IMPROVED HIGH-FIELD PERFORMANCE IN NB3SN CONDUCTOR PREPARED FROM INTERMEDIATE COMPOUND

Nb3Sn superconductors have been Fabricated using Nb6Sn5 intermediate c ompound powder synthesized by a melt diffusion process. The mixed powd er of Nb6Sn5 and Nb was encased in a Ta tube, and then fabricated into a tape without intermediate annealing. A Cu sheath with a Ta barrier was also used for the fabrication. The Nb3Sn tape shows a Bc(2) of 24. 7T at 4.2K after the reaction at 900 degrees C. In addition, the Bc(2) increased further by Ti doping. Moreover, the addition of 0.5-1.0 wt% Ge produces appreciable improvements in Te and Je at high magnetic fi elds. A Jc (Nb3Sn) of 2.7x10(4) A/cm(2) has been obtained at 21T and 4 .2K in the Ge-doped specimen. A small amount of Cu addition decreases the optimum reaction temperature to 800-850 degrees C. Present Nb3Sn c onductors seem to be useful for NMR high-field magnets as well as for refrigerator-cooled superconducting magnets.