Nb
3Sn superconductors have been fabricated through a new process starting from Nb
6Sn
5 intermediate compound powder. The mixed Nb
6Sn
5 and Nb powder is encased in a Ta tube, and rolled into tapes without annealing and then heat treated. The Nb
6Sn
5 compound powder can be easily synthesized by melt-diffusion reaction at 900°C between Nb and Sn powders. The Nb
3Sn fabricated by this process has a large ρ
n value and a
Bc2 of 24.7T at 4.2K, which is considerably higher than that of bronze-processed Nb
3Sn. In this study, the effects of different additional elements on the high-field performance of the new Nb
3Sn specimen were studied. The
Jc (core) of the specimen with 2at% Ti substitution for Nb is 3.2×10
4A/cm
2 at 20T and 4.2K. The addition of Cu to the specimen decreases the optimum heat-treatment temperature from 900-925°C to 850°C. The addition of a small amount of Ge or the substitution of a small amount of Ta for Nb raises the curvature of the log
Jc-
B curves of specimens to a convex at high magnetic fields, resulting in significant enhancement in high-field performance. The Nb
3Sn specimen with the addition of 1.0wt% Ge and a slightly richer Sn concentration shows a
Jc (core) of 3.2×10
4A/cm
2 at 21T and 4.2K. The small amount of Ta substitution for Nb has been found to be most effective to achieve large
Jc at high magnetic fields. The optimum amount of Ta substitution is 5-7at%. The
JcS (core) of the specimen with 5at% Ta at 22 and 23T at 4.2K are 3.3×10
4 and 2.4×10
4A/cm
2, respectively. The specimens with Ta substitution are composed of two Nb
3Sn phases with different Ta concentrations. The new Nb
3Sn superconductors may be quite attractive for high-field applications after multifilamentary-type conductors with Cu stabilizers become available.
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