Influence of some growth parameters upon the crystal growth of Bi-2212 family superconductor by traveling solvent floating zone method

Crystals of Bi2Sr2CaCu2Oy, Bi2Sr2PrCu2Oy and Bi2Sr2GdCu2Oy were grown using the traveling solvent floating zone (TSFZ) method, with the dimensions of approximately 6 mm×2 mm×0.2 mm. The primary crystallization field (PCF) was determined by analyzing the composition of the melt zone after self-adjusting during growth. Relative to Bi-2212 solid solution region, the PCF of Bi2Sr2PrCu2Oy shifted towards the CuO-rich corner, and the PCF of Bi2Sr2GdCu2Oy was located approximately at the BiO1.5-rich and CuO-rich side, in the pseudo-ternary BiO1.5–(Sr, Pr, Gd)O–CuO phase diagram. Such variation in solvent compositions may significantly influence the segregation behavior of each constituent so as to influence the maximum stable growth rates of each compound. The minimum critical values of G/R are 5.39×1011 Ksm−2 of Bi2Sr2GdCu2Oy, 4.5×1011 Ksm−2 of Bi2Sr2CaCu2Oy, and 2.94×1011 Ksm−2 of Bi2Sr2PrCu2Oy. These data obtained from fundamental estimations are consistent with experimental results, indicating a decreasing behavior of growth difficulty.