The doping effect of diamond nanoparticles on the superconducting properties of MgB2 bulk material was studied. It was found that the superconducting transition temperature TC of MgB2 was suppressed by the diamond doping, however, the irreversibility field Hirr and the critical current density JC were systematically enhanced. Microstructural analysis shows that the diamond-doped MgB2 superconductor consisted of tightly-packed MgB2 nano-grains (~50–100nm) with highly dispersed and uniformly distributed diamond nanoparticles (~10–20nm) inside the grains. The high density of dislocations and diamond nanoparticles may be responsible for the enhanced flux pinning in the diamond-doped MgB2.

Doping Effect of Nano-Diamond on Superconductivity and Flux Pinning in MgB2. C.H.Cheng, H.Zhang, Y.Zhao, Y.Feng, X.F.Rui, P.Munroe, H.M.Zeng, N.Koshizuka, M.Murakami: Superconductor Science and Technology, 2003, 16, 1182-6