57Fe Mössbauer study under high pressure; ε-Fe and Fe2O3

Nasu, Saburo; Kurimoto, K.; Nagatomo, S.; Endo, S.; Fujita, Francisco Eiichi

doi:10.1007/bf02399539

Cited by 47 publications

(26 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such a model leads automatically to a perovskite structure. The subsequent incomplete Mössbauer studies [10][11][12] carried to ϳ70 GPa somehow corroborated this conjecture suggesting that the HP phase is indeed characterized by two distinct Fe components. Those two spectral components were attributed to two different Fe cations (Fe 21 and Fe 41 ), one of which could be in a low-spin, diamagnetic, state explaining the nonmagnetic component.…”

supporting

confidence: 67%

“…Those two spectral components were attributed to two different Fe cations (Fe 21 and Fe 41 ), one of which could be in a low-spin, diamagnetic, state explaining the nonmagnetic component. Now it is clear that a large pressure distribution in the DAC for the Mössbauer experiments associated with their (alcohol mixture) pressure medium, particularly the one experiment carried out to 72 GPa [12], and a lack of experimental data at the higher pressures, led to the wrong and biased disproportionation model. Thus, for years the perovskite ABO 3 structure has been adopted, ruling out the A 2 O 3 corundum structure which can be assigned only in the case of a single cation, e.g., Fe 31 .…”

mentioning

confidence: 95%

“…Concurrent with the discovery of the new high-pressure dense phase by XRD investigation, Mössbauer experiments carried out at 300 K by Suzuki et al [8], Syono et al [11], and Nasu et al [12] revealed a nonmagnetic component at ϳ50 GPa, coexisting with a magnetic phase to highest pressure of 70 GPa, and assigned to the dense state. The authors also noticed that the hyperfine field, H hf , in the 56-70 GPa range, was somewhat smaller than that of the low-pressure (LP) phase.…”

mentioning

confidence: 98%

See 2 more Smart Citations

Breakdown of the Mott-Hubbard State inFe2O3: A First-Order Insulator-Metal Transition with Collapse of Magnetism at 50 GPa

et al. 1999

View full text Add to dashboard Cite

Electronic and structural properties of the high-pressure phase of Fe 2 O 3 were determined by combining the methods of Mössbauer spectroscopy, x-ray diffraction, and electrical resistance, R͑P, T͒, to 80 GPa. Because of a first-order phase transition taking place in the 50 -75 GPa range and accompanied by a volume decrease of ϳ10%, a breakdown of the electronic d-d correlation occurred, leading to a Mott transition, a metallic and a nonmagnetic single Fe 31 electronic state. The highpressure structure is of the distorted Rh 2 O 3 -II type. The accommodation of the denser phase within this six-coordinated structure is attributable to the metallic state. [S0031-9007(99)09286-8] PACS numbers: 62.50. + p, 71.30. + h, 76.80. + y More than half of the binary transition metal (TM) compounds and the majority of the undoped TM oxides are magnetic insulators that order antiferromagnetically below a certain Néel temperature (T N ). The localization of carriers in those so-called Mott insulators results from strong on-site Coulomb repulsion within the 3d band. Its insulating nature [1] is commensurate to an effective energy-gap U, far exceeding the d-band width W, splitting the d band into upper (empty) and lower (filled) subbands. In view of the "Coulomb" nature of the gap, it is expected that in ionic insulators, such as the binary TM oxides, very high pressures will be needed to reach the W͞U ¿ 1 regime. In this regime the d-electron correlation collapses, giving rise to an insulating-metal transition concurring with a magnetic moment breakdown, a phenomenon often called the Mott transition. Indeed, as shown by Cohen et al. [2] for the case of binary TM oxides, the Mott transition could be attained only at pressures close to 200 GPa. Pasternak et al. experimentally observed a pressure-induced Mott transition in the highly covalent NiI 2 , [3] using the combined methods of 129 I Mössbauer spectroscopy (MS), x-ray diffraction (XRD), and electrical conductivity in diamond anvil cells (DAC's). The isostructural transition was second order and quasi-isochoric. The question then arises whether in the case of a first-order phase transition resulting in a reduction in volume, such a TM-oxide Mott insulator might undergo a Mott transition.In this Letter we report the observation of such a transition attributable to a huge volume reduction, the first-order phase transition in a-Fe 2 O 3 (hematite) at 50 GPa. As will be shown, this work is important not only to the elucidation of such a basic phenomenon as the Mott transition, but also to ultimately untangling the baffling nature of the high-pressure phase of hematite.Fe 2 O 3 , a wide-gap antiferromagnetic insulator (T N 956 K [4]) can be regarded as archetypal of a Mott insulator. Motivated primarily by its importance in the earth sciences, high-pressure studies of this corundumtype mineral have been extensively performed since the early days of high-pressure physics. As early as in the mid-1960s shock-wave experiments were performed by McQueen and Marsh [5] who reached energy...

show abstract

supporting

confidence: 67%

mentioning

confidence: 95%

mentioning

confidence: 98%

See 1 more Smart Citation

Breakdown of the Mott-Hubbard State inFe2O3: A First-Order Insulator-Metal Transition with Collapse of Magnetism at 50 GPa

et al. 1999

View full text Add to dashboard Cite

show abstract

“…Concurrent with the discovery of the new high-pressure dense phase by XRD investigation, Mö ssbauer experiments carried out at 300 K by Suzuki et al [16], Syono et al [19], and Nasu et al [20] revealed a non-magnetic component at %50 GPa, coexisting with a magnetic phase to their highest pressure of 70 GPa, and assigned it to the denser state. The authors also noticed that the hyperfine field, H hf , in the 56-70 GPa range, was somewhat smaller than that of the low-pressure (LP) phase.…”

Section: And Feomentioning

confidence: 99%

Pressure-Induced Metallization and Electronic-Magnetic Properties of Some Mott Insulators

Pasternak

Taylor

2001

phys. stat. sol. (b)

View full text Add to dashboard Cite

“…Fast electron exchange is considered to occur among the Fe 2þ and Fe 3þ ions on octahedral sites [7][8][9][10]. The materials from the early days of ultrasonic technology such as quartz, lithium sulfate and barium titanate are almost used today.…”

Section: Introductionmentioning

confidence: 99%