[(a)–(e)] Arrhenius plots for melt viscosities in the system An–Di at various pressures. Data from Taniguchi (Ref. 40) T95 and Russell et al. (Ref. 41) RGD03 are shown for comparison for anorthite melt. In case of diopside melts we have plotted also data from Schulze et al. (Ref. 8) S99 for 0.1 MPa (dashed lines), 200 MPa (dashed-dotted line) and 300 MPa (dotted line).
[(a)–(d)] Arrhenius plots for melt viscosity of alkali silicate melts in the pressure range of 50–400 MPa.
[(a)–(c)] Activation energies for viscous flow in melts of the system An–Di (a), in alkali silicate melts (b) and vs the degree of depolymerization (c) in the high viscosity range.
[(a)–(e)] Pressure dependence of viscosity of melts along the join An–Di. Temperatures are chosen as the temperature at which viscosity equals , , and at 200 MPa. Viscosities of melts are compared with results from Schulze et al. (Ref. 8) (S99).
[(a)–(d)] Pressure dependence of the viscosity of alkali silicate melts. Temperatures are chosen as the temperature at which viscosity equals , , and at 200 MPa.
[(a) and (b)] Variation in the apparent activation volume for viscous flow with mole fraction of NBO . (a) was evaluated separately for each of the reference temperatures indicated by the corresponding viscosities. Trend lines for the system Ab–Di derived by Behrens and Schulze (Ref. 1). (b) Compilation of average apparent activation volumes for viscous flow in silicate and aluminosilicate melts. Solid line reproduces the Ab–Di system from Behrens and Schulze (Ref. 1) and dashed lines the 1 standard deviation. Error bars represent 1 standard deviation. [BS03 (Ref. 1); D07 (Ref. 30); L03 (Ref. 29); and S99 (Ref. 8)].
Glass transition temperatures along the join An–Di in the range of pressures 0.1 to 400 MPa compared to literature data at 0.1 MPa [gray line from Taniguchi (Ref. 40)].
Composition of glasses along the join An–Di in wt %.
Composition of alkali silicate glasses in wt %. (The total content was measured by IR spectroscopy, the other components by electron microprobe except for which was calculated by difference to 100 wt %.)
Viscosity data along the join An-Di. Viscosities at ambient pressure and elevated pressures were determined with two different apparatuses, see text for details.
Viscosity data in the alkali silicate system.
Arrhenius parameters for viscosity. ( is the number of viscosity measurements used for the calculation of . Reported errors correspond to one standard deviation of the fit. Arrhenius parameters were only calculated if at least data for three different temperatures were measured.)
Results of combined fitting of viscosity data.
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