Enhanced magnetic critical current density of MgB₂ at 20 K via Co-doping with nano-aluminum and nano-carbon

مقال فى مجلة

2026

تم النشر فى: https://doi.org/10.1016/j.physc.2025.1354776

We report a systematic investigation of the structural, electrical, and magnetic properties of Al–C co-doped MgB₂ superconductors with the nominal formula Mg1₋xAlₓ(B1₋yCy)₂, where x = 0.02 and y varies from 0 to 0.06. X-ray diffraction (XRD) confirms successful incorporation of dopants, along with a reduction in lattice parameter a from 3.0848 Å (pure) to 3.0654 Å (C6 %Al2 %), indicating carbon substitution at the B site. SEM analysis shows progressive grain refinement with doping, and crystallite size decreases from 26.86 nm (pure) to 18.71 nm (C4 %
Al2 %), contributing to enhanced flux pinning. Electrical transport measurements reveal increased residual re-sistivity and reduced RRR with doping, from 77.9 μΩ⋅cm and 2.67 (pure) to 880.5 μΩ⋅cm and 1.6 (C6 %Al2 %), respectively. Despite these changes, the superconducting transition temperature (TC) remains relatively high, decreasing modestly from 38.5 K (pure) to 36.2 K (C6 %Al2 %). Magnetization measurements at 20 K demon-strate significantly enhanced magnetic critical current density (JC) with optimal doping. The C1 %Al2 % sample exhibits a JC of 1.1 × 104 A/cm² at 3 T — nearly six times that of the undoped sample (1.9 × 103 A/cm²). The irreversibility field (Hirr) also peaks at ~5.3 T for this composition. These results confirm that moderate Al–C co-doping effectively enhances flux pinning while preserving superconducting performance, making MgB₂ a promising candidate for mid-field superconducting applications.

• نوع عمل المنشور: دكتوراه