This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:

fact-checked

peer-reviewed publication

trusted source

proofread

Synthesis of two new carbides provides perspective on how complex carbon structures could exist on other planets

Synthesis of new forms of carbon compounds
Crystal structure of HP-CaC2 at 44(1) GPa. a A ball and stick model with the unit cell outlined; calcium atoms are shown as white spheres, and carbon atoms as red and blue balls for two distinct crystallographic positions, C1 (Wyckoff site 4 g) and C2 (4 h), respectively. b The geometry of a single deprotonated polyacene nanoribbon; the C–C distances and C-C-C angles are labeled. Cross-sections of the calculated electron localization function (ELF) are shown in the planes perpendicular (c) and parallel (d) to the polyacene nanoribbons. Credit: Nature Communications (2024). DOI: 10.1038/s41467-024-47138-2

Researchers at the University of Bayreuth have gained new insights in the field of high-pressure carbon chemistry: They synthesized two new carbides—compounds of carbon and another chemical element—with unique structures. The results may provide an unexpected explanation of the wide spread of polycyclic aromatic hydrocarbons in the universe. The research is published in the journal Nature Communications.

Carbides are compounds of and another chemical element. The newly synthesized carbides resemble metal-organic-like compounds and can offer new insight into the behavior of complex carbon structures under extremely high pressures and high temperatures.

The possible existence or formation of such compounds at conditions of planets' interiors may have important implications for geosciences and astrobiology, as they could be the origin of hydrocarbons and could play a role in the origin of life.

Under the leadership of Prof. Dr. Leonid Dubrovinsky from the Bavarian Geoinstitute and Prof. Dr. Natalia Dubrovinskaia from the Laboratory of Crystallography at the University of Bayreuth, the research into the new carbon compounds reveals they have structural elements similar to those of , but are deprotonated (i.e., do not contain hydrogen).

To accomplish this, the researchers used diamond anvil cells that compressed the tiny calcium carbide crystals to pressures in the three-digit gigapascal range and simultaneously heated them to temperatures of about 3000°C. These conditions correspond to those at a depth of 2.900 km in the Earth's interior. The change in pressure and temperature caused the calcium carbide to form two new carbides: high-pressure polymorph of CaC2 and Ca3C7.

Synthesis of new forms of carbon compounds
Crystal structure of Ca3C7 at 38(1) GPa. a A projection of the Ca3C7 structure along the a-axis, emphasizing 2D chains of carbon atoms aligned along the b-axis. Calcium atoms are shown as white spheres, and carbon atoms as red and blue balls for the two distinct crystallographic positions C1 (4c) and C2 (8d), respectively. Carbon atoms, named C3 (8d) and C4 (8d), are shown as gray balls. b The geometry of a single deprotonated para-poly(indenoindene) (p-PInIn) chain with the C-C distances and C-C-C angles labeled. c, d Cross-sections of the calculated electron localization function (ELF) are shown in the two different planes containing p-PInIn chains. Credit: Nature Communications (2024). DOI: 10.1038/s41467-024-47138-2

Although the high-pressure polymorph of CaC2 has the same as the starting material, it differs from it in the spatial arrangement of the atoms and in its chemical properties. The polymorph possesses carbon chains that can exist under conditions that far exceed those known for the existence of conventional organic compounds.

The formation of such compounds under the conditions in the interior of planets could even have played a role in the origin of life, because they could be the origin of hydrocarbons.

The compound with the chemical formula Ca3C7 has never been observed before, so that its synthesis and structure elucidation represent a significant step forward in understanding the behavior of carbon-based materials under extreme conditions.

Prof. Dr. Leonid Dubrovinsky, the lead researcher of the study, explained, "Our findings not only expand the boundaries of known carbon chemistry but also provide a new perspective on how complex carbon structures could exist in the deep Earth and potentially in other planetary bodies."

"The similarities between these high-pressure carbides and deprotonated metal-organic compounds open up exciting possibilities for designing novel materials with unique electronic, magnetic, and ," added Prof. Dr. Natalia Dubrovinskaia.

More information: Saiana Khandarkhaeva et al, Extending carbon chemistry at high-pressure by synthesis of CaC2 and Ca3C7 with deprotonated polyacene- and para-poly(indenoindene)-like nanoribbons, Nature Communications (2024). DOI: 10.1038/s41467-024-47138-2

Journal information: Nature Communications

Citation: Synthesis of two new carbides provides perspective on how complex carbon structures could exist on other planets (2024, April 25) retrieved 23 May 2024 from https://phys.org/news/2024-04-synthesis-carbides-perspective-complex-carbon.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.

Explore further

Researchers discover new yttrium-hydrogen compounds with implications for high-pressure superconductivity

19 shares

Feedback to editors