Solid state reactions in the formation of Bi-Sr-Ca-Cu-oxide superconductor from metallo-organic precursors

Abstract

The preparation of Bi-Sr-Ca-Cu-oxide superconductor powders from citrate and carboxylate precursors is discussed. Solid state reactions following the pyrolysis of the precursors were examined by means of thermal analysis and X-ray diffraction. The initial powder was identified as a homogeneous mixture of bismuth trioxide, copper oxide and the double carbonate of strontium and calcium. With heat treatment CuBi 2O 4 was detected as early as 500°C, and Bi 2Sr 2CuO 6 after 700°C. The Bi-Sr-Cu phase was identified as an intermediate for the formation of Bi-Sr-Ca-Cu-oxide superconductors. Further heat treatment at higher temperatures resulted in the formation of the 2212 superconductor phase. Various phase transformations were identified through-out the process.