A trapped magnetic field of 3 T in homogeneous, bulk MgB2 superconductors fabricated by a modified precursor infiltration and growth process

作者：Bhagurkar A G^*; Yamamoto A; Anguilano L; Dennis A R; Durrell J H; Babu N Hari; Cardwell D A

来源：Superconductor Science and Technology, 2016, 29(3): 035008.

DOI：10.1088/0953-2048/29/3/035008

• MgB2
• infiltration and growth
• trapped field

The wetting of boron with liquid magnesium is a critical factor in the synthesis of MgB2 bulk superconductors by the infiltration and growth (IG) process. Poor wetting characteristics can therefore result potentially in non-uniform infiltration, formation of defects in the final sample structure and poor structural homogeneity throughout the bulk material. Here we report the fabrication of near-net-shaped MgB2 bulk superconductors by a modified precursor infiltration and growth (MPIG) technique. A homogeneous bulk microstructure has subsequently been achieved via the uniform infiltration of Mg liquid by enriching pre-reacted MgB2 powder within the green precursor pellet as a wetting enhancer, leading to relatively little variation in superconducting properties across the entire bulk sample. Almost identical values of trapped magnetic field of 2.12 T have been measured at 5 K at both the top and bottom surfaces of a sample fabricated by the MPIG process, confirming the uniformity of the bulk microstructure. A maximum trapped field of 3 T has been measured at 5 K at the centre of a stack of two bulk MgB2 samples fabricated using this technique. A steady rise in trapped field was observed for this material with decreasing temperature down to 5 K without the occurrence of flux avalanches and with a relatively low field decay rate (1.5%/d). These properties are attributed to the presence of a fine distribution of residual Mg within the bulk microstructure generated by the MPIG processing technique.

• 出版日期2016-3