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−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−27.6 GPa, which are possibly related with the ideal tensile strength.

► The 3R-to-2H phase transformation is expected to occur around −26.0 GPa−26.0 GPa.
► The presence of mechanical instability of 3R and 2H is at −27.5 and −27.6 GPa−27.6 GPa.
► Tensile stress dependence of band gaps of 3R and 2H has been shown.