ABSTRACT
Based on the first-principles calculations within the density functional theory and crystal structure prediction algorithms iron phosphide phases stable under pressure of the Earth’s core and temperatures up to 4000 K were determined. A new low-temperature modification FeP-P21/c stable above ∼75 GPa was predicted. Fe2P with the allabogdanite structure has been established to be stable in the low-temperature region at ambient conditions. At 750 K it transforms into the barringerite structure. The transition from Fe3P with schreibersite structure to Fe3P-Cmcm was observed at 27 GPa, and the phase transition boundary is nearly isobaric. Fe2P and FeP are thermodynamically stable at the Earth’s inner core pressures and 0 K according to the obtained results, whereas Fe3P stabilizes with respect to decomposition to Fe + Fe2P at high temperatures above ∼3200 K.
Acknowledgements
The authors are grateful to the Supercomputer Center of the Novosibirsk State University for providing access to the cluster resources.
Disclosure statement
No potential conflict of interest was reported by the author(s).
ORCID
Nursultan E. Sagatov http://orcid.org/0000-0001-5158-3523
Pavel N. Gavryushkin http://orcid.org/0000-0002-9419-2167
Talgat M. Inerbaev http://orcid.org/0000-0003-2378-4082
Konstantin D. Litasov http://orcid.org/0000-0002-6556-008X