First-principle study of phonon, elastic and thermodynamic properties of HfSi2 under high pressure

Abstract

Based on density functional theory and Debye quasi-harmonic approximation, the effects of high pressure on the phonon, electronic, elastic, and thermodynamic properties of the orthogonal phase HfSi2 have been calculated. The calculated results show that when the pressure is within the pressure range of 0 GPa to 50 GPa, HfSi2 is dynamically stable, and there is no virtual frequency on the phonon spectrum, but when the pressure is greater than 70 GPa, virtual frequencies appear near the phonon spectrum X, A structural phase change occurred. We predict that the band structure of HfSi2 is metallic. As the pressure increases, the elastic constant Cij increases and conforms to the Born criterion. It is mechanically stable in a certain pressure range. At the same time, B, E, G, and B/G all increase with the increase of pressure. This shows that changing the pressure appropriately can change the ductility and toughness of the material. The Debye temperature and sound velocity increase linearly with the increase of pressure, so the elasticity, hardness, melting point, and specific heat of the material can be improved by pressure.