Abstract
The pressure-induced B3-B1 structural phase transition and some interesting thermodynamic properties for high-pressure B1 structure of cubic copper iodide (CuI) have been studied systematically using first-principles calculations based on density functional theory. It is found that CuI has a B3 ground-state phase at zero pressure and the transition pressure from B3 to B1 structure determined by the relative enthalpy versus pressure curves is about 6.9 GPa with a volume contraction of 14.42%. As a high-pressure phase, the B1 structure will be mechanically stable up to 57 GPa according to the generalized elastic stability criteria. Through the quasi-harmonic Debye model, the dependences of the primitive cell volume, isothermal bulk modulus, volumetric thermal expansion coefficient, heat capacity, entropy, and Debye temperature of CuI with high-pressure B1 phase on pressure and temperature are successfully predicted. The thermodynamic properties are summarized in the pressure range of 0–50 GPa and the temperature up to 800 K.
•Structural, elastic, and thermodynamic properties of CuI in high-pressure rocksalt phase are investigated systematically.•Some interesting thermodynamic parameters are successfully obtained based on the quasi-harmonic Debye model.•In the whole research the pressure and temperature up to 100 GPa and 800 K, respectively.