Nb3Sn thin films and microstructures made by RF magnetron sputtering process with a reacted Nb3Sn powder target

We have been developing a high field pulsed superconductor with a high elastic modulus fiber for reinforcement called FRS (Fiber Reinforced Superconductor). These fiber reinforced superconductors will be formed by magnetron sputtering techniques of two opposed planar targets in future. In this process for Nb3Sn compound a single phase material target would be desired to be developed to shorten the deposition process. We have succeeded to make a sputtering target which consists of Nb3Sn single phase material by powder metallurgy. Fiber reinforced superconductor of Nb3Sn on Ta fiber has been successfully fabricated with this target. The Nb3Sn film as grown on a heated substrate has been attempted to form with this single phase target. The grain morphology was observed on the various films. The post annealed Nb3Sn films made by Nb3Sn single phase material target showed the equiaxed like grains with grain size increasing monotonically with temperature from about 20 nm at 1023 K to 50 nm at 1173 K, but the films as grown on heated substrate showed the columnar like grains with the shorter columnar grain dimension of about 70 nm. (author)