Proximity effect controlled superconducting behavior of novel biphasic Pb–Sn nanoparticles embedded in an Al matrix

We report the synthesis of biphasic Pb (46 at.%)–Sn (54 at.%) nanoparticles dispersed in an aluminum matrix and explore the nature of the superconducting transition in these particles. The nanoscaled Pb–Sn alloy particles were dispersed in Al by rapid solidification and the two-phase nature of these particles was characterized by transmission electron imaging, diffraction and composition mapping. A weak superconducting transition occurs at 3.1 K in these alloys, which is much lower than the TC expected for a Pb46Sn54 alloy or that due to the proximity effect between Pb and Sn. We show that it is the superconducting Al matrix with TC = 1.2 K that plays a major role in determining the effective transition temperature of the system.