▎ 摘　　要

A study of the effects of graphene doping on the superconducting properties of MgB2 bulks prepared by the diffusion method has been conducted over a range of doping levels of 0-30 wt%. The increase in a large quantity of a C-containing non-superconducting phase together with the effects of C-substitution on the phase itself results in a change of superconducting properties. While the transition temperature T-c monotonically decreases with increasing graphene addition, the critical current density J(c) is increased for small graphene additions due to the larger volume fraction of the superconducting phase. Larger additions resulted in larger quantities of the nonsuperconducting phase and consequently these samples have a lower J(c).