Synthesis and high-resolution study distinguishing between very similar interstitial iron nitride structures |
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| Authors: | G. Serghiou G. Ji N. Odling H.J. Reichmann D.J. Frost J.P. Wright |
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| Affiliation: | 1. School of Engineering, University of Edinburgh, Kings Buildings, Mayfield Road, Edinburgh EH9 3JL, UKgeorge.serghiou@ed.ac.uk;3. Unité Matériaux et Transformations, UMR CNRS 8207, Université Lille 1, Villeneuve d'Ascq, Lille 59655, France;4. School of Geosciences, The Grant Institute, University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh EH9 3JW, UK;5. German Research Centre for Geosciences, Helmholtz Centre Potsdam, Telegrafenberg, Potsdam 14473, Germany;6. Bayerisches Geoinstitut, Universit?t Bayreuth, Bayreuth D-95440, Germany;7. European Synchrotron Radiation Facility, Grenoble F-38043, France |
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| Abstract: | Angle-dispersive X-ray diffraction and microfluorescence together with precession electron diffraction (PED) and scanning electron microscopy measurements on iron nitride prepared at 15?GPa and 1800?K from iron and sodium azide starting materials reveal synthesis of both hexagonal P6322 and trigonal P312 Fe3N1+x modifications (a?=?4.745 (1) Å, c?=?4.403 (1) Å, Z?=?2). Nitrogen access to vacant interstitial sites, repulsions between nitrogen ions and metal nitride thermal stability are the factors relating iron nitride-phase relations to those of other early (Hf, Zr, Ti)-N and late (Ni-N) transition metal nitrides subjected to similar pressure and temperature conditions. Here, Fe3N1+x can accommodate pressure and x variability by situating nitrogen in a broader range of interstitial crystallographic sites in the intimately related hexagonal and trigonal crystal structures. |
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| Keywords: | interstitial nitrides high pressure synthesis iron X-ray and PED chemical analysis |
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