Exploring the Nucleation Free Energy Landscape of Barium Silicate


Jun 30, 2023

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barium silicate is a high-strength, non-crystalline material that is used in a variety of industrial applications. It acts as a getter, or unwanted gas remover, for vacuum tubes and is alloyed with steel and aluminum to make load-bearing alloys. It is produced from the mineral barite by chemical decomposition, typically in rotary tube furnaces. barium silicate is often mixed with gypsum in the production of Portland cement.

We use a Grand Canonical Monte Carlo (GCMC) model to explore the nucleation free energy landscape of stoichiometric barium silicate glass with different compositions and cluster sizes. The GCMC study is complemented by atomistic molecular dynamics (MD) simulations to probe the crystal-melt interface.

The MD results show that the GCMC models have good agreement with experimental observations. In particular, the 1-2 and 5-8 glasses both have a silica rich inner core that qualitatively agrees with the predictions from the GCMC model. The -5 glass also has a low NFE region that is closer to the melting point of silicon than the 1-2 region.

Interestingly, the MD results do not support the hypothesis that the NFE landscape of stoichiometric glass changes with temperature. The results suggest that the interaction between the crystal and the melt is not dependent on temperature. This conclusion is consistent with a number of experimental observations that have been made by Raman, static and MAS 29Si NMR spectroscopy, as well as with a systematic exploration of the Qn speciation in barium silicate without a priori assumptions.