DFT study of structural, mechanical, electronic, and thermoelectric properties of YNbNi2X2 (X=Si or Ge) double half-Heusler alloy

This work examines the structural, mechanical, electronic, and thermoelectric characteristics of YNbNi 2 X 2 (X = Si, Ge) double half-Heusler alloys using density functional theory (DFT) computations. Thermodynamic stability was demonstrated by formation energy estimates, and mechanical parameters show ductile behavior with good mechanical stability. YNbNi 2 Si 2 and YNbNi 2 Ge 2 exhibit semiconducting characteristics, with indirect band gaps of 0.51 eV and 0.56 eV, respectively. The Boltzmann transport equation is used to investigate thermoelectric properties, which yield promising Seebeck coefficients and electrical conductivities. The dimensionless figure of merit (ZT) for YNbNi 2 Ge 2 and YNbNi 2 Si 2 peaks at 0.85 and 0.68 at 300 K respectively. However, these values should be regarded as upper limits, as only the electronic contribution to thermal conductivity was considered, and the lattice contribution was not explicitly calculated. The figure of merit ( Z T ) increases with temperature suggesting that these are potential materials for energy harvesting applications at high temperature. • YNbNi 2 Si 2 and YNbNi 2 Ge 2 alloys exhibit thermodynamical and mechanical stability. • Both alloys are semiconductors with indirect band gaps of 0.51 eV and 0.56 eV, respectively. • Electronic figure of merit (ZT); YNbNi 2 Ge 2 (0.85) and YNbNi 2 Si 2 (0.68) at 300 K.