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Transformation from molecular to polymeric nitrogen at high pressures and temperatures: In situ x-ray diffraction study

2008; American Institute of Physics; Volume: 93; Issue: 9 Linguagem: Inglês

10.1063/1.2975375

1520-8842

Ivan Trojan, M. I. Eremets, Sergey A. Medvedev, Alexander Gavriliuk, Vitali B. Prakapenka,

Boron and Carbon Nanomaterials Research

We studied the mechanism of the structural transformation of molecular nitrogen to atomic single-bonded nitrogen with a cubic gauche (cg-N) crystal structure using x-ray diffraction in situ at a pressure of ∼140 GPa and temperatures up to 2000 K in a diamond anvil cell. The anvils, with a toroidal shape, allowed us to drastically increase the volume of the sample, reduce the acquisition time of the diffraction pattern, and improve the quality of the Raman spectra. Molecular nitrogen transforms to the cg-N phase through an intermediate disordered state. The Raman spectra are in good agreement with recent theoretical calculations.