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Glasses were synthesized along the jadeite-leucite (NaAlSi2O6 – KAlSi2O6) join with various amounts of dissolved fluorine (up to 4 wt.%). Na:K ratios synthesized include Jd100, Jd75Lct25, Jd62.5Lct37.5, Jd50Lct50, and Jd25Lct75, all of which have a nominal ratios of non-bridging oxygen to tetrahedrally-coordinated cations (NBO/T) of 0. For Jd50Lct50, we synthesized glasses with 0, 0.27, 0.54, 0.93, and 1.83 wt.% F. For all other Na:K ratios, we only synthesized two compositions of glass. For each Na:K ratio, glass with no fluorine was synthesized. In addition, Jd100(1.27F), Jd75Lct25(1.29F), Jd62.5Lct37.5(0.36F), and Jd25Lct75(0.25F) were synthesized. We measured the viscosity of each melt by parallel-plate viscometry at temperatures between 655 ◦C and 980 ◦C. We use the temperature at which the viscosity is 1012 Pa·s (T12) to compare the effect of F on the different composition of melts. Although melt viscosity, and thus T12 temperature, increases with decreasing Na:K ratios, the change in T12 with the addition of fluorine is similar for each melt. The addition of fluorine decreases the density and T12 of each melt relative to its F-free equivalent. However, as more F is added to a given composition, T12 decreases at a decreasing rate. With the addition of 0.5 wt.% F, T12 decreases by about 75 ◦C. With the addition of another 0.8 wt.% F (1.3 wt.% F total), T12 only decreases by an additional 50 ◦C. We conclude that increasing Na:K ratio and wt.% F both decrease the viscosity of the melts in this. Our results are consistent with the observed effect of Na:K ratio in more silica rich melts, with albite melt having a viscosity nearly 3 orders of magnitude lower than orthoclase melt at around 925 ◦C. Our results also show a similar effect of F on the viscosity of jadeite and albite melts, with a reduction in T12 for 2 wt.% F of about 130 ◦C in both melts. Further, as Jd50Lct50 becomes more depolymerized with the addition of F, the F has a smaller effect on viscosity.
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Date of Graduation
Bachelor of Science
Carty, Olin Rico and Robert, Geneviève, "The Effect of Fluorine on the Viscosity of Jadeite-Leucite Melts" (2017). Standard Theses. 34.
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