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Title: Effect of pressure on heterocyclic compounds: Pyrimidine and s-triazine

We have examined the high-pressure behaviors of six-membered heterocyclic compounds of pyrimidine and s-triazine up to 26 and 26.5 GPa, respectively. Pyrimidine crystallizes in Pna2{sub 1} symmetry (phase I) with the freezing pressure of 0.3 GPa, and transforms to another phase (phase II) at 1.1 GPa. Raman spectra of several compression-decompression cycles demonstrate there is a critical pressure of 15.5 GPa for pyrimidine. Pyrimidine returns back to its original liquid state as long as the highest pressure is below 15.1 GPa. Rupture of the aromatic ring is observed once pressure exceeds 15.5 GPa during a compression-decompression cycle, evidenced by the amorphous characteristics of the recovered sample. As for s-triazine, the phase transition from R-3c to C2/c is well reproduced at 0.6 GPa, in comparison with previous Raman data. Detailed Raman scattering experiments corroborate the critical pressure for s-triazine may locate at 14.5 GPa. That is, the compression is reversible below 14.3 GPa, whereas chemical reaction with ring opening is detected when the final pressure is above 14.5 GPa. During compression, the complete amorphization pressure for pyrimidine and s-triazine is identified as 22.4 and 15.2 GPa, respectively, based on disappearance of Raman lattice modes. Synchrotron X-ray diffraction patterns and Fourier transformmore » infrared spectra of recovered samples indicate the products in two cases comprise of extended nitrogen-rich amorphous hydrogenated carbon (a-C:H:N)« less
Authors:
; ; ; ; ; ;  [1] ; ; ;  [2] ;  [3]
  1. State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China)
  2. Beijing Synchrotron Radiation Laboratory, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)
  3. Shanghai Synchrotron Radiation Facilities, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204 (China)
Publication Date:
OSTI Identifier:
22308907
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 11; Other Information: (c) 2014 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; CARBON; COMPARATIVE EVALUATIONS; COMPRESSION; CRITICAL PRESSURE; FOURIER TRANSFORMATION; HYDROGENATION; INFRARED SPECTRA; LIQUIDS; MONOCLINIC LATTICES; NITROGEN; ORTHORHOMBIC LATTICES; PYRIMIDINES; RAMAN EFFECT; RAMAN SPECTRA; X-RAY DIFFRACTION