| 1. |
- Akbar, Fariia Iasmin, et al.
(author)
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High-pressure dysprosium carbides containing carbon dimers, trimers, chains, and ribbons
- 2024
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In: Carbon. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0008-6223 .- 1873-3891. ; 228
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Journal article (peer-reviewed)abstract
- Exploring the chemistry of materials at high pressure leads to discoveries of previously unknown compounds and phenomena. Here chemical reactions between elemental dysprosium and carbon were studied in laser-heated diamond anvil cells at pressures up to 95 GPa and temperatures of similar to 2800 K. In situ single-crystal synchrotron X-ray diffraction (SCXRD) analysis of the reaction products revealed the formation of novel dysprosium carbides, gamma-DyC2, Dy5C9, and gamma-Dy4C5, along with previously reported Dy3C2 and Dy4C3 . The crystal structures of gamma-DyC (2) and Dy (5) C (9) feature infinite flat carbon polyacene-like ribbons and cis-polyacetylene-type chains, respectively. In the structure of gamma-Dy4C5, carbon atoms form dimers and non-linear trimers. Dy3C2 contains ethanide-type carbon dumbbells, and Dy4C3 is methanide featuring single carbon atoms. Density functional theory calculations reproduce well the crystal structures of high-pressure dysprosium carbides and reveal conjugated pi-electron systems in novel infinite carbon polyanions. This work demonstrates that complex carbon homoatomic species previously unknown in organic chemistry can be synthesized at high pressures by direct reactions of carbon with metals.
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| 2. |
- Aslandukov, Andrey, et al.
(author)
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Stabilization of N6 and N8 anionic units and 2D polynitrogen layers in high-pressure scandium polynitrides
- 2024
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In: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 15:1
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Journal article (peer-reviewed)abstract
- Nitrogen catenation under high pressure leads to the formation of polynitrogen compounds with potentially unique properties. The exploration of the entire spectrum of poly- and oligo-nitrogen moieties is still in its earliest stages. Here, we report on four novel scandium nitrides, Sc2N6, Sc2N8, ScN5, and Sc4N3, synthesized by direct reaction between yttrium and nitrogen at 78-125 GPa and 2500 K in laser-heated diamond anvil cells. High-pressure synchrotron single-crystal X-ray diffraction reveals that in the crystal structures of the nitrogen-rich Sc2N6, Sc2N8, and ScN5 phases nitrogen is catenated forming previously unknown N-6(6)- and N-8(6)- units and infinity 2(N-5(3-)) anionic corrugated 2D-polynitrogen layers consisting of fused N-12 rings. Density functional theory calculations, confirming the dynamical stability of the synthesized compounds, show that Sc2N6 and Sc2N8 possess an anion-driven metallicity, while ScN5 is an indirect semiconductor. Sc2N6, Sc2N8, and ScN5 solids are promising high-energy-density materials with calculated volumetric energy density, detonation velocity, and detonation pressure higher than those of TNT.
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| 3. |
- Aslandukov, Andrey, et al.
(author)
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Stabilization Of The CN35− Anion In Recoverable High-pressure Ln3O2(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates
- 2023
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In: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 62:47
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Journal article (peer-reviewed)abstract
- A series of isostructural Ln(3)O(2)(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high-pressure (25-54 GPa) high-temperature (2000-3000 K) conditions in laser-heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single-crystal X-ray diffraction (SCXRD) as well as corroborated by X-ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln(3)O(2)(CN3) solids are composed of the hitherto unknown CN35- guanidinate anion-deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln(3)O(2)(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln(3)O(2)(CN3) compounds are recoverable to ambient conditions. The stabilization of the CN35- guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.
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