Author
Jean-Pascal Rueff
Other affiliations: Soleil Synchrotron, Pierre-and-Marie-Curie University, Brookhaven National Laboratory ...read more
Bio: Jean-Pascal Rueff is an academic researcher from University of Paris. The author has contributed to research in topics: Scattering & Resonant inelastic X-ray scattering. The author has an hindex of 34, co-authored 178 publications receiving 4509 citations. Previous affiliations of Jean-Pascal Rueff include Soleil Synchrotron & Pierre-and-Marie-Curie University.
Papers published on a yearly basis
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TL;DR: A high-spin to low-spin transition occurring in the 60- to 70-gigapascal pressure range, corresponding to depths of 2000 kilometers in Earth's lower mantle, implies that the partition coefficient of iron between ferropericlase and magnesium silicate perovskite, the two main constituents of the lower mantle), may increase by several orders of magnitude.
Abstract: We measured the spin state of iron in ferropericlase (Mg0.83Fe0.17)O at high pressure and found a high-spin to low-spin transition occurring in the 60- to 70-gigapascal pressure range, corresponding to depths of 2000 kilometers in Earth's lower mantle. This transition implies that the partition coefficient of iron between ferropericlase and magnesium silicate perovskite, the two main constituents of the lower mantle, may increase by several orders of magnitude, depleting the perovskite phase of its iron. The lower mantle may then be composed of two different layers. The upper layer would consist of a phase mixture with about equal partitioning of iron between magnesium silicate perovskite and ferropericlase, whereas the lower layer would consist of almost iron-free perovskite and iron-rich ferropericlase. This stratification is likely to have profound implications for the transport properties of Earth's lowermost mantle.
497 citations
TL;DR: The proportion of iron in the low spin state grows with depth, increasing the transparency of the mantle in the infrared region, with a maximum at pressures consistent with the D″ layer above the core-mantle boundary, which suggests the existence of nonconvecting layers in the lowermost mantle.
Abstract: We measured the spin state of iron in magnesium silicate perovskite (Mg09,Fe01)SiO3 at high pressure and found two electronic transitions occurring at 70 gigapascals and at 120 gigapascals, corresponding to partial and full electron pairing in iron, respectively The proportion of iron in the low spin state thus grows with depth, increasing the transparency of the mantle in the infrared region, with a maximum at pressures consistent with the D″ layer above the core-mantle boundary The resulting increase in radiative thermal conductivity suggests the existence of nonconvecting layers in the lowermost mantle
367 citations
TL;DR: In this article, the spectral line shape of the Fe Kb emission line was used to show that FeO remains a magnetic insulator up to 143 GPa at room temperature using high-resolution x-ray emission spectroscopy.
Abstract: We report evidence for a preserved magnetic state in FeO up to 143 GPa at room temperature using high-resolution x-ray emission spectroscopy. This observation is based on the spectral line shape of the Fe Kb emission line. Up to the highest pressure, FeO remains a magnetic insulator. Combining our results with previous Mossbauer data, we present a new magnetic phase diagram of FeO. Features like a closed-loop P-T antiferromagnetic domain confirm that high-pressure investigations can reveal new physical properties and unexpected phenomena.
172 citations
TL;DR: In this article, the authors reported the observation of the pressure-induced high-spin to low-spin transition in FeS using new high-pressure synchrotron x-ray emission spectroscopy techniques.
Abstract: We report the observation of the pressure-induced high-spin to low-spin transition in FeS using new high-pressure synchrotron x-ray emission spectroscopy techniques. The transition is evidenced by the disappearance of the low-energy satellite in the Fe Kb emission spectrum of FeS. Moreover, the phase transition is reversible and closely related to the structural phase transition from a manganese phosphidelike phase to a monoclinic phase. The study opens new opportunities for investigating the electronic properties of materials under pressure. [S0031-9007(99)08946-2]
149 citations
TL;DR: In this article, a review of electronic excitations in materials under extreme conditions using inelastic x-ray scattering (IXS) is presented, where the incident X-ray energy can easily be tuned to absorption edges, and resonant IXS is often employed.
Abstract: Investigating electronic structure and excitations under extreme conditions gives access to a rich variety of phenomena. High pressure typically induces behavior such as magnetic collapse and the insulator-metal transition in 3d transition metals compounds, valence fluctuations or Kondo-like characteristics in $f$-electron systems, and coordination and bonding changes in molecular solids and glasses. This article reviews research concerning electronic excitations in materials under extreme conditions using inelastic x-ray scattering (IXS). IXS is a spectroscopic probe of choice for this study because of its chemical and orbital selectivity and the richness of information it provides. Being an all-photon technique, IXS has a penetration depth compatible with high pressure requirements. Electronic transitions under pressure in 3d transition metals compounds and $f$-electron systems, most of them strongly correlated, are reviewed. Implications for geophysics are mentioned. Since the incident X-ray energy can easily be tuned to absorption edges, resonant IXS, often employed, is discussed at length. Finally studies involving local structure changes and electronic transitions under pressure in materials containing light elements are briefly reviewed.
141 citations
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TL;DR: The IrOx/SrIrO3 catalyst outperforms known IrOx and ruthenium oxide (RuOx) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte.
Abstract: Oxygen electrochemistry plays a key role in renewable energy technologies such as fuel cells and electrolyzers, but the slow kinetics of the oxygen evolution reaction (OER) limit the performance and commercialization of such devices. Here we report an iridium oxide/strontium iridium oxide (IrOx/SrIrO3) catalyst formed during electrochemical testing by strontium leaching from surface layers of thin films of SrIrO3 This catalyst has demonstrated specific activity at 10 milliamps per square centimeter of oxide catalyst (OER current normalized to catalyst surface area), with only 270 to 290 millivolts of overpotential for 30 hours of continuous testing in acidic electrolyte. Density functional theory calculations suggest the formation of highly active surface layers during strontium leaching with IrO3 or anatase IrO2 motifs. The IrOx/SrIrO3 catalyst outperforms known IrOx and ruthenium oxide (RuOx) systems, the only other OER catalysts that have reasonable activity in acidic electrolyte.
1,420 citations
TL;DR: This work analyzed the flow of matter to extract pressures in excess of 1034 pascals, the highest recorded under laboratory-controlled conditions, and ruled out strongly repulsive nuclear equations of state from relativistic mean field theory and weakly repulsive equation of state with phase transitions at densities less than three times that of stable nuclei.
Abstract: Nuclear collisions can compress nuclear matter to densities achieved within neutron stars and within core-collapse supernovae. These dense states of matter exist momentarily before expanding. We analyzed the flow of matter to extract pressures in excess of 10 34 pascals, the highest recorded under laboratory-controlled conditions. Using these analyses, we rule out strongly repulsive nuclear equations of state from relativistic mean field theory and weakly repulsive equations of state with phase transitions at densities less than three times that of stable nuclei, but not equations of state softened at higher densities because of a transformation to quark matter.
1,119 citations