Starting composition 1112 for Bi-Sr-Ca-Cu-oxide yields multiphase super-conductors with the proportion of constituent phases depending sensitively on the annealing temperature. The R-T curves show zero resistivity and the transition corresponding toTc = 80 K phase prominently. However, indexing of X-ray diffraction peaks reveals presence of 80 K (lowTc) as well as 108 K (highTc) phase. The lowTc phase thus corresponds to the orthorhombic structure with a unit cell ofa = 5.4Å,b = 27 Å andc = 30.56 Å. This is further understood to be composed of a pseudotetragonal cell ofa =b = 5.41 Å. The highTc phase similarly pertains to the orthorhombic structure withc = 36 Å.
Volume 97, 2023
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