Nanocomposites and nanomaterials

Shock-wave synthesis of new diamond-like carbon nitride films under laser irradiation in supercritical fluid
Liedienov N.A1,2, Prudnikov А.2, Fesenko O.3, Pashchenko A.V.1,2 Pashkevich Yu.2
1 State Key Laboratory of Superhard Materials, International Centre of Future Science of Jilin University. Qianjin Str., 2699, Changchun-130012, China.
E-mail: nikita.ledenev.ssp@gmail.com
2 Donetsk Institute for Physics and Engineering named after O. O. Galkin, NAS of Ukraine. Prospect Nauki, 46, Kyiv-03028, Ukraine.
3 Institute of Physics, NAS of Ukraine. Prospect Nauki, 46, Kyiv-03028, Ukraine.

Nitride carbon structures can be used as substitutes for diamond. The theoretical studies have shown the possibility of the existence of superhard nitride carbon phases, such as: C3N, C2N, CN, CN2, and C3N2. They demonstrate higher thermal and chemical stability than diamond as well as show hardness comparable to diamond hardness [1]. However, while searching for new phases in the experiment, the difficulties occur due to metastability, selection of precursors, determination of related crystal structures, etc.
New diamond-like carbon nitrides (nano- and microcrystals of C2N) were, for the first time, synthesized in bulk by a laser shock compression of a graphite-like nanocolonar film of carbon nitride used as a precursor. Since, the laser shock compression causes a hexagonal-cubic transformation of graphite-like carbon nitrides while maintaining their composition [2].
The laser shock wave, created in a solid state, transfers the liquid at the liquid / target interface to a supercritical liquid with temperature and pressure higher than in the initial state. In this case, a partial dissolution of the target material by a supercritical liquid and the formation of new phases occur.
SEM and Raman spectroscopy were used to characterize nano- and microcrystals. Nano- and microcrystals of carbon nitride C2N with crystalline planes and a clear morphology were found.

1. Dong H., Oganov A.R., Zhu Q. The phase diagram and hardness of carbon nitrides // Scien. Rep.-2015.-5.-P. 9870.
2. Komatsu T. Shock synthesis and characterization of new diamond-like carbon nitrides // Phys. Chem. Chem. Phys.-2004.-6.-P. 878–880.