Insight into mechanical and thermodynamic properties of Al2Si2La and Al2Si2Pr from first-principles calculations

The crystal structures, stability, mechanical behaviors, thermodynamic properties and electronic structures of Al2Si2La and Al2Si2Pr compounds have been investigated by means of first-principles calculations. It is revealed from formation enthalpies that Al2Si2La exhibit much more thermodynamically stability. According to the results of elastic constants, Al2Si2Pr has stronger incompressibility, stronger shape deformation resistance and higher stiffness. It can be concluded from Debye temperature and minimum thermal conductivity that Al2Si2Pr and Al2Si2La exhibit nearly the same thermal conductivity. Electronic structures results demonstrate that the Al-Si bonds in Al2Si2La and Al2Si2Pr are attributed to the hybridization of Al 3s state, Al 3p state and Si 3p state, while RE-Si bonds are the contribution of Si 3p state and La 5d or Pr 4f state in Al2Si2La and Al2Si2Pr, respectively.