First-principles investigation on structural, thermodynamic, and elastic properties of suboxide Zr3O phase

The lattice dynamics and finite -temperature thermodynamic and mechanical properties of three Zr 3 O polymorphs, including rhombohedral ( R 3 investigated using the first -principles calculations. The calculated lattice parameters agree well with experimental values. It is confirmed that the three Zr 3 O phases exhibit both dynamic and thermodynamic stability. The entropy, enthalpy, Gibbs free energy, specific heat capacity, thermal expansion coefficient, and elastic modulus as a function of temperature from 0 to 1500 K were systematically evaluated. It is found that Zr 3 O ( R 3 followed by Zr 3 O ( R 32) and Zr 3 O ( P 6 3 22). Structural phase transitions occur from Zr 3 O ( R 3 and then to Zr 3 O ( P 6 3 22) at 540 K. Zr 3 O ( R 32) displays superior mechanical properties compared to the other two Zr 3 O phases. Key words: first -principles; Zr 3 O; lattice dynamics; thermodynamic properties; elastic modulus - c ), rhombohedral ( R 32), and hexagonal ( P 6 3 22) phases, were theoretically - c ) is the ground state at 0 K - c ) to Zr 3 O ( R 32) at 50 K and then to Zr 3 O ( P 6 3 22) at 540 K. Zr 3 O ( R 32) displays superior mechanical properties compared to the other two Zr 3 O phases.