High-Pressure, High-Temperature Synthesis and Characterization of Boron Suboxide (B6O)

Hervé Hubert, Laurence Garvie, Bertrand Devouard, P R Buseck, William Petuskey, Paul F. McMillan

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130 Scopus citations


Boron suboxide, nominally B6O, was synthesized by reducing B2O3 with B up to 10 GPa in a multianvil press at temperatures between 1200 and 1800°C. The samples were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and parallel electron energy-loss spectroscopy (PEELS). We used high-pressure techniques to synthesize boron suboxide of improved purity and crystallinity and less oxygen-deficient (i.e., closer to the nominal B6O composition) in comparison to products of room-pressure syntheses. We describe the preparation of grains ranging from 20 nm to 40 μm in diameter, as well as the first synthesis of micrometer-sized B6O icosahedral twins and euhedral "crystals". The best materials are obtained for starting mixtures containing an excess B2O3 reacted at 1700-1800°C between 4 and 5.5 GPa. After the products were washed in water, well-crystallized single-phase product dominated by icosahedrally twinned particles to 30 μm in diameter was easily recovered. Oxygen occupancies ascertained from Rietveld refinements show data consistent with the chemical compositions determined by PEELS. These results give a composition of B6O0.77 for our room-pressure material. The highest O occupancy, B6O0.96, is obtained for the micrometer-size icosahedral particles prepared at 1700°C between 4 and 5.5 GPa.

Original languageEnglish (US)
Pages (from-to)1530-1537
Number of pages8
JournalChemistry of Materials
Issue number6
StatePublished - Jun 1998

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry


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