Correlation between the activation enthalpy and Kohlrausch exponent for ionic conductivity in oxide glasses

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1989-11-15
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Ngai, Kia
Martin, Steve
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Martin, Steve
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Materials Science and Engineering
Materials engineers create new materials and improve existing materials. Everything is limited by the materials that are used to produce it. Materials engineers understand the relationship between the properties of a material and its internal structure — from the macro level down to the atomic level. The better the materials, the better the end result — it’s as simple as that.
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We have established for alkali ions in oxide glasses a strong correlation between the fractional (Kohlrausch) exponent β in the conductivity relaxation function, exp[-(t/τ*)β], and the activation energy E*a of τ* and σ when varying the composition of oxide glass formers and the alkali ions while holding the alkali-ion concentration constant. An even stronger correlation of the trends in β and the product βE*a is found. These correlations were expected conceptually by the coupling model for conductivity relaxation, and the latter was the motivation behind the present undertaking of the establishment of the correlation from experimental data. The glass-forming oxides considered include P2O5, SiO2, B2O3, Al2O3-B2O3, GeO2, and Al2O3-GeO2. In all, some 89 different compositions were examined and the alkali oxides considered include Li2O, Na2O, K2O, Rb2O, and some of their binary mixtures. The correlation will have a bearing on the viability of theoretical models of conductivity relaxation.

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This article is from Physical Review B 40 (1989): 10550–10556, doi:10.1103/PhysRevB.40.10550. Posted with permission.

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Sun Jan 01 00:00:00 UTC 1989
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