Nano-scale TiB$_{2}$ Precipitates in MgB$_{2}$ Superconducting Wire*

Superconducting MgB$_{2}$ wire containing uniformly dispersed, nano-scale TiB$_{2}$ precipitates has been produced using a plasma synthesis method to make the starting Ti doped B powder. A powder-in-tube method is used for making the wire. Sub-micrometer size MgB$_{2}$ grains are decorated with a random dispersal of 5 to 20 nm precipitates. The superconducting properties are reported for a family of powder-in-tube wires fabricated with pure boron, carbon doped boron, and titanium doped boron. The particle size of the doped boron powder, of 50 to 100 nm, permits low reaction temperatures and short reaction times. The best reaction temperatures are in the neighborhood of 700 C for reaction times of approximately 20 min. For the Ti doped, PIT wire, at T = 20 K, J$_{c}$ crosses 10,000 A/cm$^{2}$ at 1.8 T.