Structural and superconducting properties of PIT processed sintered MgB2/Fe wires

In this paper, we report the structural and superconducting properties of MgB2/Fe wires that are produced by different sintering conditions. Good quality MgB2/Fe wires are fabricated by the powder-in-tube (PIT) method using commercially available MgB2 powder at ambient pressure. In order to check the annealing effect, the different pieces of the as-rolled wires are sintered at 1323 K for 0.30-1.20 ks. XRD data confirms that they are hexagonal MgB2 structure. All the sintered samples show higher T-c values in the range of 38.2-38.4 K with high J(c) than the as-rolled sample. No significant change in Tc is seen among the annealed samples. On the other hand, the annealed samples show significant change in the Jc values as well as in micro-structural features due to variable sintering time. On annealing at 1323 K for 0.60 ks, we obtain the best quality sample with a J(c) of 372 A/mm(2) at 33.1 K in self-field with a maximum T-c of 38.4 K. Among the annealed samples, 1.20 ks sample shows lower J(c). Longer annealing time reduced J(c), indicating a possible interfacial reaction between the Fe sheath and the MgB2 core. (C) 2004 Elsevier B.V. All rights reserved.