First-principles study of lattice stability of ReO3-type hypothetical TaO3

Tantalum trioxide is a layered material with potential application as an electrolyte, catalyst and transparent conducting oxide. Crystal structure and ground state properties of TaO3 has not been investigated. Here, lattice stability of TaO3 is studied using density functional theory calculations. The calculated free energy of formation shows that ReO3-type TaO3 is thermodynamically stable. Further, TaO3 is also found to fulfill all the elastic stability criterion, suggesting its mechanical stability. The calculated phonon spectrum of TaO3 does not show any imaginary modes, suggesting that the lattice is dynamically stable. Electronic band structure shows that TaO3 is a self-doped p-type metal.