High Trapped Fields in C-doped MgB 2 Bulk Superconductors Fabricated by Infiltration and Growth Process

• Published in: Scientific reports Vol. 8; no. 1; p. 13320
• Main Authors: Bhagurkar, A G, Yamamoto, A, Wang, L, Xia, M, Dennis, A R, Durrell, J H, Aljohani, T A, Babu, N H, Cardwell, D A
• Format: Journal Article
• Language: English
• Published: England 06.09.2018
• ISSN: 2045-2322

The grain boundaries in superconducting MgB are known to form effective magnetic flux pinning sites and, consequently, bulk MgB containing a fine-grain microstructure fabricated from nanoscale Mg and B precursor powders exhibits good magnetic field-trapping performance below 20 K. We report here that the trapped field of MgB bulk superconductors fabricated by an infiltration and growth process to yield a dense, pore-free microstructure, can be enhanced significantly by carbon-doping, which increases intra-band scattering within the superconducting grains. A maximum trapped field of 4.15 T has been measured at 7.5 K at the centre of a five-sample stack of Mg(B C ) bulk superconductors processed by infiltration and growth, which not only represents a ~40% increase in trapped field observed compared to undoped bulk MgB , but also is the highest trapped field reported to date in MgB samples processed under ambient pressure. The trapped field is observed to decay at a rate of <2%/day at 10 K, which suggests that bulk MgB superconductors fabricated using the infiltration and growth technique can be used potentially to generate stable, high magnetic fields for a variety of engineering applications.