Structural, mechanical and thermodynamic properties of N-dope BBi compound under pressure

The structural, mechanical and thermodynamic properties of N-dope BBi compound have been reported in the current study. The structural and mechanical results of the studied binary compounds (BN and BBi) and their ternary alloys BBi1-xNx structures are presented by means of density functional theory. The exchange and correlation effects are taken into account by using the generalized gradient approximation functional of Wu and Cohen which is an improved form of the most popular Perdew-Burke-Ernzerhof. The quasi-harmonic Debye model is used for the thermodynamic properties of studied materials. The basic physical properties of considered structures such as the equilibrium lattice parameter (a(0)), bulk modulus (B-0), its pressure derivative (B'), elastic constants (C-11, C-12 and C-44), Kleinman's internal-strain parameter (nu), shear modulus anisotropy (A), the average shear modulus (G), Young's modulus (Y) and Poisson's ratio (v), B-0/G ratio, microhardness parameter (H), Cauchy pressure (C ''), and 1st and 2nd Lame constants (lambda, mu), debye temperature (theta(D)), wave velocities (nu(l), nu(t) and nu(m)), melting temperature (T-m) and minimum thermal conductivity (kappa(min)) have been calculated at zero pressure. In order to obtain more information, thermodynamic properties, such as internal energy (U), Helmoltz free energy (F), entropy (S), Debye temperature (theta(D)), thermal expansion (alpha), constant volume and pressure heat capacities (C-V and C-P), are analyzed under the whole range from 0 to 20 GPa and temperature range from 0 to 1500 K. The obtained results of the studied binary compounds are in coincidence with experimental works. Graphical Abstract The calculated constant volume specific heat, CV, and constant pressure specific heat, CP, as functions of temperature for BN. [GRAPHICS] .