THE FORMATION OF HIGH Tc A15 PHASE IN SPUTTERED Nb-Ge FILMS

It has been found in this laboratory that the high TNb-Ge sputtered films （23 K） always contain some NbGewith Nb/Ge<3. The Tmeasured with the inductive method are 1—2 K lower than that wth the resistive method. This indicates that the volume fractions of T（?）22 K regions are relatively small in the sputtered films. The films with single phase A15 NbGe have broad transitions and show several steps on the curve, suggesting that only a small fraction of the A15 phase is of the high Tnature. While the films containing A15 NbGe and a certain amount of NbGehave sharp and smooth transitions. Electron microscopic examinations show an interesting distribution of NbGewith A15 phase. These results provide further support for NbGehaving a stabilization effect on the high TA15 phase.