Structure of β-iron at High Temperature and Pressure

Dubrovinsky, Leonid; Saxena, Surendra K.; Lazor, Peter; Weber, Hans‐Peter

doi:10.1126/science.281.5373.11a

Cited by 19 publications

(5 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Metallic iron was, however, not observed under the TEM in this study. Oxidation during heating, which easily occurs in a LHDAC [e.g., Dubrovinsky et al , 1998], may be a likely scenario in our experiments. Such iron metal formed by disproportionation of Fe 2+ was not commonly observed in the previous multi‐anvil experiments either [ Frost and Langenhorst , 2002].…”

Section: Discussionmentioning

confidence: 99%

Ferric iron in Al‐bearing post‐perovskite

Sinmyo¹,

Hirose²,

O’Neill³

et al. 2006

Geophysical Research Letters

View full text Add to dashboard Cite

[1] The Fe 3+ /SFe ratios in both (Al, Fe)-bearing MgSiO 3 post-perovskite phase and Ca-ferrite-type Al-phase, synthesized in a natural mid-oceanic ridge basalt (MORB) composition at 113 GPa and 2240 K, were determined by electron energy-loss near-edge structure (ELNES) spectroscopy. The results demonstrate that post-perovskite has high proportions of Fe 3+ with Fe 3+ /SFe ratio of 0.65 ± 0.04. The high Fe 3+ concentration in post-perovskite may have significant effects on its physical properties, phase stability, and iron partitioning. In contrast, the Ca-ferritetype Al-phase, which is the second Fe-bearing phase in a subducting MORB crust, is enriched in Fe 2+ rather than Fe 3+ with Fe 3+ /SFe ratio of 0.15 and 0.29. Citation: Sinmyo, R., K.

show abstract

Section: Discussionmentioning

confidence: 99%

Ferric iron in Al‐bearing post‐perovskite

Sinmyo¹,

Hirose²,

O’Neill³

et al. 2006

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…In the right panel of the figure, we report the same quantity, V/V 0 , as a function of pressure at eight equidistant temperatures (0, 300, 600, 900, 1200, 1500, 1800 and 2100 K). Experimental data are also reported as measured at 300 K at different pressures by Sato and Akimoto 74 (full circles), Grevel et al 75 (empty circles) and Dubrovinsky et al 76 (full square). We can clearly see that: (i) obviously as temperature increases the cell volume expands; (ii) a given volume (i.e.…”

Section: Effect Of Thermal Pressurementioning

confidence: 99%

“…Experimental data at 62 for a V /3 and by Munro 72 for a c À a a ; empty circles are data from White and Roberts. 73 zero pressure by Anderson et al 62 are given as full circles while those at about 11 GPa by Dubrovinsky et al 76 as full squares, with corresponding error bars. The effect of pressure is a non-linear compression of the unit cell volume.…”

Section: Effect Of Thermal Pressurementioning

confidence: 99%

Assessing thermochemical properties of materials through ab initio quantum-mechanical methods: the case of α-Al₂O₃

Erba

Maul

Demichelis

et al. 2015

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The thermochemical behavior of α-Al 2 O 3 corundum in the whole temperature range 0-2317 K (melting point) and under pressures up to 12 GPa is predicted by applying ab initio methods based on the density functional theory (DFT), the use of a local basis set and periodic-boundary conditions. Thermodynamic properties are treated both within and beyond the harmonic approximation to the lattice potential. In particular, a recent implementation of the quasi-harmonic approximation, in the CRYSTAL program, is here shown to provide a reliable description of the thermal expansion coefficient, entropy, constant-volume and constant-pressure specific heats, and temperature dependence of the bulk modulus, nearly up to the corundum melting temperature. This is a remarkable outcome suggesting α-Al 2 O 3 to be an almost perfect quasi-harmonic crystal. The effect of using different computational parameters and DFT functionals belonging to different levels of approximations on the accuracy of the thermal properties is tested, providing a reference for further studies involving alumina polymorphs and, more generally, quasiionic minerals.

show abstract

“…Reliable thermodynamic data for the Fe±Al±O system exist 20 There are indications that such a reaction is possible at much higher pressures 21,22 , but no systematic investigations of the interaction between iron and aluminium oxide at different pressures and temperatures so far been made. We therefore decided to conduct in situ and ex situ studies of the possible reactions between Fe and Al 2 O 3 in heated diamond anvil cells by means of X-ray powder diffraction and Mo Èssbauer spectroscopic analysis.…”

mentioning

confidence: 98%

Chemical interaction of Fe and Al2O3 as a source of heterogeneity at the Earth's core–mantle boundary

Dubrovinsky

Annersten

Westman

et al. 2001

Nature

View full text Add to dashboard Cite

Seismological studies have revealed that a complex texture or heterogeneity exists in the Earth's inner core and at the boundary between core and mantle. These studies highlight the importance of understanding the properties of iron when modelling the composition and dynamics of the core and the interaction of the core with the lowermost mantle. One of the main problems in inferring the composition of the lowermost mantle is our lack of knowledge of the high-pressure and high-temperature chemical reactions that occur between iron and the complex Mg-Fe-Si-Al-oxides which are thought to form the bulk of the Earth's lower mantle. A number of studies have demonstrated that iron can react with MgSiO3-perovskite at high pressures and high temperatures, and it was proposed that the chemical nature of this process involves the reduction of silicon by the more electropositive iron. Here we present a study of the interaction between iron and corundum (Al(2)O3) in electrically- and laser-heated diamond anvil cells at 2,000-2,200 K and pressures up to 70 GPa, simulating conditions in the Earth's deep interior. We found that at pressures above 60 GPa and temperatures of 2,200 K, iron and corundum react to form iron oxide and an iron-aluminium alloy. Our results demonstrate that iron is able to reduce aluminium out of oxides at core-mantle boundary conditions, which could provide an additional source of light elements in the Earth's core and produce significant heterogeneity at the core-mantle boundary.

show abstract

Structure of β-iron at High Temperature and Pressure

Cited by 19 publications

References 21 publications

Ferric iron in Al‐bearing post‐perovskite

Ferric iron in Al‐bearing post‐perovskite

Assessing thermochemical properties of materials through ab initio quantum-mechanical methods: the case of α-Al₂O₃

Chemical interaction of Fe and Al2O3 as a source of heterogeneity at the Earth's core–mantle boundary

Contact Info

Product

Resources

About

Structure of β-iron at High Temperature and Pressure

Cited by 19 publications

References 21 publications

Ferric iron in Al‐bearing post‐perovskite

Ferric iron in Al‐bearing post‐perovskite

Assessing thermochemical properties of materials through ab initio quantum-mechanical methods: the case of α-Al2O3

Chemical interaction of Fe and Al2O3 as a source of heterogeneity at the Earth's core–mantle boundary

Contact Info

Product

Resources

About

Assessing thermochemical properties of materials through ab initio quantum-mechanical methods: the case of α-Al₂O₃