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

Melt-textured YBCO in high quantity and good quality is prepared in a batch process. A mean trapped field >1. IT at 77K is achieved in batch processed material. Studying the microstructure is a necessary tool to understand the growth mechanisms and thus to opimise the material. From the growth induced structures in the material the anisotropy in growth speed is 1.37. From batch processed material function elements for different cryomagnetic applications are constructed. Motors with an output power > 200 kW at 77 K and bearings that can lift more than 200 kg were equipped with melt-textured YBCO.

• Progress in Superconductivity
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• v.8 no.1
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• pp.8-15
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• 2006

The size of the superconducting domains and the critical current density inside these domains have to be enhanced for most of cryomagnetic applications of melt-textured YBCO bulks. To enlarge the size of the domains we studied the multi-seeding technique based on a well-established procedure for preparing high quality YBCO monoliths using self-made SmBCO seeds. The distance between the seeds was optimised as a result of the investigation of the effects of various seed distances on the characteristics of the grain boundary Junctions. The influences of a-b plane intersections and c-axis misalignments were researched. Thereby, a small range of tolerance of the misorientations between the seed crystals was found. Field mapping was applied to control the materials quality and the superconductor's grain structure was investigated using polarisation microscopy. YBCO function elements with iou. seeds in a line and an arrangement of making type (100)/(100) and (110)/(110) boundary junctions, respectively, were processed. The trapped field profile in both sample types shows single domain behaviour. To demonstrate the potential of the multi-seeding method a ring-shaped sample was processed by placing sixteen seeds in a way to make both (100)/(100) and (110)/(110) grain junctions at the same time. The results up to now are very promising to prepare large single domain melt-textured YBCO semi-finished products in complex shapes.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.17-19
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• 2002

Melt textured YBCO superconductors were fabricated by the top seeding method using Sml.8($Sm_{1.8}$ $Ba_{2.4}$ $Cu_{3.4}$$O_{7-Y}$) seed. We investigated the twin structures using the optical microscope, SEM and TEM. The twin structures formed during the tetragonal to orthorhombic transition which occurred at $450^{\circ}C$ in sample oxygen annealing. The twin structures were clearly observed by SEM due to the chemical etching effects. The lengths of twin structures were increased as the oxygenation heat treatment time increased from 1hr to 10hr. We investigated twin structure by TEM. The twin spaces were considered to be related to the oxygen contents. The results suggested an oxygen diffusion model for the formation of the twin lengths.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.115-119
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• 1999

Ba$_2Cu_3O_{7-{\delta}}$ (YBCO) thin films were deposited by pulsed laser deposition using differently prepared targets: One was a conventionally solid-state sintered (SSS) target and the other was a modified melt-textured grown (MTC) target. Compared with SSS targets, MTG targets showed a well-connected microstructure consisting of much larger grains and the surface was Bess roughened with the cumulative laser incidence. YBCO films deposited from MTC targets showed a denser and smoother surface of the basal film than the case of SSS targets. The investigations of ${\alpha}$-axis outgrowths in the films indicated that the deposition using MTG targets would result in a more homogeneous and stable film growth as compared to the SSS targets. Also, TEM analysis revealed that the film deposited from MTG targets had a less granular microstructure that would reduce weak-link effects in the film.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.231-237
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• 2003

RE(Nd, Sm) elements doped (RE/Y)$_{1.8}$B $a_{2.4}$C $u_{3.4}$$O_{7-x}$ [(RE/Y)1.8] high $T_{c}$ superconductors were directionally grown by Top Seed Melt Growth(TSMG) process in air atmosphere. The (001)melt-textured N $d_{1.8}$B $a_{2.4}$C $u_{3.4}$ $O_{7-X}$(Nd1.8) seed crystals were used for achieving the c-axis alignment large grains perpendicular to surface of the samples. The (RE/Y)1.8 SEM micrographs of the melt-textured (RE/Y)1.8 samples revealed that the nonsuperconducting (RE/Y)211 inclusions are uniformly distributed in the superconducting (RE/Y)123 matrix except the region very close to the Nd seed crystal. The microstructure and superconducting properties were investigated by XRD, SEM, TEM and SQUID magnetometer. The Melt-textured (RE/Y)1.8 samples showed an onset $T_{c}$=91K and sharp superconducting transition. Also, the magnetization value of the (RE/Y)1.8 samples were compared with those of Y1.8 sample at 77 K. 77 K. 77 K. 77 K.K.

• Proceedings of the Materials Research Society of Korea Conference
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• 1996.05a
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• pp.154-154
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• 1996

• 한국초전도학회:학술대회논문집
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• v.16
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• pp.16-16
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• 2006

• Progress in Superconductivity
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• v.2 no.1
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• pp.15-19
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• 2000

[ $YBa_2Cu_3O_{7-\delta}$ ] thin films were deposited by laser ablation using modified melt-textured grown targets. As the laser energy density was increased, the films showed an increasing c-axis orientation and an improvement of superconducting properties. However, at 4 $J/cm^2$, the degree of c-axis alignment and $J_c$ of the film were considerably reduced. These were attributed to the enhanced a-axis outgrowths. It was shown that the increased laser energy density resulted in the formation of $Y_2O_3$ inclusions during the c-axis film growth, and that these inclusions nucleated the a-axis outgrowths.

• 한국초전도학회:학술대회논문집
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• v.14
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• pp.17-17
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• 2004

• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.70-70
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• 2007