters and the transition temperature with Cd doping content is discussed in connection with the possible formation of $Pb^{+2}$ ions and the removal of excess oxygen caused by Cd substitution in the charge reservoir layer. A correlation between transition temperature and c/a lattice parameter ratio was observed for the $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.6
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• pp.622-625
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• 2022

YBa₂Cu₃O_7-y bulk as a high temperature oxide superconducting conductor has the high critical temperature of 92 K. YBa₂Cu₃O_7-y bulk superconductors have been fabricated by a seeded melting growth. Magnetic properties were studied by using superconductor of melted YBa₂Cu₃O_7-y oxides. It was demonstrated that Y₂BaCuO₅ 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 YBa₂Cu₃O_7-y bulk was formed at 40 mm with 55 g of the composition, and the YBa₂Cu₃O_7-y 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.

• Progress in Superconductivity and Cryogenics
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• v.10 no.2
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• pp.12-15
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• 2008

Nano-sized dots have been formed on the buffered metal substrates using the novel approach of the electro-spray deposition, to modulate the substrate surface and induce the columnar defects in REBCO films grown on it. The $BaZrO_3$ precursor solution was synthesized and electro-sprayed out onto the negatively charged substrate surface. Using the electrostatic force, nano-sized dots can be grown and uniformly distributed on the buffered metal substrate. The height of BZO nanodots was observed above the 200nm, which are beneficial to induce the columnar defects onto the BZO as a seed. The density of BZO nanodots was also investigated and ${\sim}7.8/{\mu}m^2$ was obtained. As the deposition distance of electro-spray was shortened there was ${\sim}8times$ increase of density of nanodots. The optimization of process variables in electro-spray deposition are discussed in respect to the superconducting REBCO films processed by the Metal-Organic Deposition with the effective flux pinning properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.137-140
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• 1999

Effects of annealing and impurities on the superconducting properties were investigated by the magnetization measurement in $Bi_2Sr_2CaCu_2O_{8+{\delta}}(Bi2212)$ single crystals grown by flux method. It has been found that the superconducting properties are affected by Mg and Al impurities remarkably. The transition temperature$(T_c)$ has been lowered by the impurity of Mg. However, the diamagnetism is remarkably increased in an annealed crystal grown in MgO crucible compared to that in $Al_2O_3$ crucible. The content of Mg impurity can not be considered as a principal parameter for the decay of superconducting properties probably because the diamagnetism is remarkably improved in annealed crystal containing Mg.

• Progress in Superconductivity
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• v.13 no.1
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• pp.24-27
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• 2011

High voltage insulation in cryogenic environment is one of big issues for development of superconducting power application, such as superconducting fault current limiter, transformer, transmission cable, and so on. We had proposed a composite solid insulator composed of plastics and polymer insulation sheets for a use of high voltage superconducting power applications. It is well known that the G10 FRP keeps its mechanical strength at very low temperature and the PPLP is very good insulator adopted as insulations for superconducting transmission cables. The composition of these two materials will show very good electrical and mechanical properties adequate for the insulation components of superconducting power applications, such as bushing, insulation barrier, and even for a cryostat. Dielectric strengths of prepared samples were measured at the temperature of boiling point of liquid nitrogen at atmospheric pressure, which will be presented in this paper to show a usefulness of this technique.