In situ X-ray diffraction studies of iron to Earth-core conditions

Yanzhang Ma, Maddury Somayazulu, Guoyin Shen, Ho kwang Mao, Jinfu Shu, Russell J. Hemley

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164 Scopus citations

Abstract

The high-pressure, high-temperature behavior of iron has been investigated to 161 GPa and 3000 K by in situ synchrotron X-ray diffraction with double-side laser-heated diamond anvil cells. We found that only α-, γ- and ε-Fe can be clearly verified as the stable solid phase in the P - T range studied. Only ε-Fe is observed from deep lower mantle (∼1500 km) to outer core conditions. Within the P - T range examined, we did not observe a significant change with pressure or temperature on the c / a ratio of ε-Fe. The melting curve of iron has been determined to 105 GPa. A Lindeman law fit gives a melting point of iron at the inner core boundary of 5800 (±200) K, which provides an upper bound on the temperature at that depth. We also examine numerous experimental factors that may complicate the analysis of high P - T diffraction data, and discuss the effects of sample stress on the X-ray diffraction results.

Original languageEnglish
Pages (from-to)455-467
Number of pages13
JournalPhysics of the Earth and Planetary Interiors
Volume143
Issue number1-2
DOIs
StatePublished - Jun 15 2004

Keywords

  • High pressure
  • High temperature
  • Iron
  • Phase diagram
  • X-ray diffraction

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