Electrical conductivity of dry and hydrous NaAlSi3O8 glasses and liquids at high pressures

Ni, Huaiwei; Keppler, Hans; Manthilake, Geeth; Katsura, Tomoo

doi:10.1007/s00410-011-0608-5

Cited by 43 publications

(58 citation statements)

References 69 publications

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“…The inflection point has been identified for some anhydrous melts including albite [ Bagdassarov et al ., ] and tephrite [ Pommier et al ., ] (Figure b), with a higher H a in the liquid than in the glass region, but the T g established is sometimes lower than the calorimetric glass transition temperature. For hydrous melts, however, the glass transition often occurs across an extended interval, and H a in the liquid region is typically lower than that in the glass region [ Pommier et al ., ; Ni et al ., ]. The temperature dependence of electrical conductivity in hydrous melts is similar to that of the non‐Arrhenian diffusivities (Figure ) and is consistent with the prediction of relaxation theory.…”

Section: Electrical Conductivitysupporting

confidence: 84%

“…Within the liquid region, where the majority of experimental data display Arrhenian dependence, some melts, such as basalt [ Waff and Weill , ; Tyburczy and Waff , ; Ni et al ., ], show convex log σ versus 1/ T curves and can be regressed by a VFT‐type expression similar to equation . On the other hand, the data for albite melt at 6 GPa yield concave curves [ Ni et al ., ] (Figure b). The departure from Arrhenian behavior at temperatures well above T g may indicate a variation of the conduction mechanism with temperature (e.g., relative contributions from different ions).…”

Section: Electrical Conductivitymentioning

confidence: 99%

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Transport properties of silicate melts

Hui

Steinle‐Neumann

2015

Reviews of Geophysics

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A quantitative description of the transport properties, diffusivity, viscosity, electrical, and thermal conductivity, of silicate melts is essential for understanding melting-related petrologic and geodynamic processes. We here provide a systematic overview on the current knowledge of these properties from experiments and molecular dynamics simulations, their dependence on pressure, temperature, and composition, atomistic processes underlying them, and physical models to describe their variations. We further establish phenomenological and physical links between diffusivity, viscosity, and electrical conductivity that are based on structural rearrangement in the melt. Neutral molecules and network-modifying cations with low electric field strength display intrinsic diffusivity, which is controlled by the intrinsic properties (size and valence) of the species. By contrast, oxygen and network formers with high field strength show extrinsic diffusivity, which is more sensitive to extrinsic parameters including temperature (T), pressure (P), and melt composition (X). Similar T-P-X dependence of diffusivity and electrical conductivity and their quantitative relation reveal the role of intrinsically diffusing species in electrical transport, while viscosity is tied to the extrinsically diffusing species in a similar way. However, the differences in the structural role and mobility of various atomic species diminish with increasing temperature and/or pressure: all transport processes are increasingly coupled, eventually converging to a uniform rate and mechanism. Accurate comprehension of interatomic interactions and melt structure is vital to fully accounting for the compositional dependence of transport properties, and simple polymerization parameters such as nonbridging oxygen per tetrahedrally coordinated cation are inadequate.

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Section: Electrical Conductivitysupporting

confidence: 84%

Section: Electrical Conductivitymentioning

confidence: 99%

Transport properties of silicate melts

Hui

Steinle‐Neumann

2015

Reviews of Geophysics

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“…They demonstrated that the electrical conductivity of dry feldspar is dominated by Na + diffusion, whereas hydrous feldspar is controlled largely by free proton diffusion. However, Ni et al, [14] who studied the electrical conductivities of dry and hydrous albite melt glasses at 0.9 and 1.8 GPa and at temperatures up to 1773 K, argued that the conductivities of both dry and hydrous albite glasses are dominated by alkali ions. Hu et al [16] measured the electrical conductivity of alkali feldspars in solid solutions ranging in chemical composition from albite to K-feldspar, and they showed that the electrical conductivity increases with increasing Na content under subsolidus conditions.…”

Section: Introductionmentioning

confidence: 98%

“…More recently, several studies on minerals and melts with feldspar compositions have been carried out at high pressures. [13][14][15][16] Yang et al [13] investigated the electrical conductivity of dry and hydrous polycrystalline plagioclase (An66Ab32Or2). They demonstrated that the electrical conductivity of dry feldspar is dominated by Na + diffusion, whereas hydrous feldspar is controlled largely by free proton diffusion.…”

Section: Introductionmentioning

confidence: 99%

Electrical conductivity anisotropy in alkali feldspar at high temperature and pressure

Wang

Zhou

2014

High Pressure Research

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The electrical conductivity of alkali feldspar along different orientations was determined at 1.0 GPa and at temperatures of 823-1286 K in a cubic anvil apparatus using alternating current impedance spectroscopy. Impedance arcs representing crystal conductivity occur in the frequency range of ∼10 3 -10 6 Hz. The electrical conductivity of alkali feldspar increases with increasing temperature. The highest electrical conductivities in alkali feldspars were measured along the a-axis, with somewhat lower conductivities along the b-axis, and the lowest conductivities along the c-axis, suggesting minor anisotropy. The activation enthalpies ranged from 100 to 110 kJ/mol. The anisotropic results were combined to yield an isotropic model with an activation enthalpy of 102 kJ/mol. By comparing these results with previous results, we suggest that the dominating charge carriers for alkali feldspars are alkali ions. The minor anisotropy in conductivity for alkali feldspar may not account for the anisotropy of the crust.

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“…The Haven ratio depends on ion transport mechanism and typically ranges between 0.2 and 1. H R is generally assumed to be 1 when its exact value is not known (Ni et al 2011). …”

Section: Geophysical Applicationsmentioning

confidence: 99%