▎ 摘　　要

The key to improve the application of MgB2 is to improve its critical current density J(c) at high magnetic fields. The graphene and reduced graphene oxide (rGO) are added to MgB2 bulks to contribute to the flux pinning and J(c) improvement. Graphene and rGOare added in the ratio of C:B = x:1-x, in which x = 0-5 wt% to the MgB2 bulks. The effects of the graphene and rGO addition on the superconducting properties of MgB2 bulks are investigated. The dense and uniform MgB2 bulks are obtained by diffusion method with the addition of graphene and rGO. The superconducting transition temperature T-c decreases with increasing graphene and rGO addition. The T-c of the rGO-added sample declines more dramatic than that of the graphene-added sample. The addition of graphene and rGO (in the ratio C: B = x:1-x, where x = 1-5 wt%) to theMgB(2) shows the improved J(c) at whole range of magnetic fields compared with the no-added MgB2 sample, except for theMgB(2) sample with 5 wt% of rGO addition. The sample with 1 wt% rGO addition exhibits the highest J(c) value, which is attributed to the improvement of intergrain connectivity and flux pinning caused by appropriate amount of rGO addition. However, nonsuperconducting phase MgB2C2 appears and MgO content increases in the MgB2 bulk samples with 5 wt% rGO addition, which result in the reduction in J(c).