New high-pressure phases of Fe₇N₃ and Fe₇C₃ stable at Earth's core conditions: evidences for carbon-nitrogen isomorphism in Fe-compounds.

ABSTRACT: We carried out ab initio calculations on the crystal structure prediction and determination of P-T diagrams within the quasi-harmonic approximation for Fe₇N₃ and Fe₇C₃. Two new isostructural phases Fe₇N₃-C2/m and Fe₇C₃-C2/m which are dynamically and thermodynamically stable under the Earth's core conditions were predicted. The Fe₇C₃-C2/m phase stabilizes preferentially to the known h-Fe₇C₃ at 253-344 GPa in the temperature range of 0-5000 K, and the Fe₇N₃-C2/m stabilizes preferentially relative to the β-Fe₇N₃ - at ∼305 GPa over the entire te

SUBMITTER: Sagatov N 

PROVIDER: S-EPMC9060559 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature