An X-Ray Spectral Study of Some Compounds of Niobium and Carbon

The emission spectra of the niobium carbides NbC0.66, NbC0.83, and NbC0.98 have been investigated. An increase in the intensity of the second region of the band and a decrease in that of the short-wave region have been observed. This is due to an increase in the number of local Nb-C bonds with rise in carbon concentration. The concentration of collective electrons varies only slightly, being 2.7–3.6 × 1022 cm-3. It is concluded that there is a reduction in the weight of d-states in the wave functions of the collective electrons as compared with pure niobium and that the value is 0.5–0.66.