Viscosity and mixing between K and alkaline-earth silicate melts

Abstract:

The configurational properties of melts and glasses provide fundamental information needed to characterize magmatic processes. A principal difficulty, however is to link the "macroscopic" configurational entropy with the structure of melts. This has been done by combining viscometry with Raman spectroscopic structural studies. From the viscosity measurements at low and high temperatures, we have obtained the configurational entropy, Sconf (log η = A_e + B_e/TSconf, were η is the viscosity, T the temperature and A_e, B_e two constants).

We are using Raman spectroscopy at room temperature between the alkali and alkaline-earth silicate melts. For these compositions, we establish some link between the variation of the viscosity, the configurational entropy as the function of chemical composition and the Q species obtained from the Raman spectroscopy. These structural variations are related to the changes in configurational entropy. It is possible, to understand this variation of viscosity and mixing between K and (Ca, Sr, Mg, Ba) in silicate melts.