The physical properties of ThCr2Si2-type Ru-based compounds SrRu2X2 (X = P, Ge, As): An ab-inito investigation

Abstract We have studied the physical properties containing structural, elastic, mechanical, electronic, optical and thermodynamic properties of recently discovered SrRu 2 X 2 (X = P, Ge, As) type compounds. All the calculations have been performed by the first-principles method depend on the density functional theory (DFT) with generalized gradient approximation (GGA). For all phases the optimized lattice parameters show a good agreement with the available experimental data. The elastic constants for all compounds are positive which ensures that all phases possess the mechanical stability in nature. The calculated values of Pugh's ratio and Poisson's ratio refer the brittle nature of SrRu 2 P 2 and SrRu 2 Ge 2 and ductility behaviors of SrRu 2 As 2 . The zero value of the Universal anisotropy index A U and also the zero value of the percentage of anisotropy in compression and shear ( A B and A G ) represent the pure isotropic compounds. For any others values compound processes the anisotropic characteristics. The calculated values of A U , A B and A G ensure that all these phases have anisotropic characteristics in nature. The values of Vickers hardness indicate that the rigidity decreases in the order of SrRu 2 Ge 2 >SrRu 2 P 2 >SrRu 2 As 2 . Since the conduction band and valence band are overlapped at the Fermi level so the band structure analysis ensures the metallic character of all these phases. The analysis of Mulliken population and charge density ensure the existing of ionic and covalent bonds in these phases. The investigation of dielectric function also ensures the metallic behavior of these compounds. The thermodynamic study provides the Debye temperature of SrRu 2 P 2 , SrRu 2 Ge 2 and SrRu 2 As 2 are 363.86 K, 334.92 K and 329.83 K correspondingly.