• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.290-291
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• 2005

A high Tc superconducting with a nominal composition of $Bi_2Sr_2Ca_2Cu_3O_Y$ was prepared by the citarte method. The solid precursor produced by the dehydration of the gel at $120^{\circ}C$ for 12h is not in the amorphous state as expected but in a crystalline state. X-ray diffraction peaks of nearly the same angular position as the peaks of high Tc phase were observed in the precursor. After pyrolysis at $400^{\circ}C$ and calcination at $840^{\circ}C$ for 4h. the (001)peak of the high Tc phase was cleary observed. Experimental results suggest that the intermediate phase formed before the formation of the superconducting phase may be the most important factor in determining whether it is easy to form the high Tc phase or not. because the nucleation barriers of the two superconducting phase may be altered by the variation of the crystal structures of those intermediate phase.

• Progress in Superconductivity
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• v.11 no.2
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• pp.92-95
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• 2010

$SrPd_2Ge_2$ single crystals were grown by self-flux method. Several shiny plate-like single crystals were obtained. The crystal structure and lattice parameters were characterized using the x-ray diffractometor, which indicates the crystals are in a single phase of $ThCr_2Si_2$-type. We confirmed superconducting transition temperature at 2.7 K by measuring magnetization and electrical resistivity.

• Journal of the Korean institute of surface engineering
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• v.24 no.2
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• pp.67-72
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• 1991

The feasibility of preparing superconducting $Y_1Ba_2Cu_3O_y$ films on metallic substrate was exmined in an attempt to fabricate a tape conductor. Deposition methods employed were sputtering, laser ablation, and plasma flash evaporation. Although zero resistance temperature (Tc) is achieved above 90 K, critical current density values (Jc) obtained so far is still low as compared with those reported in the films grown on single crystal substrates. This may be caused by the misalignment of the crystal structure of the films on metal substrates. A further improvement if Jc for highly-oriented polycrystalling films is being investigated at the present time.

• Transactions on Electrical and Electronic Materials
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• v.6 no.4
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• pp.186-189
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• 2005

We have fabricated superconducting HTSC ceramic thick films by chemical process. c-axis oriented HTSC thick films have been attempted bi-axially textured Ni tapes. The x-ray diffraction pattern of the HTSC thick films contained superconducting phase crystal. The critical temperature and critical current density was 110K.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.08a
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• pp.48-48
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• 2008

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.4
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• pp.172-175
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• 2003

We have investigated effects of the lattice mismatch between the LPE films and the substrates. We have grown $La_{2-x}Sr_{x}CuO_{4}$(x=0.1 to 0.15) single crystalline films on single crystalline substrates having different lattice parameter ratio c/a e.g., $La_{2-x}Sr_{x}Cu_{1-y}Zn_{y}O_{4},\;La_{2-x}Ba_{x}CuO_{4},\; LaSrAlO_{4}\;and\;La_{2-x}Sr_{x}Cu_{1-y}Al_{y}O_{4}$ etc., using the IR-LPE technique. The superconducting properties of the grown films were found to vary significantly depending on the lattice mismatch with different substrates.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.2
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• pp.83-87
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• 2003

$(Nd/Y)_{1.8}Ba_{}2.4Cu_{3.4}O_{7-x}$high $T_c$ superconductor was directionally grown by floating Bone melt growth process with a large temperature gradient in air. Cylindrical green rods of (Nd/Y)1.8 oxides were fabricated by cold isostatic pressing (CIP) method using rubber mold. Microstructures were observed by SEM and TEM and superconducting properties were measured by a SQUID magnetometer. Nonsuperconducting $(Nd/Y)_2BaCuO_5$ inclusions were uniformly distributed within the superconducting $(Nd/Y)Ba_2Cu_3O_x$ matrix. The directionally melt-textured (Nd/Y) 1.8 superconductor showed an onset Tc $\geq$ 90 K and a sharp superconducting transition.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.05a
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• pp.224-233
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• 2002

A common YBCO powder has been made from a mixture of Y123 and Y211 that heated at different temperatures, respectively. The synthesis temperature of Y211 is lower than Y123. If Y211 has been heated as a synthesis temperature of Y123, a particle size of it may be very coarse. It exist as one of main defects for superconductor. But We simultaneously synthesize a YBCO(its composition is (Y123+0.4Y211)+$lwt%CeO_2$) using polymeric complex method. In the YBCO, the Y123 is synthesized lower temperature than other methodes, and its crystal structure is orthorombic. For measurement of these superconducting properties, we fabricated a YBCO single crystal. The manufactured YBCO single crystal is measured a magnetic distribution device using 0.5Tesla magnet and trapped magnet fields in it are 0.2Tesla.

• Journal of the Korean Ceramic Society
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• v.27 no.4
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• pp.536-542
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• 1990

Single crystals of YBa2Cu3O7-x have been grown in BaCuO2 flux at temperature of 125$0^{\circ}C$ and examined using XRD, EDAX and light microscopy. The YBCO crystals were grown in a cavity which was formed by the reduction of CuO and became large by the directional solidification in the crucible. The observed crystal growth habit is square planar with the c-axis normal to the plane. The surface morphology of grown crystals were growth ledges and growth sprial paterns on a (001) face.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.451-454
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• 2011

The traditional BCS superconductors $AOs_2O_6$ (A=K, Rb, and Cs) were investigated to find the relationship between their structures and superconducting transition temperatures. The $T_c$ decreases with increasing the unit cell parameter of $AOs_2O_6$. This is in contrast to the case of conventional BCS superconductivity in a single bond model, where $T_c$ may increase with increasing the the unit cell parameter since the DOS at Fermi level increases as the unit cell parameter increases. Instead, the $T_c$ of a $\beta$-pyrochlore oxide is proportional to the lattice softness of the compound.