Electronic properties ofTi3SiC2-based solid solutions

The electronic structure of the silicocarbide ${\mathrm{Ti}}_3{\mathrm{SiC}}_2$ has been determined by the full-potential linear-muffin-tin-orbital (FLMTO) method. The spectra of the core-electron levels and valence bands of ${\mathrm{Ti}}_3{\mathrm{SiC}}_2$ 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 $1s$) and the results of band calculations, the nature of chemical bonding in the silicocarbide was analyzed. The high plasticity of ${\mathrm{Ti}}_3{\mathrm{SiC}}_2$ is explained by a weak interaction between the layers comprising ${\mathrm{Ti}}_6\mathrm{C}$ octahedra and plane nets composed of silicon atoms. The electronic and cohesive energy properties of the nonstoichiometric ${\mathrm{Ti}}_3\mathrm{SiC}$ and hypothetical ${\mathrm{Ti}}_3{\mathrm{SiC}}_2$-based solid solutions (SS’s), namely ${\mathrm{Ti}}_3\mathrm{SiCN}$ and ${\mathrm{Ti}}_3\mathrm{SiCO},$ were simulated by the FLMTO method. An analysis of the cohesive properties shows probable destabilization of the hexagonal structure of ${\mathrm{Ti}}_3{\mathrm{SiC}}_2$ in the presence of C vacancies and oxygen impurities. By contrast, the partial substitution of N for C $({\mathrm{Ti}}_3{\mathrm{SiC}}_x{\mathrm{N}}_{1-x}$ SS’s) should lead to an increase in the cohesive properties of the crystal.