Nb3Sn superconducting wire and precursor therefor

A precursor for fabricating a Nb3Sn superconducting wire, the precursor being used for fabricating the Nb3Sn superconducting wire by an internal Sn process, the precursor comprising:

• one or a plurality of stabilizing copper portions collectively disposed in the center, each stabilizing copper portion being provided with a diffusion barrier layer in the periphery thereof;
• and
• a superconducting matrix portion disposed so as to surround the one or the plurality of stabilizing copper portions, the superconducting matrix portion including a Nb or Nb-based alloy core and a Sn or Sn-based alloy core embedded in a Cu or Cu-based alloy matrix,
• wherein the superconducting matrix portion includes an aggregate of precursor elements each including a plurality of Nb or Nb-based alloy cores and at least one Sn or Sn-based alloy core, the aggregate being embedded in a Cu or Cu-based alloy matrix, and
• wherein, apart from the diffusion barrier layer, a diffusion barrier layer made of Nb or an Nb-based alloy is provided for each precursor element.