Crystallization of nano calcium fluoride in CaF2–Al2O3–SiO2 system

• Published in: Solid state sciences 2013-03, Vol.17, p.76-82
• Main Authors: Imanieh, Mohammad Hassan, Yekta, Bijan Eftekhari, Marghussian, V., Shakhesi, Saeed, Martín, I.R.
• Format: Article
• Language: English
• Subjects: CaF2 nanocrystals; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; General studies of phase transitions; Glass ceramic; Nucleation; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Oxyfluoride; Oxyfluoride glass ceramic; Physics; Solid-solid transitions; Solubility, segregation, and mixing; phase separation; Specific phase transitions
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2012.11.008

The effects of alumina and CaF2 content on the crystallization behavior, fluorine loss, phase separation mechanism and optical properties of oxyfluoride glass ceramics were investigated. Three series of glasses in which their SiO2/Al2O3 ratio was different such as 1.8, 2.18 and 2.5 were examined. Results showed that the adopted ratios played key role significantly in the mechanism of phase separation of the glass. It modified from spinodal decomposition to nucleation and growth by decreasing the mentioned ratio. UV spectroscopy showed that owing to the small size of precipitated CaF2 crystals, i.e. 20nm, in the glass with a silicon oxide to alumina ratio of 2.18 and initial CaF2 amount of 35 mol%, it remained transparent after heat treatment at 740°C. [Display omitted]