Title

Glass Transition and Fragility of Iron Phosphate Glasses.: II. Effect of Mixed-alkali

Abstract

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.

Department(s)

Materials Science and Engineering

Sponsor(s)

United States. Department of Energy

Keywords and Phrases

M250

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2003 Elsevier, All rights reserved.

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