Critical Current Measurements of CVD Prepared Nb sub 3 Ge Containing Various Amounts of Second Phase (Nb sub 5 Ge sub 3 ) Material

摘要

Data are presented which show a relationship between the critical current density and second phase (tetragonal Nb sub 5 Ge sub 3 ) material in CVD deposited Nb sub 3 Ge for deposition temperatures ranging from 750 to 900 exp 0 C. The data were measured in the temperature range from T/sub c/ (approximately 21 exp 0 K) down to 13.8 exp 0 K and at 4 exp 0 K for several of the samples. Also reported is the slope of the critical current density with respect to temperature, dJ/sub c//dT. Samples with the largest J/sub c/ at 13.8 exp 0 K also had the largest (dJ/sub c//dT) and the lowest extrapolated intercept of the J/sub c/ curve with the temperature axis. J/sub c/ at 13.8 exp 0 K as a function of second phase has a maximum of 2.5 x 10 exp 6 A/cm exp 2 for approximately 2 to 3 percent Nb sub 5 Ge sub 3 present in the coat. The temperature dependence of the critical current was represented by J/sub c/(T) = J/sub c/(0) (1-(T/T/sub c/) exp 2 ) for most samples. 5 figures. (ERA citation 02:007526)