IMPROVED GROWTH OF LARGE YBCO SINGLE-CRYSTALS

A new crystal pulling process was developed to produce large YBCO (Y12 3) single crystals under 1 atm oxygen pressure at a high growth rate, 1.5-2.5 times higher than that in air. A large crystal, 19.8 x 19.5 mm (2) in the a-b plane and 16.5 mm in thickness, was obtained. It is cle ar that a high oxygen partial pressure played a significant role in in creasing the growth rate. The superconducting transition temperature T -c was measured to be 92.7 K for an oxygenated sample.