A revised estimate of the conductivity of iron alloy at high pressure and implications for the core energy balance

Stacey, Frank D.; Loper, David E.

doi:10.1016/j.pepi.2006.12.001

Cited by 132 publications

(127 citation statements)

References 31 publications

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“…7). Together, these results demonstrate the reasonable 424 accuracy of this model for predicting thermal and electrical conductivity at the 425 melting curve for ideal metals, and support proposed extensions of this law to impure 426 and nonideal metals (Stacey and Anderson, 2001;Stacey and Loper, 2007). 427…”

Section: Discussion 396mentioning

confidence: 57%

“…While further investigations into the validity and physical origin of Stacey's 457 law should be made in future studies, attention should be paid to the assumptions 458 (Stacey and Anderson, 2001;Stacey and Loper, 2007) that permit its application to 459 planetary cores. Of primary importance is the assumed value of conductivity at the 460 ambient-pressure melting point, which can differ significantly between experimental 461 and theoretical studies Stacey and Anderson, 2001).…”

Section: Conclusion 430mentioning

confidence: 99%

“…Lorenz number L for Fe at high pressure and temperature also needs to be accurately 463 determined; use of the theoretical value for a free-electron metal (Stacey and 464 Anderson, 2001;Stacey and Loper, 2007) is of questionable validity considering the 465 wide range of values seen in transition metals (French and Mattsson, 2014;Slack, 466 1964) and the proposed significance of electron-electron scattering at high 467 temperatures (Zhang et al, 2015). Measurements of Fe thermal conductivity at in-situ 468 high-pressure and temperature as well as studies on other transition metals are needed 469 to improve constraints on this important problem.…”

Section: Conclusion 430mentioning

confidence: 99%

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A flash heating method for measuring thermal conductivity at high pressure and temperature: Application to Pt

McWilliams

Konôpková

Goncharov

2015

Physics of the Earth and Planetary Interiors

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20 21The transport properties of matter at high pressure and temperature are critical 22 components in planetary interior models, yet are challenging to measure or predict at 23 relevant conditions. Using a novel flash-heating method for in-situ high-temperature 24 and high-pressure thermal conductivity measurement, we study the transport 25 2 properties of platinum to 55 GPa and 2300 K. Experimental data reveal a simple high-26 pressure and high-temperature behavior of the thermal conductivity that can be 27 described as linear in both pressure and temperature. The corresponding electrical 28 resistivity evaluated through the Wiedemann-Franz-Lorenz law is nearly constant 29 along the melting curve, experimentally confirming the prediction of Stacey for an 30 ideal metal. This study together with prior first-principles predictions of transport 31 properties in Al and Fe at extreme conditions suggests a broad applicability of 32 Stacey's law to diverse metals, supporting a limit on the thermal conductivity of iron 33 at the conditions of Earth's outer core of 90 W/mK or less. 34 35

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Section: Discussion 396mentioning

confidence: 57%

Section: Conclusion 430mentioning

confidence: 99%

Section: Conclusion 430mentioning

confidence: 99%

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A flash heating method for measuring thermal conductivity at high pressure and temperature: Application to Pt

McWilliams

Konôpková

Goncharov

2015

Physics of the Earth and Planetary Interiors

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“…Results have only been obtained recently [23][24][25][26][27][28] , and turn out to be 2-3 times higher than conventional estimates 29,30 31 on a perfect iron crystal at ICB conditions suggests that a new effect (electron-electron scattering) would reduce the electrical conductivity back to old values that were estimated for the liquid 29 . The proposed importance of strong correlation effects appears at odds with previous work 32 , so these results await both experimental and theoretical confirmation.…”

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confidence: 88%

Constraints from material properties on the dynamics and evolution of Earth’s core

et al. 2015

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The Earth's magnetic field is powered from energy supplied by slow cooling and freezing of the liquid iron core. Core thermal history calculations have been hindered in the past by poor knowledge of the properties of iron alloys at the extreme pressures and temperatures pertaining in the core. This obstacle is now being overcome by developments in high pressure experiments and computational mineral physics. Here we review the relevant properties of iron alloys at core conditions and discuss their uncertainty and geophysical implications.Powerful constraints on core evolution are now possible, due partly to recent factor 2-3 upward revisions of the all-important electrical and thermal conductivities. This has dramatic implications for the thermal history of the entire Earth, not just the core: the inner core is very young, the core is cooling quickly, and was so hot in the past that the lowermost mantle

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“…However, ρ el is not directly proportional to T (Fig. 2), as is assumed in the oft-used extrapolations of experimental measurements to core conditions (8,9). Augmenting the Bloch-Grünei-sen formalism (29), we construct model descriptions for k el and ρ el as a function of volume and temperature for the different liquid phases considered (Table 1; see Methods).…”

mentioning

confidence: 99%

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T , and heat flux in Earth’s core

Koker

Steinle‐Neumann

Vlček

2012

Proc. Natl. Acad. Sci. U.S.A.

295

244

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Earth’s magnetic field is sustained by magnetohydrodynamic convection within the metallic liquid core. In a thermally advecting core, the fraction of heat available to drive the geodynamo is reduced by heat conducted along the core geotherm, which depends sensitively on the thermal conductivity of liquid iron and its alloys with candidate light elements. The thermal conductivity for Earth’s core is very poorly constrained, with current estimates based on a set of scaling relations that were not previously tested at high pressures. We perform first-principles electronic structure computations to determine the thermal conductivity and electrical resistivity for Fe, Fe–Si, and Fe–O liquid alloys. Computed resistivity agrees very well with existing shock compression measurements and shows strong dependence on light element concentration and type. Thermal conductivity at pressure and temperature conditions characteristic of Earth’s core is higher than previous extrapolations. Conductive heat flux near the core–mantle boundary is comparable to estimates of the total heat flux from the core but decreases with depth, so that thermally driven flow would be constrained to greater depths in the absence of an inner core.

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A revised estimate of the conductivity of iron alloy at high pressure and implications for the core energy balance

Cited by 132 publications

References 31 publications

A flash heating method for measuring thermal conductivity at high pressure and temperature: Application to Pt

A flash heating method for measuring thermal conductivity at high pressure and temperature: Application to Pt

Constraints from material properties on the dynamics and evolution of Earth’s core

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T , and heat flux in Earth’s core

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