2019
Ultrahigh pressure structural changes in a 60 mol. % Al2O3-40 mol. % SiO2 glass
Geochemical Perspectives Letters
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- Volume
- 10
- Number
- First page
- 41
- Last page
- 45
- Language
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.7185/geochemlet.1913
Structure of an Al-containing silicate glass (60 mol. % Al2O3-40 mol. % SiO2, A40S) is investigated up to 131 GPa, a pressure close to that of the Earth's core-mantle boundary, by using our recently developed double stage large volume cell. The first peak (r1) of the pair distribution function, which corresponds to T-O distance (T = Al, Si), rapidly increases below 16 GPa, indicating an increase of average coordination number (CN) of T-O from ~4 to 6. The r1 linearly decreases in the pressure range of 25-110 GPa, but it displays a slope change and becomes nearly constant above 110 GPa. The slope change may imply a structural change in the A40S glass around 110 GPa, and may be explained by the change in Al-O distance associated with the Al-O CN increase from 6 to >6 as predicted by molecular dynamics simulations (Ghosh and Karki, 2018). Our observations suggest an important role for aluminum in densification of aluminosilicate at the deep lower mantle, which might imply a dense aluminosilicate magma with negative buoyancy.
- Link information
- ID information
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- DOI : 10.7185/geochemlet.1913
- ISSN : 2410-339X
- eISSN : 2410-3403
- ORCID - Put Code : 63779610
- SCOPUS ID : 85068156290