P-V-T measurements of iron silicide (epsilon -FeSi) implications for silicate-metal interactions in the early Earth
P-V-T measurements of iron silicide (epsilon -FeSi) implications for silicate-metal interactions in the early Earth (in EMPG-VI; Experimental mineralogy, petrology and geochemistry, E. A. J. Burke (editor), C. Chopin (editor), W. V. Maresch (editor), L. Ungaretti (editor) and C. Willaime (editor))
European Journal of Mineralogy (April 1997) 9 (2): 277-285
The high-P, high-T equation of state of epsilon -FeSi has been determined by synchrotron XRD in situ in a multi-anvil apparatus. The thermoelastic parameters are V (sub 0) 90.39 Aa (super 3) , K (sub 0) 172 GPa, (Delta I>K/Delta I>T) (sub p) -0.043 GPa/K, alpha 5.1 X 10 (super -5) /K with fixed K' (sub 0) = 4. These equation-of-state parameters were included in a thermodynamic model of the reaction between Fe and SiO (sub 2) , showing that the reduction of the silicates by iron presents a maximum at P 8-15 GPa, could benefit at high T, depending on the values of the activity coefficient of Si in Fe-Si alloys. Similar reduction reactions in the Earth's complex system could have profound implications for the compositions of mantle and core, as well as for reactions at the core-mantle boundary.