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Structure of B 2 O 3 Glass at High Pressure: A B 11 Solid-…

2005; American Physical Society; Volume: 94; Issue: 16 Linguagem: Inglês

10.1103/physrevlett.94.165507

1092-0145

Sung Keun Lee, Kenji Mibe, Yingwei Fei, George D. Cody, Bjørn O. Mysen,

Solid-state spectroscopy and crystallography

We report spectroscopic evidence for the pressure-induced structural changes in ${\mathrm{B}}_{2}{\mathrm{O}}_{3}$ glass quenched from melts at pressures up to 6 GPa using solid-state NMR. While all borons are tri-coordinated at 1 atm, the fraction of tetra-coordinated boron increases with pressure, being about 5% and 27% in the ${\mathrm{B}}_{2}{\mathrm{O}}_{3}$ glass quenched from melts at 2 and 6 GPa, respectively. The fraction of boroxol ring species increases with pressure up to 2 GPa and apparently decreases with further compression up to 6 GPa. Two densification mechanisms are proposed to explain the variation of boron species with pressure.