Ultra-Flexible Boron-Oxygen 3D Solid-State Networks

Neil L Allan, Judy N Hart, Nick C Norman, Frederik Claeyssens

Research output: Contribution to journalArticle (Academic Journal)peer-review

7 Citations (Scopus)


The existence of ultra-flexible low-energy forms of boron oxides (B 2O3 and BO) is demonstrated, in particular structures in which B3O3 or B4O2 six-membered rings are linked by single B-O-B bridges. The minima in the energy landscapes are remarkably broad; the variation in the internal energies is very small over a very large range of volumes. Such volume changes may even exceed 200%. This remarkable behavior is attributed predominantly to the pronounced angular flexibility of the B-O-B bridges linking the rings, which is unusual for a covalent bond. At larger volumes, the structures are nanoporous; the pores collapse upon compression with negligible change in energy, making these suitable as guest-host materials. In marked contrast, in other materials where low density frameworks have been reported or predicted, such low-density phases are considerably higher in energy. The flexibility of the structures also offers a resolution of the long-standing controversy reconciling the structure and density of vitreous B2O3.
Original languageEnglish
Pages (from-to)5887-5892
Number of pages6
JournalAdvanced Functional Materials
Issue number47
Early online date5 Jun 2013
Publication statusPublished - 5 Jun 2013


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