Solubility of silicon in liquid metal at high pressure: implications for the composition of the Earth’s core

Geßmann, C. K.; Wood, Bernard J.; Rubie, D. C.; Kilburn, Matt R.

doi:10.1016/s0012-821x(00)00325-3

Cited by 102 publications

(62 citation statements)

References 28 publications

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“…A considerable amount of Si may be incorporated into the core through chemical reactions, especially under reducing conditions (31,32). Geochemical data suggest that, depending on the accretion history and the distribution of Si in various layers inside the Earth, the Si content of the core may vary between virtually zero to 14 wt.…”

Section: Resultsmentioning

confidence: 99%

Thermal expansion of iron-rich alloys and implications for the Earth's core

Chen

Gao

Funakoshi

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Understanding the thermal-chemical state of the Earth's core requires knowledge of the thermal expansion of iron-rich alloys at megabar pressures and high temperatures. Our survey of literature revealed a significant lack of such data. We have determined the unit-cell parameters of the iron-sulfur compound Fe3S by using synchrotron x-ray diffraction techniques and externally heated diamond-anvil cells at pressures up to 42.5 GPa and temperatures up to 900 K. The zero-pressure thermal expansivity of Fe3S is determined in the form ␣ ‫؍‬ a1 ؉ a2T, where a1 ‫؍‬ 3.0 ؎ 1.3 ؋ 10 ؊5 K ؊1 and a2 ‫؍‬ 2.8 ؎ 1.5 ؋ 10 ؊8 K ؊2 . The temperature dependence of isothermal bulk modulus (٢KT,0/٢T)P is estimated at ؊3.75 ؎ 1.80 ؋ 10 ؊2 GPa K ؊1 . Our data at 42.5 GPa and 900 K suggest that Ϸ2.1 at. % (1.2 wt. %) sulfur produces 1% density deficit in iron. We have also carried out energy-dispersive x-ray diffraction measurements on pure iron and Fe0.864Si0.136 alloy samples that were placed symmetrically in the same multianvil cell assemblies, using the SPring-8 synchrotron facility in Japan. Based on direct comparison of unit cell volumes under presumably identical pressures and temperatures, our data suggest that at most 3.2 at. % (1.6 wt. %) silicon is needed to produce 1% density deficit with respect to pure iron.Fe3S ͉ Fe-Si alloy ͉ light element

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Section: Resultsmentioning

confidence: 99%

Thermal expansion of iron-rich alloys and implications for the Earth's core

Chen

Gao

Funakoshi

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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“…Similarly, Javoy (1995), Guyot et al (1997), Gessmann and , and Gessmann et al (2001) suggested that several wt% Si could be incorporated in metal according to reaction 1 at high temperature and at pressures between 5 and 20 GPa, under more reducing conditions than the present redox state of the mantle. Such silicon incorporation, however, is impossible at higher pressure as suggested by Javoy (1995) and O'Neill et al (1998) and by the experimental results of Boehler (1998, 1999) and Dubrovinsky et al (2003), in agreement with the model of Guyot et al (1997).…”

Section: Introductionmentioning

confidence: 91%

“…All the multianvil press investigations carried out to measure silicon incorporation in metal between 5 and 27 GPa (e.g., Ito and Katsura, 1991;Ito et al, 1995;Gessmann and Rubie, 1998;Gessmann et al, 1999Gessmann et al, , 2001O'Neill et al, 1998) potentially suffer from problems with chemical equilibrium. These difficulties are intrinsic to the configuration of high-pressure and high-temperature experiments in multianvil press.…”

Section: Introductionmentioning

confidence: 99%

Si in the core? New high-pressure and high-temperature experimental data

Malavergne

Siebert

Guyot

et al. 2004

Geochimica et Cosmochimica Acta

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“…If the core is cooling and the central temperature drops below the liquidus for the core alloy, then an inner core will nucleate. In Earth, we know from seismic evidence that the core is ∼10% less dense than pure iron and many suggestions have been offered for the identity of the light elements that are mixed with the iron (Poirier 1994;Gessmann et al 2001). As the inner core freezes, it is likely that some or all of these light elements are partially excluded from the crystal structure.…”

Section: The Nature Of Planets and Their Evolutionmentioning

confidence: 99%

Planetary Magnetic Fields: Achievements and Prospects

Stevenson

2009

Space Sci Rev

111

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The past decade has seen a wealth of new data, mainly from the Galilean satellites and Mars, but also new information on Mercury, the Moon and asteroids (meteorites). In parallel, there have been advances in our understanding of dynamo theory, new ideas on the scaling laws for field amplitudes, and a deeper appreciation on the diversity and complexity of planetary interior properties and evolutions. Most planetary magnetic fields arise from dynamos, past or present, and planetary dynamos generally arise from thermal or compositional convection in fluid regions of large radial extent. The relevant electrical conductivities range from metallic values to values that may be only about one percent or less that of a typical metal, appropriate to ionic fluids and semiconductors. In all planetary liquid cores, the Coriolis force is dynamically important. The maintenance and persistence of convection appears to be easy in gas giants and ice-rich giants, but is not assured in terrestrial planets because the quite high electrical conductivity of an iron-rich core guarantees a high thermal conductivity (through the Wiedemann-Franz law), which allows for a large core heat flow by conduction alone. This has led to an emphasis on the possible role of ongoing differentiation (growth of an inner core or "snow"). Although planetary dynamos mostly appear to operate with an internal field that is not very different from (2ρ /σ ) 1/2 in SI units where ρ is the fluid density, is the planetary rotation rate and σ is the conductivity, theoretical arguments and stellar observations suggest that there may be better justification for a scaling law that emphasizes the buoyancy flux. Earth, Ganymede, Jupiter, Saturn, Uranus, Neptune, and probably Mercury have dynamos, Mars has large remanent magnetism from an ancient dynamo, and the Moon might also require an ancient dynamo. Venus is devoid of a detectable global field but may have had a dynamo in the past. Even small, differentiated planetesimals (asteroids) may have been capable of dynamo action early in the solar system history. Induced fields observed in Europa and Callisto indicate the strong likelihood of water oceans in these bodies. The presence or absence of a dynamo in a terrestrial body (including Ganymede) appears to depend mainly on the thermal histories and energy sources of these bodies, especially the convective state of the silicate mantle and the existence and history of a growing inner solid core. As a consequence, the understanding of planetary

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Solubility of silicon in liquid metal at high pressure: implications for the composition of the Earth’s core

Cited by 102 publications

References 28 publications

Thermal expansion of iron-rich alloys and implications for the Earth's core

Thermal expansion of iron-rich alloys and implications for the Earth's core

Si in the core? New high-pressure and high-temperature experimental data

Planetary Magnetic Fields: Achievements and Prospects

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