High-quality RE-123 single crystals grown in BaZrO 3 crucible

Abstract

In detailed studies on the flux-pinning property of high- T c superconducting copper oxides, high-quality single crystals are indispensable to clarify the influence of defects of different types such as the grain boundary, oxygen inhomogeneous distribution, and cation impurities. In the present study, we successfully grew high-quality RE-123 single crystals using BaZrO 3 crucibles and measured the magnetization of the crystals. High density (∼99%) and small grain size (<1 μm) are characteristic to the BaZrO 3 crucible as compared to crucibles of other types. With BaZrO 3 crucibles we obtained a Y-123 single crystal as large as 11×12×1 mm 3 and a decent sized Lu-123 single crystal of 3×3×0.1 mm 3 which had never been able to be synthesized in single phase before. To our best knowledge, this crystal is the largest one for Y-123 grown by a flux method. Crystals of typically ∼1.5×1.5×0.1 mm 3 in size were annealed at 450 °C for 200 h in flowing O 2 gas. The crystals exhibited critical temperatures of ∼93.4 K and sharp transitions with ΔT c<0.8 K. The M– T curves for the crystals exhibited significantly broadened transitions even at fields as low as H ∥c=10 Oe. Such broadening in the transition curve reflects weak flux-pinning capability of the crystal.