Fe-sheathed MgB2 tapes were prepared by the in situ powder-in-tube technique by 5at% ZrSi2, ZrB2 and WSi2 doping, respectively. The doping effect of these compounds on the microstructure and superconducting properties of MgB2 tapes was investigated by using X-ray diffraction, scanning electron microscope, transport measurements and direct-current susceptibility measurements. Compared to the undoped samples, JC for all the doped samples were much improved; the best result in terms of JC was achieved for ZrSi2 doping, by up to a factor of 3.4 at 4.2K in magnetic fields up to 12T. Moreover, these dopants did not significantly decrease the transition temperature. The JC–B curves of WSi2-doped tapes exhibited better performance in higher magnetic fields in comparison to undoped tapes, suggesting that pinning centers effective in a high-field region were possibly introduced.

Improvement of Critical Current Density in Fe-Sheathed MgB2 Tapes by ZrSi2, ZrB2 and WSi2 Doping. Y.Ma, H.Kumakura, A.Matsumoto, H.Hatakeyama, K.Togano: Superconductor Science and Technology, 2003, 16, 852-6