• Journal of the Korean Ceramic Society
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• v.28 no.1
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• pp.86-89
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• 1991

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.24-25
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• 1994

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.22-23
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• 1994

• Journal of the Korean Ceramic Society
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• v.27 no.5
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• pp.702-704
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• 1990

• Journal of the Korean Ceramic Society
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• v.27 no.6
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• pp.829-830
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• 1990

• Progress in Superconductivity
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• v.2 no.2
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• pp.71-75
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• 2001

The effect of annealing step-edges of LaAlO$_3$ and MgO single crystal substrates on YBa$_2$Cu$_3$O$_{7}$ junction has been studied. The step-edge was fabricated by argon ion milling and was annealed at 105$0^{\circ}C$ in 1 attn oxygen pressure. We compared AFM image near step-edge of the substrates between before and after annealing process. And YBa$_2$Cu$_3$O$_{7}$ thin film was deposited on the step-edge by a standard pulsed laser deposition. The step-edge junctions were characterized by current-voltage curves at 77 K. The annealing of step-edges of MgO substrate improved the current-voltage characteristic of Josephson junction: double steps in the current-voltage characteristic disappeared. However the annealing for LaAlO$_3$ did not improve the junction property.rty.

• Bulletin of the Korean Chemical Society
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• v.12 no.5
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• pp.499-504
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• 1991

EPR spectra of the high $T_c$ superconductor $YBa_2Cu_3O_{7-y}$ (YBCO) doped with $Pd^{2+} or Zn^{2+}$ have been measured at several temperatures and dopant concentrations. The spectral intensity of $YBa_2({Cu_{1-x}}{Pd_x})_3O_{7-y}$ is proportional to the dopant concentration. The behavior of $YBa_2(Cu_{1-x}Zn_x)_3O_{7-y}$ is quite different: the spectral intensity remains almost constant up to x=0.10 and then increases rapidly above x=0.10. The results are interpreted in terms of localized and antiferromagnetically spin-paired d holes in both CuO chain and planes. The $Pd_{2+}$ ion substitutes on the CuO chain consisting of "CuOCu dimers", and a $Cu_{2+}$ ion with an unpaired spin is gene rated for each $Pd_{2+}$ ion substituted. On the other hand, $Zn_{2+}$ substitutes on the CuO planes, and all or most of the spins in the two-dimensional plane manage to pair up in the region of low dopant concentration. When the dopant concentration exceeds a certain limit, it becomes more difficult for the spins to find partners, and the number of unpaired spins increases rapidly with increasing dopant concentration. The $Zn_{2+}$ ion is more effective than the $Pd_{2+}$ ion in suppressing the superconductivity of YBCO. This is attributed to the fact that $Zn_{2+}$ substitutes on the CuO planes which are mainly responsible for the superconductivity, while $Pd_{2+}$ substitutes on the CuO chain which is of secondary importance in the superconductivity.

• Journal of the Korean Ceramic Society
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• v.27 no.1
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• pp.48-54
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• 1990

YBa2Cu3O7-x(=YBCO) single crystals were grown by flux method and the growing process of crystals was investigated. YBCO and 3BaO-7CuO composition powders were mixed by the ratio of 25 : 75(wt%), and the mixtures were melted at 105$0^{\circ}C$ in a electric furnace with no temperature-gradient. Then the melt was cooled at a rate 2-1$0^{\circ}C$/h in the above furnace. YBCO single crystal plate with average size of $1.5\times$2.0$\times$0.1㎣ were obtained in the cavities between crucible and solidified ingot, and the single crystals were oriented to <001> direction. The ingots of flux parts were analyzed by XRD and EDS for the purpose of presuming the growing process of the crystals. It was assumed that the divorced eutectic reaction, by which YBCO crystals were grown first and then BaCuO2 and CuO crystals, occured in the case of cooling rate faster than 2$^{\circ}C$/h. When the cooling rate was 2$^{\circ}C$/h, it was assumed that quasi-equilibrium eutectic reaction occured, so that YBCO, BaCuO2 and CuO crystals were grown at the same time.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.9
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• pp.908-912
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• 1991

YBaCuO oxide superconductor-shows superconductive at Liquid Nitrogen temperature-must be preparate wire or thin film form for utility. The wiring is possible with heat treatment after appropriate mixture of polymeric binder and YBaCuO oxide superconductor has fabricated. This study, analyzed the characteristics of fabricated superconductor and extruded wire after application to each of a mixed at different rate in the superconductor and compared with an original pure sample. From the result, we knew that the binder component influences superconducting characteristics. The best condition for superconductivity occurred at a criticla temperature of 86.4K (8:2 rate) and at a critical current density of 100.27A/cmy with a binder packing ratio of about 20~25 percent.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.372-373
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• 2009

In this work, the effects of substrate on the formation of YBaCuO by CVD were investigated by observing the microstructure and the crystallographic orientation and by measuring the temperature dependence of electrical resistance. Source materials used to synthesize the YBaCuO superconducting film were beta-diketone chelates of Y, Ba and Cu. These chelates were evaporated at $137-264^{\circ}C$. The source vapors of Y, Ba and Cu were transported into hot zone by using Ar gas and $O_2$ gas was introduced separately.