Abstract

A Sr2Cu2Oy sample was prepared and the obtained Tc and Tc were 109 K and 51 K, respectively. A comparison of the M2+ ionic radius, lattice constants a and c, and the interatomic distance sum of the Cu-O and -O samples in the Sr2Cu2Oy system was made, where M = Sr, Ca, Mg, Hg, Cd or Cu. It was found that if the atomic radius of M2+, which is in the -O plane of the -1212 specimen, is larger, then the sample will have a higher Tc and the major effect of the M2+ on the Tc of Sr2Cu2Oy samples was to change the interatomic distance sum of Cu-O and -O when the Cu2+ ion was exchanged for an M2+ ion