Grain size and film thickness of Nb3Sn formed by solid-state diffusion in the range 650–800 °C

A simple etching and replication technique for the determination of grain size in thin films of Nb3Sn has been established. The resulting data compares well with previous reports of grain size as a function of reaction temperature and of the pinning force Fpmax as a function of grain size. The possibility of an optimum grain size for Fpmax is indicated.