▎ 摘　　要

Graphene nanopowder (G) with average thickness particle size of about 6-8 nm was added to MgB2 commercial powder. Starting composition was (MgB2)((1-x))(G)(x),x = 0.0125, 0.025, 0.05. Processing was performed by Spark Plasma Sintering (SPS) technique. All added samples have high density (above 95%). The critical temperature (T-c) and the lattice parameter a (c-axis lattice parameter is constant) show a small variation suggesting that carbon substitution for boron is low. TEM observations show the presence of un-reacted graphene plates supporting the T-c and structural results. It also indicates that G-addition does not modify the MgB2 microstructure. Despite this, there is an optimum doped sample (MgB2)(0.9875)(G)(0.0125) for which the critical current density at temperatures below 25 K is slightly higher at high magnetic fields than for the pristine sample. The addition of G is found as one of the least effective C-source additions enhancing J(c). We discuss results as being strongly related to variation of the residual stress. (C) 2016 Elsevier Ltd. All rights reserved.