J Mater Sci Technol ›› 1992, Vol. 8 ›› Issue (5): 353-358.

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Directional Solidification and Superconductive Transition of Bi_2Sr_2 CaCu_2O_(8+δ)

ZHANG Cheng ZHANG Jishan GE Yunlong HU Zhuangqi Institute of Metal Research,Academia Sinica,Shenyang,110015.China   

  • Received:1992-09-28 Revised:1992-09-28 Online:1992-09-28 Published:2009-10-10

Abstract: By laser heated pedestal growth method, Bi_2Sr_2CaCu_2O_(8+δ) as-grown fibers with different morphologies were solidified in non-equilibrium condition at the rates of 0.1~14mm/min.At low rates,a(Sr_(1-x)Ca_x)CuO_2 phase with long and straight strips in shape and a white Cu-rich phase having a morphology of globular shape were found. With the increase of solidification rates,the phase (Sr_(1-x)Ca_x)CuO_2 becomes thinner and the Cu-rich phase becomes smaller and dispersive.When the solidification rates were last.another unstable phase(Sr_(1-x)Ca_x)Cu_2O_3 occurred.In fact,the tran- sition of the semiconductive as-grown fiber to the superconductor is a peritectoid reaction influenced by the annealing temperature and time.

Key words: Bi-Sr-Ca-Cu-O, system, directional, solidification, superconductive transition