Simulations of mechanical responses in v-B2O3 glass under indentation and shear deformation

S Urata, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 109, e70438 (2025).

DOI: 10.1111/jace.70438

The boroxol ring is a planar three-membered ring and represents a characteristic microstructure in vitreous borate glass (v-). Molecular dynamics simulations of indentation were conducted using a machine- learning force field to investigate the mechanical response of v- models containing different concentrations of boroxol rings. According to indentation simulations performed with a V-shaped indenter, plastic deformation was observed regardless of the boroxol ring population in the glass models. A certain fraction of boroxol rings was disrupted during loading, and the ring structures were rarely reformed upon unloading the indenter. In addition, irreversible distortion of B-O-B and O-B-O bond angles was observed as a signature of plastic deformation. In contrast, increased boron coordination due to loading was largely recovered upon unloading. Furthermore, boron atoms rarely changed their coordination number under shear deformation, indicating that changes in boron coordination are not responsible for plastic deformation under shear deformation. Analysis of the cross-correlation function of boroxol ring orientations has revealed that boroxol rings are unable to align their orientations when they are brought closer than approximately 3 & Aring; due to shear deformation. Consequently, we conclude that the slip motion of boroxol rings under shear deformation does not occur in v-, which is in contrast to sodium borate glass, (, where slip motion has been suggested based on an experimental indentation study.

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