  MgB2-diamond nanocomposite superconductors have been synthesized by addition
of nano-diamond powder. Microstructural analysis shows that the nanocomposite
superconductor consists of tightly-packed MgB2 nano-grains (~50-100 nm) with
highly-dispersed and uniformly-distributed diamond nanoparticles (~10-20 nm)
inside the grains. The Jc-H and Hiir-T characteristics have been significantly
improved in this MgB2-diamond nanocomposite, compared to MgB2 bulk materials
prepared by other techniques. Also, the Jc value of 1x104 A/cm2 at 20 K and 4 T
and the Hirr value of 6.4 T at 20 K have been achieved
