Iron-Silicon Alloy in Earth's Core?

• Published in: Science (American Association for the Advancement of Science) Vol. 295; no. 5553; pp. 313 - 315
• Main Authors: Lin, Jung-Fu, Heinz, Dion L., Campbell, Andrew J., Devine, James M., Shen, Guoyin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 11-01-2002; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Alloys; Chemistry; Climate; Core; Core (Geology); Earth; Earth sciences; Earth, ocean, space; Electrical phases; Environmental aspects; Exact sciences and technology; Face centered cubic lattices; Geology; Grade Point Average; High pressure; Ice sheets; Internal geophysics; Iron; Iron alloys; Iron-silicon alloys; Laser beams; Lasers; Mineralogical chemistry; Phase diagrams; Rapid quenching; Silicon; Silicon alloys; Solid-earth geophysics, tectonophysics, gravimetry; Topology; X ray diffraction; experimental studies; scanning electron microscopy; alloys; phase diagrams; SEM data; Earth interior; phase relations; chemical analysis; high pressure; high temperature; silicon; iron; inner core; stability
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1066932

We have investigated the phase relations in the iron-rich portion of the iron-silicon (Fe-Si) alloys at high pressures and temperatures. Our study indicates that Si alloyed with Fe can stabilize the body-centered cubic (bcc) phase up to at least 84 gigapascals (compared to ∼10 gigapascals for pure Fe) and 2400 kelvin. Earth's inner core may be composed of hexagonal close-packed (hcp) Fe with up to 4 weight percent Si, but it is also conceivable that the inner core could be a mixture of a Si-rich bcc phase and a Si-poor hcp phase.