Body-Centered Cubic Iron-Nickel Alloy in Earth's Core

• Published in: Science (American Association for the Advancement of Science) Vol. 316; no. 5833; pp. 1880 - 1883
• Main Authors: Dubrovinsky, L, Dubrovinskaia, N, Narygina, O, Kantor, I, Kuznetzov, A, Prakapenka, V.B, Vitos, L, Johansson, B, Mikhaylushkin, A.S, Simak, S.I, Abrikosov, I.A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 29.06.2007; The American Association for the Advancement of Science; AAAS
• Subjects: ALLOYS; Crystalline rocks; DIAMONDS; differential rotation; Earth; Earth core; Earth sciences; Earth, ocean, space; Electrical phases; Exact sciences and technology; Experimental petrology; fe-ni alloys; Fees; Fysik; Geochemistry; Geophysical studies; Geophysics; gpa; High pressure; High temperature; in-situ; Inner cores; inner-core; Internal geophysics; IRON; IRON ALLOYS; Materials; MATERIALS SCIENCE; Mineralogy; NATURAL SCIENCES; NATURVETENSKAP; NICKEL; Nickel alloys; Non silicates; phase transition; phase-diagram; Physics; planet; Shock waves; SILICON; situ x-ray; Solid-earth geophysics, tectonophysics, gravimetry; SULFUR; temperature; X ray diffraction; experimental studies; nickel; alloys; X-ray diffraction; phase transitions; high pressure; core; crystal structure; iron; P-T conditions; diamond anvil cells; inner core; shock waves
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.1142105

Cosmochemical, geochemical, and geophysical studies provide evidence that Earth's core contains iron with substantial (5 to 15%) amounts of nickel. The iron-nickel alloy Fe₀.₉Ni₀.₁ has been studied in situ by means of angle-dispersive x-ray diffraction in internally heated diamond anvil cells (DACs), and its resistance has been measured as a function of pressure and temperature. At pressures above 225 gigapascals and temperatures over 3400 kelvin, Fe₀.₉Ni₀.₁ adopts a body-centered cubic structure. Our experimental and theoretical results not only support the interpretation of shockwave data on pure iron as showing a solid-solid phase transition above about 200 gigapascals, but also suggest that iron alloys with geochemically reasonable compositions (that is, with substantial nickel, sulfur, or silicon content) adopt the bcc structure in Earth's inner core.