Enhancement of critical current density ofin situprocessed MgB2tapes by WB addition

The effect of tungsten boride (WB) addition on the microstructure and superconducting properties of Fe-sheathed MgB 2 tapes has been investigated. The microstructure was not influenced appreciably by the addition, whereas the superconducting properties changed. Even by a 5 mol% addition, the critical temperature ( T c ) decreased by about 0.5 K. However, the field dependence of the inductive critical current density ( J ci ) became smaller with the increase in the amount of addition, suggesting that pinning centres effective in a high-field region were possibly introduced. The transport critical current density ( J ct ) at 4.2 K increased about twice by the 5 mol% addition and reached 15 and 5 kA cm −2 at 8 and 10 T, respectively.