Density functional theory study of 3R- and 2H-CuAlO2 in tensile stress

We report a direct computational result of a phase transformation from the 3R phase to the 2H phase in CuAlO₂ with the application of tensile stress using the first-principles density functional theory calculations. The calculations of enthalpy variation with tensile stress indicates the 3R-to-2H phase transformation is expected to occur around −26.0 GPa. As the applied tensile stress increases, the independent elastic constants of 3R- and 2H-CuAlO₂ show the presences of mechanical instability at −27.5 and −27.6 GPa, which are possibly related with the ideal tensile strength.