Elastic properties and high-pressure behavior of MgAl2O4MgAl2O4 from ab initio calculations

Local density approximation within the density functional theory was applied to study the behavior of MgAl2O4MgAl2O4 at pressures below 30 GPa. The microscopic contributions to the elasticity are analyzed and the octahedral and tetrahedral bond compressibilities are determined. The effect of lattice vibrations on predictions of phase stability is shown. Debye approximation is used to estimate the zero-point vibrational energy. The compound decomposes into the binary oxides at 14 GPa. Seismic velocities are derived from the ab initio calculated elastic constants. Comparison with existing theoretical and experimental data is discussed.