Triple Point on the Melting Curve and Polymorphism of Nitrogen at High Pressure

Alexander F. Goncharov, Jonathan C. Crowhurst, Viktor V. Struzhkin, and Russell J. Hemley
Phys. Rev. Lett. 101, 095502 – Published 26 August 2008

Abstract

Raman spectra of solid and fluid nitrogen to pressures up to 120 GPa and temperatures up to 2500 K reveal that the melting line exhibits a maximum near 70 GPa, followed by a triple point near 87 GPa, after which the melting temperature rises again. Fluid nitrogen remains molecular over the entire pressure range studied, and there is no sign of a fluid-fluid transition. Solid phases obtained on quenching from the melt above 48 GPa are identical to the recently discovered ι and ζ phases. We find that kinetics plays a major role in the experimentally observed phase changes and account for the metastability of various crystalline molecular phases and the existence of an amorphous single bonded ηN.

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  • Received 27 March 2008

DOI:https://doi.org/10.1103/PhysRevLett.101.095502

©2008 American Physical Society

Authors & Affiliations

Alexander F. Goncharov1, Jonathan C. Crowhurst2, Viktor V. Struzhkin1, and Russell J. Hemley1

  • 1Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington, D.C. 20015, USA
  • 2Lawrence Livermore National Laboratory, University of California, 7000 East Avenue, Livermore, California 94551, USA

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Issue

Vol. 101, Iss. 9 — 29 August 2008

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