Bi-Sr-Ca-Cu-O Superconducting Oxides Synthesized from Different Diffusion Couples

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Abstract
Thick Bi-Sr-Ca-Cu-O(BSCCO) layers have been synthesized by a reaction diffusion between a Sr-base oxide substrate and a Bi-base oxide coating layer. Effects of the composition of diffusion couples on superconducting properties and structures of resulting reaction layers have been studied. The most favorable diffusion couple to form a uniform 2212 layer was 2001 (Bi2CuO4) and 0212(Sr2CaCu2O5). The Pb substitution for Bi in the coating layer produced a thick 2223 layer with no crystal orientation, unlike the 2212 reaction layer which showed a strong a-axis orientation. The Li substitution for Bi significantly enhanced the reaction diffusion, and an offsetTcof 83 K was obtained after a heat treatment at 800°C for 10 min. A study was also performed on the powder-diffusion process in which powders of a Sr-base oxide and a Bi-base oxide were mixed and sintered.