Crystallization of monoclinic WO3 in tungstate fluorophosphate glasses
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Data
2009-03-15
Autores
Poirier, Gael
Cassanjes, Fabia C.
Messaddeq, Younes [UNESP]
Ribeiro, Sidney José Lima [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Resumo
Tungstate fluorophosphate glass compositions with high WO3 concentration were prepared in the ternary system (80-0.8x)NaPO3-(20-0.2x)BaF2-xWO(3) with x = 40,50 and 60 mol%. Transparency decreases as WO3 concentration increases but can be improved by addition of oxidizing systems such as CeO2 or Sb2O3/NaNO3. Characterizations by thermal analysis (DSC) point out that an increase in the amount of WO3 results in a higher glass transition temperature. In addition, such compositions are very stable against devitrification since samples containing 40% and 50% of WO3 donot even exhibit the expected crystallization event. In these samples, the stability against crystallization decreases with the WO3 content and vitreous sample containing 60% of WO3 exhibits an endothermic event around 620 degrees C due to crystallization of monoclinic WO3 phase. In these glasses, it was shown that the nucleation stage can be induced by thermal-treatment when external nucleating agents such as Ti or Sb are used. Finally, gold-doped samples exhibit a higher crystallization tendency and monoclinic WO3 phase can be grown in such glasses. (C) 2009 Elsevier B.V. All rights reserved.
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Palavras-chave
Glass-ceramics, X-ray diffraction, Phosphates
Como citar
Journal of Non-crystalline Solids. Amsterdam: Elsevier B.V., v. 355, n. 7, p. 441-446, 2009.