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Ultra‐Flexible Boron‐Oxygen 3D Solid‐State Networks
Author(s) -
Claeyssens Frederik,
Hart Judy N.,
Norman Nicholas C.,
Allan Neil L.
Publication year - 2013
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201300172
Subject(s) - materials science , boron , covalent bond , chemical physics , flexibility (engineering) , crystallography , nanoporous , nanotechnology , range (aeronautics) , density functional theory , molecular physics , computational chemistry , composite material , chemistry , organic chemistry , statistics , mathematics
The existence of ultra‐flexible low‐energy forms of boron oxides (B 2 O 3 and BO) is demonstrated, in particular structures in which B 3 O 3 or B 4 O 2 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 B 2 O 3 .