• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1549-1551
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• 2004

The Electromagnetic properties in BiPbSrCaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depanding on the direction of applied magnetic flux less than 2.5${\times}$10-5 T, the voltage in the magnetized sample increases or decreases. It is considered that mechanism of voltage occurrence can be explained by applying filament model.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.269-273
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• 1991

High Tc oxide superconductor with a Tc above 100 K has been successfully prepared by solid state reaction method in added-Pb BiSrCaCuO system. As compared with 123 compound, the formation reaction of the high Tc requires long time heat treatment. It is due to the transformation from the low Tc phase to high Tc phase. The sintering just below the melting point of the calcined powder mixture is effective on the formation of the high Tc phase in BiSrCaCuO system to be added with Pb. The growth of the high Tc superconducting phase has a thin plate shape, which is characterized by the c parameter of 37${\AA}$. The formation kinetics is also investigated in the samples with different Bi/Pb ratio and the 30% Pb addition is most preferable for the formation of the high Tc phase. The formation of the high Tc phases is delayed by the excessive addition of Pb. The lattice parameter(c) of the unit cell(both the low and high Tc phases) is increased with increase of Pb.

• Korean Journal of Materials Research
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• v.1 no.2
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• pp.71-76
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• 1991

The superconducting powders in $YBa_2Cu_3O_{7-x}$ and Bi-Pb-Sr-Ca-Cu-O system were easily prepared from water in oil type emulsion by loading each cation into the aqueous phase. In $YBa_2Cu_3O_{7-x}$ system, the superconducting orthorhombic phase was formed by calcining at $750^{\circ}C$ for 10h in $O_2$. The size of the superconducting phase powders was submicron. The density of the sintered specimen using this powders was about 95% of the theoretical density and the resistance sharply decreases at about 90K, In Bi-Pb-Sr-Ca-Cu-O system the low Tc phase($(Bi, Pb)_2Sr_2Ca_1Cu_2O_y$) was formed by calcining at $800^{\circ}C$ for 10h in a low oxygen partial pressure of 1/20 atm The shape of clacined powder is thin plate of which size is about $2\mu\textrm{m}$ and thickness is smaller than $\mu\textrm{m}$. It was observed that the high Tc phase ($(Bi, Pb)_2Sr_2Ca_2Cu_3O_y$) was formed by sintering at $850^{\circ}C$ for 30h in oxygen pressure of 1/20 atm without intermediary grinding. The above sintered sample exhibited superconductivity with a Tc(zero)=105K.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.471-477
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• 1996

During Bi(Pb)-Sr-Ca-Cu-O superconductor wire fabrication the effect of the initial packing density on the final characteristics of superconductor wire was systematically studied. To increase the powder packing density with uniform distribution of superconducting core a billet insertion method processed by CIP was applied instead of the commonly used vibration and ramming method of powder insertion into silver sheath. Compared with the vibration and ramming method the billent insertion technique processed by CIP cause the 30% incre-specimen with 130${\mu}{\textrm}{m}$(core thickness : 45 ${\mu}{\textrm}{m}$)and 5.24 mm width processed at 84$0^{\circ}C$for 200hrs. shows specimen with 130${\mu}{\textrm}{m}$ (core thickness ; 45${\mu}{\textrm}{m}$)and 5.24 mm width processed at 84$0^{\circ}C$ for 200 hrs. shows maximum 34A for Ic and 16, 700 A/cm2 for Ic measured at 77K and 0T. Also the sample rolled 3 times shows maximum 7, 2A for Ic and 11, 000 A/cm2 for 77K and 0T. Based on X-ray experimental results the formation of Bi-2223 and texture were significantly well developed at the interface between the superconducting core and silver sheath as compared with those of the interior area of superconducting core.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.05a
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• pp.22-27
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• 1993

we prepared 70K new BiPbAgSrCaCuO superconductor used diffusion of dual layer which composed of SrCaCuO and BiPbAgCuO compound. This method is used permeation and diffusion on partial melting point of BiPbAgCuO compound. Samples were analyzed by means of X-ray diffraction analysis, Thermal analysis, critical temperature and scanning electron microscopy. It was found that the best results were obtained for spread volume (A:B=1:0.6) and sintring time 210hours.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.6
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• pp.241-248
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• 2003

$Bi_{1.84}Pb_{0.34}Sr_{1.91}Ca_{2.03}Cu_{3.06}O_{10+\delta}$ high $T_{c}$ superconductors containing Ag as an additive were fabricated by a solid-state reaction method. The superconducting properties, such as the structural characteristics, the critical temperatures, the grain size and the image of mapping on the surface were investigated. Samples with Ag and Au of 50 wt% each were sintered at various temperature(820~$850^{\circ}C$). The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD and SEM, EDS and four-prove methode respectively. The critical temperature showed the result which the Ag additive samples are higher than Au additive samples. The microstructure of the surface showed the tendency which the Ag additive samples become more minuteness than Au additive samples.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.1
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• pp.13-18
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• 1991

The formation of high $T_c$ phase is very sluggish and c parameter of unit cell of high $T_c$ phase is about $37{\AA}$. High $T_c$ oxide superconductor with a $T_c$ above 100 K has been successfully prepared by solid state reaction method in BiSrCaCuO system by Pb adding. The microstructure related to the formation of the high $T_c$ phase has been investigated. As compared with YBCO compound, the formation reaction of the high $T_c$ requires long time heat treatment. It is due to the transformation from the low $T_c$ phase to high $T_c$ phase. The sintering just below the melting point of the calcined powder mixture is effective on the formation of the high $T_c$ phase in Pb-added BiSrCaCuO system. The growth of the high $T_c$ superconducting phase has a thin plate shape, which is characterized by the c parameter of $37{\AA}$. The formation of the high $T_c$ phases is delayed by the excessive addition of Pb. The lattice parameter(c) of the unit cell (both the low and high $T_c$ phases) is increased with increase of Pb.

• Bulletin of the Korean Chemical Society
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• v.11 no.6
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• pp.560-563
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• 1990

A.c. susceptibility for $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor is measured as a function of temperature at different value of a.c. magnetic field amplitude. Two transition steps are attributed to the intergranular and intragranular properties. Based on Bean's critical state model, intergranular critical current density, $J_c^{gb}$ (11 $A/cm^2$ at 77 K) and intragranular critical current density, $J_c^g (7{\times}10^3\;A/cm^2$ at 100 K) are estimated. The low values of $J_c^{gb}$and $J_c^g$ reflect a poor nature of coupling between grains and the low pinning force density of intragrain in $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.522-531
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• 2003

Samples with the nominal composition, B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{\delta}}$ high- $T_{c}$ superconductors containing MgO as an additive were fabricated by a solid-state reaction method. Samples with MgO of 5~30 wt% each were sintered at 820~86$0^{\circ}C$ for 24 hours. The structural characteristics, critical temperature, grain size and image of mapping with respect to MgO contents were analyzed by XRD(X-Ray Diffraction), SEM(Scanning Electron Microscope) and EDS(Energy dispersive X-ray spectrometer) respectively. As MgO contents increased, intensity of MgO Peaks and ratio of Bi-2212 phase in superconductors intensified and the proportion of the phase transition from Bi-2223 to Bi-2212 was increased.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.306-311
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• 1994

In this study, the influence of the powder sintering, the 2nd sinteiing and the grinding time on the Superconducting properties in the Bi(Pb)SiCaCuO Superconductor has been studied. From the analysis of SEM and XRD patterns, it was known that the sample prepared by the process of powder sintering has a porous microstructure with the critical temperature(Tc) below 77K, while the sample prepared by the 2nd sintering has a highly oriented microstructure with the Tc above 100K. The Critical Current Density(Jc) of the sample prepared by the 2nd sintering was better than the sample prepared by the process of powder sinteiing, but it's Jc, was low in practical use. Also, the effect of grinding time from 0[min] to 120[min] was investigated. As the grinding time is increased, the samples degraded from high-Tc phase to low-Tc phase and nonsuperconducting phases.