Superconducting Properties of Reactively Sputtered Thin-Film Ternary Nitrides, Nb–Ti–N and Nb–Zr–N

Superconducting critical fields, currents, and temperatures of reactively sputtered thin films of Nb–Ti–N and Nb–Zr–N ternary alloys have been determined as a function of composition, and these properties are compared with those of sintered bulk nitrides of the same composition. The thin films have substantially higher critical current densities, higher critical fields, but lower critical temperatures than the bulk samples. In fields as high as 136 kOe, the Jc characteristics of the nitride films compare favorably with the thin-film characteristics of Nb3Sn and V3Si. The Jc-H properties of the nitride films are relatively insensitive to the Nb:Ti(Nb:Zr) ratio, a characteristic which favors these materials for certain practical applications such as thin-film solenoids. An unusual temperature independence of the electrical resistance was found for several compositions.