| 1. |
- Aslandukov, Andrey, et al.
(författare)
-
Stabilization of N6 and N8 anionic units and 2D polynitrogen layers in high-pressure scandium polynitrides
- 2024
-
Ingår i: Nature Communications. - : NATURE PORTFOLIO. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 2. |
- Aslandukov, Andrey, et al.
(författare)
-
Stabilization Of The CN35− Anion In Recoverable High-pressure Ln3O2(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) Oxoguanidinates
- 2023
-
Ingår i: Angewandte Chemie International Edition. - : WILEY-V C H VERLAG GMBH. - 1433-7851 .- 1521-3773. ; 62:47
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 3. |
- Laniel, Dominique, et al.
(författare)
-
Synthesis of Ultra‐Incompressible and Recoverable Carbon Nitrides Featuring CN4 Tetrahedra
- 2024
-
Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095. ; 36:3
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon nitrides featuring three-dimensional frameworks of CN4 tetrahedra are one of the great aspirations of materials science, expected to have a hardness greater than or comparable to diamond. After more than three decades of efforts to synthesize them, no unambiguous evidence of their existence has been delivered. Here, the high-pressure high-temperature synthesis of three carbon-nitrogen compounds, tI14-C3N4, hP126-C3N4, and tI24-CN2, in laser-heated diamond anvil cells, is reported. Their structures are solved and refined using synchrotron single-crystal X-ray diffraction. Physical properties investigations show that these strongly covalently bonded materials, ultra-incompressible and superhard, also possess high energy density, piezoelectric, and photoluminescence properties. The novel carbon nitrides are unique among high-pressure materials, as being produced above 100 GPa they are recoverable in air at ambient conditions.
|
|
| 4. |
- Yin, Yuqing, et al.
(författare)
-
Synthesis of rare-earth metal compounds through enhanced reactivity of alkali halides at high pressures
- 2022
-
Ingår i: Communications Chemistry. - : Nature Portfolio. - 2399-3669. ; 5:1
-
Tidskriftsartikel (refereegranskat)abstract
- Chemical stability of the alkali halides NaCI and KCI has allowed for their use as inert media in high-pressure high-temperature experiments. Here we demonstrate the unexpected reactivity of the halides with metals (Y, Dy, and Re) and iron oxide (FeO) in a laser-heated diamond anvil cell, thus providing a synthetic route for halogen-containing binary and ternary compounds. So far unknown chlorides, Y2Cl and DyCl, and chloride carbides, Y2ClC and Dy2ClC, were synthesized at -40 GPa and 2000 K and their structures were solved and refined using in situ single-crystal synchrotron X-ray diffraction. Also, FeCl2 with the HP-PdF2-type structure, previously reported at 108 GPa, was synthesized at similar to 160 GPa and 2100 K. The results of our ab initio calculations fully support experimental findings and reveal the electronic structure and chemical bonding in these compounds.
|
|
| 5. |
- Yin, Yuqing, et al.
(författare)
-
Unraveling the Bonding Complexity of Polyhalogen Anions: High-Pressure Synthesis of Unpredicted Sodium Chlorides Na2Cl3 and Na4Cl5 and Bromide Na4Br5
- 2023
-
Ingår i: JACS Au. - : AMER CHEMICAL SOC. - 2691-3704. ; 3:6, s. 1634-1641
-
Tidskriftsartikel (refereegranskat)abstract
- The field of polyhalogen chemistry, specifically polyhalogenanions(polyhalides), is rapidly evolving. Here, we present the synthesisof three sodium halides with unpredicted chemical compositions andstructures (tP10-Na2Cl3, hP18-Na4Cl5, and hP18-Na4Br5), a series of isostructural cubic cP8-AX(3) halides (NaCl3, KCl3, NaBr3, and KBr3), and a trigonal potassiumchloride (hP24-KCl3). The high-pressuresyntheses were realized at 41-80 GPa in diamond anvil cellslaser-heated at about 2000 K. Single-crystal synchrotron X-ray diffraction(XRD) provided the first accurate structural data for the symmetrictrichloride Cl-3 (-) anion in hP24-KCl3 and revealed the existence of two different typesof infinite linear polyhalogen chains, [Cl]( infinity ) ( n-) and [Br]( infinity ) ( n-), in the structures of cP8-AX(3) compounds and in hP18-Na4Cl5 and hP18-Na4Br5. In Na4Cl5 and Na4Br5, we found unusually short, likely pressure-stabilized, contactsbetween sodium cations. Ab initio calculations support the analysisof structures, bonding, and properties of the studied halogenides.
|
|
