Physics and Chemistry of Minerals

, Volume 38, Issue 10, pp 801–807 | Cite as

Density measurements of liquid Fe–Si alloys at high pressure using the sink–float method

  • Ryuji TateyamaEmail author
  • Eiji Ohtani
  • Hidenori Terasaki
  • Keisuke Nishida
  • Yuki Shibazaki
  • Akio Suzuki
  • Takumi Kikegawa
Original Paper


The compositional dependence on the density of liquid Fe alloys under high pressure is important for estimating the amount of light elements in the Earth’s outer core. Here, we report on the density of liquid Fe–Si at 4 GPa and 1,923 K measured using the sink–float method and our investigation on the effect of the Si content on the density of the liquid. Our experiments show that the density of liquid Fe–Si decreases from 7.43 to 2.71 g/cm3 non-linearly with increasing Si content (0–100 at%). The molar volume of liquid Fe–Si calculated from the measured density gradually decreases in the compositional range 0–50 at% Si, and increases in the range 50–100 at% Si. It should be noted that the estimated molar volume of the alloys shows a negative volume of mixing between Fe and Si. This behaviour is similar to Fe–S liquid (Nishida et al. in Phys Chem Miner 35:417–423, 2008). However, the excess molar volume of mixing for the liquid Fe–Si is smaller than that of liquid Fe–S. The light element contents in the outer core estimated previously may be an underestimation if we take into account the possible negative value of the excess mixing volume of iron–light element alloys in the outer core.


Density Fe–Si Non-ideality High pressure 



The synchrotron X-ray diffraction studies at the BL-14C2 were performed with the approval of the Photon Factory Advisory Committee (Proposal No. 2007S2-002). This work was partly supported by grants from the Japan Society for the Promotion of Science (Grant Nos 18104009 and 22000002 to Eiji Ohtani and Nos 21684032 and 20103003 to Akio Suzuki).


  1. Allègre CJ, Poirier JP, Humler E, Hofmann AW (1995) The chemical composition of the Earth. Earth Planet Sci Lett 134:515–526CrossRefGoogle Scholar
  2. Birch F (1952) Elasticity and constitution of the Earth’s interior. J Geophys Res 57:227–286CrossRefGoogle Scholar
  3. Dumay C, Cramb AW (1995) Density and interfacial tension of liquid Fe–Si alloys. Metall Mat Trans B 26:173–176Google Scholar
  4. Funamori N, Tsuji K (2002) Pressure-induced structural change of liquid silicon. Phys Rev Lett 88:255508. doi: 10.1103/PhysRevLett.88.255508 CrossRefGoogle Scholar
  5. Hixson RS, Winkler MA, Hodgdon ML (1990) Sound speed and thermophysical properties of liquid iron and nickel. Phys Rev B42:6485–6491Google Scholar
  6. Kawai Y, Mori K, Kishimoto M, Ishikura K, Shimoda T (1974) Surface tension of liquid Fe–C–Si alloys. Tetsu-to-Hagané 60:29–37Google Scholar
  7. MacDonald GJ, Knopoff L (1958) On the chemical composition of the outer core. Geophys J R Astron Soc 1:284–297Google Scholar
  8. Morard G, Sanloup C, Guillot B, Fiquet G, Mezouar M, Perrillat JP, Garbarino G, Mibe K, Komabayashi T, Funakoshi K (2008) In situ structural investigation of Fe–S–Si immiscible liquid system and evolution of Fe–S bond properties with pressure. J Geophys Res 113:B10205. doi: 10.1029/2008JB005663
  9. Nasch PM, Steinmann SG (1995) Density and thermal expansion of molten manganese, iron, nickel, copper, aluminum and tin by means of the gamma-ray attenuation technique. Phys Chem Liq 29:43–58CrossRefGoogle Scholar
  10. Nasch PM, Manghnani MH, Secco RA (1997) Anomalous behavior of sound velocity and attenuation in liquid Fe–Ni–Si. Science 277:219–221CrossRefGoogle Scholar
  11. Nishida K, Terasaki H, Ohtani E, Suzuki A (2008) The effect of sulfur content on density of the liquid Fe–S at high pressure. Phys Chem Miner 35:417–423CrossRefGoogle Scholar
  12. Ohtani E, Moriwaki K, Kato T, Onuma K (1998) Melting and crystal–liquid partitioning in the system Mg2SiO4–Fe2SiO4 to 25 GPa. Phys Earth Planet Inter 107:75–82CrossRefGoogle Scholar
  13. Poirier JP (1994) Light elements in the Earth’s outer core: a critical review. Phys Earth Planet Inter 85:319–337CrossRefGoogle Scholar
  14. Ringwood AE (1959) On the chemical evolution and densities of the planets. Geochim Cosmochim Acta 15:257–283CrossRefGoogle Scholar
  15. Sanloup C, Guyot F, Gillet P, Fei Y (2002) Physical properties of liquid Fe alloys at high pressure and their bearings on the nature of metallic planetary cores. J Geophys Res 107:2272. doi: 10.1029/2001JB000808 Google Scholar
  16. Sanloup C, Fiquet G, Gregoryanz E, Morard G, Mezouar M (2004) Effect of Si on liquid Fe compressibility: implications for sound velocity in core materials. Geophys Res Lett 31:L07604. doi: 10.1029/2004GL019526
  17. Sasaki H, Tokizaki E, Terashima K, Kimura S (1994) Density variation of molten silicon measured by an improved Archimedian method. Jpn J Appl Phys 33:3803–3807CrossRefGoogle Scholar
  18. Schürmann E, Hensgen U (1980) Studies of the melting equilibria in the system iron–silicon. Arch Eisenhüttenwesen 51:1–4Google Scholar
  19. Suzuki A, Ohtani E, Terasaki H, Nishida K, Hayashi H, Sakamaki T, Shibazaki Y, Kikegawa T (2011) Pressure and temperature dependence of the viscosity of a NaAlSi2O6 melt. Phys Chem Miner 38:59–64CrossRefGoogle Scholar
  20. Urakawa S, Morishima M, Kato T, Suzuki A, Shimomura O (1996) Equation of state for h-BN. Photon Fact Act Rep 13:383Google Scholar
  21. Wänke H (1981) Constitution of terrestrial planets. Philos Trans R Soc Lond A 303:287–302CrossRefGoogle Scholar
  22. Waseda Y (1980) The structure of non-crystalline materials: liquids and amorphous solids. McGraw-Hill, New York, pp 74–79Google Scholar
  23. Yu X, Secco R (2008) Equation of state of liquid Fe-17 wt%Si to 12 GPa. High Pres Res 28:19–28CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Ryuji Tateyama
    • 1
    Email author
  • Eiji Ohtani
    • 1
  • Hidenori Terasaki
    • 1
    • 2
  • Keisuke Nishida
    • 1
  • Yuki Shibazaki
    • 1
  • Akio Suzuki
    • 1
  • Takumi Kikegawa
    • 3
  1. 1.Department of Earth and Planetary Materials ScienceTohoku UniversitySendaiJapan
  2. 2.Department of Earth and Space ScienceOsaka UniversityToyonakaJapan
  3. 3.Photon FactoryHigh Energy Accelerator Research Institute (KEK)TsukubaJapan

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