Synthesis of FeN4 at 180 GPa and its crystal structure from a submicron-sized grain

Maxim Bykov; Saiana Khandarkhaeva; Timofey Fedotenko; Pavel Sedmak; Natalia Dubrovinskaia; Leonid Dubrovinsky

doi:10.1107/S2056989018012161

Synthesis of FeN₄ at 180 GPa and its crystal structure from a submicron-sized grain

Acta Crystallogr E Crystallogr Commun. 2018 Sep 7;74(Pt 10):1392-1395. doi: 10.1107/S2056989018012161. eCollection 2018 Oct 1.

Authors

Maxim Bykov¹, Saiana Khandarkhaeva¹, Timofey Fedotenko², Pavel Sedmak³, Natalia Dubrovinskaia², Leonid Dubrovinsky¹

Affiliations

¹ Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
² Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany.
³ European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France.

Abstract

Iron tetra-nitride, FeN₄, was synthesized from the elements in a laser-heated diamond anvil cell at 180 (5) GPa and 2700 (200) K. Its crystal structure was determined based on single-crystal X-ray diffraction data collected from a submicron-sized grain at the synchrotron beamline ID11 of ESRF. The compound crystallizes in the triclinic space group P . In the asymmetric unit, the Fe atom occupies an inversion centre (Wyckoff position 1d), while two N atoms occupy general positions (2i). The structure is made up from edge-sharing [FeN₆] octa-hedra forming chains along [100] and being inter-connected through N-N bridges. N atoms form catena-poly[tetraz-1-ene-1,4-di-yl] anions [-N=N-N-N-]_∞ ^2- running along [001]. In comparison with the previously reported structure of FeN₄ at 135 GPa [Bykov et al. (2018). Nat. Commun. 9, 2756], the crystal structure of FeN₄ at 180 GPa is similar but the structural model is significantly improved in terms of the precision of the bond lengths and angles.

Keywords: crystal structure; high-pressure single-crystal X-ray diffraction; iron tetranitride; polynitrides.