Interaction between fluorine and silica in quenched melts on the joins SiO2-AlF3 and SiO2-NaF determined by raman spectroscopy
Abstract
The solubility mechanism of fluorine in quenched SiO2-NaF and SiO2-AlF3 melts has been determined with Raman spectroscopy. In the fluorine abundance range of F/(F+Si) from 0.15 to 0.5, a portion of the fluorine is exchanged with bridging oxygen in the silicate network to form Si-F bonds. In individual SiO4-tetrahedra, one oxygen per silicon is replaced in this manner to form fluorine-bearing silicate complexes in the melt. The proportion of these complexes is nearly linearly correlated with bulk melt F/(F+Si) in the system SiO2-AlF3, but its abundance increases at a lower rate and nonlinearly with increasing F/(F+Si) in the system SiO2-NaF. The process results in the formation of nonbridging oxygen (NBO), resulting in stabilization of Si2O{5/2-}units as well as metal (Na+ or Al3+) fluoride complexes in the melts. Sodium fluoride complexes are significantly more stable than those of aluminum fluoride.
- Publication:
-
Physics and Chemistry of Minerals
- Pub Date:
- March 1985
- DOI:
- 10.1007/BF01046830
- Bibcode:
- 1985PCM....12...77M