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 Synthesis, structural characterization and ionic conductivity of mixed alkali titanium phosphate glasses

2018 ◽  
Vol 7 (5) ◽  
pp. 328-336 ◽  
Author(s):  
Fatima Ezzahraa Dardar ◽  
Michael Gross ◽  
Saida Krimi ◽  
Michel Couzi ◽  
Abdessadek Lachgar ◽  
...  
Keyword(s):  
Ionic Conductivity ◽  
Physical Properties ◽  
Glass Structure ◽  
Phosphate Glasses ◽  
X Ray Diffraction ◽  
Mixed Alkali ◽  
Tio6 Octahedra ◽  
Mixed Alkali Effect ◽  
Density Values ◽  
Pass Through

Glasses with formula Na3-xLixCaTi(PO4)3 [10(3-x) mol. % Na2O - 10x mol. % Li2O - 20 mol. % CaO - 20 mol. % TiO2 - 30 mol. % P2O5] (0 ≤ x ≤ 3) were prepared by standard melt-quenching technique, and their structural and physical properties were characterized by thermal analysis, density measurements, Raman, and impedance spectroscopy. When Na+ is gradually replaced by Li+ , molar volume, glass transition temperature (Tg) and ionic conductivity values decrease, pass through a minimum around the composition x = 1.5, then increase, while density values increase, pass through a maximum, then decrease. The non-linear variation of these physical properties is a result of the classical mixed alkali effect. Powder X-ray diffraction shows that crystallization of the glasses leads to the formation of a Nasicon phase for the compositions x = 0 and x = 0.5, and to a mixture of phases for the other compositions. Raman spectroscopy study shows that the glass structure contains P2O7 and PO4 groups, and short -Ti-O-Ti-O-Ti- chains, formed by TiO6 octahedra linked to each other through corners. These chains are linked by phosphate tetrahedra to form -O-Ti-O-P-O- linkages.

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.

Investigation of the Mixed Alkali Effect in a Range of Phosphate Glasses

2007 ◽  
Vol 330-332 ◽  
pp. 161-164 ◽  
Author(s):  
E. A. Abou Neel ◽  
I. Ahmed ◽  
Jonathan C. Knowles
Keyword(s):  
Degradation Rate ◽  
Potassium Phosphate ◽  
Phosphate Glasses ◽  
Oxide Content ◽  
Ion Release ◽  
Scanning Calorimetry ◽  
Degradation Behaviour ◽  
Mixed Alkali ◽  
Alkali Glass ◽  
Mixed Alkali Effect

This study investigated the mixed alkali effect in a series of phosphate based glasses. These glasses were of the composition 0.5P2O5-0.2CaO-0.3-xNa2O-xK2O where x=0 to 0.3 in steps of 0.05. This study considered density measurements using Archimedes’s principle, thermal characterisation using differential scanning calorimetry, phase analysis following crystallisation using X-ray powder diffraction (XRD), and degradation studies combined with ion release. The results showed that these mixed alkali glasses showed a linear decrease in density, with the ternary single alkali glass with 0.3mol K2O showing a 3% reduction in density as compared to that with 0.3mol Na2O which correlated well with the difference in ionic diameter and atomic weight of both cations. These glasses also showed intermediate glass transition temperature (Tg) values, compared to those of the ternary single alkali glasses having the same alkali oxide content, and the minimum Tg value was recorded for equimolar amounts of both alkali oxides. However, they did not show any significant change in the degradation rate compared to the glass with 0.3mol Na2O with the exception of the 0.25mol K2O glass. The single alkali glass with 0.3mol K2O showed a significant increase in the degradation rate by an approximate one order of magnitude. For the mixed alkali glasses with low molar concentration of K2O, only sodium phosphate-rich phases [NaCa(PO3)3 and Na4Ca(PO3)6] were detected from XRD; at high molar concentrations however, potassium phosphate-rich phases [KCa(PO3)3 and KPO3] were detected. At equimolar concentration of both alkali cations, KCa(PO3)3 and Na4Ca(PO3)6 were identified. K+, Ca2+, and P3O9 3- release followed the degradation behaviour where the highly degrading glasses with 0.25 and 0.3mol K2O released the highest amount of these ions; however, there was no definite trend in the remaining glass compositions.

Molybdenum Influence on the Mixed-Alkali Effect of Lithium–Sodium Phosphate Glasses

2018 ◽  
Vol 122 (28) ◽  
pp. 15886-15891 ◽  
Author(s):  
Luiz F. P. Pereira ◽  
Kadiali Bodiang ◽  
Eduardo H. M. Nunes ◽  
François O. Mear ◽  
Laurent Delevoye ◽  
...  
Keyword(s):  
Sodium Phosphate ◽  
Phosphate Glasses ◽  
Mixed Alkali ◽  
Mixed Alkali Effect

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

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
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