酸化物高温超伝導体の単結晶育成と物性

抄録

Crystal growth and physical properties of oxide superconductor YBa₂Cu₃Ox are reviewed. Flake crystals, which are obtained by a solution growth technique where excess CuO is used as a solvent, display a low temperature superconducting transition below 60K. On the other hand, block crystals, which are prepared using a solid-liquid reaction at peritectic temperature Tp, show a sharp transition above 90K in the as-grown state. A clear anisotropy in the upper critical field is observed in the block crystals. Twinning structures are also discussed in terms of a strain releasing model in the tetragonal-orthorhombic transformation near 600°C.