First-principles study of thermal properties and phase transition between β-Ti3O5 and λ-Ti3O5

Abstract

The first-principles density functional theory together with the quasi-harmonic Debye model is applied to investigate the thermodynamic properties and the phase transition between β-Ti3O5 and λ-Ti3O5. It is found that the phase transition from β to λ occurs only when the temperature is higher than 1420 K, and at a high temperature, λ-Ti3O5 can transform to β-Ti3O5 when a proper pressure is used. The thermal properties including the bulk modulus, the molar heat capacity and the dependences of thermal expansion coefficient α on temperature and pressure are also obtained in the pressure range from 0 to 20 GPa and temperature range from 0 to 1500 K.