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A new interpretation of the dynamic structure model of ion transport in molten and solid glasses

Armin Bunde·Malcolm D. Ingram·Stefanie Russ
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Abstract

We explore progress in understanding the behaviour of cation conducting glasses, within the context of an evolving ''dynamic structure model'' (DSM). This behaviour includes: in single cation glasses a strong dependence of ion mobility on concentration, and in mixed cation glasses a range of anomalies known collectively as the mixed alkali effect. We argue that this rich phenomenology arises from the emergence during cooling of a well-defined structure in glass melts resulting from the interplay of chemical interactions and thermally driven ionic motions. The new DSM proposes the existence of a new site relaxation process, involving the shrinkage of empty $\bar A$ sites (thus tailored to the needs of $A^+$ ions), and the concurrent emergence of empty $C'$’sites, which interrupt the conduction pathways. This reduction of $\bar A$ sites is responsible in the molten glass for the sharp fall in conductivity as temperature drops towards $T_g$. The $C'$ sites play an important role also in the mixed alkali effect, especially in regard to the pronounced asymmetries in diffusion behaviour of dissimilar cations.

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Armin Bunde, Malcolm D. Ingram, Stefanie Russ. 2004-05-18. A new interpretation of the dynamic structure model of ion transport in molten and solid glasses. https://doi.org/10.1039/b316738k

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