Miscibility and ordered structures of MgO-ZnO alloys under high pressure

Abstract

The MgxZn1-xOalloy system may provide an optically tunable family of wide band gap materials that can be used in variousUVluminescences, absorption, lighting, and display applications. Asystematic investigation of the MgO-ZnO system using ab initio evolutionary simulations shows that MgxZn1-xO alloys exist in ordered ground-state structures at pressures above about 6.5 GPa. Detailed enthalpy calculations for the most stable structures allowed us to construct the pressure-composition phase diagram. In the entire composition, no phase transition from wurzite to rock-salt takes place with increasing Mg content. We also found two different slops occur at near x= 0.75 of Eg-x curves for different pressures, and the band gaps of high pressure ground-state Mg xZn1-xO alloys at the Mg concentration of x > 0.75 increase more rapidly than x < 0.75.