Electrical and thermal transport properties of iron and iron‐silicon alloy at high pressure

Seagle, Christopher T; Cottrell, Elizabeth; Fei, Yingwei; Hummer, Daniel R.; Prakapenka, Vitali B.

doi:10.1002/2013gl057930

Cited by 94 publications

(145 citation statements)

References 35 publications

Supporting

Mentioning

107

Contrasting

Unclassified

Order By: Relevance

“…Even though several independent studies agree on the high value of thermal conductivity reported in table 2 (de Koker et al, 2012;Pozzo et al, 2012;Gomi et al, 2013), two other studies dispute it. Seagle et al (2013), as Gomi et al (2013), performed high pressure-ambient temperature electrical resistivity experiments and the experimental results agree with one another, within the error bounds. The papers differ in the proposed high temperature extrapolation because Seagle et al (2013) use the classical Bloch-Grüneisen formula all the way to the temperature of the core whereas Gomi et al (2013) additionally take into account the saturation effect of resistivity of metals that is well documented for most metals (Gunnarsson et al, 2003) but not demonstrated at high pressure.…”

Section: Parametersupporting

confidence: 58%

“…Seagle et al (2013), as Gomi et al (2013), performed high pressure-ambient temperature electrical resistivity experiments and the experimental results agree with one another, within the error bounds. The papers differ in the proposed high temperature extrapolation because Seagle et al (2013) use the classical Bloch-Grüneisen formula all the way to the temperature of the core whereas Gomi et al (2013) additionally take into account the saturation effect of resistivity of metals that is well documented for most metals (Gunnarsson et al, 2003) but not demonstrated at high pressure. However, the results of Gomi et al (2013) agree well with the ab initio calculations of de Koker et al (2012) and Pozzo et al (2012).…”

Section: Parametersupporting

confidence: 58%

“…Zhang et al (2015) used ab initio techniques to compute the contribution of electron-electron scattering to electrical resistivity of iron at core condition and found that, in contradiction to the assumption made by previous ab initio studies, it is as important as the electron-phonon scattering. Therefore they predict a thermal conductivity of the core similar to the value proposed by Seagle et al (2013). However, recent high temperature measurements of electrical resistivity by Ohta et al (2014) support the saturation model of Gomi et al (2013) and casts doubts on the validity of these new ab initio calculations.…”

Section: Parametermentioning

confidence: 64%

“…has not yet been found and the possibility of a thermal conductivity in the range proposed by Seagle et al (2013), k = 50Wm −1 K −1 , will also be considered in the following.…”

Section: Parametermentioning

confidence: 99%

“…Range of silicate melting Figure 13: Evolution of the CMB temperature with time for the model presented on figure 11 (solid line) as well as cases with varying amounts of potassium in the core and for the conductivity value proposed by Seagle et al (2013), as labeled. The shaded area corresponds to the approximate range between the solidus and the liquidus for a "chondritic mantle" (Andrault et al, 2011) or a peridotite (Fiquet et al, 2010).…”

Section: Thermal Evolution Modelsmentioning

confidence: 99%

See 4 more Smart Citations

Thermal evolution of the core with a high thermal conductivity

Labrosse

2015

Physics of the Earth and Planetary Interiors

178

271

View full text Add to dashboard Cite

The rate at which heat is extracted across the core mantle boundary (CMB) is constrained by the requirement of dynamo action in the core. This constraint can be computed explicitly using the entropy balance of the core and depends on the thermal conductivity, whose value has been revised upwardly. A high order model (fourth degree polynomial of the radial position) for the core structure is derived and the implications for the core cooling rate and thermal evolution obtained, using the recent values of the thermal conductivity. For a thermal conductivity increasing with depth as proposed by some of these recent studies, a CMB heat flow equal to the isentropic value (13.25TW at present) leads to a 700 km thick layer at the top of the core where a downward convective heat flow is necessary to maintain an isentropic and well mixed average state. Considering a CMB heat flow larger than the well mixed isentropic value leads to an inner core less than 700 Myr old and the thermal evolution of the core is largely constrained by the conditions for dynamo action without an inner core. Analytical calculations for that period show that a CMB temperature larger than 7000 K must have prevailed 4.5 Gyr ago if the geodynamo has been driven by thermal convection for that whole time. This raises questions regarding the onset of the geodynamo and its continuous operation for the last 3.5 Gyr. Implications regarding the evolution of a basal magma ocean are also considered.

show abstract

Section: Parametersupporting

confidence: 58%

Section: Parametersupporting

confidence: 58%

Section: Parametermentioning

confidence: 64%

“…has not yet been found and the possibility of a thermal conductivity in the range proposed by Seagle et al (2013), k = 50Wm −1 K −1 , will also be considered in the following.…”

Section: Parametermentioning

confidence: 99%

Section: Thermal Evolution Modelsmentioning

confidence: 99%

See 3 more Smart Citations

Thermal evolution of the core with a high thermal conductivity

Labrosse

2015

Physics of the Earth and Planetary Interiors

178

271

View full text Add to dashboard Cite

show abstract

Influence of plate tectonic mode on the coupled thermochemical evolution of Earth's mantle and core

Nakagawa

Tackley

2015

Geochem Geophys Geosyst

View full text Add to dashboard Cite

We investigate the influence of tectonic mode on the thermochemical evolution of simulated mantle convection coupled to a parameterized core cooling model. The tectonic mode is controlled by varying the friction coefficient for brittle behavior, producing the three tectonic modes: mobile lid (plate tectonics), stagnant lid, and episodic lid. The resulting compositional structure of the deep mantle is strongly dependent on tectonic mode, with episodic lid resulting in a thick layer of subducted basalt in the deep mantle, whereas mobile lid produces only isolated piles and stagnant lid no basaltic layering. The tectonic mode is established early on, with subduction initiating at around 60 Myr from the initial state in mobile and episodic cases, triggered by the arrival of plumes at the base of the lithosphere. Crustal production assists subduction initiation, increasing the critical friction coefficient. The tectonic mode has a strong effect on core evolution via its influence on deep mantle structure; episodic cases in which a thick layer of basalt builds up experience less core heat flow and cooling and a failed geodynamo. Thus, a continuous mobile‐lid mode existing from early times matches Earth's mantle structure and core evolution better than an episodic mode characterized by large‐scale flushing (overturn) events.

show abstract

Seismic parameters of hcp‐Fe alloyed with Ni and Si in the Earth's inner core

et al. 2016

View full text Add to dashboard Cite

Iron alloyed with Ni and Si has been suggested to be a major component of the Earth's inner core. High‐pressure results on the combined alloying effects of Ni and Si on seismic parameters of iron are thus essential for establishing satisfactory geophysical and geochemical models of the region. Here we have investigated the compressional (VP) and shear (Vs) wave velocity‐density (ρ) relations, Poisson's ratio (ν), and seismic heterogeneity ratios (dlnρ/dlnVP, dlnρ/dlnVS, and dlnVP/dlnVS) of hcp‐Fe and hcp‐Fe86.8Ni8.6Si4.6 alloy up to 206 GPa and 136 GPa, respectively, using multiple complementary techniques. Compared with the literature velocity values for hcp‐Fe and Fe‐Ni‐Si alloys, our results show that the combined addition of 9.0 wt % Ni and 2.3 wt % Si slightly increases the VP but significantly decreases the VS of hcp‐Fe at a given density relevant to the inner core. Such distinct alloying effects on velocities of hcp‐Fe produce a high ν of about 0.40 for the alloy at inner core densities, which is approximately 20% higher than that for hcp‐Fe. Analysis of the literature high P‐T results on VP and VS of Fe alloyed with light elements shows that high temperature can further enhance the ν of hcp‐Fe alloyed with Ni and Si. Most significantly, the derived seismic heterogeneity ratios of this hcp alloy present a better match with global seismic observations. Our results provide a multifactored geophysical constraint on the compositional model of the inner core which is consistent with silicon being a major light element alloyed with Fe and 5 wt % Ni.

show abstract

Electrical and thermal transport properties of iron and iron‐silicon alloy at high pressure

Cited by 94 publications

References 35 publications

Thermal evolution of the core with a high thermal conductivity

Thermal evolution of the core with a high thermal conductivity

Influence of plate tectonic mode on the coupled thermochemical evolution of Earth's mantle and core

Seismic parameters of hcp‐Fe alloyed with Ni and Si in the Earth's inner core

Contact Info

Product

Resources

About