A5086117959- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- X-ray Diffraction in Crystallography
- Diamond and Carbon-based Materials Research
- Crystallization and Solubility Studies
- Advanced Condensed Matter Physics
- Crystal Structures and Properties
- Rare-earth and actinide compounds
- Lightning and Electromagnetic Phenomena
- earthquake and tectonic studies
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Advanced Chemical Physics Studies
- Iron-based superconductors research
- Millimeter-Wave Propagation and Modeling
- Magnetic Properties and Synthesis of Ferrites
- Metal and Thin Film Mechanics
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Electronic and Structural Properties of Oxides
- Boron and Carbon Nanomaterials Research
- Radio Wave Propagation Studies
- Indoor and Outdoor Localization Technologies
- Earthquake Detection and Analysis
- Hydrogen Storage and Materials
University of Chicago
2017-2025
University of Edinburgh
2011-2025
Tel Aviv University
2010-2024
Rafael Advanced Defense Systems (Israel)
2010-2024
Argonne National Laboratory
2017-2023
Israel Atomic Energy Commission
2020-2023
Soreq Nuclear Research Center
2020-2023
Arizona State University
2021
Center for High Pressure Science & Technology Advanced Research
2020
Center for High Pressure Science and Technology Advanced Research
2020
Hydrogen-rich superhydrides are believed to be very promising high-Tc superconductors as they expected mimic characteristics of metallic hydrogen. Recent experiments discovered at high pressures, e.g. FeH5 130 GPa and LaH10 170 GPa. With the motivation discovering new hydrogen-rich lowest possible pressure, here we report prediction experimental synthesis cerium superhydride CeH9 below 100 in laser-heated diamond anvil cell. Ab-initio calculations were carried evaluate detailed chemistry...
The discovery of superconducting H
Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors which is believed to be described within the conventional phonon-mediated mechanism coupling. Here we report synthesis yttrium hexahydride Im3m-YH$_6$ that demonstrates superconducting transition with T$_c$ = 224 K at 166 GPa, much lower than theoretically predicted (>270 K). The measured upper critical magnetic field B$_c$$_2$(0) YH$_6$ was found 116-158 T, 2-2.5 times larger calculated value. A...
Abstract Polymorphism, which describes the occurrence of different lattice structures in a crystalline material, is critical phenomenon materials science and condensed matter physics. Recently, configuration disorder was compositionally engineered into single lattices, leading to discovery high-entropy alloys oxides. For these novel entropy-stabilized forms with extremely high structural stability, polymorphism still possible? Here by employing situ high-pressure synchrotron radiation X-ray...
Encapsulating Earth's deep water filter Small inclusions in diamonds brought up from the mantle provide valuable clues to mineralogy and chemistry of parts Earth that we cannot otherwise sample. Tschauner et al. found high-pressure form called ice-VII sourced between 410 660 km depth, part known as transition zone. The zone is a region where stable minerals have high storage capacity. suggest local aqueous pockets at boundary owing release chemically bound rock cycles out this region....
Formation of uranium polyhydrides UH 5–9 is predicted using the evolutionary algorithm USPEX and proved by high-pressure synthesis.
The realization of a novel guest/host carbon-boron sp 3 framework opens the door for new class 3D carbon-based materials.
Recent reports of the superconductivity in hydrides two different families (covalent lattice, as SH3 and clathrate-type H-cages containing La Y atoms, LaH10 YH6) have revealed new high-Tc materials with Tc’s near room temperature values. These findings confirm earlier expectations that may very high due to fact light H atoms vibrational frequencies, leading Tc values within conventional Bardeen–Cooper–Schrieffer phonon mechanism superconductivity. However, is pointed out by Ashcroft, it...
The discovery of high-temperature conventional superconductivity in H3S with a critical temperature Tc=203 K was followed by the recent record Tc ~250 face-centered cubic (fcc) lanthanum hydride LaH10 compound. It realized new class hydrogen-dominated compounds having clathrate-like crystal structure which hydrogen atoms form 3D framework and surround host atom rare earth elements. Yttrium hydrides are predicted to have even higher exceeding room temperature. In this paper, we synthesized...
The amount of heat transport from the core, which constrains dynamics and thermal evolution region, depends on properties iron. Ohta et al.(2016) Konopkova measured electrical resistivity conductivity iron, respectively, in laser-heated diamond anvil cells (DACs) at relevant Earth's core pressure-temperature (P-T) conditions, obtained dramatically contradictory results. Here we measure hcp-iron up to ~170 GPa ~3,000 K using a four-probe van der Pauw method coupled with homogeneous flat-top...
${\mathrm{WN}}_{6}$ phase discovered at 126--165 GPa after heating of W in nitrogen. XRD refinements reveal a unit cell space group $R\overline{3}m$ which is consistent with the structure armchairlike hexazine (${\mathrm{N}}_{6}$) rings, while strong ${A}_{1g}$ Raman mode confirms its $\mathrm{N}─\mathrm{N}$ single bonds. Density functional theory (DFT) calculations balanced contributions attractive interactions between and covalent ${\mathrm{N}}_{6}$ repulsions rings that make ultrastiff...
We report on high-pressure powder synchrotron x-ray diffraction studies $M$Fe${}_{2}$As${}_{2}$ ($M$$=$Ba, Ca) over a range of temperatures and pressures up to about 56 GPa using membrane diamond-anvil cell. Our data indicate phase transition collapsed tetragonal in both compounds upon compression. The at 300 K are measured pressure-increasing -decreasing cycles. measurements show that the Ba compound, occurs 27 GPa, which is much higher than pressure 1.7 Ca compound. At low temperature, we...
Abstract As a new class of multi-principal component oxides with high chemical disorder, high-entropy (HEOs) have attracted much attention. The stability and tunability their structure properties are great interest importance, but remain unclear. By using in situ synchrotron radiation X-ray diffraction, Raman spectroscopy, ultraviolet–visible absorption ex high-resolution transmission electron microscopy, here we show the existence lattice distortion crystalline (Ce 0.2 La Pr Sm Y )O 2−δ HEO...
The exceptional ability of carbon to form ${\mathit{sp}}^{2}$ and ${\mathit{sp}}^{3}$ bonding states leads a great structural chemical diversity carbon-bearing phases at nonambient conditions. Here we use laser-heated diamond-anvil cells combined with synchrotron x-ray diffraction, Raman spectroscopy, first-principles calculations explore phase transitions in $\mathrm{CaC}{\mathrm{O}}_{3}$ $P>40\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$. We find that postaragonite transforms the previously...
Synchrotron x-ray diffraction and Raman spectroscopy have been used to study the chemical reactions of molecular hydrogen $({\mathrm{H}}_{2})$ with sulfur (S) at high pressures. We find theoretically predicted Cccm $Im\overline{3}m$ ${\mathrm{H}}_{3}\mathrm{S}$ be reaction products 50 140 GPa, respectively. is a stable crystalline phase above GPa it transforms $R3m\phantom{\rule{0.16em}{0ex}}{\mathrm{H}}_{3}\mathrm{S}$ on pressure release below GPa. The latter (meta)stable down least 70...
Gamma radiation observed in space has been associated with lightning flashes thunderstorms. These special do not appear to be the large and energetic positive ground that also produce sprites. Considerations of gamma ray attenuation air indicate such may at sufficient altitude enable their escape space. High‐altitude intracloud lightning, most prevalent tropics where tropopause is high, a necessary source.
Under high pressures the hydrogen bonds were predicted to transform from a highly asymmetric soft O-H···O symmetric rigid configuration in which proton lies midway between two oxygen atoms. Despite four decades of research on hydroxyl containing compounds, pressure induced bond symmetrization remains elusive. Following single crystal x-ray diffraction, Mössbauer and Raman spectroscopy measurements supported by ab initio calculations, we report H-bonds iron oxyhydroxide, FeOOH, resulting...
Raman and optical spectroscopy are versatile tools for nondestructive characterization of a wide range properties novel materials minerals in situ at extreme ambient conditions. These techniques genuinely complementary to X-ray (diffraction spectroscopy) the probe energy, momentum transfer, time scale, making concomitant probes available advanced sample analysis. We have built state-of-the-art, user-friendly integrated system Sector 13 (GeoSoilEnviroCARS, University Chicago, IL) Advanced...
Using in situ synchrotron x-ray diffraction and Raman spectroscopy concert with first principles calculations we demonstrate the synthesis of stable Xe(Fe,Fe/Ni)_{3} XeNi_{3} compounds at thermodynamic conditions representative Earth's core. Surprisingly, case both Xe-Fe Xe-Ni systems Fe Ni become highly electronegative can act as oxidants. The results indicate changing chemical properties elements under extreme by documenting that electropositive ambient pressure could gain electrons form anions.
We provide experimental and theoretical evidence for a pressure-induced Mott insulator-metal transition in Fe2O3 characterized by site-selective delocalization of the electrons. Density functional plus dynamical mean-field theory (DFT+DMFT) calculations, along with Mössbauer spectroscopy, x-ray diffraction, electrical transport measurements on up to 100 GPa, reveal this between 50 68 such that metallization can be described (Fe3+HSVI)2O3 [R3¯c structure]→50 GPa(Fe3+HSVIII FeVIM)O3 [P21/n...
Abstract Chenmingite (FeCr2O4; IMA 2017-036) is a high-pressure mineral, occurring as micrometer- to submicrometer-sized lamellae within precursor chromite grains along with xieite and Fe,Cr-rich ulvöspinel next shock-induced melt pockets, from the Tissint martian meteorite. The composition of type chenmingite by electron probe analysis shows an empirical formula (Fe2+0.75Mg0.23Mn0.02) (Cr1.60Al0.29Fe3+0.06Fe2+0.04Ti0.02)Σ2.01O4. general end-member formulas are (Fe,Mg)(Cr,Al)2O4 FeCr2O4....