Investigation on the substitution of Y in bismuth cuprates (2212)
Previous work on rare-earth substitution for Ca in Bi 2212 bulk superconductors have led to the belief that the rare-earth ions substitute in a uniform manner, as suggested by the smooth variation of the lattice parameters with increasing amount of rare-earth substitution. In this work, results of investigations on the melting behavior of Y-substituted Bi 2212 bulk superconductors are presented. Based on these results, there is reason to believe that two types of Bi 2212 phases coexist – a Ca-rich phase and a rare earth-rich phase. This indicates non-uniform substitutional behavior of Y for Ca in Bi 2212, which deviates from the presently accepted belief of uniform substitutional behavior.