• 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.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.447-454
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• 2003

Samples were prepared by the solid-state reaction method. The nominal composition of the samples was B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$C $a_{2.03}$C $u_{3.06}$ $O_{10+{delta}$ prepared from powder of B $i_2$ $O_3$, PbO, SrC $O_3$, CaC $O_3$, and CuO. They were pulverized, mixed with AgO, A $u_2$ $O_3$and MgO of 50 wt%. Finally, they were sintered at 820 to 85$0^{\circ}C$ in air. The structural characteristics, the microstructure of surface and the critical temperature with respect to the each samples were analyzed by XRD, $T_{c}$, SEM and EDS respectively. It was found that the the critical temperature of the silver oxide additive samples (99.58 K) is higher than those of gold or magnesium oxides additive samples, but all those values are lower than that of pure Bi-2223 phase. The microstructure of surface showed the tendency which the AgO additive samples become more minuteness than A $u_2$ $O_3$ and MgO additive samples.s.samples.s.

• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.115-118
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• 1994

Samples of ($Bi_{2-x}Sb_x)PbSr_2Ca_2Cu_3O_y$, compositions with x=0.0, 0.1, and 0.2 were prepared by solid-state reaction. The solubility of Sb into the 2223 phase is lower than 0.05 for the ratio of Sb/Bi. The lack of stability of the Sb-substituted $Bi_2O_2$ double layers is likely to cause the solubility low. There is no great dependence of lattice parameters on the Sb-content, and bonds around the square-pyramidal Cu atom are not affected by the $Sb^{3+}$ ion substituted. The superconducting transition temperature of this system is decreased gradually with increase of Sb, which is tentatively attributable to the perturbation of the Bi 6p-O 2p band and/or to the low volume fraction of the 2223 phase.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.31-35
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• 1990

In the ($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ (x=0∼0.5) superconductors, DTA and XRD-pattern analyses were performed to obviousely define optimal calcining and sintering temperature. And, understanding behaviors of High-Tc phase with preparation condition of superconductors, that is, calcining and sintering temperature, sintering time, and variation of Pb contents, in order to make single phase of superconductor, microstructure and its composition were analyzed with SEM, XRD, and EDAX. continuously, the cause of phase transition was define with synthetically studying mutural relation between measured electrical resistivity and current density. Also, in order to design enhancement of critical current density, Jc required for realization, samples varied with pressing condition were made, and measured its, Jc.

• 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.

• Journal of the Korean Ceramic Society
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• v.37 no.12
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• pp.1212-1220
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• 2000

Bi-2223 초전도체계에서 석출물을 flux-pinning center로 이용할 수 있는지 가능성을 타진하기 위하여 $Bi_{1.8}$P $b_{0.4}$S $r_{2}$C $a_{2.2}$C $u_3$ $O_{8}$ 조성을 가진 Bi-2223/Ag 선재를 반응온도, 산소분압, 시간 등을 변화시키면서 열처리를 행하였다. 열처리 후 석출물들은 XRD, SEM, TEM, EDS로 분석하였다. Bi-2223 모상내의 (Ca, Sr)$_2$(Pb,Bi) $O_4$, B $i_{0.5}$ P $b_3$S $r_2$C $a_2$Cu $O_{12+}$$\delta$/ (3221)와 같은 2차상들의 크기와 분포는 2223 입자들의 연결성을 파괴하지 않고 열처리 조건에 의해서 조절할 수 있었다. 서냉 열처리가 된 시편은 임계전류밀도( $J_{c}$)값이 증가하였는데, 이는 2223 입자내 나노미터 크기로 형성된 석출물들이 flux-pinning sites로 작용한 것으로 추정된다.다.

• Progress in Superconductivity and Cryogenics
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• v.25 no.2
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• pp.5-9
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• 2023

The effect of La_0.7Sr_0.3MnO₃ (LSMO) addition on the superconducting property of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_10+δ ((Bi, Pb)-2223) polycrystalline samples was studied. LSMO (0.3 wt.% to 2.0 wt.%) added (Bi, Pb)-2223 samples were prepared by using a solid-state reaction method. The XRD analyses show that as the LSMO addition increases, the volume fraction of the Bi-2223 phase is gradually decreased. The critical temperature (T_c) exhibits a gradual decrease with a single transition as the LSMO amount increases up to 1.0 wt.%, but a further addition of LSMO induces an abrupt decrease of T_c with a dual transition. The analyses on the local structure of the CuO₂ plane from the X-ray absorption fine structure (EXAFS) measurements showed that for the samples with low concentration of LSMO up to 1.0 wt.%, the Cu-O bond length and the CuO₂ plane ordering do not degrade from the values of pure (Bi, Pb)-2223, while they get worsen with a further increase of LSMO addition. These results open up the possibility of LSMO as artificial pinning centers of the (Bi, Pb)-2223 system for power application.

• Progress in Superconductivity
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• v.4 no.2
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• pp.157-161
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• 2003

We have performed the electrochemical method to fabricate high temperature superconducting (TlPbBi) -(SrBa)-Ca-Cu-O films. The precursors of the superconducting sample were codeposited at a periodic pulsed-potential cycle (1 second at -4V and 1 second at -1V) on a silver substrate. The variation of structure, microstructure and element were analysed by ICP and SEM techniques. The specimens were consisted predominantly of the Tl-1212 phase and have a transition temperature of 80～87 K in low magnetic field. It was showed that each grain has the stoichiometric ratio of $T1_{0.7}$Pb_$Bi_{0.3}$ $_Sr{0.1}$ $Ba_{2.4}$ $Ca_{0.2}$ $Cu_{1.2}$ $2.5/O_{x}$ by EDX analysis.sis.

• Progress in Superconductivity
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• v.6 no.1
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• pp.41-45
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• 2004

Polycrystalline Tl-1223 superconductors with a chemical composition of (Tl, Pb, Bi)TEX>$ (Sr, Ba)<_2$$Ca_2$$Cu_3$$O_{x}$ were synthesized by the solid state reaction method. The optimum chemical composition was $Tl_{0.8}$ $Pb_{0.2}$ $Bi_{0.2}$ $Sr_{1.8}$ $Ba_{0.2}$ $Ca_{2.2}$ $Cu_3$$O_{x}$ And the optimum sintering temperature and time were $905^{\circ}C$ and 7.5h, respectively. The sample was evaluated for their superconducting properties by magnetization measurement. The critical temperature $T_{c}$ is 120 K and the critical current density $J_{c}$ (T=5K, 0T) is estimated to be ∼ $10^{5}$ A/$\textrm{cm}^2$ for $Tl_{0.8}$ $Pb_{0.2}$ $Bi_{0.2}$ $Sr_{1.8}$ $Ba_{0.2}$ $Ca_{2.2}$$Cu_3$$O_{x}$ .

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.123-125
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• 2003

We joined 19-multifilamentary (Bi, Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_{x}$ Superconducting tapes and fabricated double-pancake coils by using resistive- and superconducting-joint methods. The joint resistance of the coils were characterized by the field decay technique and standard four-probe method. It was evaluated that joint resistance was 3.21$\times$10$^{-11}$ $\Omega$ in the superconducting-joint coil, which is approximately 4 orders of magnitude smaller than that in the resistive-joint coil (107$\times$10$^{-9}$ $\Omega$). The low value of joint resistance obtained by superconducting-joint is expected to be suitable for the practical applications in the persistent current mode.e.