Crystal engineering of YBa₂Cu₃O_7-δ structures

In order to produce more stable and processable forms of YBa₂Cu₃O_7-δ superconductors, a series of cation substitution reactions have been completed. Compounds in the family of Y_1-yCa_yBa_1-yLa_yCu₃O _7-δ display an increased corrosion resistance with increasing substitution level. The composition of Y_{0. 6}Ca_{0. 4}Ba_{1. 6}La_{0. 4}Cu₃O_{6. 96} (T_c = 80 K) is found to be at least 100 times more stable than the parent compound, YBa₂Cu₃O_{6. 94}. In this paper, compositions yielding transition temperature above 83-85 K have been identified in YBa_2-xSr_xCu₃O_7-δ and Gd_1-xCa_xBa_2-yLa_yCu₃O _7-δ systems suggesting that the surface reactivity, processability and superconducting properties can be tailored with the use of the appropriate cation compositions. Rational approaches for the systematic tailoring of high-T_c superconductors based on lattice engineering approaches are thus developed.