TY - JOUR
T1 - Synthesis of ultra-incompressible sp3-hybridized carbon nitride with 1:1 stoichiometry
AU - Stavrou, Elissaios
AU - Lobanov, Sergey
AU - Dong, Huafeng
AU - Oganov, Artem R.
AU - Prakapenka, Vitali B.
AU - Konôpková, Zuzana
AU - Goncharov, Alexander F.
N1 - Publisher Copyright:
© 2016 American Chemical Society.
PY - 2016/10/11
Y1 - 2016/10/11
N2 - The search of compounds with CxNy composition holds great promise for creating materials which would rival diamond in hardness due to the very strong covalent C-N bond. Early theoretical and experimental works on CxNy compounds were based on the hypothetical structural similarity of predicted C3N4 phases with known binary A3B4 structural types; however, the synthesis of C3N4 other than g-C3N4 remains elusive. Here, we explore an "elemental synthesis" at high pressures and temperatures in which the compositional limitations due to the use of precursors in the early works are substantially lifted. Using in situ synchrotron X-ray diffraction and Raman spectroscopy, we demonstrate the synthesis of a highly incompressible Pnnm CN compound (x = y = 1) with sp3-hybridized carbon above 55 GPa and 7000 K. This result is supported by first-principles evolutionary search, which finds that CN is the most stable compound above 14 GPa. On pressure release below 6 GPa, the synthesized CN compound amorphizes, maintaining its 1:1 stoichiometry as confirmed by energy-dispersive X-ray spectroscopy. This work underscores the importance of understanding the novel high-pressure chemistry laws that promote extended 3D C-N structures, never observed at ambient conditions. Moreover, it opens a new route for synthesis of superhard materials based on novel stoichiometries.
AB - The search of compounds with CxNy composition holds great promise for creating materials which would rival diamond in hardness due to the very strong covalent C-N bond. Early theoretical and experimental works on CxNy compounds were based on the hypothetical structural similarity of predicted C3N4 phases with known binary A3B4 structural types; however, the synthesis of C3N4 other than g-C3N4 remains elusive. Here, we explore an "elemental synthesis" at high pressures and temperatures in which the compositional limitations due to the use of precursors in the early works are substantially lifted. Using in situ synchrotron X-ray diffraction and Raman spectroscopy, we demonstrate the synthesis of a highly incompressible Pnnm CN compound (x = y = 1) with sp3-hybridized carbon above 55 GPa and 7000 K. This result is supported by first-principles evolutionary search, which finds that CN is the most stable compound above 14 GPa. On pressure release below 6 GPa, the synthesized CN compound amorphizes, maintaining its 1:1 stoichiometry as confirmed by energy-dispersive X-ray spectroscopy. This work underscores the importance of understanding the novel high-pressure chemistry laws that promote extended 3D C-N structures, never observed at ambient conditions. Moreover, it opens a new route for synthesis of superhard materials based on novel stoichiometries.
UR - http://www.scopus.com/inward/record.url?scp=84991328148&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.6b02593
DO - 10.1021/acs.chemmater.6b02593
M3 - 文章
AN - SCOPUS:84991328148
SN - 0897-4756
VL - 28
SP - 6925
EP - 6933
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 19
ER -