Crystal structure and chemical bonding of the high-pressure phase of MgAl2O4 from first-principles calculations

Abstract First-principles calculations using density functional theory and the pseudopotential method have been performed for the crystal structure and phase relationship of MgAl2O4 and the binary components (MgO and α-A12O3). Calculations show that the spinel MgAl2O4 first decomposes into MgO and A12O3, and then the binary components react again into the high-pressure form of MgAl2O4 (hp-MgAl2O4) at higher pressures. The influence of different factors (temperature, structural disordering, etc.) has been taken into account. It was found that hp-MgAl2O4 has a smaller volume and a higher bulk modulus than those of spinel phase. The calculated results are in agreement with the experiments. The chemical bonding and physical properties of hp-MgAl2O4 are addressed.