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High‐pressure metallization of FeO and implications for the Earth's core
Author(s) -
Knittle Elise,
Jeanloz Raymond
Publication year - 1986
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl013i013p01541
Subject(s) - mantle (geology) , outer core , core–mantle boundary , inner core , alloy , diamond anvil cell , geology , earth (classical element) , materials science , thermodynamics , high pressure , geophysics , metallurgy , physics , mathematical physics
The phase diagram of FeO has been experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock‐wave and diamond‐cell techniques. We have discovered a metallic phase of FeO at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the Earth's outer core, in accord with the geochemical predictions of Ringwood. The high pressures necessary for this metallization suggest that the core has acquired its composition well after the initial stages of the Earth's accretion. Direct experimental observations at elevated pressures and temperatures indicate that core‐forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core‐mantle boundary is likely to be a zone of active chemical reactions.