Superconductivity in FCC Mo x Nb 1-x (N y C 1-y ) z thin films

In an attempt to prepare the predicted high superconducting transition temperature material MoN, films of Mo x NB 1-x (N y C 1-y ) z where 0.93>x>0, 1.0>y>0.8, and 1.0>z>0.5, have been prepared in a UHV system by reactive rf sputtering of a split Mo-Nb target in mixtures of argon, nitrogen and cyanogen gases. These films prepared at elevated temperatures (600- 800 C) are all single phase FCC (Bl) structure with varying amounts of nitrogen deficiencies. The lattice parameter and Tc are smoothly varying functions of composition with a maximum T c of 18 K for NbN 0.8 C 0.2 T c initially decreases with increasing Mo content reaches a minimum and begins to increase on the very Mo rich composition side where the nitrogen deficiencies in the structure are significant. Nitrogen implantation increases the lattice properties of the Nb rich samples.