Glass Transition and Fragility of Iron Phosphate Glasses.: II. Effect of Mixed-alkali
Changes in the heat capacity from the glass state (Cpg) to the supercooled liquid state (Cpl), ΔCp=Cpl−Cpg, the ratio of heat capacities, Cpl/Cpg, width of the glass transition temperature, ΔTg, and activation enthalpy for structural relaxation, ΔH*, in the glass transition region for the xNa2O-(20−x)R2O-32Fe2O3-48P2O5 (R=K and Cs) mol% glasses, where x=0, 5, 10, 15, 20, have been investigated using differential scanning calorimetry. ΔCp and Cpl/Cpg are in the range of 57-68 J/mol/K and 1.41-1.51, respectively, for the xNa2O-(20−x)R2O-32Fe2O3-48P2O5 (R=K and Cs) mol% glasses, which suggests that the alkali-containing iron phosphate glasses, similar to the alkali-free binary iron phosphate glass, also belong in the category of fragile liquids. Adding 20 mol% of alkali oxides to the 40Fe2O3-60P2O5 (mol%) composition does not change the glass transition behavior or melt fragility very much, but does increase the glass transition temperature, Tg. No mixed-alkali effect is observed on any glass transition properties for the iron phosphate glass.
X. Fang et al., "Glass Transition and Fragility of Iron Phosphate Glasses.: II. Effect of Mixed-alkali," Journal of Non-Crystalline Solids, Elsevier, May 2003.
The definitive version is available at http://dx.doi.org/10.1016/S0022-3093(02)01965-8
Materials Science and Engineering
United States. Department of Energy
Keywords and Phrases
Article - Conference proceedings
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