Improved flux pinning properties of Mg exceed MgB₂ ceramics with B₄C and Dy₂O₃ additions

In this study, MgB₂ polycrystals were synthesized via the addition of B₄C and Dy₂O₃. X-ray diffraction confirmed that MgB₂ was the predominant phase in all the samples. The superconducting properties of the samples were characterized by in-field temperature-dependent resistivity and magnetization measurements. The upper critical field (H_c2) and the critical current density (J_c) of each sample were estimated. The results indicate significant enhancements in H_c2 and J_c with the optimal addition levels of B₄C and Dy₂O₃. According to collective pinning theory, δl pinning was identified as the dominant pinning type in the fabricated samples. The dominant pinning mechanism was determined to be core surface pinning induced by grain boundaries, which is consistent with predictions made by the Dew–Hughes model.