OPTIMUM GROWTH CONDITION OF BI2SR2CACU2OY SINGLE-CRYSTALS IN A VERTICAL BRIDGMAN METHOD

We prepared the Bi2Sr2CaCu2Oy (BSCCO) single crystals by a vertical Br idgman method changing the compositions of starting materials, the tem peratures for melting and the pulling down rates. The prepared BSCCO s ingle crystals were plate-like and were a (2 2 1 2) phase. From the re sults, we found that the optimum temperature for melting and the optim um pulling down rate for obtaining a large size BSCCO single crystal w ere 985 degrees C and less than 1 mm/h, respectively. The superconduct ing phases of BSCCO single crystals were independent of the compositio ns in the range of Bi: Sr:Ca:Cu = 2 : 2 : 2 : 2-5. As a result, the (2 2 1 2) phase plate-like BSCCO single crystal with a size of 15 x 7 mm (2) was obtained. (C) 1998 Elsevier Science B.V. All rights reserved.