Influence of cerium addition to the bronze on growth kinetics and superconductivity of bronze-processed Nb3Sn

Growth kinetics of Nb3Sn layers in Ce-doped and Ce-Ti-doped samples were investigated. Their superconducting transition temperatures and critical current densities were measured. The results show that the layer thickness for Ce-doped Nb3Sn are obviously larger than pure Nb3Sn heat treated both at 700 degrees C and 750 degrees C. The layer thickness of the samples which were simultaneously doped with Ti and Ce are less than Ti-doped samples, but larger than others. The Jc difference between samples with small amount of Ce and pure Nb3Sn is not obvious. JC decreases slightly in low-field with increasing Ce content. The critical temperature Tc of Ce-doped samples treated at 700 degrees C are obviously higher than pure Nb3Sn. For the samples heated at higher temperature (750 degrees C), the Tc difference between Ce-doped samples and pure Nb3Sn samples is not obvious, but they are slightly higher than that of Ti-doped samples. It is expected that an optimum superconductor would possess better carrying properties in a wider magnetic field range. Mechanical properties and optical nature such as infrared, far infrared, visible, ultraluminescence spectra for some samples have been studied