Abstract
•Pure and Melanin doped MgB2 were synthesized under the same conditions in one batch.•The in-field critical current density, JC, enhancement was specified.•Flux pinning mechanisms were appointed.•Transition temperature and critical fields were determined from magnetic measurements.
In this work, the melanin-doped MgB2 samples were prepared under the same condition at different sintering temperatures. The XRD quantitative analysis indicates an increase in crystallite size with increasing sintering temperature. The pinning mechanism tends to be a collective of surface and point pinning in an indication of the role of the impurities and secondary phases in the forming of flux pinning centers. The electrical and magnetic measurements show significant enhancement on critical current density obtained from the doped samples compared to the pure ones. Enhancing critical current density and critical fields depend on the sintering conditions. Sintering at low-temperature results in a high critical current density and critical field values. The resistivity and the related superconducting parameters measurements were also completed.