Ultrahigh-pressure study on the magnetic state of iron hydride using an energy domain synchrotron radiation <sup>57</sup>Fe Mössbauer spectrometer

Mitsui, Takaya; Hirao, Naohisa

doi:10.1557/proc-1262-w06-09

Cited by 15 publications

(14 citation statements)

References 18 publications

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“…XMCD vanishes between 23 and 28 GPa, which is consistent with the observation made by Mössbauer spectroscopy [33] and previous XMCD experiments [28] that magnetic ordering vanishes at pressures higher than approximately 27 GPa. The XAS spectrum also exhibits drastic changes at 28 GPa: the shoulders a and b are enhanced and the maximum c is reduced.…”

Section: Compression Of Feh and Disappearance Of Magnetismsupporting

confidence: 91%

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

et al. 2018

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The application of a 3.5 GPa pressure on Fe in a H 2 environment leads to the formation of iron hydride FeH. Using a combination of high pressure x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at the Fe K edge, we have investigated the modification of electronic and magnetic properties induced (i) by the transition from bcc-Fe to dhcp (double hexagonal)-FeH under pressure and (ii) by the compression of FeH up to 28 GPa. XAS and XMCD spectra under pressure have been computed in bcc-Fe and dhcp-FeH within a monoelectronic framework. Our approach is based on a semirelativistic density-functional theory (DFT) calculation of the electron density in the presence of a core hole using plane waves and pseudopotentials. Our method has been successful to reproduce the experimental spectra and to interpret the magnetic and electronic structure of FeH. In addition, we have identified a transition around 28 GPa, which is a purely magnetic transition from a ferromagnetic state to a paramagnetic state.

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Section: Compression Of Feh and Disappearance Of Magnetismsupporting

confidence: 91%

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

et al. 2018

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“…The calculated Curie temperature decreases rapidly with applying pressure, and becomes comparable to the ambient temperature at the highest pressure. This behavior is consistent with previous Mössbauer spectroscopy measurements reported by Mitsui and Hirao (2010), as well as XRD study by Hirao et al (2004). In this study, we only considered the ground state ferromagnetism and the LMD state at the Curie temperature.…”

Section: Magnetic Transition Pressuresupporting

confidence: 90%

“…At pressures above 50 GPa, the experimental data become consistent with theoretical EoS of non-magnetic FeH again. Mitsui and Hirao (2010) conducted in-situ Mössbauer measurement up to ~65 GPa. They found rapid disappearance of ferromagnetic 6-line pattern at 27.6 GPa, but there still remains residual weak hyperfine field up to 64.7 GPa.…”

Section: Magnetic Transition Pressurementioning

confidence: 99%

The effects of ferromagnetism and interstitial hydrogen on the equation of states of hcp and dhcp FeHx: Implications for the Earth's inner core age

Gomi

Fei

Yoshino

2018

American Mineralogist

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Hydrogen has been considered as an important candidate of light elements in the Earth's core. Because iron hydrides are unquenchable, hydrogen content is usually estimated from in-situ X-ray diffraction measurements assuming the following linear relation: x = (V FeHx-V Fe) / V H , where x is the hydrogen content, V H is the volume expansion caused by unit concentration of hydrogen, V FeHx and V Fe are volumes of FeH x and pure iron, respectively. To verify the linear relationship, we computed the equation of states of hexagonal iron with interstitial hydrogen by using the Korringa-Kohn-Rostoker method with the coherent potential approximation (KKR-CPA). The results indicate a discontinuous volume change at the magnetic transition and almost no compositional (x) dependence in the ferromagnetic phase at 20 GPa, whereas the linearity is confirmed in the non-magnetic phase. In addition to their effects on density-composition relationship in the Fe-FeH x system, which is important for estimating the hydrogen incorporation in planetary cores, the magnetism and interstitial hydrogen also affect the electrical resistivity of FeH x. The thermal conductivity can be calculated from the electrical resistivity by using the Wiedemann-Franz law, which is a critical parameter for modeling the thermal evolution of the Earth. Assuming an Fe 1-y Si y H x ternary outer core model (0.0  x  0.7), we calculated the thermal conductivity and the age of the inner core. The resultant thermal conductivity is ~100 W/m/K and the maximum inner core age ranges from 0.49 to 0.86 Gyr.

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“…The counting rate is ∼2.0 × 10 4 Hz for 57 FeBO 3 111 (∼1.2 × 10 4 Hz for 57 FeBO 3 333). As a transmission experiment, the SRMS of FeH was studied under high pressures up to 65 GPa at 300 K [4]. A tiny polycrystalline iron metal ( 57 Fe 95%, φ <50 μm) and ruby pressure markers were enclosed in a DAC filled with liq.…”

Section: Introductionmentioning

confidence: 99%

Synchrotron radiation 57Fe-Mössbauer spectroscopy using nuclear monochromator

et al. 2011

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A synchrotron radiation (SR) Mössbauer spectrometer has been developed by using a nuclear Bragg monochromator (NBM). It enables energy-domain 57 Fe SR-Mössbauer spectroscopy (SRMS). Doppler-shifted SR-Mössbauer radiation is produced by pure nuclear Bragg reflection (PNBR) from an oscillating 57 FeBO 3 crystal near the Néel point. In this paper, we describe the optics and its applications, including high-pressure SRMS, grazing incidence SRMS and γ -ray diffraction studies with the Rayleigh scattering of Mössbauer radiation (RSMR) method.

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Ultrahigh-pressure study on the magnetic state of iron hydride using an energy domain synchrotron radiation ⁵⁷Fe Mössbauer spectrometer

Cited by 15 publications

References 18 publications

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

The effects of ferromagnetism and interstitial hydrogen on the equation of states of hcp and dhcp FeHx: Implications for the Earth's inner core age

Synchrotron radiation 57Fe-Mössbauer spectroscopy using nuclear monochromator

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Ultrahigh-pressure study on the magnetic state of iron hydride using an energy domain synchrotron radiation 57Fe Mössbauer spectrometer

Cited by 15 publications

References 18 publications

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

Electronic and magnetic properties of iron hydride under pressure: An experimental and computational study using x-ray absorption spectroscopy and x-ray magnetic circular dichroism at the Fe K edge

The effects of ferromagnetism and interstitial hydrogen on the equation of states of hcp and dhcp FeHx: Implications for the Earth's inner core age

Synchrotron radiation 57Fe-Mössbauer spectroscopy using nuclear monochromator

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Ultrahigh-pressure study on the magnetic state of iron hydride using an energy domain synchrotron radiation ⁵⁷Fe Mössbauer spectrometer