First principles study of the structural stability of intermetallic compounds in the Si-Zr system
Résumé
The total energies of intermetallic compounds in the Si-Zr system are calculated employing electronic density-functional theory (DFT). The calculated zero-temperature lattice parameters and internal parameters of the stable intermetallic compounds agree well with those obtained experimentally at ambient temperature. The calculated formation enthalpies are in good agreement with the most recent available experimental data. They are also compared with values estimated in CALPHAD calculation of the Si-Zr phase diagram. Using the first-principles computations, the phonon-dispersion relations and the phonon density of states for B27-SiZr and B33-SiZr are calculated. Using the harmonic approximation and by taking into account electronic excitations, the Gibbs free energy difference between B27-SiZr and B33-SiZr is estimated as a function of temperature at zero pressure. The relative stability of B27-SiZr with respect to B33-SiZr is discussed.