Effect of defect clustering on the high-pressure behaviour of wüstite. High-pressure X-ray diffraction and lattice energy simulations

Abstract

The effect of pressure on the defect structure and phase relations of wüstite, Fe_1−xO, has been studied by high-pressure X-ray diffraction and lattice energy simulations. Both the experiments and the simulations suggest that the bulk modulus of wüstite does not vary significantly with composition, and moreover does not seem to depend on the defect structure of the compound. Thermodynamic modeling using a composition independent bulk modulus of 150 GPa suggests a significant widening of the stability field of wüstite relative to iron and magnetite at high pressure. This conclusion is in general agreement with the increased binding energy of defect clusters in wüstite at high pressure.