LAUSR

The mechanical and thermodynamic properties of β and α structures of SiC and also monoclinic and cubic structures of ZrO2 have been considered via first-principles investigations based on the ultrasoft pseudopotential plane-wave DFT method. The calculated lattice constants, elastic constants, and mechanical properties of all the structures are in agreement with earlier DFT works and experimental reports, which show that the applied method is applicable. Also, the pressure-dependency performances of thermodynamic and mechanical properties of cubic structures of ZrO2 and SiC, from 0 to 50 Gpa pressure, have been studied. The obtained elastic constants and mechanical properties of both structures increase with the enhancement of pressure. These results show that SiC is more difficult to be compacted as pressure increases. The thermodynamic properties of these structures show that variations of thermodynamic properties with temperature and pressure for ZrO2 are slightly higher than SiC.