Electronic properties of Ti3SiC2-based solid solutions

The electronic structure of the silicocarbide Ti3SiC2 has been determined by the full-potential linear-muffin-tin-orbital (FLMTO) method. The spectra of the core-electron levels and valence bands of Ti3SiC2 have been obtained by x-ray photoelectron spectroscopy (XPS) and compared with the results of FLMTO calculations and x-ray-emission spectroscopy (XES) data. Using XPS data of the inner electron levels (Ti 2p (3/2), Si 2p, and O Is) and the results of band calculations, the nature of chemical bonding in the silicocarbide was analyzed. The high plasticity of Ti3SiC2 is explained by a weak interaction between the layers comprising Ti6C octahedra and plane nets composed of silicon atoms. The electronic and cohesive energy properties of the nonstoichiometric Ti3SiC and hypothetical Ti3SiC2-based solid solutions (SS's), namely Ti3SiCN and Ti3SiCO, were simulated by the FLMTO method. An analysis of the cohesive properties shows probable destabilization of the hexagonal structure of Ti3SiC2 in the presence of C vacancies and oxygen impurities. By contrast, the partial substitution of N for C (Ti3SiCxN1-xSS's) should lead to an increase in the cohesive properties of the crystal. [S0163-1829(98)02148-1].