PRODUCTION OF NIOBIUM TITANIUM NITRIDE COATINGS BY REACTIVE DIFFUSIONFOR SUPERCONDUCTING CAVITY APPLICATIONS

In view of their potential interest for the construction of radiofrequ ency superconducting cavities for particle accelerators, surface coati ngs 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 me asurements, 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 transitio n width of 0.2 K, may be obtained.