Effects of glass-forming histories on the crystallization kinetic of the 20Li(2)O-80TeO(2) glass
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Data
2011-10-01
Autores
Araujo, E. B. [UNESP]
Idalgo, E. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Resumo
In the present work, tellurite 20Li(2)O-80TeO(2) glasses were prepared with identical nominal composition under different glass-forming histories to produce a stressed and stress-free samples. X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) techniques were used to study the effects of the glass-forming histories on the thermal and structural properties of these glasses. The gamma-TeO2 (metastable), alpha-TeO2 and alpha-Li2Te2O5 phases were identified during the controlled devitrification in these glasses. The mestastable character of the gamma-TeO2 phase was clearly observed in the glass under stress but this effect is not so clear in the stress-free glass. The gamma-TeO2 and alpha-TeO2 phases crystallizes during the initial stages of crystallization in both studied glasses while the alpha-Li2Te2O5 phase crystallize in the final stages of the crystallization. The activation energies and Avrami exponent were calculated for both studied glasses with different particle size leading to E-3 > E-2 > E-1 for stressed glass and E-3 > E-2 approximate to E-1 for stress-free glass, where E-1, E-2 and E-3 were associated to the gamma-TeO2, alpha-TeO2 and alpha-Li2Te2O5 phases, respectively. The observed distinct (n) over bar (1) < <(n)over bar>(2) < <(n)over bar>(3) in both glasses is an indicative that nucleation and growth takes place by more than one mechanism in the early stages of the crystallization. (C) 2011 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
Nucleation, Crystallization, Tellurite glasses
Como citar
Optical Materials. Amsterdam: Elsevier B.V., v. 33, n. 12, p. 1847-1852, 2011.