Study of MgB/sub 2/ powders and Cu/MgB/sub 2/ powder-in-tube composite wires with Zn addition

In this paper, we investigate the effect of Zn addition in magnesium diboride. This study comprises free powders and Cu-sheathed wires. The powders were prepared by the solid-state reaction of the elements in a sealed silica tube and it has been observed that most of Zn remained unreacted. However, crystal cell parameters and superconducting transition temperatures varied slightly with the nominal ratio of Zn in the superconductor. Cu sheathed superconducting wires were fabricated by conventional powder-in-tube techniques followed by the in situ reaction of Mg, B and Zn powders inside the Cu tube at temperatures below 700/spl deg/C. The analysis of the X-Ray patterns and the magnetic and electrical properties of the materials obtained from different initial Zn concentration are presented.