Recent investigations on the electronic structure of the fourth and fifth group transition metal monocarbides, mononitrides, and monoxides

Abstract

An overview is given here of band structure calculations on the fourth and fifth group transition metal monocarbides, mononitrides, and monoxides, published since the review article by Calais [J.-L. Calais, Adv. Phys. 26,847 (1977)l. Furthermore, the relations of three categories of experimental properties, which allow insight into the electronic structure of the above mentioned compounds, and the results of band structure calculations are discussed. Theoretical predictions are compared with experimental findings. The considered experimental properties are valence band photoemission spectra, valence band x-ray emission spectra, and optical properties.

Electron Energy Loss Near Edge Structure (ELNES) on the Carbon K-Edge in Transition Metal Carbides with the Rock Salt Structure

“…The deep minimum present -8 eV above the threshold in the 3d compounds also becomes less significant. This is consistent with the band structure calculations of Neckel and co-workers; the band structure of TiC shows a band-gap at a similar energy above the Fermi level [11] whereas that for NbC shows no bandgap in this region [12]. Figure 2, the spectra are shown with an expanded energy scale and reordered to facilitate comparison of compounds with metal species from the same transition series.…”

Electron densities and chemical bonding in TiC, TiN, and TiO derived from energy band calculations

“…3. The results have been discussed in subsequent papers [9-1 I], in review articles [ 1,2], and in references therein. The complete band structures of these three compounds have been shown in Ref.…”

“…They represent the energy dependence of ul(r,E). The coefficients Alp, and BI, are determined by the requirement that the basis functions (2) and ( Table I and are chosen approximately at the center of the corresponding bands. This choice allows to cover all valence bands (over an energy range of about 1 Ry) and the linearization yields accurate bands which agree with the APW energies to within 1 mRy.…”

“…The rock-salt structure is sufficiently simple so that theoreticans are challenged to study the chemical bonding in these systems. Many groups, theoreticans, and experimentalists have thoroughly investigated these compounds and the reader is referred to the review article by Calais [ 11 or the more recent one by Neckel [2].…”

Tight-Binding Description of Tic_{x}

“…Various theoretical attempts have been made to explain the above mentioned experimental findings of both stoichiometric [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and off-stoichiometric [35][36][37][38][39][40][41][42][43][44][45][46] titanium carbides. We classify the recent theoretical works devoted to the study of TiC x in table 1.…”