Dense MgB2/Fe/Cu wires, with and without Zr doping, were successfully prepared via the in situ powder-in-tube method. MgB2/Fe/Cu wires were sintered (650 to 850C, 2h) in Ar. The critical current density of the wires was measured at various temperatures in magnetic fields of up to 8T, using a standard 4-probe method. As shown by inductive measurements, the heat treatment temperature had an obvious influence upon flux pinning in MgB2 wire. It was also found that the flux-pinning in MgB2 wire could be markedly improved by Zr doping. Microstructural observations of MgB2 wires showed that MgB2/Fe/Cu wires with Zr doping had a better grain connectivity and a higher density than did other samples. The mechanism leading to high transport critical current densities of MgB2/Fe/Cu wires based on MgB2 grain size was considered. The results indicated that JC could be further improved, to meet the requirements of applications, by optimizing the process conditions.

Significant Enhancement of Flux Pinning in MgB2/Fe/Cu Superconducting Wires Fabricated by in situ Powder-in-Tube Method. Y.Feng, G.Yan, Y.Zhao, P.X.Zhang, E.Mossang, A.Sulpice, L.Zhou: Physica C, 2005, 426-431[2], 1216-9