Abstract
We examine the effect on the superconducting transition temperature of chemical inhomogeneities in and single crystals. Cation disorder at the Sr crystallographic site is inherent in these materials and strongly affects the value of Partial substitution of Sr by Ln (Ln = La, Pr, Nd, Sm, Eu, Gd, and Bi) in results in a monotonic decrease of with increasing ionic radius mismatch. By minimizing Sr site disorder at the expense of Ca site disorder, we demonstrate that the of can be increased to 96 K. Based on these results we discuss the effects of chemical inhomogeneity in other bulk high-temperature superconductors.
- Received 8 October 2003
DOI:https://doi.org/10.1103/PhysRevB.69.064512
©2004 American Physical Society