Effects of MgO on the Electronic and Superconducting Properties in Succinic Acid (C 4 H 6 O 4 ) Doped MgB 2 Bulks

In this paper, we report the doping effects of succinic acid, C 4 H 6 O 4 (from 0 to 30 wt%) on the lattice parameter, critical temperature ( T c ), critical current density ( J c ), upper critical field ( H c2 ), and irreversibility field ( H irr ) in MgB 2 superconductor. It was found that MgB 2 doped with 10 wt% C 4 H 6 O 4 and sintered at 900 °C exhibited excellent J c above 10 4 A cm −2 at 5 K and 8 T. Impurity scattering due to C substitution, improved crystallinity and the least amount of MgO in 10 wt% doped sample improves J c very significantly. The MgO amount is rapidly increased in 20 and 30 wt% doped samples which causes a strong depression of J c , H c2 , H irr due to poor inter and intra-grain connectivity.