Superconducting niobium-tin thin film prodn. for HF applications - by reactive vapour deposition at controlled growth rate, ensures good surface quality

摘要

Prodn. of a superconducting Nb3Sn film on a Nb surface for h.f. applications involves heating the Nb surface with a Sn source in an evacuated reactor, so that the Sn diffuses into the Nb surface, a film with a thickness of 0.1-0.4 mu, being produced by adjusting the Sn vapour pressure to give a growth rate of min. 0.05 mu m/h and pref. max 0.3 mu m/h. The prodn. of a very thin Nb3Sn film ensures that the good surface qualities of the Nb substrate are transferred to the film and subsequent surface treatment is made superfluous. Superconductors of this type are useful at frequencies of ca. 10 MHz and more, esp. as resonators and separators for particle accelerators or h.f. resonators for other purposes, e.g. frequency standards or esp. hollow cavity resonators or resonator coils.