Hydrogen in the earth's core. Experimental approach.

Fukai, Yuh; Akimoto, Syun‐iti

doi:10.2183/pjab.59.158

Cited by 23 publications

(15 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Iron hydride formation at Earth's surface is unlikely because the equilibrium hydrogen solubility in iron at atmospheric conditions is prohibitively low. However, as hydrogen solubility increases with pressure, so does the likelihood of FeH X formation within the Earth's interior (Fukai & Akimoto, 1983). Nearly stoichiometric iron hydride (FeH X , X$1) has been shown to result from either the reaction of Fe and hydrous silicates (Yagi & Hishinuma, 1995) or the reaction of Fe and water at lower mantle conditions (Ohtani et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

High‐Pressure Geophysical Properties of Fcc Phase FeH_X

Thompson

Davis

et al. 2018

Geochem Geophys Geosyst

View full text Add to dashboard Cite

Face centered cubic (fcc) FeHX was synthesized at pressures of 18–68 GPa and temperatures exceeding 1,500 K. Thermally quenched samples were evaluated using synchrotron X‐ray diffraction (XRD) and nuclear resonant inelastic X‐ray scattering (NRIXS) to determine sample composition and sound velocities to 82 GPa. To aid in the interpretation of nonideal (X ≠ 1) stoichiometries, two equations of state for fcc FeHX were developed, combining an empirical equation of state for iron with two distinct synthetic compression curves for interstitial hydrogen. Matching the density deficit of the Earth's core using these equations of state requires 0.8–1.1 wt % hydrogen at the core‐mantle boundary and 0.2–0.3 wt % hydrogen at the interface of the inner and outer cores. Furthermore, a comparison of Preliminary Reference Earth Model (PREM) to a Birch's law extrapolation of our experimental results suggests that an iron alloy containing ∼0.8–1.3 wt % hydrogen could reproduce both the density and compressional velocity (VP) of the Earth's outer core.

show abstract

Section: Introductionmentioning

confidence: 99%

High‐Pressure Geophysical Properties of Fcc Phase FeH_X

Thompson

Davis

et al. 2018

Geochem Geophys Geosyst

View full text Add to dashboard Cite

show abstract

“…The solubility of hydrogen in iron is very low at ambient pressure, but increases greatly at high pressure4. Experiments on iron and hydrous minerals5678 have shown, albeit indirectly, that hydrogen might indeed be one of the light elements in the core. Other light elements can stably remain in iron once incorporated under high- P – T conditions, and thus their behaviour can be studied in detail using recovered samples.…”

mentioning

confidence: 99%

Hydrogenation of iron in the early stage of Earth’s evolution

et al. 2017

View full text Add to dashboard Cite

Density of the Earth's core is lower than that of pure iron and the light element(s) in the core is a long-standing problem. Hydrogen is the most abundant element in the solar system and thus one of the important candidates. However, the dissolution process of hydrogen into iron remained unclear. Here we carry out high-pressure and high-temperature in situ neutron diffraction experiments and clarify that when the mixture of iron and hydrous minerals are heated, iron is hydrogenized soon after the hydrous mineral is dehydrated. This implies that early in the Earth's evolution, as the accumulated primordial material became hotter, the dissolution of hydrogen into iron occurred before any other materials melted. This suggests that hydrogen is likely the first light element dissolved into iron during the Earth's evolution and it may affect the behaviour of the other light elements in the later processes.

show abstract

“…for driving the mantle convection and the plate tectonics, was estimated to be 1300 K. Hydrogen has been proposed as an important light element in the core [1][2][3][4][5][6][7], but the quantity of it that was transported to the core during the Earth's formation was not investigated experimentally until very recently, due to the difficulties in handling molten FeH x . Okuchi [9] showed that hydrogen transported to the molten iron during the core formation may reach x = 0.41 and that hydrogen in the inner core, once it begins to crystallize, may reach x = 0.34.…”

Section: Discussionmentioning

confidence: 99%

“…In previous high-pressure quenching experiments on FeH x , this ratio could not be examined because hydrogen completely escaped from iron during decompression at a usual rate of several GPa h −1 [2]. The melting of FeH x was identified only when the surrounding material was also molten; in this, 'balls of iron' were formed [4].…”

Section: Methodsmentioning

confidence: 99%

“…The possible existence of the lightest element in the universe, hydrogen, in the deepest part of the Earth has been widely discussed during the last two decades [1][2][3][4][5][6][7]. Despite the experimental difficulties due to the rapid decomposition of the metallic alloy of iron and hydrogen under room conditions, the stability of solid crystalline iron hydride (FeH x ) at the high pressures relevant to the Earth's core is now firmly established through the experimental results from in situ x-ray diffraction techniques [5,7,8].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tracking Dependence on Readout Signal Characteristics of Two-Beam Optical Heads for Real-Time Verification

Shinoda

Satoh

Karaki

et al. 1993

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

The Earth's core is about 10% less dense than pure iron under the relevant pressure and temperature conditions, so elements lighter than iron should exist in it. Recent experiments support the hypothesis that hydrogen dominates this light component. The hydrogen dissolved in metallic iron has a large potential to reduce its melting temperature. To estimate the melting temperature of the iron-hydrogen core, experiments were carried out at pressures up to 10 GPa by means of a new technique to determine the melting temperature and chemical composition from the textures of rapidly decompressed iron hydride grains. The rate of reduction of the melting temperature induced by adding hydrogen to iron was obtained as (1.8 ± 0.2) × 10 3 K per unit mole fraction. If this behaviour of hydrogen persists to the much higher pressure deep inside the Earth, the isentrope in the iron-hydrogen core is about 600 K lower than the previous estimates based on experiments on the iron-sulphur-oxygen system.

show abstract

Hydrogen in the earth's core. Experimental approach.

Cited by 23 publications

References 4 publications

High‐Pressure Geophysical Properties of Fcc Phase FeH_X

High‐Pressure Geophysical Properties of Fcc Phase FeH_X

Hydrogenation of iron in the early stage of Earth’s evolution

Tracking Dependence on Readout Signal Characteristics of Two-Beam Optical Heads for Real-Time Verification

Contact Info

Product

Resources

About

Hydrogen in the earth's core. Experimental approach.

Cited by 23 publications

References 4 publications

High‐Pressure Geophysical Properties of Fcc Phase FeHX

High‐Pressure Geophysical Properties of Fcc Phase FeHX

Hydrogenation of iron in the early stage of Earth’s evolution

Tracking Dependence on Readout Signal Characteristics of Two-Beam Optical Heads for Real-Time Verification

Contact Info

Product

Resources

About

High‐Pressure Geophysical Properties of Fcc Phase FeH_X

High‐Pressure Geophysical Properties of Fcc Phase FeH_X