In the Bi-Sr-Ca-Cu-O system stringent conditions of heat-treatment lead to the formation of a mixture of both the low and highTc phases and obtaining a single-phase material becomes extremely difficult. This study reports preparation of samples with single superconducting transitions at ∼ 75 K and ∼ 108 K; the compositions of which correspond ton=2,3 in the series Bi2Sr2Can−1CunO4 + 2n. X-ray diffraction studies show that the lowerTc material is a relatively pure phase while the higherTc phase only co-exists with the lowerTc phase. The most obvious effect of doping the system with lead is to make the reaction take place faster and thereby increase the volume fraction of the 110K phase.
Volume 42 | Issue 6
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