Influence of Additional Nickel and Sinter Temperature of MgB2: Micro-Structural Characteristics, Phase Transformation, and Superconductivity

The development of materials and manufacturing techniques is essential for optimizing the superconducting properties of MgB₂-Ni alloys, which hold promise for applications such as electrical cable transmission, MRI magnets, and maglev systems. In this study, MgB₂-Ni alloys were synthesized using the Powder in Sealed Tube (PIST) method, where powdered magnesium (Mg) and boron (B) were doped with nickel (Ni) to enhance superconductivity. The sealed powders were compressed in stainless-steel tubes and sintered at various temperatures (750 °C, 800 °C, and 850 °C) to identify the optimal conditions for phase formation and material performance. Phase formation was characterized by X-ray diffraction (XRD), while scanning electron microscopy (SEM) was used to assess the microstructure, and cryogenic measurements determined the critical temperature (Tc). Our results show that Ni doping improves crystallinity and increases the crystallite size, with a maximum of 46.6 nm achieved with the addition of 2 wt.% Ni. The distribution of Mg-B-Ni grains was uniform, contributing to enhanced superconducting properties. Low-temperature resistance tests revealed that the critical temperature (Tc onset) increased from 41.7 K in undoped samples to 42.3 K with 2 wt.% Ni, highlighting the positive impact of Ni doping. These findings suggest that 2 wt.% Ni is the optimal composition for improving both crystallinity and Tc, providing valuable insights for further optimizing MgB₂-based superconductors for high-performance electrical and magnetic applications.