MgB 2 for MRI applications: dual sintering induced performance variations in in situ and IMD processed MgB 2 conductors

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2020-02, Vol.8 (7), p.2507-2516
• Main Authors: Patel, Dipak, Matsumoto, Akiyoshi, Kumakura, Hiroaki, Maeda, Minoru, Kim, Su-Hun, Al Hossain, Md Shahriar, Choi, Seyong, Kim, Jung Ho
• Format: Article
• Language: English
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C9TC06114B

Magnesium diboride (MgB 2 ) is known to have good potential to be used in a commercial liquid helium-free magnetic resonance imaging (MRI) magnet. The magnet is expected to be fabricated using reacted MgB 2 conductors to minimize modifications in the existing magnet production technologies and operated in the persistent mode by forming a closed-loop using superconducting joints. The superconducting joints of the reacted MgB 2 conductors are typically formed by placing unreacted magnesium and boron powders in between them followed by sintering. During this process, the MgB 2 conductors will inevitably experience dual sintering in the vicinity of the superconducting joints. However, the effects of dual sintering on the performance of MgB 2 conductors are still unknown. Therefore, herein, we dual sintered commercially available multifilament in situ and laboratory-made monofilament internal magnesium diffusion (IMD) processed MgB 2 conductors (un-doped and C-doped) and evaluated their transport performance, microstructure, lattice parameters, and critical temperature in detail. In the IMD processed wires, the C-doped boron powder was found to promote a better diffusion of magnesium compared with the un-doped boron powder. Under typical dual sintering conditions, surprisingly, the C-doped in situ wire showed a simultaneous improvement in the engineering critical current density and n -value in different magnetic fields at 4.2 K and 20 K. On the other hand, the remaining conductors showed a strong dual sintering induced transport performance variation. Our findings provide insights into MgB 2 conductors' performance after dual sintering for their further development towards MRI applications.