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Title: Synthesis of Ultra-incompressible sp 3 -Hybridized Carbon Nitride with 1:1 Stoichiometry

Search of materials with C-N composition hold a great promise in creating materials which would rival diamond hardness due to the very strong and relatively low-ionic C-N bond. Early experimental and theoretical works on C-N compounds were based on structural similarity with binary A 3B 4 structural types; however, the synthesis of C 3N 4 remains elusive. Here we explored an unbiased synthesis from the elemental materials at high pressures and temperatures. Using in situ synchrotron X-ray diffraction and Raman spectroscopy we demonstrate the synthesis of highly incompressible Pnnm CN compound with sp 3 hybridized carbon above 55 GPa and 7000 K. This result is supported by first principles evolutionary search, which finds that Pnnm CN is the most stable compound above 10.9 GPa. On pressure release below 6 GPa the synthesized CN compound amorphizes reattaining its 1:1 stoichiometry as confirmed by Energy-Dispersive X-ray Spectroscopy. Here, this work underscores the importance of understanding of novel high-pressure chemistry rules and it opens a new route for synthesis of superhard materials.
Authors:
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Publication Date:
Report Number(s):
LLNL-JRNL-669803
Journal ID: ISSN 0897-4756; TRN: US1701534
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
Journal Volume: 28; Journal Issue: 19; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1342047