Atomic structure and mechanical response of coincident stacking faults in boron suboxide

Abstract

We report the atomic structure of coincident stacking faults (SFs) in superhard boron suboxide (B6O) by combining annular bright field scanning transmission electron microscopy and quantum mechanics (QM) simulations. Different from simple SFs, which only lead to the symmetry breaking, the coincident SF junctions in the complex B6O result in local chemical configuration changes by forming an abnormal three-oxygen-atoms chain linking boron icosahedra, instead of the regular two-oxygen-atoms chain in a perfect B6O crystal. QM studies demonstrate that coincident SFs lead to the decreased shear strength under pure shear and indentation conditions and are responsible to the initial failure and amorphization of B6O.

Keywords

• Boron suboxide
• transmission electron microscopy
• stacking fault
• shear amorphization
• mechanical behavior