Monofilamentary In Situ Fe/MgB2 Superconducting Wires Fabricated by Pellet-in-Tube Method

Thin monofilamentary Fe/MgB2 superconducting wires without barriers are investigated by means of electrical transport measurements and surface and structural analysis methods. Small diameter wires are fabricated by pellet-in-tube method (PeIT) to obtain a high uniform initial filling density and heat treated as a function of various sintering temperatures and times. The results are discussed in terms of the grain connectivity, Fe2B phase formation, and the relation between wire diameter and sintering conditions. We suggest that PeIT has a crucial importance to achieve homogeneous initial filling density, which leads to the fabrication of uniform long-length MgB2 wires.