Ab Initio Modeling of Boron Impurities Influence on the Electronic and Atomic Structure of Titanium Carbide

The first-principle calculation of boron impurities influence on the electronic and atomic structure of titanium carbide is presented. The density functional theory in the general gradient approximation using the software package ABINIT has been used for numerical calculation. The titanium carbide supercell consisted of 24 atoms. The total energy of titanium carbide supercell and boron impurity atoms with different numbers and locations of impurity atoms was calculated. As a result of this research, it was found that impurity boron atoms showed no tendency to clustering in titanium carbide. The atomic structure changing of titanium carbide in the presence of boron impurities in the substitution and interstitial positions was discussed. The equilibrium distances between adjacent planes of titanium carbide supercell with boron impurities in the substitution and interstitial positions were calculated and analyzed. The boron atoms accumulation on (111) titanium carbide plains leads to an increase in the distance between the adjacent close-packed Ti atoms layers. The electronic structure of titanium carbide, titanium diboride and TiC-supercell with different numbers and locations of boron impurities are discussed. A characteristic feature of titanium carbide supercell spectra with impurity boron atoms is the presence of an impurity subzone, which is located between the local electronic spectra of the 2s and 2p carbon states by about 0.24 Hartry below the Fermi level. There is also a slight increase in the density of electronic states directly below the Fermi level. Different coordinate positions of impurity boron atoms affect only the shape and half-width of the impurity subzone, namely, the half-width of the impurity subzone becomes larger with an increase in the number of impurity atoms in the first coordination sphere of nonmetallic atoms around the impurity.