Formation of superconductors by YAG laser irradiation of laminated thin layers

CO2 laser beam irradiation was successfully applied to the formation of several intermetallic compound superconductors e.g., Nb3Al and Nb3Ge. In the case of Nb3Al, for example, a composite tape of Nb containing powders of Nb and Al is irradiated with a CO2 laser beam of >1 kW. When irradiated, the powders are instantaneously heated and partially melted in the tape moving at a rather high velocity, typically 10 m/min, and very rapidly solidified. This results in the formation of Nb3Al of high stoichiometry. In this process, however, most of the high power emitted is probably reflected at the shiny surface of the Nb sheath. Since both high power and high moving velocity are needed, the process consumes energy and is not controllable. In the present study a new and well controlled process was developed where YAG laser beam irradiation was combined with thin layer formation techniques to produce superconductive tapes of NbC, NbN, Nb3Al, etc. The results may be summarized as follows: A controllable process for producing superconductive tapes is possible by using a YAG laser based apparatus operated at power levels of 10-100 W. In this process carbon coating is essential. This helps the absorption of the laser beam by the tape and induces reactions among the elements in the tape. In the case of superconductors containing C, the coating provides an essential component