Publication Title

Journal of Non-Crystalline Solids

Document Type

Article

Department or Program

Geology

Publication Date

11-15-2019

Keywords

viscosity, aluminosilicate melts, alkali mixing, configurational entropy modelling

Abstract

We provide new viscosity data in the system SiO2-(Na,K)AlSiO4, for the nepheline-kalsilite and jadeite-leucite joins. We present a configurational entropy model for the viscosity of melts in the system as a function of Na/(Na+K) and Al/(Al+Si) ratios. Our modelling indicates that: i) Viscosity data are reproduced well by a non-ideal, symmetrical form of the parameters Sconf (Tg) and Be, ii) Na-K mixing is the main source of additional entropy in the system based on the limited dependence of Sconf (Tg) and Be parameters on Al/(Al+Si) ratio, iii) Ae likely varies as a function of Al/(Al+Si) ratio. Melt fragility in the system increases with increasing Al/(Al+Si) ratio and is greater for Na or K end-member melts than mixed melts. The viscosity of nominally fully-polymerized melts in the SiO2- (Na,K)AlSiO4 system can be modelled through chemical mixing, without explicit consideration of the important changes in structure related to changes in K/(Na+K) and Al/(Al+Si) ratios.

Comments

Original version is available from the publisher at: https://doi.org/10.1016/j.jnoncrysol.2019.119635

Copyright Note

This is the author's version of the work. This publication appears in Bates College's institutional repository by permission of the copyright owner for personal use, not for redistribution.

Required Publisher's Statement

© 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

Available for download on Monday, November 15, 2021

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