Atomic Ordering and Superconductivity in High-TcA−15Compounds

Abstract

Large, reversible changes in the superconducting transition temperature $T_c$ of the Nb-based $A-15\mathrm{}$ compounds ${\mathrm{Nb}}_3$Al, ${\mathrm{Nb}}_3$Sn, ${\mathrm{Nb}}_3$Ga, ${\mathrm{Nb}}_3$(Al, Ge), and ${\mathrm{Nb}}_3$Ge are observed when irradiated with high-energy ($E>\mathrm{}1\mathrm{}$ MeV) neutrons at 60°C. The transition widths of the irradiated samples are of the same order as the unirradiated samples and the original $T_c\text{'}\mathrm{s}$ are recovered by annealing. The results are discussed in terms of atomic ordering in the $A-15\mathrm{}$ structure.