Theoretical Investigation of Elastic, Electronic, and Thermodynamic Properties of Half-Heusler Semiconductors ZrNiPb and ZrPdPb Under Pressure

The half-Heusler semiconductors ZrNiPb and ZrPdPb have attracted considerable attention due to their excellent thermoelectric performance, owing largely to their appropriate energy bandgap. However, the bandgap is sensitive to pressure, which may influence their thermoelectric behavior. In this study, the effects of pressure on the elastic, electronic, and thermodynamic properties of the half-Heusler semiconductors ZrNiPb and ZrPdPb are investigated based on first-principles calculations combined with the quasi-harmonic Debye model. After verifying their structural, dynamic, and mechanical stability, we found a small indirect bandgap of 0.36 eV for ZrNiPb and 0.49 eV for ZrPdPb, and they increase with increasing pressure. According to the obtained elastic modulus, ZrNiPb and ZrPdPb become more and more ductile as the pressure increases. In addition, the thermodynamic properties of ZrNiPb and ZrPdPb are investigated using the quasi-harmonic Debye model, as implemented in the Gibbs program, which will provide a reference for the experiment.