We have investigated the effect of nano-carbon doping on phase formation, critical current density, flux pinning and irreversibility field in MgB2-x bulk sample where x = 0, 0.05, 0.1, 0.2 and 0.3. XRD results showed a systematic shift of lattice parameter a, which is attributed to carbon substitution, while the lattice parameter c almost did not change as the carbon content increased. Enhancement of magnetic J(c) by two orders at 5 K and 8 T was observed for the sample of x = 0.1, as the J(c)(H) reached the value of > 10(4) at 8 T. In addition, the H-irr of the 5% doped carbon was enhanced from 4.9 T to 5.8 T as compared to the undoped sample. Boron substitution for carbon is proposed to be responsible for the enhancement of flux pinning. (c) 2007 Elsevier B.V. All rights reserved.
Funding
Current limiting mechanisms in magnesium diboride superconductors
Yeoh, W., Kim, J., Horvat, J., Xu, X. & Dou, S. X. (2007). Enhancement of critical current density and irreversibility field by nano carbon substitution in MgB2. Physica C: Superconductivity and its Applications, 460-462 568-569.