Structural, mechanical and phonons properties of binary intermetallic compound BaSn3 under pressure

Abstract

In this work, based on first-principle calculations, the structural, mechanical and phonons properties of binary intermetallic compound BaSn3 have been studied through the PBEsol-GGA scheme in the framework of DFT. The ground-state properties such as bulk modulus (B), pressure derivative (B0), the lattice constants (a0, c0), bond-lengths and unit cell volume are presented in detail from 0 GPa to 100 GPa. The results show a significant impact of the pressure on these parameters, and the axial compressibility along the c axis is always stiffer than the a-axis. Our calculations are in accord with the previously measured ones which prove the validity and the accuracy of the chosen theoretical approach.Furthermore, polycrystalline elastic constants, the single-crystal, and its pressure dependence are numerically predestined. After analyzing the calculated elastic constants, it is shown that this compound is mechanically stable over the pressure range of 0 GPa–100 GPa and shows a very weak resistance to elastic shear deformation. The mechanical properties obtained from the calculated values of elastic constants and its relevant quantities, such as hardness parameter Hv, bulk modulus B, Young's modulus E, shear modulus G, have been reported. The dependence of the elastic constants Cij, the aggregate B, G moduli, and the anisotropies on pressure have been investigated. Moreover, the calculated value of Young's and shear moduli affirms the softening behavior of this material. Besides, brittleness/ductility for BaSn3 is further estimated by calculating the ratio of B/G, Poisson's ratio and Cauchy pressure. Among the intermetallic compound, BaSn3 is found to be a brittle system at the low pressure whereas it exhibits ductile deformation behavior at high pressure. Furthermore, the mechanical anisotropy proved by analyzing several anisotropy indexes (A1, AU, A3,..), 3D curved surface of Young's moduli that this compound is elastically anisotropic, and strongly pressure dependent. The Debye temperature is also obtained from calculating the mean elastic wave velocity in different directions of the single crystal. We also performed calculations for phonon dispersions at high pressure. It's found that this structure is dynamically stable under pressure.