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Structural analysis of oxyfluoride borate glass and BaF2 crystallization from phase separation

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Autor(es):
Rodriguez Chialanza, Mauricio [1, 2] ; Schneider, Jose Fabian [3] ; Keuchkerian, Romina [2] ; Romero, Mariano [4] ; Faccio, Ricardo [4] ; Olivera, Alvaro [5] ; Bentos Pereira, Heinkel [5]
Número total de Autores: 7
Afiliação do(s) autor(es):
[1] CURE, Udelar, Rocha - Uruguay
[2] Fac Quim Montevideo, GDMEA, Area Radioquim, Montevideo - Uruguay
[3] Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos, SP - Brazil
[4] Fac Quim Montevideo, Ctr NanoMat, DETEMA, Montevideo - Uruguay
[5] CURE, GDMEA, DDT, Udelar, Rocha - Uruguay
Número total de Afiliações: 5
Tipo de documento: Artigo Científico
Fonte: Journal of the American Ceramic Society; v. 103, n. 5 JAN 2020.
Citações Web of Science: 0
Resumo

Oxyfluoride glass and glass-ceramics are being studied due to the possibility of their utilization in many applications, such as thermoluminescent dosimeters, optical fibers, fluorescent concentrators, and temperature sensors. In order to improve the properties of glass, they are often crystallized. For this crystallization to be effective, knowledge and control of the structure of the starting material is required. Much work was done on silicate glass; however, a great interest exists in obtaining these kinds of materials in other matrices such as germanates, phosphates, and borates. Here, we present a structural study of some oxyfluoride borate glass with different concentrations of PbF2 by means of Nuclear Magnetic Resonance (NMR), Raman, and Fourier Transform Infrared (FTIR) spectroscopies. We also analyzed glass-crystallization using Differential Scanning Calorimetry (DSC). The crystallization study was complemented with the use of Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED), for the purpose of identifying possible mechanisms of crystallization. Our results indicate, from the structural point of view, that the glass present groups with one or two BO4 species, such as diborate or pentaborate. The small variation in the BO4 fraction with the increase in PbF2 concentration would be an indication of the formation of F-BO3/2 species. Oxyfluoride borate glass containing BaO as a cation modifier and 30% PbF2 represents a good starting point for obtaining glass-ceramics with a narrow size distribution of BaF2 nanocrystals. We also propose that the possible mechanism for oxyfluoride borate glass crystallization started with a separation of phases. (AU)

Processo FAPESP: 13/07793-6 - CEPIV - Centro de Ensino, Pesquisa e Inovação em Vidros
Beneficiário:Edgar Dutra Zanotto
Linha de fomento: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs