Local structure of silicate glasses

Effect of alkali and alkaline-earth cations on the neodymium environment in a rare-earth rich aluminoborosilicate glass

“…In the seven-oxide glass, these cations are Na + and Ca 2+ , but a great variety of neighboring cations must be assumed in the nuclear glass with complete composition. The RE 3+ , modifying cations and NBO's probably form depolymerized regions throughout the network, according to widely accepted models of glass structure [5,6], though their extent is matter of debate. To improve this model, we now investigate how the distribution of sites of the rare-earth ion may be dependent on the nature of the surrounding alkali and alkaline-earth ions.…”

Molecular-dynamics simulations of(NaO2)x(SiO2Oviedo1, Sanz2 1998Phys. Rev. B494300View full textAdd to dashboardCite

“…This model results from XAFS data in which the number of nonbridging oxygens ͑NBO͒ around alkali ions was found to be larger than that of bridging oxygens ͑BO͒. [1][2][3] In this model, there is a process of microsegregation in the glass and the modifying cations form clusters in the SiO 2 rich matrix, to which they are predominantly linked via the NBO's. At higher concentrations, the clusters percolate through the glass bulk giving rise to pathways for ionic conduction.…”

Temperature-dependent structural heterogeneity in calcium silicate liquids

“…2,3 This is despite the analysis of quenched glass structures that indicate atomic to nanometer scale structural heterogeneity must occur in the liquid state. [4][5][6][7] Silica is classified as a strong liquid with an Arrhenius viscosity-temperature relation and only subtle differences occur between the liquid and glass structures. 8,9 In contrast CaO-SiO 2 liquids can be considered fragile based on viscosity measurements 10,11 and consequently larger structural rearrangements are likely to be necessary to form a glass.…”