Minute pinning and doping additions for strong, 20 K, in-field critical current improvement in MgB2

Minute additions of a combination of Dy2O3 and B4C have been used to enhance both pinning and upper critical field in MgB2. A delicate balance of Dy2O3 and B4C additions is required to improve properties. The Dy2O3 nanoparticles react with B to form 10-15 nm DyB4 nanoparticles, while B4C supplies carbon into the MgB2 crystal lattice and increases the upper critical field. The optimum level of Dy2O3 and B4C additions is similar to 0.5 wt % of Dy2O3 and 0.04 wt % of B4C, yielding a J(c) (20 K) of 10(5) A cm(-2) at 2.7 T. (c) 2007 American Institute of Physics.