Critical current measurements of CVD prepared Nb3Ge containing various amounts of second phase (Nb5Ge3) material

Data are presented which show a relationship between the critical current density and second phase (tetragonal Nb5Ge3) material in CVD deposited Nb3Ge for deposition temperatures ranging from 750 to 900°C. The data were measured in the temperature range from Tc(≈ 21 K) down to 13.8 K and at 4 K for several of the samples. Also reported is the slope of the critical current density with respect to temperature, dJc/dT. Samples with the largest Jcat 13.8 K also had the largest (dJc/dT) and the lowest extrapolated intercept of the Jccurve with the temperature axis. Jcat 13.8 K as a function of second phase has a maximum of 2.5 × 10⁶A/cm²for approximately 2 to 3% Nb5Ge3present in the coat. The temperature dependence of the critical current was represented by Jc(T) = Jc(0)[1-(T/Tc)²] for most samples.