A thermodynamically-based structural model for the cationic conductivity and mixed-modifier effect in borate glasses

作者：Wright Adrian C^*; Vedishcheva Natalia M

来源：Physics and Chemistry of Glasses-European Journal of Glass Science and Technology Part B, 2015, 56(3): 98-107.

DOI：10.13036/17533562.56.3.098

Based on the neutron diffraction data discussed in an accompanying paper (pp 85-97), and on the results of thermodynamic modelling using the model of associated solutions, it is concluded that the (network-modifying) cationic conduction, and the mixed-modifier effect, in alkali and related borate glasses is best described by a reformulated combination of the cluster-bypass and dynamic structure models. In this revised approach, the clusters are replaced by the (chemical) groupings that characterise the chemical structure of the glasses, and the network-modifying cation transport is via conduction pathways located in the interfacial/boundary regions that separate these groupings. The proposed model can explain the rapid fall-off in the cationic conductivity on the initial introduction of the second network-modifying cation species, and the increasing magnitude of the conductivity depression with increasing total modifier content. A comparison with the case of the corresponding silicate glasses indicates that the spatial distribution of the network-modifying cations in silicate glasses is more complicated than suggested by the well known two-dimensional schematic diagram representing the modified random network theory.

• 出版日期2015-6