Densification of Sodium Borosilicate Glasses at Ambient Temperature: Structural Investigations by Solid-State Nuclear Magnetic Resonance and Raman Scattering

Author(s)

Logrado, Millena ; Inoue, Tomiki ; Nakane, Shingo ; Kato, Yoshinari ; Yamazaki, Hiroki ; Yamada, Akihiro ; Eckert, Hellmut

• Document type: Journal article
• Source: Journal of Physical Chemistry Letters; v. 14, n. 19, p. 11-pg., 2023-05-08.

Abstract

Alkali-borosilicate glasses with composition (80-x)SiO2-xB2O3-20Na2O (10 < x < 30) were subjected to a 25 GPa compression and decompression at room temperature, resulting in density increases between 1.4% and 1.9%. The structural changes associated with this process have been investigated and compared with uncompressed glasses having the same thermal history. Systematic trends are identified, using Raman scattering and multinuclear solid-state Nuclear Magnetic Resonance (ssNMR). Perhaps counterintuitively, pressurization tends to increase the concentration of three-coordinated boron species (B(III) units) at the expense of four coordinated boron (B(IV) units). 23Na NMR spectra show a systematic shift toward higher frequencies in the pressurized glasses, consistent with shorter average Na-O distances. The results are consistently explained in terms of a breakage of Si-O-B4 linkages resulting in the formation of nonbridging oxygen species. Pressure effects on the spectra are reversed by annealing the glasses at their respective glass transition temperatures. (AU)

• FAPESP's process: 13/07793-6 - CEPIV - Center for Teaching, Research and Innovation in Glass
• Grantee: Edgar Dutra Zanotto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC