Vibrational dynamics and stability of the high-pressure chain and ring phases in S and Se

Olga Degtyareva, Eduardo R. Hernandez, Jorge Serrano, Maddury Somayazulu, Ho-Kwang Mao, Eugene Gregoryanz, Russell J. Hemley

Research output: Contribution to journalArticlepeer-review

Abstract

The high-pressure phases of group-VI elements sulfur and selenium in their spiral chain and ring structures are examined by in situ Raman and x-ray diffraction techniques combined with first principles electronic structure calculations. The S-II, S-III, Se-I, and Se-VII having spiral chain structures and S-VI with a molecular six-member ring structure are studied in a wide P-T range. The square spiral chain structure of S-III and Se-VII is characterized by seven Raman modes that harden with increasing pressure. The calculations reproduce the observed frequencies and allow the authors to make the mode assignment. The "p-S" and "hplt" phases of sulfur reported by previous Raman studies are identified as S-II and S-III with the triangular and square spiral chain structures, respectively. The phase relations obtained by the x-ray and Raman measurements show that the high-pressure high-temperature phases of sulfur, observed by x-ray, can be induced by laser illumination at room temperature. (c) 2007 American Institute of Physics.

Original languageEnglish
Article number084503
Number of pages11
JournalThe Journal of Chemical Physics
Volume126
Issue number8
DOIs
Publication statusPublished - 28 Feb 2007

Keywords

  • X-RAY-DIFFRACTION
  • TOTAL-ENERGY CALCULATIONS
  • SOLID SULFUR ALLOTROPES
  • AUGMENTED-WAVE METHOD
  • ULTRASOFT PSEUDOPOTENTIALS
  • RAMAN-SPECTROSCOPY
  • SELENIUM
  • GPA
  • TEMPERATURE
  • TRANSITIONS

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