Mössbauer study of hydrides and deuterides of iron and cobalt

Schneider, Günter; Baier, M.; Wordel, R.; Wagner, F. E.; Antonov, V.E.; Ponyatovsky, E.G.; Kopilovskii, Yu.; Makarov, E. F.

doi:10.1016/0022-5088(91)90464-f

Cited by 24 publications

(19 citation statements)

References 12 publications

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“…The pressure at which the changes are observed corresponds to the pressure of a transition reported in the literature [5,29,30] from Fe to iron hydride FeH. To confirm the nature of the transition, we performed calculations of the XAS and XMCD spectra of dhcp-FeH.…”

Section: A Transition From Fe To Feh Under Pressurementioning

confidence: 75%

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: A Transition From Fe To Feh Under Pressurementioning

confidence: 75%

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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“…According to the phase rule, only single-phase fields are possible in the equilibrium T -P diagrams of binary Me-H systems, but the composition of every phase can vary continuously with T and P within the corresponding field. At temperatures up to 350 • C, the composition of the ε -hydride is close to FeH independent of the pressure [11,17,18], while at higher [20]. 1, 2 are the midpoints of anomalies of the electrical resistance isotherms measured at increasing and decreasing pressure, respectively (figure 2(a)); 3, 4 are the midpoints of anomalies of the isobars of electrical resistance and magnetic permeability measured at increasing and decreasing temperature, respectively (figure 2(b)); 5, 6 are the formation [11,12] and decomposition [13] pressure of ε -FeH at room temperature from measurements in diamond anvil cells.…”

Section: The Fe-h Systemmentioning

confidence: 99%

High-pressure hydrides of iron and its alloys

Antonov

Baier

Dörner

et al. 2002

J. Phys.: Condens. Matter

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Hydrides of iron and iron-based alloys are thermodynamically stable only at hydrogen pressures in the gigapascal range and rapidly lose hydrogen under ambient conditions. At low temperatures, however, these hydrides can be retained in a metastable state at atmospheric pressure after being cooled under high pressure to liquid nitrogen temperature. This review will discuss the current state of studies on phase transformations in the Fe-H and related systems and also on the composition, crystal structure and physical properties of the hydrides, both under high hydrogen pressures and in the 'quenched' metastable state at ambient pressure. The studies at ambient pressure include magnetization measurements, x-ray and neutron diffraction, Mössbauer spectroscopy and inelastic neutron scattering. In the sections on Mössbauer and structural investigations of hydrides of Fe-Cr and Ni-Fe alloys new experimental results will be presented.

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“…15) Schneider et al experimentally reported that a nonmagnetic phase with the hydrogen content x ¼ 0:3 was found at 4.2 K by Mössbauer spectroscopy; however, if x is increased to more than 0.4, the FeH x phase might show ferromagnetic ground states. 22) An hcp phase was found by neutron diffraction measurements for the "-phase using a sample of a FeD 0:42 . 12) It is also interesting that hcp Fe at high pressures is widely known as a nonmagnetic ground state, but hcp FeH x can be ferromagnetic with the incorporation of hydrogen.…”

Section: Hcp Feh Xmentioning

confidence: 99%

“…18,19) Two distinct values of hyperfine fields arising from two different Fe sites in dhcp FeH are observed by Mössbauer spectroscopy. [20][21][22][23] However, a clear correspondence between different hyperfine fields and Fe sites has never been identified yet. Although the ferromagnetic order of dhcp FeH disappears at about 30 GPa, in situ X-ray diffraction measurements show that the crystal structure stays stable up to a H pressure of 62 GPa at room temperature.…”

Section: Introductionmentioning

confidence: 99%

First-Principles Study on the Structural and Magnetic Properties of Iron Hydride

et al. 2012

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The magnetic and structural properties of iron hydride FeH with the double hexagonal close-packed (dhcp) and hexagonal close-packed (hcp) structures are investigated by first-principles density-functional theory calculations with a spin-polarized form of generalized gradient approximation. All the calculations are performed using all-electron fullpotential linearized augmented plane wave method. Both dhcp and hcp FeH are ferromagnetic at ambient pressure. The ferromagnetic ordering of the dhcp structure collapses at a pressure of 48 GPa, while that of the hcp structure vanishes gradually from 48 GPa. The modification in the density of states (DOS) due to the applied pressure causes the collapse of the magnetization. The difference in magnetic moment reduction between dhcp and hcp FeH is attributed to their DOS around the Fermi level. The calculated magnetocrystalline anisotropy energies between in-plane and out-of-plane spin orientations are found to be 124 eV/Fe for the dhcp structure, and 100 eV/Fe for the hcp structure. The easy axis is in-plane direction for both structures.

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Mössbauer study of hydrides and deuterides of iron and cobalt

Cited by 24 publications

References 12 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

High-pressure hydrides of iron and its alloys

First-Principles Study on the Structural and Magnetic Properties of Iron Hydride

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