Free volume anomalies in mixed-cation glasses revealed by positron annihilation lifetime spectroscopy (PALS)

PALS experiments reveal a minimum in ortho-positronium (o-Ps) lifetimes and a maximum in the corresponding intensities that emerge when mixed-cation (Li/Na) borate glasses are heated from ambient temperatures up to 473 K. These free volume 'anomalies' appear to be a true manifestation of t...

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Bibliographic Details
Published inPhysical chemistry chemical physics : PCCP Vol. 7; no. 8; p. 1620
Main Authors Ingram, Malcolm D, Pas, Steven J, Cramer, Cornelia, Gao, Yong, Hill, Anita J
Format Journal Article
LanguageEnglish
Published England 21.04.2005
Subjects
Borates - chemistry
Cations - chemistry
Glass
Metals, Alkali - chemistry
Spectrum Analysis
Surface Properties
Temperature
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Summary:PALS experiments reveal a minimum in ortho-positronium (o-Ps) lifetimes and a maximum in the corresponding intensities that emerge when mixed-cation (Li/Na) borate glasses are heated from ambient temperatures up to 473 K. These free volume 'anomalies' appear to be a true manifestation of the mixed alkali effect (MAE). They are consistent with a mechanism of ion transport involving cooperation between hops of unlike cations, resulting in increased disturbance of the glass network. The result lends support to the dynamic structure model.
ISSN:1463-9076
DOI:10.1039/b419201j