Nanotwinned Boron Suboxide (B6O): New Ground State of B6O
No Thumbnail Available
Authors
An, Qi
Reddy, K. Madhav
Dong, Huafeng
Chen, Mingwei
Oganov, Artem R.
Goddard III, William A.
Issue Date
2016
Type
Citation
Language
Keywords
DFT , Deformation mechanism , stacking faults energy , Superhard ceramics
Alternative Title
Abstract
Nanotwinned structures in superhard ceramics rhombohedral boron suboxide (R-B6O) have been examined using a combination of transmission electron microscopy (TEM) and quantum mechanics (QM). QM predicts negative relative energies to R-B6O for various twinned R-B6O (denoted as τ-B6O, 2τ-B6O, and 4τ-B6O), consistent with the recently predicted B6O structure with Cmcm space group (τ-B6O) which has an energy 1.1 meV/B6O lower than R-B6O. We report here TEM observations of this τ-B6O structure, confirming the QM predictions. QM studies under pure shear deformation and indentation conditions are used to determine the deformation mechanisms of the new τ-B6O phase which are compared to R-B6O and 2τ-B6O. The lowest stress slip system of τ-B6O is (010)/⟨001⟩ which transforms τ-B6O to R-B6O under pure shear deformation. However, under indentation conditions, the lowest stress slip system changes to (001)/⟨110⟩, leading to icosahedra disintegration and hence amorphous band formation.
Description
Citation
Publisher
American Chemical Society
License
In Copyright
Journal
Volume
Issue
PubMed ID
ISSN
1530-6984