Equation of state of pyrite to 80 GPa and 2400 K

Thompson, E. C.; Chidester, B.; Fischer, R. A.; Myers, Gregory I.; Heinz, Dion L.; Prakapenka, Vitali B.; Campbell, A. J.

doi:10.2138/am-2016-5527

Cited by 9 publications

(16 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The cotunnite-type and Fe 2 P-type FeS 2 are energetically unfavorable in the calculated pressure range, though both of them have been identified as the postpyrite phase for many AX 2 compounds (Dekura, Tsuchiya, Kuwayama, & Tsuchiya, 2011;Wu et al, 2011). (Liu et al, 2014;Merkel et al, 2002;Thompson et al, 2016). The resultant phonon spectra, lacking any imaginary frequencies imply that these three phases of FeS 2 all present dynamically stable at each given pressure.…”

Section: Resultsmentioning

confidence: 91%

“…The electronic density of states (DOS) were obtained by the static calculation, utilizing the tetrahedral smearing method with Blöchl corrections. The k (Merkel et al, 2002) and orange line (Thompson et al, 2016)) and theoretical (green line (Liu et al, 2014)) data are plotted for comparison. (Togo et al, 2008) and 2 × 2 × 2, 2 × 2 × 2, and 3 × 3 × 2 supercells were constructed for the pyrite-type, R3m-type, and I4/mmm-type FeS 2 and FeO 2 , respectively.…”

Section: Methodsmentioning

confidence: 99%

“…FeS 2 ( Figure S1a) shock experiments found that the Pa3-type FeS 2 could be stable up to 320 GPa (Ahrens & Jeanloz, 1987). Because of this, FeS 2 is often used to roughly calculate the upper limit of sulfur content in Earth's core (Badro et al, 2007;Thompson et al, 2016). However, theoretical simulations predicted a Pa3 -P4 2 /n phase transition in NiS 2 at 150 GPa, in which the stable range of the Pa3 structure was much smaller than that of the Pa3-type FeS 2 (Yu & Ross, 2010).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior

Huang

Qin

2018

JGR Solid Earth

View full text Add to dashboard Cite

Iron oxides play an important role in planetary evolution, but little information about the structural properties of AX2‐type iron oxides under extreme conditions limits our understanding of the so‐called “super‐Earth” planets. Here an investigation into the high‐pressure behavior of FeO2 as well as its sulfide counterpart FeS2, has been conducted by first‐principle calculations based on density functional theory. Both FeO2 and FeS2 are predicted to undergo a italicPatrue3¯‐ Rtrue3¯m‐I4/mmm transition sequence at extreme pressure. Differences in high‐pressure behaviors between FeO2 and FeS2 have been discussed in detail, such as effective coordination number and elasticity. This study not only resolves the controversy about the structural stability of FeS2 under high pressure but also suggests the tenfold coordinated I4/mmm‐type FeO2 may contribute to local chemical heterogeneity by accumulation in the deep interior of a large super‐Earth or water‐rich planet, whose pressure at the core‐mantle boundary can reach 2 TPa.

show abstract

Section: Resultsmentioning

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior

Huang

Qin

2018

JGR Solid Earth

View full text Add to dashboard Cite

show abstract

“…where the thermal expansion is calculated from the thermal EOS with (28) a The electronic and anharmonic contributions to thermal pressure are approximated by adding the theoretically determined P el and P anh of hcp-Fe (Dewaele et al, 2006) Thompson et al (2016): XRD with laser heating up to 80 GPa and 2400 K. The electronic and anharmonic contribution to thermal pressure (A 2 ) as reported in Thompson et al (2016) is included in this treatment. and the Grüneisen parameter is calculated with equation (4).…”

Section: Thermal Eosmentioning

confidence: 99%

“…To examine the effect of other light elements, we include three thermal EOS studies in Figure 10: FeO (Fischer et al, 2011), Fe 7 C 3 (Chen et al, 2012), and FeS 2 (Thompson et al, 2016). High-temperature DAC experiments by Fischer et al (2011) investigated B1-structured FeO with X-ray diffraction and laser heating using a NaCl pressure medium and an iron pressure standard.…”

Section: Iron Alloys At Inner Core Conditionsmentioning

confidence: 99%

Equations of State and Anisotropy of Fe‐Ni‐Si Alloys

et al. 2018

View full text Add to dashboard Cite

We present powder X‐ray diffraction data on body centered cubic (bcc)‐ and hexagonal close packed (hcp)‐structured Fe0.91Ni0.09 and Fe0.8Ni0.1Si0.1 at 300 K up to 167 and 175 GPa, respectively. The alloys were loaded with tungsten powder as a pressure calibrant and helium as a pressure transmitting medium into diamond anvil cells, and their equations of state and axial ratios were measured with high statistical quality. These equations of state are combined with thermal parameters from previous reports to improve the extrapolation of the density, adiabatic bulk modulus, and bulk sound speed to the pressures and temperatures of Earth's inner core. We propagate uncertainties and place constraints on the composition of Earth's inner core by combining these results with available data on light‐element alloys of iron and seismic observations. For example, the addition of 4.3 to 5.3 wt% silicon to Fe0.95Ni0.05 alone can explain geophysical observations of the inner core boundary, as can up to 7.5 wt% sulfur with negligible amounts of silicon and oxygen. Our findings favor an inner core with less than ∼2 wt% oxygen and less than 1 wt% carbon, although uncertainties in electronic and anharmonic contributions to the equations of state may shift these values. The compositional space widens toward the center of the Earth, considering inner core seismic gradients. We demonstrate that hcp‐Fe0.91Ni0.09 and hcp‐Fe0.8Ni0.1Si0.1 have measurably greater c/a axial ratios than those of hcp‐Fe over the measured pressure range. We further investigate the relationship between the axial ratios, their pressure derivatives, and elastic anisotropy of hcp‐structured materials.

show abstract

Effects of hydrogen on the phase relations in Fe--FeS at pressures of Mars-sized bodies

Piet

Leinenweber

Greenberg

et al. 2021

Preprint

View full text Add to dashboard Cite

Hydrogen (H) and sulfur (S) are light element candidates to enter the core of planetary bodies. Although Fe-S and Fe-H systems have been studied individually, the Fe-S-H ternary system has only been investigated up to 16 GPa and 1723 K. We have investigated the Fe-S-H system at pressures and temperatures (P-T) relevant to the cores of Mars-sized planets (up to 45 GPa and well above the melting temperature of FeS) in the laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. We found that at high P-T, Fe3S is unstable if H exists in the system. Instead, separate Fe-H and Fe-S phases appear at 23-35 GPa. At pressures above 35 GPa, we found a new phase appearing while Fe-S phases disappear and Fe-H phases remain. Our analysis indicates that the new phase likely contains both S and H in the crystal structure (tentatively FeSH). The observed pressure dependent changes in the phase relation may be important for understanding the structure and dynamics of the Martian core and the cores of Mars-sized exoplanets.

show abstract

Equation of state of pyrite to 80 GPa and 2400 K

Cited by 9 publications

References 48 publications

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior

Equations of State and Anisotropy of Fe‐Ni‐Si Alloys

Effects of hydrogen on the phase relations in Fe--FeS at pressures of Mars-sized bodies

Contact Info

Product

Resources

About

Equation of state of pyrite to 80 GPa and 2400 K

Cited by 9 publications

References 48 publications

Ultrahigh‐Pressure Phase Transitions in FeS2 and FeO2: Implications for Super‐Earths' Deep Interior

Ultrahigh‐Pressure Phase Transitions in FeS2 and FeO2: Implications for Super‐Earths' Deep Interior

Equations of State and Anisotropy of Fe‐Ni‐Si Alloys

Effects of hydrogen on the phase relations in Fe--FeS at pressures of Mars-sized bodies

Contact Info

Product

Resources

About

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior

Ultrahigh‐Pressure Phase Transitions in FeS₂ and FeO₂: Implications for Super‐Earths' Deep Interior