High rate calorimetry derived viscosity of oxide melts prone to crystallization

Al-Mukadam, Raschid; Genova, Danilo Di; Bornhöft, Hansjörg; Deubener, Joachim

doi:10.1016/j.jnoncrysol.2020.119992

Cited by 34 publications

(50 citation statements)

References 42 publications

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“…Here we fit both the DSC-based values, that is, 10 data points with 9 12 10 10    Pa s (Figure 6) as well as the viscometric measurements compiled by Al-Mukadam et al (2020), using the MYEGA expression (Equation 7) and assuming 2.9 A   (Zheng et al, 2011). Our fit and that by Al-Mukadam et al (2020)-which leaves A free-to viscometry data show good agreement overall. The deviation at high T stems from the differing values in A.…”

Section: Diopside: a Test Casementioning

confidence: 66%

“…Al‐Mukadam et al. (2020) performed calorimetric measurements of Di and provided two rate‐dependent characteristic

T

in the vicinity of

T_{g}

T_{onset}

marks the sudden drop in heat flow measured in DSC, and

T_{peak}

corresponds to the (endothermic) minimum of the heat flow undershoot of the glass transformation interval.

T_{onset}

and

T_{peak}

were measured at five heating rates, leading to 10 data points.…”

Section: Using Dsc For Modeling Melt Viscositymentioning

confidence: 99%

“…We test this approach for DSC-based data of a diopside melt (Di), an Fe-free system that is a good proxy of volcanic melt not prone to crystallisation around T g , and for which a large number of viscometry measurements in both Hη and Lη ranges as well as DSC data exist. Al-Mukadam et al (2020) performed calorimetric measurements of Di and provided two rate-dependent characteristic T in the vicinity of T g : T onset marks the sudden drop in heat flow measured in DSC, and T peak corresponds to the (endothermic) minimum of the heat flow undershoot of the glass transformation interval. T onset and T peak were measured at five heating rates, leading to ten data points.…”

Section: Diopside: a Test Casementioning

confidence: 99%

“…Pa s (Figure 6) as well as the viscometric measurements compiled by Al-Mukadam et al (2020), using the MYEGA expression (eq. 7) and assuming A = −2.9 (Zheng et al, 2011).…”

Section: Diopside: a Test Casementioning

confidence: 99%

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Modeling the Viscosity of Anhydrous and Hydrous Volcanic Melts

Langhammer

Genova

Steinle‐Neumann

2021

Geochem Geophys Geosyst

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The viscosity of volcanic melts is a dominant factor in controlling the fluid dynamics of magmas and thereby eruption style. It can vary by several orders of magnitude, depending on temperature, chemical composition, and water content. The experimentally accessible temperature range is restricted by melt crystallization and gas exsolution. Therefore, modeling viscosity as a function of temperature and water content is central to physical volcanology. We present a model that describes these dependencies by combining a physically motivated equation for temperature dependence of viscosity and a glass transition temperature (Tg) model for the effects of water. The equation uses the viscosity at infinite temperature η∞, Tg, and the steepness factor m as fitting parameters. We investigate the effect of leaving η∞ free as a parameter and fixing its value, by fitting anhydrous viscosity data of 45 volcanic melts using the temperature dependent model. Both approaches describe experimental data well. Using a constant η∞ therefore provides a viable route for extrapolating viscosity from data restricted to small temperature intervals. Our model describes hydrous data over a wide compositional range of terrestrial magmas (26 data sets) with comparable or better quality than literature fits. With η∞ constrained, we finally apply our model to viscosities derived by differential scanning calorimetry and find—by comparing to viscometry based data and models—that this approach can be used to reliably describe the dependence of viscosity on temperature and water content. This introduces important implications for modeling the effects of nanostructure formation on viscosity.

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Section: Diopside: a Test Casementioning

confidence: 66%

“…Al‐Mukadam et al. (2020) performed calorimetric measurements of Di and provided two rate‐dependent characteristic

T

in the vicinity of

T_{g}

T_{onset}

marks the sudden drop in heat flow measured in DSC, and

T_{peak}

corresponds to the (endothermic) minimum of the heat flow undershoot of the glass transformation interval.

T_{onset}

and

T_{peak}

were measured at five heating rates, leading to 10 data points.…”

Section: Using Dsc For Modeling Melt Viscositymentioning

confidence: 99%

Section: Diopside: a Test Casementioning

confidence: 99%

“…Pa s (Figure 6) as well as the viscometric measurements compiled by Al-Mukadam et al (2020), using the MYEGA expression (eq. 7) and assuming A = −2.9 (Zheng et al, 2011).…”

Section: Diopside: a Test Casementioning

confidence: 99%

See 2 more Smart Citations

Modeling the Viscosity of Anhydrous and Hydrous Volcanic Melts

Langhammer

Genova

Steinle‐Neumann

2021

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…The shift factor K (here K peak ) (Scherer 1984;Stevenson et al 1995;Gottsmann et al 2002;Yue et al 2004;Al-Mukadam et al 2020) can be derived from the DSC measurements (Figure 3) by matching the characteristic glass transition temperature T peak for a given cooling/heating (q, K/s) cycle to the temperature of the viscosity measurement:…”

Section: Shift Factormentioning

confidence: 99%