Document Type
Article
Publication Date
11-21-2018
Publication Title
Physical Review B
Volume
98
Issue
17
First page number:
1
Last page number:
6
Abstract
We search for stable compounds of boron and oxygen at pressures from 0 to 500 GPa using the ab initio evolutionary algorithm uspex. Only two stable stoichiometries of boron oxides, namely, B6O and B2O3, are found to be stable, in good agreement with experiment. A hitherto unknown phase of B6O at ambient pressure, Cmcm−B6O, has recently been predicted by us and observed experimentally. For B2O3, we predict three previously unknown stable high-pressure phases—two of these (Cmc21 and P212121) are dynamically and mechanically stable at ambient pressure, and should be quenchable to ambient conditions. Their predicted hardnesses, reaching 33–35 GPa, make them harder than SiO2-stishovite. These are the hardest known oxides (if one disregards B6O, which is essentially a boron-based insertion compound). Under pressure, the coordination number of boron atoms changes from 3 to 4 to 6, skipping fivefold coordination.
Disciplines
Physics
File Format
File Size
1.176 Kb
Language
English
Repository Citation
Dong, H.,
Oganov, A. R.,
Brazhkin, V. V.,
Wang, Q.,
Zhang, J.,
Esfahani, M. M.,
Zhou, X.,
Wu, F.,
Zhu, Q.
(2018).
Boron Oxides under Pressure: Prediction of the Hardest Oxides.
Physical Review B, 98(17),
1-6.
http://dx.doi.org/10.1103/PhysRevB.98.174109