ELECTRONIC-STRUCTURE OF NB-MO ALLOYS

Thermoreflectance measurements on NbxMo1-x alloys (x=0.2,0.5,0.8) have been carried out in the 0.5-5.0 eV energy region. Augmented-plane-wave (APW) calculations for Nb at two different lattice parameters and for Mo, as well as coherent-potential-approximation calculations (CPA), have been carried out and have been used in the interpretation of the experimental results. Several optical transitions [1(EF)→3, G4(EF)→G1,N2→N′;1], have been identified, and their concentration dependence followed. These results contribute significantly toward putting the interpretation of the optical properties of Nb, Mo, and their alloys on a much more secure footing. In particular, it has been confirmed that while the lower conduction bands behave roughly as predicted by the rigid-band model, the higher-lying conduction bands show distinctly non-rigid-band-like behavior. © 1979 The American Physical Society.