Fabrication process of twin-free orthorhombic Nd123 single crystal under uni-axial compression

摘要

A fabrication process of twin-free orthorhombic NdBa_2Cu_3O_(7-#delta#) (Nd123) single crystals was studied, in which the as-grown tetragonal single crystals were directly annealed under uni-axial compression in order to fabricate the complete twin-free single crystals. Almost twinfree orthorhombic Nd123 single crystals could be obtained by modifying the annealing conditions from the viewpoint of the distribution of the oxygen contents and the release of the stress in the crystals during annealing. The critical current density (Jc)-H curves for the twin-free, the detwinned, and the not-detwinned Nd123 single crystals, which were affected by the Nd/Ba ratio fluctuation appearing in these crystals during annealing, showed a quite different tendency from those for YBa_2Cu_3O_(7-#delta) (Y123) single crystals.