The Mixed Alkali Effect in Sodium Rubidium Germanate Glasses

1985 ◽  
Vol 61 ◽  
Author(s):  
J. N. Mundy ◽  
G.-L. Jin
Keyword(s):  
Ionic Conductivity ◽  
Glass Network ◽  
Theoretical Models ◽  
General Applicability ◽  
Alkali Ions ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
The Many ◽  
The Relationship ◽  
Germanate Glasses

ABSTRACTThe lack of general applicability of the many theoretical models for the mixed alkali effect (MAE) in glasses is briefly reviewed. Although the MAE appears to be related to the bonding affinity of alkali ions to charge compensating centers in the glass network, experimental scatter and the difficulty of comparing different glass networks have prevented systematic tests of this relationship. The present paper discusses why the mixed alkali germanate glasses should provide a glass system where the concentration and strength of charge-compensating centers can be systematically varied and the relationship to the MAE tested. Such tests are only possible if the ionic conductivity of a series of mixed alkali germanate glasses can be measured in a reproducible manner. The measurements of the ionic conductivity of two series of X(Na,Rb)2O:(1-X)GeO2 glasses, with X = 0.19 and X = 0.29, respectively, suggest the necessary reproducibility can be attained.

scholarly journals Influence of glass network ionicity on the mixed‐alkali effect

2020 ◽  
Vol 11 (3) ◽  
pp. 396-414
Author(s):  
Courtney Calahoo ◽  
Yang Xia ◽  
Ru Zhou
Keyword(s):  
Glass Network ◽  
Mixed Alkali ◽  
Mixed Alkali Effect

scholarly journals Mixed-Alkali Effect in Borate Glasses: Thermal, Elastic, and Vibrational Properties

Solids ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 16-30
Author(s):  
Seiji Kojima
Keyword(s):  
Vibrational Properties ◽  
Borate Glasses ◽  
Lithium Borate ◽  
Cauchy Type ◽  
Oxide Glasses ◽  
Raman Scattering Spectroscopy ◽  
Alkali Ions ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Longitudinal Modulus

When oxide glasses are modified by dissimilar alkali ions, a maximum in the electric resistivity or the expansion coefficient appears, called the mixed-alkali effect (MAE). This paper reviews the MAE on the thermal, elastic, and vibrational properties of the mixed-cesium lithium borate glasses, x{(1−y)Cs2O-yLi2O}-(1−x)B2O3. For the single-alkali borate glasses, xM2O(1−x)-B2O3 (M = Li, Na, K, Rb, and Cs), the glass transition temperature, Tg = 270 °C, of a borate glass monotonically increases as the alkali content x increases. However, for the mixed-cesium lithium borate glasses the Tg shows the minimum against the lithium fraction y. The dependences of the elastic properties on the lithium fraction y were discussed regarding the longitudinal modulus, Poisson’s ratio, and Cauchy-type relation. The internal vibrational bands related to the boron-oxide structural groups and the splitting of a boson peak were discussed based on Raman scattering spectroscopy. The MAE on various physical properties are discussed on the basis of the changes in the coordination number of the borons and the nonbridging oxygens caused by the dissimilar alkali ions.

Structural Features and the Effect of Two Alkalis in Chalcogenide and Phosphate Glasses

2019 ◽  
Vol 822 ◽  
pp. 824-833
Author(s):  
Viktor A. Markov ◽  
Ivan Sokolov ◽  
Alexey Povolotskiy
Keyword(s):  
Ionic Conductivity ◽  
Electric Current ◽  
Structural Features ◽  
Phosphate Glasses ◽  
Electrical Parameters ◽  
Mixed Alkali ◽  
Mixed Alkali Effect

This paper presents data on the mixed alkali effect in two fundamentally different systems: chalcogenide and oxide (phosphate). In the first system (Ag – Cu)0.44AsSe1.5, the predominantly ionic conductivity of silver-containing glasses is replaced by purely electronic in copper-containing, in the second - 0.5(Li2O-Na2O) – 0.4P2O5 – 0.1Nb2O5 carriers of electric current are alkaline ions and the extreme dependences of the electrical parameters associated with their joint migration.

scholarly journals Sodium-free mixed alkali bioactive glasses

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Delia S. Brauer ◽  
Raika Brückner ◽  
Maxi Tylkowski ◽  
Leena Hupa
Keyword(s):  
Coefficient Of Thermal Expansion ◽  
Release Rates ◽  
Ion Release ◽  
Bioactive Glasses ◽  
Ionic Radii ◽  
Alkali Ions ◽  
Processing Window ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
High Temperature Processing

AbstractTwo sodium-free mixed alkali series of bioactive glasses based on compositions Bioglass 45S5 and ICIE1, containing lithium and/or potassium as alkali ions, were prepared by a melt-quench route. Thermal properties showed the well-known mixed alkali effect, with glass transition and crystallisation temperatures and the coefficient of thermal expansion going either through a minimum or a maximum for the mixed alkali composition, resulting in a wider processing window. Ion release, by contrast, was controlled by the modifier ionic radius, with ion release rates in dynamic and static dissolution studies increasing for potassium-substituted glasses compared to the composition containing lithium as the only alkali ion. This was caused by pronounced changes in oxygen packing density and molar volume of the glasses owing to the differences in ionic radii (76 pm for Li+ and 138 pm for K+). Partially substituting one alkali for another therefore helps to improve high temperature processing of bioactive glasses and can also be used to control or tailor ion release.

Ionic conductivity and the mixed alkali effect inLixRb1−xPO3glasses

2003 ◽  
Vol 68 (6) ◽  
Author(s):  
C. Karlsson ◽  
A. Mandanici ◽  
A. Matic ◽  
J. Swenson ◽  
L. Börjesson
Keyword(s):  
Ionic Conductivity ◽  
Mixed Alkali ◽  
Mixed Alkali Effect
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