Decomposition of W(CO) 6 at high pressures and temperatures

Nadine Rademacher, Lkhamsuren Bayarjargal, Alexandra Friedrich, Wolfgang Morgenroth, Miguel Avalos-Borja, Sven C. Vogel, Thomas Proffen, Björn Winkler

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The decomposition of hexacarbonyltungsten, W(CO) 6, has been studied. The decomposition was induced by heating W(CO) 6 in an autoclave at 523 K and pressures up to 1.8 MPa, and by laser heating in a diamond anvil cell at pressures between 5 and 18 GPa. The products have been characterized using synchrotron X-ray diffraction, pair distribution function analysis, Raman spectroscopy and scanning electron microscopy. Decomposition in the autoclave at the lower pressures resulted in the formation of a metastable tungsten carbide, W 2C, with an average particle size of 1-2 nm, and an unidentified nanocrystalline tungsten oxide and nanocrystalline graphite with average particle sizes of 1-2 and 11 nm, respectively. The existence of nanocrystalline graphite was deduced from micro-Raman spectra and the graphite particle size was extracted from the intensities of the Raman modes. The high-pressure decomposition products obtained in the diamond anvil cell are the monoclinic tungsten oxide phase WO 2 and the high-pressure phase W 3O 8(I). The approximate average size of the graphite particles formed here was 6-8 nm. The bulk modulus of W(CO) 6 is B 0 ≈ 13 GPa.

Original languageEnglish
Pages (from-to)820-830
Number of pages11
JournalJournal of Applied Crystallography
Volume44
Issue number4
DOIs
StatePublished - Aug 2011
Externally publishedYes

Keywords

  • Decomposition
  • Raman spectroscopy
  • X-ray diffraction
  • pair distribution function
  • scanning electron microscopy

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