Effect of nitrogen on some properties of vapor-deposited Nb3Sn

Measurements of critical currentsIc, transition temperaturesTc, as well as transmission electron microscopy, scanning electron microscopy and X-ray analysis have established a correlation between critical currentIc, the tape heating temperature during deposition, and the presence of a fine dispersion of precipitates. As the tape heating current (temperature) increased from 3 to 5 Amps,Ic increased from 20 to 430 Amps/3 mm tape width at 50 kG. A fine precipitate of the Nb2N phase was observed for highest tape heating temperatures. It is concluded that the precipitate particles may act as flux-pinning centers in the Nb3Sn layer.