Density functional perturbation theory calculations of vibrational and thermodynamic properties of Zn1−xBexO alloys

The elastic, phonon and thermodynamic properties of Zn1−xBexO alloy are investigated by performing density functional theory (DFT) and density functional perturbation theory (DFPT) calculations. The calculated lattice parameters decreases with the increase of Be content that is in good agreement with the available theoretical and experimental data. The effect of Be composition on elastic constants was investigated for Zn1−xBexO alloys. Phonon dispersion curves show that Zn1−xBexO are dynamically stable. Thermodynamic properties, including Helmholtz free energy, enthalpy, entropy and heat capacity, were evaluated under quasi-harmonic approximation using the calculated phonon density of states. Finally, the results show that Zn1−xBexO alloys with lower Be content are more thermodynamically stable. The agreement between the present results and the known data that are available only for ZnO and BeO is generally satisfactory.