Elastic, Electronic, Optical, and Thermodynamic Properties of the Half-Heusler LiScSi1−xCx Alloy in α-Phase: A DFT Simulation Study

The structural, elastic, electronic, and thermodynamic properties of a LiScSi_1−xC_x alloy in the α-phase were investigated using density functional theory with the plane-wave pseudopotential method and the alchemical mixing approximation in ABINIT code. We computed ground-state properties including lattice constants, bulk modulus, energy gap, refractive index, and optical dielectric constant for the LiScSi_1−xC_x compounds. Our results align well with existing theoretical data for the parent compounds LiScSi and LiScC. We found that the fundamental bandgap for the α-LiScSi_1−xC_x alloy varied from 0.865 eV to 1.143 eV using the B3LYP approach, indicating potential applications in optoelectronic devices such as photodetectors and light-emitting diodes (LEDs), where precise control over electronic and optical properties is crucial. Additionally, we calculated the electron and hole effective masses, which showed a decrease with increasing carbon concentration; the electron effective mass ranged from 0.042m* for LiScSi to 0.035m* for LiSiC. The LiScSi_1−xC_x alloy in the α-phase consistently exhibited direct semiconductor behavior (X → X) across all concentrations. We also predicted the variation in thermodynamic properties, including unit cell volume, bulk modulus, heat capacity, and thermal expansion coefficient, with temperature for various carbon concentrations. These findings contribute to a deeper understanding of the material’s potential applications in electronic and thermoelectric devices.