Mixed alkali effect in lithium-sodium phosphate glasses modified with tungsten oxide

Kód výsledku v IS VaVaI

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Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Mixed alkali effect in lithium-sodium phosphate glasses modified with tungsten oxide

Popis výsledku v původním jazyce

Lithium and sodium phosphates belong to materials studied as solid electrolytes for batteries. Their modification with other oxides can be due to the optimization of electrical properties or chemical durability thermal stability etc. This contribution is devoted to the study of lithium-sodium tungsten-phosphate glasses of the composition xLi2O-(40-x)Na2O-30P2O5-30WO3 with x = 0, 10, 20, 30 a 40 mol% Li2O. Basic parameters of the glasses were determined (density, molar volume, chemical durability) and their thermal behavior was studied by differential thermal analysis, dilatometry and hot-stage microscopy. Temperature dependence of glass transition temperature reveals a minimum at x = 20 mol% Li2O, characteristic for the mixed-alkali effect, whereas the thermal expansion coefficient decreases monotonously from 19.9 to 13.1 ppm/K. The replacement of sodium cations by lithium cations results in a lower ionicity of W-O bonds, which is reflected by the shift of band of W-O vibrations from 941 to 954 cm-1. Electrical and dielectric properties were measured within the range of 106 Hz to 0,01 Hz and the temperature range 303-513 K. From the obtained dependences of D.C. electrical conductivity on temperature, the activation energy was calculated using Arrhenius equation. Activation energy reaches a maximum at the glass with 20 mol% Li2O, whereas electrical conductivity reveals a minimum at the same composition. The observed nonmonotonous behavior of electrical conductivity and its activation energy is characteristic for the mixed-alkali effect observed previously also in other phosphate glasses.

Název v anglickém jazyce

Mixed alkali effect in lithium-sodium phosphate glasses modified with tungsten oxide

Popis výsledku anglicky

Lithium and sodium phosphates belong to materials studied as solid electrolytes for batteries. Their modification with other oxides can be due to the optimization of electrical properties or chemical durability thermal stability etc. This contribution is devoted to the study of lithium-sodium tungsten-phosphate glasses of the composition xLi2O-(40-x)Na2O-30P2O5-30WO3 with x = 0, 10, 20, 30 a 40 mol% Li2O. Basic parameters of the glasses were determined (density, molar volume, chemical durability) and their thermal behavior was studied by differential thermal analysis, dilatometry and hot-stage microscopy. Temperature dependence of glass transition temperature reveals a minimum at x = 20 mol% Li2O, characteristic for the mixed-alkali effect, whereas the thermal expansion coefficient decreases monotonously from 19.9 to 13.1 ppm/K. The replacement of sodium cations by lithium cations results in a lower ionicity of W-O bonds, which is reflected by the shift of band of W-O vibrations from 941 to 954 cm-1. Electrical and dielectric properties were measured within the range of 106 Hz to 0,01 Hz and the temperature range 303-513 K. From the obtained dependences of D.C. electrical conductivity on temperature, the activation energy was calculated using Arrhenius equation. Activation energy reaches a maximum at the glass with 20 mol% Li2O, whereas electrical conductivity reveals a minimum at the same composition. The observed nonmonotonous behavior of electrical conductivity and its activation energy is characteristic for the mixed-alkali effect observed previously also in other phosphate glasses.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

10402 - Inorganic and nuclear chemistry

Projekt

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Návaznosti

S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings of the 5th International Conference on Chemical Technology

ISBN

978-80-86238-65-4

ISSN

2336-811X

e-ISSN

neuvedeno

Počet stran výsledku

6

Strana od-do

278-283

Název nakladatele

Česká společnost průmyslové chemie

Místo vydání

Praha

Místo konání akce

Mikulov

Datum konání akce

10. 4. 2017

Typ akce podle státní příslušnosti

CST - Celostátní akce

Kód UT WoS článku

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