biostudies-literatureKono YMEXT | Japan Society for the Promotion of ScienceMEXT | Japan Society for the Promotion of Science (JSPS)2292https://www.ebi.ac.uk/biostudies/studies/S-EPMC9051114biostudies-literatureUnknown13(1)Bimodal behavior in the translational order of silicon's second shell in SiO₂ liquid at high temperatures and high pressures has been recognized in theoretical studies, and the fraction of the S state with high tetrahedrality is considered as structural origin of the anomalous properties. However, it has not been well identified in experiment. Here we show experimental evidence of a bimodal behavior in the translational order of silicon's second shell in SiO₂ glass under pressure. SiO₂ glass shows tetrahedral symmetry structure with separation between the first and second shells of silicon at low pressures, which corresponds to the S state structure reported in SiO₂ liquid. On the other hand, at high pressures, the silicon's second shell collapseNature communicationsExperimental evidence of tetrahedral symmetry breaking in SiO₂ glass under pressure.PMC905111420H00201, 19KK0093Yamazaki HHayashi YKoyama TOhashi HYamada JSekizawa OYamada HGoto SInoue ISenba YTamasaku KYabashi MOhara KKono YYumoto HOsaka THigo YTange YHiroi SNoritake FNitta KKondo NMfalseExperimental evidence of tetrahedral symmetry breaking in SiO₂ glass under pressure.Bimodal behavior in the translational order of silicon's second shell in SiO₂ liquid at high temperatures and high pressures has been recognized in theoretical studies, and the fraction of the S state with high tetrahedrality is considered as structural origin of the anomalous properties. However, it has not been well identified in experiment. Here we show experimental evidence of a bimodal behavior in the translational order of silicon's second shell in SiO₂ glass under pressure. SiO₂ glass shows tetrahedral symmetry structure with separation between the first and second shells of silicon at low pressures, which corresponds to the S state structure reported in SiO₂ liquid. On the other hand, at high pressures, the silicon's second shell collapse2022-01-01T00:00:00Z2022 Apr2025-04-05T14:43:26.111Z2025-04-05T14:43:26.111ZS-EPMC90511143548412210.1038/s41467-022-30028-w