Effect of Ti3SiC2 doping on critical current density and flux pinning in MgB2

Ti3SiC2 is used as the dopant, which not only provides C source for C substitution for B in the MgB2 lattice, but also produces more non-superconducting precipitates locating in MgB2 grain boundaries acting as the pinning centers. Carbon substitution of boron can be confirmed by the (1 0 0) peak of MgB2 shift behavior with increasing Ti3SiC2 doping level. The critical current density (Jc) values are determined by M-H hysteresis loops. In low magnetic fields, the Jc values for the undoped sample are higher than that for the doped samples. However, with increasing magnetic fields, the Jc values for the doped samples are found to be enhanced for MgB1.9(Ti3SiC2)0.05 and MgB1.85(Ti3SiC2)0.075. The flux pinning behavior has been investigated and it reveals that the flux pinning force can be improved by Ti3SiC2 doping, when the non-superconducting phases uniformly distribute in MgB2 matrix and they do not depress the intergrain connectivity.

► Ti3SiC2 doped in MgB2 plays a role in both substitution and addition effects.
► The Jc could be improved for MgB1.9(Ti3SiC2)0.05 and MgB1.85(Ti3SiC2)0.075 at the fields larger than 2 T.
► The Fp is significantly enhanced for sample MgB1.85(Ti3SiC2)0.075 at higher magnetic fields.