Full text loading...
Calorimetric response to heating at 20 K/min in argon for the (76−x)SiO2−xAl2O3−16Na2O−8CaO glasses with x = 0, 2.7, 5.3, 8, 10.7, 13.3, 16, 18.7, 21.3, and 24. The dashed blue line indicates the change in glass transition temperature (T g) with composition. The red circles indicate the onset of crystallization in the glasses with 21.3 and 24 mol% Al2O3.
(a) Composition dependence of the glass transition temperature obtained from DSC (T g,DSC) and equilibrium viscosity (T g,vis) measurements. (b) Angell fragility plot showing the logarithmic viscosity (log η) as a function of the T g scaled inverse temperature (T g/T) for five selected liquids.
Composition dependence of the liquid fragility index m obtained from fitting the MYEGA equation (see Ref. 24) to the viscosity data. The dashed line is the guide for eyes.
27Al MAS NMR spectra of the aluminosilicate glasses (see Ref. 36). The spectra show unchanging lineshapes for glasses having [Al2O3]< [Na2O] and asymmetrical broadening for glasses with [Al2O3] ≥ [Na2O]. The inset shows simulation of the AlIV and AlV resonances for the x = 24 glass.
Composition dependence of the number of NBO/T calculated based on the analyzed compositions and the fraction of tetrahedral aluminum from 27Al MAS NMR.
Article metrics loading...