Deviations from Matthiessen's rule in nitrogen doped niobium

Abstract
The deviations from Matthiessen's rule (DMR) were measured between 10K and 320K for high-purity niobium doped with interstitial nitrogen. At temperatures where the residual resistivity is comparable to the ideal resistivity due to electron-phonon scattering, DMR reached a maximum. The results can be described by a 'two-band model'.