Fluorine sites in glasses and transparent glass-ceramics of the system Na{sub 2}O/K{sub 2}O/Al{sub 2}O{sub 3}/SiO{sub 2}/BaF{sub 2}

Journal Article · Tue Feb 15 00:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.12.001· OSTI ID:21494202

Bocker, Christian ^[1]; Munoz, Francisco; Duran, Alicia ^[2]; Ruessel, Christian ^[1]

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1. Otto-Schott-Institut, Jena University, Fraunhoferstr. 6, 07743 Jena (Germany)
2. Instituto de Ceramica y Vidrio (CSIC), Kelsen 5, 28049 Madrid (Spain)

The transparent glass-ceramics obtained in the silicate system Na{sub 2}O/K{sub 2}O/SiO{sub 2}/BaF{sub 2} show homogeneously dispersed BaF{sub 2} nano crystals with a narrow size distribution. The X-ray diffraction and the nuclear magnetic resonance spectroscopy were applied to glasses and the respective glass-ceramics in order to clarify the crystallization mechanism and the role of fluorine during crystallization. With an increasing annealing time, the concentration and also the number of crystals remain approximately constant. With an increasing annealing temperature, the crystalline fraction increases until a saturation limit is reached, while the number of crystals decreases and the size of the crystals increases. Fluoride in the glassy network occurs as Al-F-Ba, Al-F-Na and also as Ba-F structures. The latter are transformed into crystalline BaF{sub 2} and fluoride is removed from the Al-F-Ba/Na bonds. However, some fluorine is still present in the glassy phase after the crystallization. -- Graphical abstract: The X-ray diffraction and the nuclear magnetic resonance spectroscopy were applied to glasses in the silicate system Na{sub 2}O/K{sub 2}O/SiO{sub 2}/BaF{sub 2} and the respective glass-ceramics with BaF{sub 2} nano crystals in order to clarify the crystallization mechanism and the role of fluorine during crystallization. Display Omitted Research highlights: {yields} BaF{sub 2} nano crystals are precipitated from a silicate glass system. {yields} Ostwald ripening during the late stage of crystallization does not occur. {yields} Fluorine in the glass is coordinated with Ba as well as Al together with Ba or Na.{yields} In the glass-ceramics, the residual fluorine is coordinated as Al-F-Ba/Na.

• OSTI ID: 21494202
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 2; Other Information: DOI: 10.1016/j.jssc.2010.12.001; PII: S0022-4596(10)00539-6; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALUMINIUM OXIDES
ANNEALING
BARIUM FLUORIDES
CERAMICS
CRYSTAL GROWTH
CRYSTALLIZATION
CRYSTALS
GLASS
NUCLEAR MAGNETIC RESONANCE
POTASSIUM OXIDES
SILICATES
SILICON OXIDES
SODIUM OXIDES
SPECTROSCOPY
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COHERENT SCATTERING
DIFFRACTION
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HEAT TREATMENTS
MAGNETIC RESONANCE
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
POTASSIUM COMPOUNDS
RESONANCE
SCATTERING
SILICON COMPOUNDS
SODIUM COMPOUNDS