• Progress in Superconductivity
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• 제7권1호
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• pp.17-21
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• 2005

We report the oscillation of the Josephson vortex-flow resistance in the rectangular stacks of $Bi_{2}Sr_{2}CaCu_{2}O_{8+x}$(Bi-2212) intrinsic Josephson junctions (IJJs). Apiece of Bi-2212 single crystal containing a few tens of IJJs was sandwiched between two gold electrodes and fabricated into a rectangular shape with the typical lateral size of about $1.5{\times}10\;{\mu}m^2$, using e-beam lithography and focused ion-beam etching techniques. In a tesla-range magnetic field applied in parallel with the junction planes, the oscillation of the Josephson vortex flow resistance was observed at temperatures near 60 K. The oscillation results from the interplay between the triangular Josephson vortex lattice and the potential barrier at the boundary of a single crystal. The oscillatory magnetoresistance for different bias currents, external magnetic fields, and the tilt-angles provides useful information on the dynamics of the coupled Josephson-vortex lattice system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.221-223
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• 1999

In this work, samples were manufactured variously by changing conventional calcining and sintering conditions and we tried the utilization by making the heat treatment time, which is demanded to high-Tc phase formation, much shorter. We found out optimal heat treatment conditions with the analysis on formation process at superconducting phase in term of the change of calcining and sintering time and then, examined X-ray diffraction(XRD) patterns, scanning electron microscope(SEM) measurement and energy dispersive X-ray spectrometer(EDX) of the samples manufactured under heat treatment conditions which we suggest here. As a result, 2223 high-$T_c$, phase of (Bi,Pb)SrCaCuO superconductor starting with ($Bi_l$ xPbx,)$_2$$Sr_2$$Ca_2$$Cu_3$$O_y$, composition was formed from 1 hr sintering sample at temperature nearby melting point and also the completed sample with calcining and sintering time of 9 hr was formed high-$T_c$.low-$T_c$ phase appearing in sight above the critical temperature of liquid $N_2$.

• 한국세라믹학회지
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• 제40권5호
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• pp.455-459
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• 2003

LPE(Liquid Phase Epitaxial)법을 이용하여 성장시킨 B $i_2$S $r_2$Ca(C $u_{1-x}$ N $i_{x}$ )$_2$ $O_{8+}$$\delta$/ 막(film)을 break junction 법을 이용하여 터널링 분광을 측정하였다. Ni 조성비 $\chi$$_{L}$의 증가에 따라 에너지 간격 2$\Delta$의 크기는 증가하였다. 에너지 간격 2$\Delta$(4.2 K)는 54.4~64 meV, 2$\Delta$/ $k_{B}$ $T_{c}$ $^{zero}$는 7.36~10.14로 BCS 이론에 의한 값 보다 큰 결과를 얻었다. 융액(melting solution) 속의 Ni 조성비 $\chi$$_{L}$의 증가에 따라, 임계온도 $T_{c}$ $^{zero}$와 격자상수 c-축의 길이는 감소하는 경향을 보였다.을 보였다.$^{zero}$와 격자상수 c-축의 길이는 감소하는 경향을 보였다.

• Transactions on Electrical and Electronic Materials
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• 제5권5호
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• pp.199-203
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• 2004

Superconducting B $i_2$S $r_2$C $a_{n-l}$C $u_{n}$ $O_{x}$(n=2～4) thin films were prepared by single target DC-magnetron sputtering. And, that was compared with the B $i_2$S $r_2$C $a_{n-l}$C $u_{n}$ $O_{x}$(n=1～3) thin film fabricated by using the ion beam sputtering. Phase intergrowth among n=2-3, 3-4 and 4-5 phases was observed. The molar fraction of each phase in the mixed crystal of the deposited films was determined by x-ray diffraction analyses and investigated as a function of $O_2$ gas pressure during sputtering. We investigated the changes of the superconducting properties by molar fraction of each phase. Also, the thin film surface observation was carried out by atomic force microscope. The images show the average particle size decreases, and the distribution density of particles on the film surface was to increase with lower gas pressures. The fabrication conditions for selective growth of the single n=2, 3 and 4 phases in BiSrC $a_{n-l}$C $u_{n}$ $O_{x}$(n=2～4) thin film are discussed.e discussed.ussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.474-477
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• 2002

We performed a continuous heat treatment experiment for long Si$_2$Sr$_2$CaCuO$_{x}$ (Bi2212) superconductor tapes on copper substrates. A precursor that contains a mixture of Bi$_2$O$_3$, SrCO$_3$, and CaCO$_3$ powders was prepared and screen-printed on Cu tapes. The screen- printed tapes were thermally treated by consecutive processes with various temperature settings using an air-filled tube furnace. The diffraction patterns and the microstructures of the high temperature superconductor thick films were analyzed by X-ray diffractometry (XRD) and optical Microscopy respectively, and the critical temperatures of the superconducting thick films were measured. The critical temperatures of the superconducting films were measured to be about 77K, and the films'crystallographic c-axes were confirmed to be normal to the film surfaces by XRD and morphology observation. We also observed that the thick superconducting layer is formed and aligned on the copper substrate via partial melted state that consists of a liquid phase and a secondary phase.e.

• 한국세라믹학회지
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• 제29권2호
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• pp.95-100
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• 1992

A high-Tc superconducting phase was obtained using long sintering time of 210 hours. From XRD and SEM analyses, it could be confirmed that the particles were plate phase, of which the structure is tetragonal system with lattice parameter a=b=5.44${\AA}$, C=37.18${\AA}$. Resistance and current density measurements were carried out using 4 probe method. The experimental data revealed that the stable high-Tc superconducting phase was easily formed by addition of Pb to Bi-system. Therefore, we could find the sintering condition to synthesis the system having the largest fraction of high Tc phase.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.503-504
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• 2007

$Bi_2Sr_2Ca_{n-1}Cu_nO_x$(n=0, 1, 2)superconducting thin films have been fabricated by atomic layer-by-layer deposition at an ultra low growth rate using IBS(Ion Beam Sputtering) method. During the deposition, 90 mol% ozone gas of typical pressure of $1{\sim}9{\times}10^{-5}$ Torr are supplied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less than 10 units cell and then Bi-2201 oriented along the c-axis is grown.

• 한국세라믹학회지
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• 제40권5호
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• pp.405-409
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• 2003

The effect of substitution of Gd ions for Ca ions in the B $i_{1.84}$P $b_{0.34}$S $r_{1.91}$(C $a_{1-x}$ G $d_{x}$)$_{2.03}$ C $u_{3.06}$ $O_{ 10+{\delta}}$/ (x=0.0~0.06) was investigated by measuring x-ray diffraction patterns, lattice constants, do resistivity and Hall effect. We found the solubility limit of Gd in the 110 K phase to be x < 0.015. Within the solubility limit, the c-axis seemed to decrease with increasing x. In the region of the 110 K single phase, the critical temperature $T_{c}$ gradually decreased with an increasing the Gd concentration x, corresponding to a small change of the carrier concentration.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2000년도 춘계총회,특별강연,심포지움,연구발표회
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• pp.116.2-116.2
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• 2000

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2004년도 High Temperature Superconductivity Vol.XIV
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• pp.7-7
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• 2004