Decoupling Substitution and Connectivity in Chalcone‐Doped MgB 2 via Spark Plasma Sintering

Pure and C 15 H 12 O (chalcone)‐doped MgB 2 bulk superconductors were synthesized via spark plasma sintering (SPS) at 850°C under 50 MPa. The influence of organic doping on structural, electrical, and magnetic properties was systematically investigated. Phase analysis via XRD and T c measurements confirmed successful carbon substitution into the MgB 2 lattice, evidenced by an a ‐axis contraction. Magnetic characterization at 20 K revealed that low doping levels (5 wt%) enhance critical current density ( J c ) and pinning force ( F p ) by forming effective nanoscale pinning centers at grain boundaries. However, higher doping concentrations significantly degrade performance, particularly in high magnetic fields. This degradation is attributed to reduced grain‐to‐grain connectivity caused by increased porosity and the accumulation of non‐superconducting secondary phases (MgO and amorphous carbon) resulting from the organic precursor's decomposition. Dew–Hughes analysis indicated a shift in pinning behavior, reflecting a trade‐off between enhanced flux pinning and compromised connectivity. The results highlight the critical importance of balancing lattice substitution and inter‐grain binding in organic‐doped MgB 2 systems, demonstrating the potential of chalcone as an effective carbon source for optimized superconducting applications.