Production of niobium titanium nitride coatings by reactive diffusion for superconducting cavity applications

In view of their potential interest for the construction of radiofrequency superconducting cavities for particle accelerators, surface coatings of (Nb1-xTix)N have been produced by heating Nb1-xTix sheets in a nitrogen atmosphere, Samples of two different compositions, namely Nb0.37Ti0.63 and Nb0.55Ti0.45, have been treated to optimise the process parameters. The results have been evaluated by critical temperature measurements, metallographic examinations and X-ray diffraction. In the best cases a homogeneous ternary phase of sufficient thickness (up to 2 mu m), providing a critical temperature up to 17.2 K and a transition width of 0.2 K, may be obtained.