Enhancement of Critical Current Density of MgB 2 by Glutaric Acid Doping: a Simultaneous Improvement on the Intrinsic and Extrinsic Properties

In this study, we report an enhancement of critical current density of bulk MgB2 superconductors by glutaric acid (C5H8O4) doping. The effects of glutaric acid doping on MgB2 lattice resulted in a record self-field J c of the order of 106 A/cm2. A simultaneous improvement in the connectivity, pinning force, and H c2 is the major factor that determined excellent J c performance. X-ray diffraction analysis showed that samples were single-phase MgB2 with a minor trace of impurities. A dramatic change in grain morphology and homogeneity in grain distribution was found in the SEM images of doped samples. We observed that homogeneity in grain distribution played a crucial role in the connectivity and the upper critical field (H c2) of the doped samples. We were able to introduce a new dopant through a two-step mixing approach which is suitable to overcome the degradation of low field and self-field J c reported for carbon-doped MgB2 superconductor samples.