Phase Relations of Iron Carbides Fe2C, Fe3C, and Fe7C3 at the Earth's Core Pressures and Temperatures

N. E. Sagatov, P. N. Gavryushkin, I. Medrish, T. M. Inerbaev, K. D. Litasov

Research output: Contribution to journalArticlepeer-review

Abstract

Based on first-principle calculations in the framework of the density functional theory and structure prediction algorithms, we have determined iron carbide phases stable at the Earth's core pressures and temperatures. It is shown that Fe2C3 is unstable and decomposes into the mixture Fe2C3 + Fe3C over the entire range of pressures and temperatures specific to the Earth's inner core. Subsequent decomposition of Fe3C into the mixture Fe + Fe2C is unfavorable. We also predict a new low-temperature modification Fe3C-C2/m-II dynamically and thermodynamically stable over the pressure range 290-305 GPa.

Original languageEnglish
Pages (from-to)1345-1353
Number of pages9
JournalRussian Geology and Geophysics
Volume61
Issue number12
DOIs
Publication statusPublished - Dec 2020

Keywords

  • iron carbides
  • USPEX
  • AIRSS
  • crystal structure prediction
  • quasi-harmonic approximation
  • CRYSTAL-STRUCTURE
  • STRUCTURE PREDICTION
  • C SYSTEM
  • CARBON
  • 1ST-PRINCIPLES
  • MORPHOLOGY
  • STABILITY
  • STATE
  • GPA

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