Due to the helium shortage, demand for cost-effective MgB2 superconductors is growing. MgB2 offers high performance without requiring helium cryogenics, even though it operates at lower temperatures than YBa2Cu3Oy superconductors [1]. Its advantages include simpler fabrication, lower-cost materials, and strong superconducting properties. The cost and performance of MgB2 superconductors are influenced by the production of the nano boron powders initially added during manufacturing. We have successfully optimized the UX-600 ultrasonication process for producing low-cost nano boron. By refining parameters such as power, time, and temperature, we reduced the nano boron particle size from 508 nm to 128 nm. This optimization resulted in a significant improvement in critical current performance, increasing from 268 kA/cm² to 461 kA/cm² at 20K and in a self-field—a 72% enhancement, as reported in our latest patent. Furthermore, the critical current was measured at an impressive 657 kA/cm² at 10K and in a self-field, which can be attributed to the fine nano particle formation, as confirmed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. These advancements mark the highest Jc value reported in the literature for bulk MgB2 material produced through sintering. The quality of the MgB2 material was further validated by X-ray diffraction and magnetization-temperature (M-T) measurements. The improved critical current performance is explained by the combination of power, time, and sedimentation processes, which enabled the control of commercial boron particle size to the nano scale for MgB2 production.
[1] J. Nagamatsu, N. Nakagawa, T. Muranaka, Y. Zenitani, J. Akimitsu, Superconductivity at 39K in magnesium diboride, Nature 410 (2001) 63-64.
Keywords: Bulk MgB2 , ultrasonication, nano boron, critical current density