Ab initio simulation on structural, mechanical, electronic, optical and thermodynamic properties of disilicide materials ThX2Si2 (X = Ru, Rh, Ir, Pt)

Abstract

The present dissertation reports a comprehensive investigation of the structural, bulk, electronic, optical and thermodynamics features of Th-based intermetallics compounds ThX₂Si₂ (X = Ru, Rh, Ir, Pt). All the investigation was completed using ab initio scheme depend upon the density functional theory. Extremely well concurrence involving the experimental records and our calculated values of all the compounds has been observed. The dynamical and structural stability is ensured from phonon dispersion curves and formation enthalpy calculations. The investigated elastic constants show positive values and hold Born’s stability criteria which confirmed the mechanical stable nature of these materials. The large bulk and Young’s moduli of ThX₂Si₂ (X = Ru, Rh, Ir, Pt) ensured their high stiffness characteristics whereas ThIr₂Si₂ carries high stiffness characteristics. Except the phase ThIr₂Si₂, the phases ThRu₂Si_2, ThRh₂Si₂, ThPt₂Si₂ show ductility nature as ensured from Pugh's ratio and Poisson's ratio data. According to hardness calculations only the phase ThIr₂Si₂ shows hard nature whereas the phase ThRh₂Si₂ lies on the hardness border line. On the other hand, the remaining phases ThRu₂Si₂ and ThPt₂Si₂ show soft nature as they have hardness value below 10 GPa. High machinable index, µ_m of ThPt₂Si₂ compared to other phases ensures it high industrial application for cutting tool geometry, cutting fluids and so on. ThX₂Si₂ (X = Ru, Rh, Ir, Pt) materials exhibit metallic behavior ensured by the explanation of band structure, DOS and optical phenomena. At UV energy region, the major peak of absorption and conductivity is observed. The studied intermetallics can be good candidates for solar reflector in UV region as they possess high reflectivity in UV zone. ThRh₂Si₂ is thermally more conductive among other three compounds because of its large Debye temperature. The high melting temperature and extremely lower thermal conductivity of ThX₂Si₂ (X = Ru, Rh, Ir, Pt) ensured their potential use in Thermal Barrier Coating (TBC) materials.