Structural stability and electronic properties of XyTa1−yTa2N3, (X=B, C, N, O, F) compounds

Using the plane-wave pseudopotential method, the total energy and electronic structure calculations of XyTa1−yTa2N3, y = 1 (X=B, C, N, O, F) alloys have been performed to understand the structural stability and electronic properties. The exchange–correlation has been treated using the generalized gradient approximation (GGA). The virtual crystal approximation (VCA) was used to study the order/disorder to examine the effect of the substitution of B, N, C, O and F for Ta in the cell corner on the structural stability. The results show that the substitution of B, C, N, O and F for Ta at the corner sites slightly changes the lattice constant. We have evaluated the ground state quantities such as lattice constant, bulk modulus and elastic constants. We derived the bulk and shear moduli, Young’s modulus and Poisson’s ratio for an ideal polycrystalline c(X)(Ta2N3)(X=B,C,N,O,F) aggregate. Also, the results of densities of states are presented. The elastic, mechanical and electronic properties of c(X)(Ta2N3)(X=B,C,N,O,F) alloys are predicted. Also, the Debye temperature ( θ D ), TDOS at the Fermi level n ( E f ) , the X-p (X==B,C,N,O) states and the enthalpies of formation of the XTa2N3 compounds are investigated.