Data on niobium sputtered films obtained by different techniques are presented and discussed. The residual resistivity is shown to be determined by grain boundary scattering. It is then proven that, also in this case, the residual resistivity behaves as a ‘‘universal’’ parameter determining the detailed superconducting properties of the films. The effect of film nonuniformity in the growth direction is also discussed.

• Received 3 February 1995

DOI:https://doi.org/10.1103/PhysRevB.52.4473