Improvement of critical current density in Fe-sheathed MgB<sub>2</sub> tapes by ZrSi<sub>2</sub>, ZrB<sub>2</sub> and WSi<sub>2</sub> doping
Yanwei Ma; H Kumakura; A Matsumoto; H Hatakeyama; K Togano; Yanwei Ma; Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan; H Kumakura; Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan; A Matsumoto; Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan; H Hatakeyama; Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan; K Togano; Superconducting Materials Center, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
Журнал:
Superconductor Science and Technology
Дата:
2003-08-01
Аннотация:
Fe-sheathed MgB<sub>2</sub> tapes were prepared by the in situ powder-in-tube technique by 5 at ZrSi<sub>2</sub>, ZrB<sub>2</sub> and WSi<sub>2</sub> doping, respectively. The doping effect of these compounds on the microstructure and superconducting properties of MgB<sub>2</sub> tapes has been investigated by using x-ray diffraction, scanning electron microscope, transport measurements and dc susceptibility measurements. Compared to the undoped samples, J<sub>c</sub> for all the doped samples were much improved; the best result in terms of J<sub>c</sub> was achieved for ZrSi<sub>2</sub> doping, by up to a factor of 3.4 at 4.2 K in magnetic fields up to 12 T. Moreover, these dopants did not significantly decrease the transition temperature. The J<sub>c</sub>–B curves of WSi<sub>2</sub>-doped tapes show better performance in higher magnetic fields in comparison to undoped tapes, suggesting that pinning centres effective in a high-field region were possibly introduced.
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