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Please use this identifier to cite or link to this item: http://acervodigital.unesp.br/handle/11449/26139
Title: 
Crystallization of monoclinic WO3 in tungstate fluorophosphate glasses
Author(s): 
Institution: 
  • Universidade Federal de Alfenas (UNIFAL)
  • Universidade Estadual Paulista (UNESP)
ISSN: 
0022-3093
Sponsorship: 
  • Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)
  • Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
  • Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Abstract: 
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.
Issue Date: 
15-Mar-2009
Citation: 
Journal of Non-crystalline Solids. Amsterdam: Elsevier B.V., v. 355, n. 7, p. 441-446, 2009.
Time Duration: 
441-446
Publisher: 
Elsevier B.V.
Keywords: 
  • Glass-ceramics
  • X-ray diffraction
  • Phosphates
Source: 
http://dx.doi.org/10.1016/j.jnoncrysol.2009.01.008
URI: 
Access Rights: 
Acesso restrito
Type: 
outro
Source:
http://repositorio.unesp.br/handle/11449/26139
Appears in Collections:Artigos, TCCs, Teses e Dissertações da Unesp

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