Monofilamentary wires and tapes were successfully prepared, using various sheath metals such as Cu, Ta/Cu and Fe, via the powder-in-tube method. The phase composition, superconducting properties and microstructure features were investigated by X-ray diffractometry, standard 4-probe techniques, SQUID magnetometry, scanning electron microscopy and transmission electron microscopy. The results indicated that JC in MgB2/Ta/Cu wires was higher than 105A/cm2 at 5K in 0.1T and 104A/cm2 at 20K in 1T. By Ti-doping, JC could be significantly improved. The MgB2/Fe wires exhibited very high transport critical current densities of 1.43 x 105A/cm2 (4.2K, 4T), 3.72 x 104A/cm2 (15K, 4T) and 2.34 x 104A/cm2 (25K, 3T). Also the results indicated that small grain size should respond to the large JC in Ti-doped MgB2 tape and MgB2/Fe wire.

Preparation and Enhancement of Critical Current Density in MgB2 Wires and Tapes. Y.Feng, G.Yan, Y.Zhao, C.F.Liu, X.H.Liu, P.X.Zhang, L.Zhou, A.Sulpice, E.Mossang, B.Hebral: Journal of Physics - Condensed Matter, 2004, 16, 1803-11