SUPERCONDUCTIVITY OF A15 COMPOUNDS IN THE SYSTEM NB-GE-SN SYNTHESIZED BY CHEMICAL VAPOR-DEPOSITION

A series of ternary NbGeSn superconducting compounds with the A15 crystal structure were synthesized by the method of chemical vapor transport. For constant Nb content and varying ratio of Ge/Sn, the lattice parameters were found to follow a linear Vegard-type behavior while both the superconducting transition temperatures Tc and residual resistance ratios exhibited minima. These results are interpreted on the basis of Tc in this system being governed by disorder at the Ge-Sn sites. © 1978.