The effect of NbxB2 addition on the critical current density in applied magnetic fields (JC–B characteristics) of Fe-sheathed MgB2 tapes prepared via an in situ powder-in-tube technique was investigated. The results showed that the JC–B characteristics of MgB2 tapes were enhanced by the addition of an appropriate amount of NbxB2. This effect was considered to be due to the introduction of a pinning center and the densification of the superconducting core. Furthermore, the effect of NbxB2 addition was not dependent upon the stoichiometry of Nb. The NbxB2 had the same crystal structure as MgB2 (AlB2 type), and the lattice parameter was close to that of MgB2, hence utilization of NbxB2 was expected to have some advantages in the tape fabrication of MgB2.

Effect of NbxB2 Addition on the JC–B Characteristics of MgB2 Tapes. T.Nakane, H.Takeya, H.Fujii, H.Kumakura: Superconductor Science and Technology, 2005, 18, 521-5