title: Single-bonded cubic form of nitrogen.
abstract: Nitrogen usually consists of molecules where two atoms are strongly triple-bonded. Here, we report on an allotropic form of nitrogen where all atoms are connected with single covalent bonds, similar to carbon atoms in diamond. The compound was synthesized directly from molecular nitrogen at temperatures above 2,000 K and pressures above 110 GPa using a laser-heated diamond cell. From X-ray and Raman scattering we have identified this as the long-sought-after polymeric nitrogen with the theoretically predicted cubic gauche structure (cg-N). This cubic phase has not been observed previously in any element. The phase is a stiff substance with bulk modulus >or=300 GPa, characteristic of strong covalent solids. The polymeric nitrogen is metastable, and contrasts with previously reported amorphous non-molecular nitrogen, which is most likely a mixture of small clusters of non-molecular phases. The cg-N represents a new class of single-bonded nitrogen materials with unique properties such as energy capacity: more than five times that of the most powerfully energetic materials.
authors.affiliation: Max Planck Institute für Chemie, Postfach 3060, 55020 Mainz, Germany. eremets@mpch-mainz.mpg.de
authors.forename: Mikhail I
authors.initials: MI
authors.lastname: Eremets
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Gavriliuk
authors.forename: Ivan A
authors.initials: IA
authors.lastname: Trojan
authors.forename: Dymitro A
authors.initials: DA
authors.lastname: Dzivenko
authors.forename: Reinhard
authors.initials: R
authors.lastname: Boehler
mesh_terms: D003460:Crystallization / Q000379:methods*; D003461:Crystallography; D008420:Manufactured Materials; D008422:Materials Testing; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D009584:Nitrogen / Q000737:chemistry*; D044367:Phase Transition; D011312:Pressure; D013696:Temperature
chemical_list: D009584:Nitrogen