Title

Dynamics of Mixed Alkali Metaphosphate Glasses and Liquids

Abstract

Dynamic mechanical, stress relaxation, and oscillatory shear experiments were performed to examine relaxation processes in a series of mixed alkali metaphosphate glasses and liquids. At temperatures less than the glass transition temperature, Tg, dynamic processes are dominated by hopping of alkali ions and local network relaxations that accommodate the motion of the cations. The average relaxation times associated with these dynamic processes were sensitive to the molar ratio of alkali ions in the glass. For T > Tg, viscous relaxations were controlled primarily by the translational dynamics of P-O-P chains. These longer time viscous relaxation processes also appear to be affected by the dynamics of the alkali ions. The high frequency elastic modulus, G0, the fragility of the liquid, the heat capacity changes at Tg, Δcp(Tg), and the breadth of the distribution of relaxation times, W, were all dependent on the molar ratio of the alkali oxides. Correlations between the fragility, W and Δcp(Tg), which were found to describe the effects of single alkali oxide modified glasses, failed to describe related properties in these mixed alkali metaphosphates.

Department(s)

Materials Science and Engineering

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 1999 Elsevier, All rights reserved.


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