| 1. |
- Bykov, Maxim, et al.
(författare)
-
High-Pressure Synthesis of Metal-Inorganic Frameworks Hf4N20 center dot N-2, WN8 center dot N-2, and Os5N28 center dot 3 N-2 with Polymeric Nitrogen Linkers
- 2020
-
Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 59:26, s. 10321-10326
-
Tidskriftsartikel (refereegranskat)abstract
- Polynitrides are intrinsically thermodynamically unstable at ambient conditions and require peculiar synthetic approaches. Now, a one-step synthesis of metal-inorganic frameworks Hf4N20 center dot N2, WN 8 center dot N2, and Os5N28 center dot 3N2 via direct reactions between elements in a diamond anvil cell at pressures exceeding 100 GPa is reported. The porous frameworks (Hf4N20, WN 8, and Os5N28) are built from transition-metal atoms linked either by polymeric polydiazenediyl (polyacetylene-like) nitrogen chains or through dinitrogen units. Triply bound dinitrogen molecules occupy channels of these frameworks. Owing to conjugated polydiazenediyl chains, these compounds exhibit metallic properties. The high-pressure reaction between Hf and N2 also leads to a non-centrosymmetric polynitride Hf2N11 that features double-helix catenapoly[tetraz-1-ene-1,4-diyl] nitrogen chains [-N-N-N=N-](infinity.)
|
|
| 2. |
- Dubrovinsky, Leonid, et al.
(författare)
-
Materials synthesis at terapascal static pressures
- 2022
-
Ingår i: Nature. - London, United Kingdom : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 605:7909, s. 274-278
-
Tidskriftsartikel (refereegranskat)abstract
- Theoretical modelling predicts very unusual structures and properties of materials at extreme pressure and temperature conditions(1,2). Hitherto, their synthesis and investigation above 200 gigapascals have been hindered both by the technical complexity of ultrahigh-pressure experiments and by the absence of relevant in situ methods of materials analysis. Here we report on a methodology developed to enable experiments at static compression in the terapascal regime with laser heating. We apply this method to realize pressures of about 600 and 900 gigapascals in a laser-heated double-stage diamond anvil cell(3), producing a rhenium-nitrogen alloy and achieving the synthesis of rhenium nitride Re7N3-which, as our theoretical analysis shows, is only stable under extreme compression. Full chemical and structural characterization of the materials, realized using synchrotron single-crystal X-ray diffraction on microcrystals in situ, demonstrates the capabilities of the methodology to extend high-pressure crystallography to the terapascal regime.
|
|
| 3. |
- Fedotenko, Timofey, et al.
(författare)
-
Synthesis and Compressibility of Novel Nickel Carbide at Pressures of Earths Outer Core
- 2021
-
Ingår i: Minerals. - : MDPI. - 2075-163X. ; 11:5
-
Tidskriftsartikel (refereegranskat)abstract
- We report the high-pressure synthesis and the equation of state (EOS) of a novel nickel carbide (Ni3C). 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. Ni3C has the cementite-type structure (Pnma space group, a = 4.519(2) angstrom, b = 5.801(2) angstrom, c = 4.009(3) angstrom), which was solved and refined based on in-situ synchrotron single-crystal X-ray diffraction. The pressure-volume data of Ni3C was obtained on decompression at room temperature and fitted to the 3rd order Burch-Murnaghan equation of state with the following parameters: V-0 = 147.7(8) angstrom(3), K-0 = 157(10) GPa, and K-0 = 7.8(6). Our results contribute to the understanding of the phase composition and properties of Earths outer core.
|
|
| 4. |
- Khandarkhaeva, Saiana, et al.
(författare)
-
Novel Rhenium Carbides at 200 GPa
- 2020
-
Ingår i: European Journal of Inorganic Chemistry. - : WILEY-V C H VERLAG GMBH. - 1434-1948 .- 1099-1948 .- 1099-0682. ; 2020:22, s. 2186-2190
-
Tidskriftsartikel (refereegranskat)abstract
- Laser heating of rhenium in a diamond anvil cell to 3000 +/- 300 K at about 200 GPa results in formation of two previously unknown rhenium carbides, hexagonal WC-type structured ReC and orthorhombic TiSi2-type structured ReC2. The shortest C-C distances [1.758(3) angstrom at 219(5) GPa and 1.850(4) angstrom at 180(7) GPa] found in honeycomb-like carbon nets in the structure of ReC2 are quite unusual. The Re-C solid solution formed at multimegabar pressure has the carbon content of approximate to 20 at%.
|
|
