Mixed alkali effect on crystallization kinetics of xNa2O:(50 −x)Li2O:50P2O5
| Autor: | Krishnaswamy Hariharan, Benson K. Money |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Chemistry
Enthalpy Analytical chemistry Mineralogy General Chemistry Condensed Matter Physics Alkali metal Ion law.invention Differential scanning calorimetry Devitrification law Crystallization Crystallization kinetics Glass Glass transition Ions Thermodynamic stability Crystallization temperature Dynamic structure models Glass compositions Glass modifiers High activation energy Low enthalpies Mixed alkali effect Small concentration Lithium General Materials Science Thermal stability |
| Zdroj: | Solid State Ionics. 262:824-828 |
| ISSN: | 0167-2738 |
| Popis: | The main aim of the present study is to investigate the effect of second glass modifier Na2O on the crystallization kinetics and thermal stability of the mol% xNa2O:(50 -x)Li2O:50P 2O5 glasses, where Li+ ions are progressively substituted with Na+ ions, using differential scanning calorimetry. The DSC studies showed the classical 'mixed alkali effect' on the glass transition temperature, with the Tg minima for the glass composition of [Na+/(Li++ Na+)] = 0.5 i.e. x = 25 mol%. The crystallization temperature decreases as Na+ ions completely replaces Li+ ions. The presence of small concentration of second alkali (either the guest ion or host ion) tends to enhance the thermal stability, S, against devitrification as observed for 5 ? x ? 15 and 37.5 ? x ? 45. The 'mixed alkali effect' tends to thermally stabilize the intermediate compositions of mol% xNa2O:(50 -x)Li2O: 50P2O5 as these compositions exhibited high S parameter, high activation energy for crystallization and low enthalpy of crystallization, ?Hc. � 2013 Elsevier B.V. All rights reserved. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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