Superconductivity and Moessbauer effect of Nb3Sn produced by Sn implantation

We have implanted Sn, Ge, and Si into Nb films. The resulting Nb-Sn compounds and their annealing behavior have been analyzed by the Moessbauer effect and compared to samples obtained by diffusion of Sn into Nb foils. Moessbauer spectra show that Nb3Sn is obtained just by implantation, but with a T/sub c/ of only 5 K. The 9250C annealing temperature necessary to form the A15 structure with long-range order of Nb chains and T/sub c/ values up to 17.8 K is at least 1000C higher in implanted samples than in samples than in samples prepared by diffusion of Sn into Nb. This is explained in terms of implantation-induced lattice defects. The metastable A15 phases of Nb3Ge and Nb3Si could not be formed by Ge or Si implantation, regardless of target or annealing temperature. It is suggested that the high-energy ions only form phases stable at high temperatures and with low T/sub c/ values