Demonstration of better superconducting performance in a solder with low lead content

Lead-free SnIn solders are promising for superconducting magnet applications. However, their superconducting properties are not as good as lead solders. In order to improve the superconducting performance of the Sn-In solders, researchers have investigated the superconducting properties of ternary systems such as Sn-In-Bi for solder joints. In this study, powders of Pb, Nb, AgCu and grapheme nano pellets in the ratios of 0.5-5 wt% have been added into SnIn (35:65) to investigate their microstructural, thermal and superconducting properties. The added materials enhance the superconducting properties. We find that even low Pb additions show a dramatic improvement in superconducting properties, with an increase in both T (c) and J (c) values of up to 6.35 K and 1.47 x 10(4) A m(-2), respectively. This shows that much lower Pb content superconducting solders can be effective and could be used to replace the PbBi solder commonly used with the superconducting properties T (c) =8.4 K, H (C2) = 1.77 T, H (C) = 0.0909 T.