High-pressure synthesis of ultraincompressible hard rhenium nitride pernitride Re2(N2)(N)2 stable at ambient conditions

Maxim Bykov; Stella Chariton; Hongzhan Fei; Timofey Fedotenko; Georgios Aprilis; Alena V Ponomareva; Ferenc Tasnádi; Igor A Abrikosov; Benoit Merle; Patrick Feldner; Sebastian Vogel; Wolfgang Schnick; Vitali B Prakapenka; Eran Greenberg; Michael Hanfland; Anna Pakhomova; Hanns-Peter Liermann; Tomoo Katsura; Natalia Dubrovinskaia; Leonid Dubrovinsky

doi:10.1038/s41467-019-10995-3

High-pressure synthesis of ultraincompressible hard rhenium nitride pernitride Re₂(N₂)(N)₂ stable at ambient conditions

Nat Commun. 2019 Jul 5;10(1):2994. doi: 10.1038/s41467-019-10995-3.

Authors

Maxim Bykov¹, Stella Chariton², Hongzhan Fei², Timofey Fedotenko³, Georgios Aprilis³, Alena V Ponomareva⁴, Ferenc Tasnádi⁵, Igor A Abrikosov⁵, Benoit Merle⁶, Patrick Feldner⁶, Sebastian Vogel⁷, Wolfgang Schnick⁷, Vitali B Prakapenka⁸, Eran Greenberg⁸, Michael Hanfland⁹, Anna Pakhomova¹⁰, Hanns-Peter Liermann¹⁰, Tomoo Katsura², Natalia Dubrovinskaia³, Leonid Dubrovinsky²

Affiliations

¹ Bayerisches Geoinstitut, University of Bayreuth, Universitätstraβe 30, 95440, Bayreuth, Germany. [email protected].
² Bayerisches Geoinstitut, University of Bayreuth, Universitätstraβe 30, 95440, Bayreuth, Germany.
³ Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, Universitätstraβe 30, 95440, Bayreuth, Germany.
⁴ Materials Modeling and Development Laboratory, National University of Science and Technology 'MISIS', Leninskiy prospekt 4, Moscow, Russia, 119049.
⁵ Department of Physics, Chemistry and Biology (IFM), Linköping University, Campus Valla, Fysikhuset, SE-58183, Linköping, Sweden.
⁶ Materials Science and Engineering, Institute I, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) Martensstraβe. 5, D-91058, Erlangen, Germany.
⁷ Chair in Inorganic Solid State Chemistry, Department of Chemistry, University of Munich (LMU), Butenandtstraβe 5-13 (D), D-81377, Munich, Germany.
⁸ Center for Advanced Radiation Sources, University of Chicago, 5640 S. Ellis, Chicago, IL, 60637, USA.
⁹ European Synchrotron Radiation Facility, BP 220, 38043, Grenoble Cedex, France.
¹⁰ Photon Science, Deutsches Elektronen-Synchrotron, Notkestraβe 85, 22607, Hamburg, Germany.

Abstract

High-pressure synthesis in diamond anvil cells can yield unique compounds with advanced properties, but often they are either unrecoverable at ambient conditions or produced in quantity insufficient for properties characterization. Here we report the synthesis of metallic, ultraincompressible (K₀ = 428(10) GPa), and very hard (nanoindentation hardness 36.7(8) GPa) rhenium nitride pernitride Re₂(N₂)(N)₂. Unlike known transition metals pernitrides Re₂(N₂)(N)₂ contains both pernitride N₂^4- and discrete N^3- anions, which explains its exceptional properties. Re₂(N₂)(N)₂ can be obtained via a reaction between rhenium and nitrogen in a diamond anvil cell at pressures from 40 to 90 GPa and is recoverable at ambient conditions. We develop a route to scale up its synthesis through a reaction between rhenium and ammonium azide, NH₄N₃, in a large-volume press at 33 GPa. Although metallic bonding is typically seen incompatible with intrinsic hardness, Re₂(N₂)(N)₂ turned to be at a threshold for superhard materials.