Decomposition of fayalite (Fe2SiO4) in an oxygen potential gradient at 1,418 K

The decomposition of fayalite (Fe₂SiO₄) in oxygen potential gradients is studied at T=1,418 K. The compound will be decomposed into its component oxides wüstite, Fe_1?δO, and silica, SiO₂, by the simultaneous action of two different oxygen partial pressures, exceeding a critical ratio, despite the fact that fayalite is stable at both the lower and the higher oxygen potential. A quantitative analysis of the decomposition process caused by defect fluxes within the bulk Fe₂SiO₄ is given.