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Title: Backbone N{sub x}H compounds at high pressures

Optical and synchrotron x-ray diffraction diamond anvil cell experiments have been combined with first-principles theoretical structure predictions to investigate mixtures of N{sub 2} and H{sub 2} up to 55 GPa. Our experiments show the formation of structurally complex van der Waals compounds [see also D. K. Spaulding et al., Nat. Commun. 5, 5739 (2014)] above 10 GPa. However, we found that these N{sub x}H (0.5 < x < 1.5) compounds transform abruptly to new oligomeric materials through barochemistry above 47 GPa and photochemistry at pressures as low as 10 GPa. These oligomeric compounds can be recovered to ambient pressure at T < 130 K, whereas at room temperature, they can be metastable on pressure release down to 3.5 GPa. Extensive theoretical calculations show that such oligomeric materials become thermodynamically more stable in comparison to mixtures of N{sub 2}, H{sub 2}, and NH{sub 3} above approximately 40 GPa. Our results suggest new pathways for synthesis of environmentally benign high energy-density materials. These materials could also exist as alternative planetary ices.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [5] ;  [2] ;  [3] ;  [6] ;  [7] ;  [2] ;  [2] ;  [3] ;  [8] ; ;  [4] ;  [9] ;
  1. Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, 350 Shushanghu Road, Hefei, Anhui 230031 (China)
  2. (United States)
  3. (China)
  4. Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, Washington, D.C. 20015 (United States)
  5. Department of Geosciences, State University of New York, Stony Brook, New York 11794-2100 (United States)
  6. Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)
  7. Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 143026 (Russian Federation)
  8. (Russian Federation)
  9. University College London, Gower St., London WC1E 6BT (United Kingdom)
Publication Date:
OSTI Identifier:
22415938
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 21; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMMONIA; COMPARATIVE EVALUATIONS; DIAMONDS; ENERGY DENSITY; HYDROGEN; ICE; NITROGEN HYDRIDES; PHOTOCHEMISTRY; PRESSURE DEPENDENCE; PRESSURE RELEASE; SYNTHESIS; TEMPERATURE RANGE 0273-0400 K; VAN DER WAALS FORCES; X-RAY DIFFRACTION