Viscosities of melts in Na/sub 2/O-FeO-Fe/sub 2/O/sub 3/-SiO/sub 2/ system and factors controlling relative viscosities of fully polymerized silicate melts
The viscosity-temperature relationships of nine melts in the Na/sub 2/O-FeO-Fe/sub 2/O/sub 3/-SiO/sub 2/ system (in equilibrium with air) have been measured in the temperature range of 1450-800/sup 0/C, using the concentric cylinder method. /sup 57/Fe Moessbauer spectra were obtained on quenched samples and show that all melts with greater than or equal to 20 mole% ferrite component contain greater than or equal to 95% Fe as tetrahedrally-coordinated ferric ions. The compositions investigated lie along the SiO/sub 2/-NaFeO/sub 2/ and Na/sub 2/Si/sub 4/O/sub 9/-Na/sub 6/Fe/sub 4/O/sub 9/ joins. The viscosities of melts decrease strongly with decreasing silicate content along these joins. In contrast, the temperature dependence of viscosity does not vary significantly along these joins. Comparison with equivalent melt compositions (related by the trivalent cation exchange operators AlFe..sqrt../sub 1/, BFe..sqrt../sub 1/ and GaFe..sqrt../sub 1/) in the Na/sub 2/O-Al/sub 2/O/sub 3/SiO/sub 2/, Na/sub 2/O-B/sub 2/O/sub 3/-SiO/sub 2/ and Na/sub 2/O-Ga/sub 2/O/sub 3/-SiO/sub 2/ systems, shows that viscosities decrease in the order aluminosilicate > ferrosilicate, (galliosilicate .) > borosilicate. The electronegativities of the trivalent cations are inversely correlated with the relative viscosities of melts in these systems. Similarly, the electronegativities of network-stabilizing cations are inversely correlated with melt viscosity for alkali and alkaline-earth aluminosilicate melt systems. The variation in the viscosity of tectosilicate melts is correlated with estimated average T-O-T bond angles, and exothermic heats of solution of quench glasses. Structural controls of viscosity discussed are tetrahedral ordering and relative bond strengths.
- Research Organization:
- Carnegie Institution of Washington, Washington, DC (USA)
- OSTI ID:
- 5100354
- Journal Information:
- Geochim. Cosmochim. Acta; (United States), Journal Name: Geochim. Cosmochim. Acta; (United States) Vol. 52:2; ISSN GCACA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580400* -- Geochemistry-- (-1989)
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BOND ANGLE
BORON COMPOUNDS
BORON SILICATES
CHARGED PARTICLES
CHEMICAL ANALYSIS
CHEMICAL BONDS
CHEMISTRY
FLUID FLOW
GEOCHEMISTRY
IGNEOUS ROCKS
IONIC COMPOSITION
IONS
IRON COMPOUNDS
IRON SILICATES
MAGMA
MINERALS
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
STRUCTURAL CHEMICAL ANALYSIS
TEMPERATURE EFFECTS
TRANSITION ELEMENT COMPOUNDS
VISCOSITY
VISCOUS FLOW