Abstract
In this study, we report an enhancement of critical current density of bulk MgB
2
superconductors by glutaric acid (C
5
H
8
O
4
) doping. The effects of glutaric acid doping on MgB
2
lattice resulted in a record self-field
J
c
of the order of 10
6
A/cm
2
. 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 MgB
2
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 MgB
2
superconductor samples.