Doping and effect of nano-diamond and carbon-nanotubes on flux pinning properties of MgB2

Doping effects of two types of nano-carbons: nano-diamond and carbon-nanotubes (CNTs), on the flux pinning properties of MgB2 bulk materials have been studied. Compared with nano-diamond, CNTs is prone to be doped into MgB2 lattice. Nano-diamond doping improves Jc(H) characteristics more significantly than CNTs doping in MgB2. TEM analysis reveals a unique microstructure in diamond-doped MgB2, which consists of tightly packed MgB2 nanograins (50-100 nm) with dense distribution of diamond nanoparticles (10-20 nm) inside the grains. Relatively, such a unique microstructure is not easy to form in CNTs-doped MgB2 due to an active reaction between CNTs and MgB2.