We report the effects of carbon doping on the trapped field properties of MgB2 bulks doped with graphite (C) and B4C, which were prepared by an in-situ hot isostatic pressing method. The trapped fields, BT's were degraded by the graphite and B4C doping above 15 K, which was predominantly due to the lowered Tc by the C substitution. However, the slope of BT(T) and the irreversibility line, Birr(T), determined from the resistive transitions indicated that the BT of the graphite-doped bulk was expected to exceed that of the pristine bulk below 15 K. Contrary to the literature by other groups, B4C did not enhance the vortex pinning properties.
- carbon doping
- trapped field