Structural Aspects of Ambient-Temperature Densification of Highly Crack-Resistant Borosilicate and Aluminoborosilicate Glasses: Two Case Studies Examined by Solid-State NMR

• DOI: 10.1021/acs.jpcb.4c00560
• Publication Date: 2024-04-01T20:48:50Z
• Authors: Yara Hellen Firmo...; Millena Logrado; Tomiki Inoue; Shingo Nakane; Yoshinari Kato; Hiroki Yamazaki; Akihiro Yamada; Hellmut Eckert
• Keywords: Borosilicate glass

The structural aspects of ambient-temperature densification via pressurization at 25 GPa were studied by solid-state NMR for two case studies: An alkaline earth boroaluminosilicate glass with the composition 6CaO-3SrO-1BaO-10Al2O3-10B2O3-70SiO2 (labeled SAB) and a sodium magnesium borosilicate 10Na2O-10MgO-20B2O3-60SiO2 MNBS). For SAB glass, cold results in significant increases average coordination numbers both boron aluminum, line previous found hot-compressed alkali aluminoborosilicate glasses. In addition, 27Al/11B dipolar recoupling experiments reveal decrease 11B/27Al interaction strength upon pressurization, suggesting that higher-coordinated aluminum species experience weaker magnetic interactions. While this is an expected consequence longer internuclear distances involving higher states, magnitude effect also consistent B–O–Al connectivity. By conjecture, decreased connectivity may present mechanism plastic flow inhibiting crack initiation MNBS no change number was observed within experimental error; however, extent B–O–Si expense small ring structures dominant B–O–B With regard to coordination, data obtained studies differ from those previously series glasses, which had shown unexpected N4 increased pressure. study highlight importance changes medium-range order regarding densification.