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Structural analysis of oxyfluoride borate glass and BaF 2 crystallization from phase separation
Author(s) -
Rodríguez Chialanza Mauricio,
Schneider José Fabian,
Keuchkerian Romina,
Romero Mariano,
Faccio Ricardo,
Olivera Alvaro,
Bentos Pereira Heinkel
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17022
Subject(s) - crystallization , materials science , differential scanning calorimetry , boron , borate glass , lithium borate , fourier transform infrared spectroscopy , raman spectroscopy , phase (matter) , analytical chemistry (journal) , glass ceramic , mineralogy , differential thermal analysis , chemical engineering , ceramic , diffraction , chemistry , metallurgy , thermodynamics , optics , organic chemistry , engineering , physics , chromatography
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 PbF 2 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 BO 4 species, such as diborate or pentaborate. The small variation in the BO 4 fraction with the increase in PbF 2 concentration would be an indication of the formation of F − BO 3/2 species. Oxyfluoride borate glass containing BaO as a cation modifier and 30% PbF 2 represents a good starting point for obtaining glass‐ceramics with a narrow size distribution of BaF 2 nanocrystals. We also propose that the possible mechanism for oxyfluoride borate glass crystallization started with a separation of phases.