Superconducting properties of MgB₂ tapes and films

Akiyoshi Matsumoto, Hiroaki Kumakura
High-Tc Superconducting Wires Group, Superconducting Materials Center

Mission

Magnesium diboride (MgB₂) is a new superconductor discovered in 2001 in Japan. 39 K of transition temperature (T_c) is the highest values among metal superconductors. MgB₂ is one of the promissing candidates for applications at around 10-20K, because of high T_c and no weak link which is big problem for high T_c superconductors. In this research, we are developing the MgB₂ tapes and films with high performances.

The properties of MgB2 tape The upper critical fields(Hc2) of MgB2 single crystal was 9T. On the other hand, Hc2 values of MgB2 tapes havingimpurities such as nano sized SiC increased up to 40T. Critical current densities(Jc) in high magnetic fields also increased with increasing Hc2 values. Fig.1 Jc -B curve of various MgB2 tapes

The properties of MgB2 film Jc properties of MgB2 films in high magnetic fields at low temperatures were much higher than those of tape materials. Jc values in high magnetic fields of our films fabricated by precursor and post-annealing process were almost same as the Nb3Sn wire. Fig.2 Jc -B curve of various MgB2 films