• Progress in Superconductivity
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• 제10권2호
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• pp.92-98
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• 2009

The magnetic field profiles near the surface of a $Sm_1Ba_2Cu_3O_{7-\delta}$ coated conductor(CC-tape) under magnetic field and current that were applied simultaneously with phase differences ${\phi}s$ were measured using scanning Hall probe method. Measurements were carried out along the elliptic load lines with $\phi=90^{\circ}\;and\;45^{\circ}$ for some $B_{peak},\;I_{peak}$ values. From the measured field profiles, sheet current density J(x, $B_a,\;I_a$) and magnetic flux density $B_0(x,\;B_a,\;I_a)$ profiles in the CC-tape were calculated. Using these J(x, $B_a,\;I_a$) and $B_0(x,\;B_a,\;I_a)$ profiles, we estimated the hysteresis energy loss Q in the CC-tape. The estimated Qs, together with our previous results for $\phi=0^{\circ}$ from [9], were compared with theoretical values based on Brandt's calculation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.361-363
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• 1995

High quality $Y_1Ba_2Cu_3O_{7-x}$ thin films have been fabricated by pulsed Nd:YAG laser deposition using an unusual 'off-axis' target-substrate geometry. Various properties of superconducting $Y_1Ba_2Cu_3O_{7-x}$ thin films have been studied systematically as a function of oxygen pressure during the deposition, in both 'on-axis' and the unusual 'off-axis' target substrate geometry. In the 'off-axis' geometry, one can completely eliminate the so-called 'laser droplets' form the thin surface and thus obtain smooth high qualify films. It is found that films with optimum structural and electrical properties are obtained at a lower oxygen pressure range during the 'off-axis' deposition when compared with that required in the 'on-axis' deposition geometry.

• Progress in Superconductivity
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• 제7권1호
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• pp.92-96
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• 2005

YBCO thin films on metal substrates were prepared by the metal-organic deposition using trifluoroacetates (TFA-MOD). To compensate the loss of Ba element from the precursor films due to the reaction with $CeO_2$ cap layer, we have employed Ba-excessive precursor solutions of $YBa_{2+x}Cu_{3}O_{7-{\delta}}$ ($0{\le}x{\le}0.1$). The precursor solutions were dip-coated on the metal substrates with $CeO_2$ cap layer, initially heated up to $400^{\circ}C$, and finally fired at the various high temperatures for 2 h in a reduced oxygen atmosphere. With this approach, YBCO films possessing critical temperature over 85 K could be successfully prepared on the metal substrates. The highest $T_{c,zero}$ value of 86 K was obtained from the Ba-excessive YBCO film of x=0.005 in $YBa_{2+x}Cu_{3}O_{7-{\delta}}$ fired at $750^{\circ}C$ for 2 h. However, unexpected $T_c$ suppression even in Ba-excessive YBCO samples requires further identification.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 추계학술발표회
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• pp.167-167
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• 1996

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 The 1st International Symposium on Advanced Magnetic Materials
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• pp.80.1-80.1
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• 2007

• 한국초전도ㆍ저온공학회논문지
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• 제6권3호
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• pp.21-26
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• 2004

Deposition condition of YBa$_2$Cu$_3$$O_{7-x}$ (YBCO) films on moving IBAD templates (CeO$_2$/IBAD-YSZ/SS) was studied in a hot-wall type metal organic chemical vapor deposition (MOCVD) process using single liquid source. The reel velocity was 40 cm/hr and the source mole ratios of Y(tmhd)$_3$:Ba(tmhd)$_2$:Cu(tmhd)$_2$ were 1:2.3:3.1 and 1:2.1:2,9, Two different types of IBAD templates with thin CeO$_2$ and thick CeO$_2$ layers were used, The YBCO films were successfully deposited at the deposition temperatures of 780~89$0^{\circ}C$ ; the a-axis growth was observed together with the c-axis growth up to 83$0^{\circ}C$. while the c-axis growth became dominant above 83$0^{\circ}C$. The top surface of the c-axis film was fairly dense and included a small amount of the a-axis growth, although the peaks of the a-axis grains were not observed in XRD pattern, The YBCO film deposited on IBAD template with thin CeO$_2$ layer showed low critical current of 2.5 A/cm-width. while the YBCO film deposited on IBAD template with thick CeO$_2$ layer showed higher critical current of 50 A/cm-width. This result indicates that thick CeO$_2$ layer is thermally more stable than thin CeO$_2$ layer at the high deposition temperature of the MOCVD process.s.

• 대한전기학회논문지
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• 제41권5호
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• pp.525-532
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• 1992

Fluorine-doped YBaS12TCuS13TOS17-xTFS1yT superconducting materials with y varing two orders of magnitude form 0.02 to 2.0 have been prepared by a sol-gel process by using metal nitrate salts, sodium hydroxide and sodium fluoride. Fluorine contents have been measured using an ion-selective electrode. All fluorine doped as reactant were found to be present in the resulted samples. From the observation of XRD it has been concluded that the samples with y 0.2 formed simply the single phase of perovskite structure, whereas those with y 0.5 yielded together some compounds such as BaFS12T, YFS13T and CuO in the resulted samples. The observation of solid state S019TF NMR has been carried out in order to check whether fluorine was actually incorporated into the lattice sites, and the experimental results revealed that the mole ratio of fluorine incorporated into the lattice sites of YBaS12TCuS13TOS17-xT was approximately 0.2 per mole of the compound. Also electrical resistivity measurement indicated that onset transition temperature has the tendency to increase slightly with increasing y in the dilute region as y 0.2.

• 한국전기전자재료학회논문지
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• 제13권11호
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• pp.959-962
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• 2000

We have fabricated good quality superconducting YBa$_2$Cu$_3$$O_{7-x}$(YBCO) thin films on Hastelloy(Ni-Cr-Mo alloys) metallic substrates with CeO$_2$and BaTiO$_3$buffer layers in-situ by pulsed laser deposition in a multi-target processing chamber. YBCO film with CeO$_2$single buffer layer shows T$_{c}$ of 71.64 K and the grain size less than 0.1${\mu}{\textrm}{m}$. When BaTiO$_3$ is used as a single buffer layer, the grain size of YBCO is observed to be larger than that of YBCO/CeO$_2$by 200 times and the transition temperature of the film is enhanced to be about 84 K. CeO$_2$/BaTiO$_3$double buffer layer has been adopted to enhance the superconducting properties, which results in the enhancement of the critical temperature and the critical current density to be about 85 K and 8.4$\times$10$^4$ A/$\textrm{cm}^2$ at 77 K, respectively mainly due to the enlargement of the grain size of YBCO film.ilm.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2009년도 Korea Superconductivity Society Meeting 2009
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• pp.50-50
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• 2009

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2007년도 High Temperature Superconductivity Vol.XVII
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• pp.36-36
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• 2007