The influence of the shock compression conditions on the graphite transformations into lonsdaleite and diamond

Kurdyumov, A. V.; Britun, V. F.; Yarosh, V. V.; Danilenko, Alexandre I.; Zelyavskii, V. B.

doi:10.3103/s1063457612010029

Cited by 39 publications

(39 citation statements)

References 9 publications

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“…However, these exceptional properties have not been proven experimentally because of the inability to synthesize lonsdaleite as a pure phase. It has been reported to form during static compression of graphite 3,9,13,[15][16][17][18] ; highpressure-high-temperature treatment of powdered diamond, graphite and amorphous carbon 19 ; explosive detonation and shock compression of graphite 11,20 and diamond 21 ; and chemical vapour deposition of hydrocarbon gases 22 ; however, in all cases the synthesis product also contained cubic diamond, graphite or both.…”

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“…Published powder X-ray diffraction (XRD) patterns of lonsdaleite show peaks of cubic diamond plus extra, very broad and poorly resolved maxima at 0.218, 0.193, 0.151 and 0.116 nm that have been indexed using a hexagonal unit cell [1][2][3]14,15,20 . However, these maxima either occur on the shoulders of diamond peaks (Fig.…”

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confidence: 99%

“…Results 'Lonsdaleite' diffraction features. The XRD patterns of Canyon Diablo diamonds and the synthetic material display the poorly resolved diffraction maxima attributed [1][2][3]14,15,19,20 to 'lonsdaleite' (Fig. 1a).…”

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confidence: 99%

“…These patterns are consistent with diamond projected along o0114 or o1214, respectively, although the streaking and hexagonally arranged 111 reflections are incompatible with defect-free single-crystal cubic diamond. Such data have been interpreted as evidence for 'lonsdaleite' projected along o0104 and o0014 [4][5][6][7]14,15,20 . The circularly integrated intensity profiles of these SAED patterns ( Supplementary Fig.…”

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Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material

et al. 2014

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Lonsdaleite, also called hexagonal diamond, has been widely used as a marker of asteroidal impacts. It is thought to play a central role during the graphite-to-diamond transformation, and calculations suggest that it possesses mechanical properties superior to diamond. However, despite extensive efforts, lonsdaleite has never been produced or described as a separate, pure material. Here we show that defects in cubic diamond provide an explanation for the characteristic d-spacings and reflections reported for lonsdaleite. Ultrahigh-resolution electron microscope images demonstrate that samples displaying features attributed to lonsdaleite consist of cubic diamond dominated by extensive {113} twins and {111} stacking faults. These defects give rise to nanometre-scale structural complexity. Our findings question the existence of lonsdaleite and point to the need for re-evaluating the interpretations of many lonsdaleite-related fundamental and applied studies.

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Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material

et al. 2014

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“…This phenomenon is often observed in the diamonds prepared by HPHT and shock wave compression methods [8][9][10][11]. Herewith, some authors [8,9,11] reported that the diamond products fabricated by the shock wave synthesis involve both cubic (3C) diamond (space group Fd3m, the lattice constant a ¼ 3.567 Å, Z ¼ 8, C-C bond length 1.544 Å) and hexagonal diamond phases, particularly Lonsdaleite 2H (space group P6 3 /mmc, a ¼ 2.52 A, c ¼ 4.12 A, Z ¼ 4) and 6H polytypes.…”

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XRD, NMR, and EPR study of polycrystalline micro‐ and nano‐diamonds prepared by a shock wave compression method

Shames

Mogilyansky

Panich

et al. 2015

Physica Status Solidi (a)

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Phone: þ 7 812 904 5298, Fax: þ 7 812 297 1017We report on XRD, NMR, and EPR study of commercial micro-and nano-diamonds of the SSX series fabricated by a shock wave compression method. XRD data analysis shows that SSX samples consist of nanometer cubic diamond domains intermixing with stacking faults and twins. We show that as-received samples reveal a graphitic component, which may be removed by additional purification. Crushing the initial microdiamond powder into submicron and nanometer sizes does not result in noticeable variations of the XRD, NMR, and EPR parameters. This finding is explained by the fact that SSX diamonds are polycrystalline aggregates consisting of numerous nanocrystallites of $20-25 nm in size. Therefore, soft crushing of these aggregates diminishes their size, but leaves constituting nanocrystallites and their intrinsically facet surfaces mainly untreated. With that some modification of the outer nanocrystallite surface on crushing is observed.

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Theoretical Investigation of Phase Transitions of Graphite and Cubic 3C Diamond Into Hexagonal 2H Diamond Under High Pressures

Greshnyakov

Belenkov

Brzhezinskaya

2019

Physica Status Solidi (b)

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Possible techniques for experimentally obtaining hexagonal diamond are studied in the scope of the density functional theory method. It has been found that hexagonal diamond may be created as a result of structural transition at 61-68 GPa uniaxial compression from orthorhombic AB graphite and at 57-66 GPa from hexagonal AA graphite. Also the formation of hexagonal diamond is shown to take place in case of very strong (300-380 GPa) compression of cubic diamond. X-ray and electron-microscopic data on nanodiamonds from meteorite craters are analyzed for the presence of hexagonal diamond. The analysis shows that impact-origin carbon materials do not contain pure cubic and hexagonal diamonds, and the layers of nascent crystals of diamond polytypes are randomly packed.

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The influence of the shock compression conditions on the graphite transformations into lonsdaleite and diamond

Cited by 39 publications

References 9 publications

Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material

Lonsdaleite is faulted and twinned cubic diamond and does not exist as a discrete material

XRD, NMR, and EPR study of polycrystalline micro‐ and nano‐diamonds prepared by a shock wave compression method

Theoretical Investigation of Phase Transitions of Graphite and Cubic 3C Diamond Into Hexagonal 2H Diamond Under High Pressures

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