Structural, elastic, electronic, optical and thermal properties of YMAu (M = Si or Ge or Sn) Half-Heusler compounds; A DFT study

Abstract

The structural, elastic, electronic, optical and thermal properties of the half-Heusler alloys; YSiAu, YGeAu and YSnAu were investigated using the density functional theory. For the YSiAu, YGeAu and YSnAu HH alloys, equilibrium lattice constants of 6.462 Å, 6.540 Å, and 6.739 Å were determined; these values are comparable to previous theoretical studies. The alloys’ elastic constants fulfill the Born-Huang requirements for cubic system stability and absence of imaginary phonons, suggesting that the alloys are mechanically and dynamically stable. Band gaps of 0.5366 eV, 0.2579 eV and 0.2959 eV for YSiAu, YGeAu and YSnAu structures respectively were computed by HSE hybrid functional. Degeneracy in TO modes in the YSiAu, YGeAu and YSnAu HH alloys suggest lower thermal conductivity due to scattering. YSnAu and YGeAu HH alloys have broad absorption spectrum ranging from 1 eV to 15 eV with prominent peaks appearing inside the visible area which implies that the two materials are suitable for solar absorption.

Keywords

• Half-heusler
• YSiAu
• YGeAu
• YSnAu
• DFT