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Diffusion and microstructure in sodium silicate liquids
Ist Teil von
The European physical journal. B, Condensed matter physics, 2018-12, Vol.91 (12), p.1-7, Article 306
Ort / Verlag
Berlin/Heidelberg: Springer Berlin Heidelberg
Erscheinungsjahr
2018
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
We use molecular dynamics simulation to investigate the diffusion and microstructure of Na
2
O⋅3SiO
2
and Na
2
O⋅4SiO
2
liquid. It is shown that the temporal locations of Na are placed nearby O atoms. The O and Si atoms diffuse via the NBO ↔BO and SiO
4
↔SiO
3
transformations. Meanwhile the diffusion of sodium is realized by mixed hopping-like and cooperative mechanism. Accordingly, Na atoms move from sites to other sites that are located nearby O atoms. Each NBO and BO has two and one sites, respectively. The Na atom prefers to move to NBO sites rather than to BO sites. Furthermore, Na atoms are collectively redistributed between different O atoms as the NBO ↔BO transformation happens. The diffusion pathways for sodium located in overlapped NF
x
B
y
cells contain large number of NF sites and small amount of BO sites. The dynamics of O atoms is analyzed through specified sets of most mobile and immobile atoms. The simulation showed that the dynamics of O atoms is heterogeneous. During moderately long time, the Si–O network consists of separate immobile domains where the local density of Na atoms is smaller than that in the rest of the network.
Graphical abstract