Superconducting properties of bulk YBa₂Cu₃O_7-y prepared by a quench and melt growth process

Large crystals of YBa₂CuO₃O_7-y were undirectionally and continuously grown by a modified Quench and Melt Growth (QMG) process with a temperature gradient. Superconducting properties of these crystals were measured. Samples prepared by a conventional QMG process without a temperature gradient have high critical current density (Jc) values exceeding 10⁴A/cm² at 1T and 77K. However, crystals prepared by this process without a temperature gradient were small, i.e. 30mm²×1mm. We modified the QMG method to grow superconducting crystals using a temperature gradient, and obtained large crystals up to 200mm²×1.5mm. It was found that superconducting current flowed throughout the crystal. A Jc value as high as conventional QMG processed materials was confirmed by the magnetic induced field method.