130 research outputs found
Front Cover: Chemical Stability of FeOOH at High Pressure and Temperature, and Oxygen Recycling in Early Earth History (Eur. J. Inorg. Chem. 30/2021)
No full textThe Front Cover shows a possible deep oxygen cycle in early Earth. FeOOH (“rust”), produced by anoxygenic photosynthesis and accumulated on the ocean floor, was transferred to the lower mantle by subducting slabs. At high pressures and temperatures, FeOOH decomposes into a mixture of complex iron oxides, water, and oxygen. Oxidizing fluids rising to the Earth′s surface could then possibly contribute to (or even be one of the main causes of) the Great Oxidation Event about 2.5 billion years ago. Image credits: Egor Koemets, Timofey Fedotenko, Leonid Dubrovinsky (Bayreuth University). More information can be found in the Full Paper by E. Koemets and co-workers
Laser heating setup with high-magnification imaging for studies of physical and chemical phenomena up to ultra-high pressures in diamond anvil cells
Get PDFSuperconductivity in bcc-selenium under megabar pressure
No full textAbstract We report enhanced superconductivity in the selenium on the verge of the β-Po–bcc phase transition, achieving up to 9.4 K at 140 GPa. The onset of superconductivity is confirmed by a direct zero-resistance drop R(T), and its nature was further validated by its suppression under an external magnetic field, at 140 GPa. An anomalously high R(T) peak preceding the zero resistance state suggests granular superconductivity. Our studies indicate that selenium does not react with hydrogen at 182 GPa at room temperature nor 102 GPa with laser heating to 3000 K, implying that the synthesis of selenium hydride requires higher energy conditions than the ones predicted theoretically. Our findings offer insights into the mechanism of phase-transition-related enhanced superconductivity and motivate further study into the search for high superconductors in elements at extremely high pressure
FORMING STUDENTS' PREPAREDNESS TO USE ART IN SOCIAL WORK WITH ELDERLY PEOPLE
No full textf students' preparedness to use various types of art in social work
with the elderly. The author considers the essence, the
structure of preparedness as a psychological and pedagogical
phenomenon, the principles of organization of experimental
work, reflecting the content of training. The author highlights the
organizational and pedagogical conditions that stimulate the
desire of students to use various types of art. The results of the
study show that students were interested to include art into
their palette of technologies they appropriated for social
practice with elderly people.
The purposeful formation of students' preparedness to use
various types of art in social work contributed to several things:
formation of their understanding of the aesthetic and humanistic
nature of art, its potential in solving professional issues in a
situation of uncertainty; improving the professionalism of
future social workers; development of their moral and
aesthetic qualities of personality
Synthesis and Compressibility of Novel Nickel Carbide at Pressures of Earth’s Outer Core
No full textWe report the high-pressure synthesis and the equation of state (EOS) of a novel nickel carbide (NiC). It was synthesized in a diamond anvil cell at 184(5) GPa through a direct reaction of a nickel powder with carbon from the diamond anvils upon heating at 3500 (200) K. NiC has the cementite-type structure (Pnma space group, a = 4.519(2) Å, b = 5.801(2) Å, c = 4.009(3) Å), which was solved and refined based on in-situ synchrotron single-crystal X-ray diffraction. The pressure-volume data of NiC was obtained on decompression at room temperature and fitted to the 3rd order Burch-Murnaghan equation of state with the following parameters: V = 147.7(8) Å, K = 157(10) GPa, and K ' = 7.8(6). Our results contribute to the understanding of the phase composition and properties of Earth's outer core
Synthesis of FeN₄ at 180 GPa and its crystal structure from a submicron-sized grain
Get PDFIron tetranitride, FeN4, was synthesized from the elements in a laser-heated diamond anvil cell at 180 (5) GPa and 2700 (200) K. Its crystal structure was determined based on single-crystal X-ray diffraction data collected from a submicron-sized grain at the synchrotron beamline ID11 of ESRF. The compound crystallizes in the triclinic space group P\overline{1}. In the asymmetric unit, the Fe atom occupies an inversion centre (Wyckoff position 1d), while two N atoms occupy general positions (2i). The structure is made up from edge-sharing [FeN6] octahedra forming chains along [100] and being interconnected through N—N bridges. N atoms form catena-poly[tetraz-1-ene-1,4-diyl] anions [–N=N—N—N–]∞2− running along [001]. In comparison with the previously reported structure of FeN4 at 135 GPa [Bykov et al. (2018). Nat. Commun. 9, 2756], the crystal structure of FeN4 at 180 GPa is similar but the structural model is significantly improved in terms of the precision of the bond lengths and angles
Raman Spectroscopy Study on Chemical Transformations of Propane at High Temperatures and High Pressures
No full textThis study is devoted to the detailed in situ Raman spectroscopy investigation of propane C3H8 in laserheated diamond anvil cells in the range of pressures from 3 to 22 GPa and temperatures from 900 to 3000 K. We show that propane, while being exposed to particular thermobaric conditions, could react, leading to the formation of hydrocarbons, both saturated and unsaturated as well as soot. Our results suggest that propane could be a precursor of heavy hydrocarbons and will produce more than just sooty material when subjected to extreme conditions. These results could clarify the issue of the presence of heavy hydrocarbons in the Earth’s upper mantle.QC 20200203</p
Equations of state of rhodium, iridium and their alloys up to 70 GPa
No full textKnowledge of the compressional and thermal behaviour of metals and alloys is of a high fundamental and applied value. In this work, we studied the behaviour of Ir, Rh, and their fcc-structured alloys, IrRh and IrOsPtRhRu, up to 70 GPa using the diamond anvil cell technique with synchrotron X-ray diffraction. We found that all these materials are structurally stable upon room-temperature hydrostatic compression in the whole pressure interval, as well as upon heating to 2273 K both at ambient and high pressure. Rh, IrRh and IrOsPtRhRu were investigated under static compression for the first time. According to our data, the compressibility of Ir, Rh, fcc–IrRh, and fcc–IrOsPtRhRu, can be described with the 3rd order Birch-Murnaghan equation of state with the following parameters: V = 14.14(6) Å·atom, B = 341(10) GPa, and B0' = 4.7(3); V = 13.73(7) Å·atom, B = 301(9) GPa, and B' = 3.1(2); V = 13.90(8) Å·atom, B = 317(17) GPa, and B' = 6.0(5); V = 14.16(9) Å·atom, B = 300(22) GPa, B' = 6(1), where V is the unit cell volume, B and B' – are the bulk modulus and its pressure derivative
Evidence for ultra-water-rich ammonia hydrates stabilized in icy exoplanetary mantles
No full textUnderstanding the behavior of the water-ammonia system at high pressure-high temperature conditions is important for modeling the internal dynamics of exoplanet icy mantles. Conventionally, mixtures of ammonia hemihydrate AHH (2:1 ammonia-water molar ratio) and H2O ice VII have been regarded as the ultimate solid phase assembly in the system. Here we report evidence for chemical reactions between AHH and ice VII above 750 K and 16 GPa that stabilize water-rich ammonia hydrates, including a novel ultra-water rich hydrate NH3.6H2O (1:6 ratio) coexisting with ammonia dihydrate ADH (1:2 ratio) and excess ice VII. This assembly is stable up to at least 30 GPa and 1600 K and can be quenched to room temperature. Our results demonstrate that water-rich ammonia hydrates are favored in the icy mantle of 1-2 MEarth exoplanets regardless of the ammonia content of the hydrate crystallized during accretion and/or evolution as long as excess H2O ice is available. The buoyancy contrast between water-rich hydrates and ice VII may lead to chemical stratification in exoplanet icy mantles, hence affecting their thermal evolution
Evidence for ultra-water-rich ammonia hydrates stabilized in icy exoplanetary mantles
No full textUnderstanding the behavior of the water-ammonia system at high pressure-high temperature conditions is important for modeling the internal dynamics of exoplanet icy mantles. Conventionally, mixtures of ammonia hemihydrate AHH (2:1 ammonia-water molar ratio) and H2O ice VII have been regarded as the ultimate solid phase assembly in the system. Here we report evidence for chemical reactions between AHH and ice VII above 750 K and 16 GPa that stabilize water-rich ammonia hydrates, including a novel ultra-water rich hydrate NH3.6H2O (1:6 ratio) coexisting with ammonia dihydrate ADH (1:2 ratio) and excess ice VII. This assembly is stable up to at least 30 GPa and 1600 K and can be quenched to room temperature. Our results demonstrate that water-rich ammonia hydrates are favored in the icy mantle of 1-2 MEarth exoplanets regardless of the ammonia content of the hydrate crystallized during accretion and/or evolution as long as excess H2O ice is available. The buoyancy contrast between water-rich hydrates and ice VII may lead to chemical stratification in exoplanet icy mantles, hence affecting their thermal evolution
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