An attempt to improve the superconducting properties of MgB2 by doping with Zn-containing organic compound

MgB2 doped with C and Zn were synthesised with the addition of different amounts of C4H6O4Zn by a solid-state reaction method. The dopant had a marked effect on the crystal lattice parameters, which was evidenced by the shift in the 2θ angles of the MgB2 peaks in the XRD patterns. The critical temperature of the samples decreased with increasing C4H6O4Zn addition, but the rate of decrease was slower than for those samples that were doped with carbon only. There is no evidence for improvement of the upper critical or irreversibility fields after the doping, however, the normalized volume pinning force density did increase after the doping. The amount of MgO increased significantly as a consequence of the doping, and the MgO decreased the critical current density by blocking supercurrent paths. Phase composition, electrical resistance, and microstructure are used to explain the experimental results.