• Progress in Superconductivity
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• v.6 no.1
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• pp.84-88
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• 2004

The polycrystalline superconductor $SmBa_2$$Cu_3$$O_{x}$ is fabricated, and intergranular magnetic properties are investigated using the critical state model, from which some useful parameters such as the critical current density and the intergranular volume fraction are obtained. The curve fitting for M-H hysteresis loop shows that the intergranular critical current density of $SmBa_2$$Cu_3$$O_{x}$ / decreases in the form of ($1-T/T_{c}$ )$^{1.5}$ . The intergranular volume fraction is influenced by granular morphology. From SEM image, the grains of $SmBa_2$$Cu_3$$O_{x}$ are found to be randomly shaped. This mean:; that the intergranular volume fraction of $SmBa_2$$Cu_3$$O_{x}$ / should be smaller than those of superconductors, of which grains are plate-shaped such as Tl-based superconductor.

• Journal of the Korean Society for Heat Treatment
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• v.4 no.3
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• pp.47-53
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• 1991

In this study, the structural phase transition and decomposition of superconducting ceramic, Y-Ba-Cu-O system was studied. The results of the study are as follows. The high Tc superconductor $Y_2Ba_2Cu_3O_{7-x}$ is made in solid state reaction of $O_2$ atmosphere and the valve of X in $Y_2Ba_2Cu_3O_{7-x}$ is 0.1~0.2. The transition temperature of tetragonal-orthorhombic phase of $Y_2Ba_2Cu_3O_{7-x}$ appear at $790^{\circ}C-900^{\circ}C$. In the result of measuring the electrical resistance of sample annealed in $O_2$ atmosphere, the electrical resistance show zero at 92 K and the best superconductor, $Y_2Ba_2Cu_3O_{7-x}$(Y 123) can be mabe.

• 한국초전도학회:학술대회논문집
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• v.13
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• pp.30-30
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• 2003

• Progress in Superconductivity and Cryogenics
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• v.18 no.4
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• pp.1-4
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• 2016

We investigated the relation between the Cu-O bond length and the superconducting properties of $BaSnO_3$ (BSO)-added $GdBa_2Cu_3O_{7-x}$ (GdBCO) thin films by using extended x-ray absorption fine structure (EXAFS) spectroscopy. 4 wt.% $BaSnO_3$ (BSO) added $GdBa_2Cu_3O_{7-x}$ (GdBCO) thin films with varying thickness from $0.2{\mu}m$ to $1.0{\mu}m$ were fabricated by using pulsed laser deposition (PLD) method. The transition temperature ($T_c$) and the residual resistance ratio (RRR) of the GdBCO films increased with increasing thickness up to $0.8{\mu}m$, where the crystalline BSO has the highest peak intensity, and then decreased. This uncommon behaviors of $T_c$ and RRR are likely to be created by the addition of BSO, which may change the ordering of GdBCO atomic bonds. Analysis from the Cu K-edge EXAFS spectroscopy showed an interesting thickness dependence of ordering behavior of BSO-added GdBCO films. It is noticeable that the ordering of Cu-O bond and the transition temperature are found to show opposite behaviors in the thickness dependence. Based on these results, the growth of BSO seemingly have evident effect on the alteration of the local structure of GdBCO film.

• Progress in Superconductivity
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• v.11 no.1
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• pp.25-29
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• 2009

Polycrystalline samples of $(R_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ (R = Lu and Y) were synthesized by a solid-state reaction route, and the phase stabilities were examined by heating at temperatures between $800^{\circ}C$ and $900^{\circ}C$ in various atmospheres. A comparative analyses of the x-ray diffraction data of the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ and $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compounds showed that the 123 phase of both compounds is stable under heating in air and $O_2$ of 1 atm. However, contrary to the $(Y_{0.8}Ca_{0.2})Ba_2Cu_3O_{7-z}$ compound, the $(Lu_{0.8}Ca_{0.2})Ba_2Cu_3O_z$ compound was found to become unstable when heated in the low oxygen partial pressure below about 8 % $O_2\;in\;N_2$, Considering the instability of parent $LuBa_2Cu_3O_z$ compound, this result suggests that the phase stability of Lu-based 123 compounds is sensitive to both the composition and the oxygen partial pressure.

• Progress in Superconductivity
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• v.1 no.2
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• pp.89-94
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• 2000

A YBCO superconductor was prepared in a short time by a melt infiltration process that utilizes meting of $Ba_3Cu5O_8$ powder and the infiltration into a porous $Y_2BaCuO_5$ compact. The processing parameters such as a reaction temperature and time, and atmosphere (air and $O_2$) were controlled to establish the fabrication condition. The formation of a $YBa_2Cu_3O_x$, phase and the developed microstructure are reported.

• Journal of the Korean institute of surface engineering
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• v.29 no.6
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• pp.829-833
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• 1996

Superconducting YBaCuO thin films were deposited on MgO (100) single crystal substrate by rf reactive sputtering method. Sputtering target was prepared by mixing the original powders of $Y_2O_3$, $BaCO_3$, and CuO at $830^{\circ}C$, and its composition was $YBa_2Cu_{3.3}O_x$ adding the excess CuO to compensate for the loss of Cu in the deposition process. The sputtering conditions for a high quality of YBCO thin film were: substrate temperature of 13$0^{\circ}C$; gas pressure of 10 mTorr; gas mixture ($O_2$: Ar =10: 90); distance of 2.5 inch; and rf power density of 4.87 W /$\textrm{cm}^2$. The deposition rate was 2.4~2.6 nm/min. From the RBS results, it was found that Cu and Ba contents in thin films decreased with the increase of substrate temperature. The increase of gas pressure resulted in significant deficiency of Ba elements.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.79-79
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• 2004

• Progress in Superconductivity and Cryogenics
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• v.10 no.2
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• pp.24-26
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• 2008

[ $Gd_{1+x}Ba_{2-x}Cu_3O_7$ ] (GdBCO) coated conductors on IBAD-MgO templates have grown by pulsed laser deposition. Critical current of the films were measured as about 90 A/cm by a four-probe method. The optical response of the films was investigated by Raman scattering spectroscopy. According to the Raman scattering spectra, the peaks at $328\;cm^{-1}$, $451\;cm^{-1}$, $504\;cm^{-1}$ were found and assigned to one $B_{1g}$ mode and two $A_{1g}$ modes, respectively. The high critical-current carrying behaviors of the GdBCO coated conductors are ascribed to their 123-structure without exchange of cation and incorporation of oxygen into the cuprates.

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.36-36
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• 2007