| Full text | |
| Author(s): |
Gomes, Yara Hellen Firmo
;
Logrado, Millena
;
Inoue, Tomiki
;
Nakane, Shingo
;
Kato, Yoshinari
;
Yamazaki, Hiroki
;
Yamada, Akihiro
;
Eckert, Hellmut
Total Authors: 8
|
| Document type: | Journal article |
| Source: | Journal of Physical Chemistry B; v. 128, n. 14, p. 13-pg., 2024-04-01. |
| Abstract | |
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-10Al(2)O(3)-10B(2)O(3)-70SiO(2) (labeled SAB) and a sodium magnesium borosilicate glass with the composition 10Na(2)O-10MgO-20B(2)O(3)-60SiO(2) (labeled MNBS). For SAB glass, cold pressurization results in significant increases in the average coordination numbers of both boron and aluminum, in line with previous results found in hot-compressed alkali aluminoborosilicate glasses. In addition, 27Al/11B dipolar recoupling experiments reveal a significant decrease in the 11B/27Al dipolar interaction strength upon pressurization, suggesting that the higher-coordinated boron and aluminum species experience weaker magnetic interactions. While this is an expected consequence of the longer internuclear distances involving higher coordination states, the magnitude of the effect also is consistent with a decrease of average B-O-Al internuclear connectivity. By conjecture, a decreased B-O-Al connectivity may present a mechanism of plastic flow inhibiting crack initiation in aluminoborosilicate glasses. In the case of the MNBS glass, no change in the average boron coordination number was observed within experimental error; however, densification increases the extent of B-O-Si connectivity at the expense of small ring structures with dominant B-O-B connectivity. With regard to boron coordination, the data obtained for both case studies differ from those previously found in a series of alkali borosilicate glasses, which had shown an unexpected decrease in N 4 upon increased pressure. The results of the present study highlight the importance of changes of medium-range order regarding densification. (AU) | |
| FAPESP's process: | 21/08871-7 - Incorporation of gallium into bioactive glasses: new structure/function relations uncovered by solid state NMR techniques |
| Grantee: | Yara Hellen Firmo Gomes |
| Support Opportunities: | Scholarships in Brazil - Scientific Initiation |
| 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 |