Irreversible high pressure phase transformation of onion-like carbon due to shell confinement

Lugvishchuk, Dmitry S.; Митберг, Э. Б.; Kulnitskiy, B.A.; Скрылева, Е. А.; Parkhomenko, Yu. N.; Popov, M.; Churkin, Valentin; Мордкович, В. З.

doi:10.1016/j.diamond.2020.107908

Cited by 9 publications

(7 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The difference in slope shape indicates that the graphitic phase is more rigid above 40 GPa. We explain such a difference in rigidity with the fact that graphite transforms into onion-like structures [ 2 , 30 ], whereas the C-N ring keeps its structure in the g-C 3 N 4 phase. Figure 7 b shows that it is possible to trace the 1620 cm −1 peak until 20 GPa, after the application of shear deformation at 70 GPa.…”

Section: Resultsmentioning

confidence: 99%

“…Transformation of the g -C 3 N 4 into 20 nm onion-like structures with low nitrogen contents after shear deformation, at a pressure or 70 GPa, makes it interesting to compare the dependence of the peak at ~1600 cm −1 on pressure for the C-N sample withthat of 20 nm pure carbon onions.Carbon onions with a diameter of ~20 nm were synthesized from natural gas by means of non-catalytic partial oxidation [ 30 ].…”

Section: Resultsmentioning

confidence: 99%

“…The abrupt decrease in the frequency of the observed Raman peak from 1605 cm −1 to 1576 cm −1 under pressure in carbon onions, is associated with the formation of an interlayer with sp 3 bonds [ 30 ]. We assume that the shift of the 1600 cm −1 peak line in the C-N system is also associated with the formation of the C-N onion-like structure.…”

Section: Discussionmentioning

confidence: 99%

“…Apparently, the partial transformation of sp 3 to sp 2 bonds at ~15 GPa during unloading, causes a “jump” in Raman frequency with one linear dependency (1560 cm −1 at 0 GPa) to another (1590 cm −1 at 0 GPa) ( Figure 7 ). After the pressure releases, 50% of the sp 3 bonds remain in the samples, according to XPS data [ 30 ]. In the Raman spectra, along with the D and G peaks ( sp 2 bonds), there is a 1560 cm −1 band ( sp 3 bonds).…”

Section: Discussionmentioning

confidence: 99%

“… Position of the Raman peak of the 1620 cm −1 peak of the g -C 3 N 4 specimen as a function of pressure: filled triangles for peaks after shear deformation; open triangles for peaks before shear deformation at 70 GPa. Center of the Raman peak of the 1600 cm −1 peak of carbon onions with a diameter of ~20 nm from Reference [ 30 ]; open circles for peaks before deformation; filled circles for peaks after shear deformation. …”

Section: Figurementioning

confidence: 99%

See 4 more Smart Citations

The Effect of Shear Deformation on C-N Structure under Pressure up to 80 GPa

et al. 2021

View full text Add to dashboard Cite

We studythe effect of shear deformation on graphitic g-C3N4 under pressures of up to 80 GPa at room temperature. g-C3N4 samples are transformed from initial amorphous flakes into onion-like structures, in which the nitrogen content in the quenched samples decreases with increasing pressure (from 42% in the initial conditions to 1% at 80 GPa). The concentration of the sp2 bonds also decreases from 1 (the initial sample) to 0.62 with increasing pressure to 80 GPa. This transformation of the sample is due to the fact that in the pressure range of 55–115 GPa, the equilibrium phase is not a diamond, but instead, carbon onions cross-linked by sp3 bonds, which are denser than diamonds. The results of our study show that the presence of nitrogen in sp3-bonded structures at pressures of higher than 55 GPa reduces the density and, accordingly, carbon structures without nitrogen become thermodynamically favorable.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

See 3 more Smart Citations