Exotic Cubic Carbon Allotropes

Hu, Meng; Tian, Fei; Zhao, Zhisheng; Huang, Quan; Xu, Bin; Wang, Limin; Wang, Hui-Tian; Tian, Yongjun; He, Julong

doi:10.1021/jp3064323

Cited by 57 publications

(38 citation statements)

References 66 publications

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“…We also find a sodalite structure with the cubic Pm 3 n space group at a higher negative formation enthalpy ( [41], which is the building block of the Pm 3 n structure. Interestingly, a similar sodalite-like cage structure has been proposed in carbon [42], and is regarded as the best candidate structure for synthesized "superdense" carbon [43]. We found that at 0 GPa C-sodalite is 0.38 eV/atom higher in energy than diamond.…”

supporting

confidence: 75%

High-Energy Density and Superhard Nitrogen-Rich B-N Compounds

et al. 2015

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The pressure-induced transformation of diatomic nitrogen into non-molecular polymeric phases may produce potentially useful high-energy-density materials. We combine first-principles calculations with structure searching to predict a new class of nitrogen-rich boron nitrides with a stoichiometry of B 3 N 5 that are stable or metastable relative to solid N 2 and h-BN at ambient pressure. The most stable phase at ambient pressure has a layered structure (h-B 3 N 5 ) containing hexagonal B 3 N 3 layers sandwiched with intercalated freely rotating N 2 molecules. At 15 GPa, a three-dimensional C222 1 structure with single N-N bonds becomes the most stable.This pressure is much lower than that required for triple-to-single bond transformation in pure solid nitrogen (110 GPa). More importantly, C222 1 -B 3 N 5 is metastable, and can be recovered under ambient conditions. Its energy density of ~3.44 kJ/g makes it a potential high-energy-density material. In addition, stress-strain calculations estimate a Vicker's hardness of ~44 GPa. Structure searching reveals a new clathrate sodalite-like BN structure that is metastable under ambient conditions.

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confidence: 75%

High-Energy Density and Superhard Nitrogen-Rich B-N Compounds

et al. 2015

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“…These latter two types of nanocrystals, almost as hard as cubic NDs, are frequently used in thin, polycrystalline films for industrial applications requiring hardness and abrasion resistance (Wen et al 2007). Ongoing investigations have been examining whether these polymorphs are simply cubic diamonds with atomic substitution of carbon by hydrogen or other elements (Wen et al 2011) or are new forms of diamond-like carbon (Hu et al 2012). Regardless, the nanoparticles in question form under exotic temperatures and pressures not present naturally at the Earth's surface or lower atmosphere but similar to conditions related to cosmic impact (Wen et al 2007) and are unlike other forms of carbon typically found naturally on Earth.…”

Section: Introductionmentioning

confidence: 99%

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Kinzie¹,

Hee

Stich

et al. 2014

The Journal of Geology

170

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. A B S T R A C TA major cosmic-impact event has been proposed at the onset of the Younger Dryas (YD) cooling episode at ≈12,800 ‫ע‬ 150 years before present, forming the YD Boundary (YDB) layer, distributed over 150 million km 2 on four continents. In 24 dated stratigraphic sections in 10 countries of the Northern Hemisphere, the YDB layer contains a clearly defined abundance peak in nanodiamonds (NDs), a major cosmic-impact proxy. Observed ND polytypes include cubic diamonds, lonsdaleite-like crystals, and diamond-like carbon nanoparticles, called n-diamond and i-carbon. The ND abundances in bulk YDB sediments ranged up to ≈500 ppb (mean: 200 ppb) and that in carbon spherules up to ≈3700 ppb (mean: ≈750 ppb); 138 of 205 sediment samples (67%) contained no detectable NDs. Isotopic evidence indicates that YDB NDs were produced from terrestrial carbon, as with other impact diamonds, and were not derived from the impactor itself. The YDB layer is also marked by abundance peaks in other impact-related proxies, including cosmic-impact spherules, carbon spherules (some containing NDs), iridium, osmium, platinum, charcoal, aciniform carbon (soot), and high-temperature melt-glass. This contribution reviews the debate about the presence, abundance, and origin of the concentration peak in YDB NDs. We describe an updated protocol for the extraction and concentration of NDs from sediment, carbon spherules, and ice, and we describe the basis for identification and classification of YDB ND polytypes, using nine analytical approaches. The large body of evidence now obtained about YDB NDs is strongly consistent with an origin by cosmic impact at ≈12,800 cal BP and is inconsistent with formation of YDB NDs by natural terrestrial processes, including wildfires, anthropogenesis, and/or influx of cosmic dust.

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“…Basic structure searching simulations were performed through use of the swarm-intelligencebased CALYPSO code, 31 which has successfully proposed several novel carbon allotropes, [32][33][34] with system sizes containing up to 24 carbon atoms. The calculations of the structural relaxation and electronic and mechanical properties were performed using the DFT framework with the CASTEP code.…”

Section: Computational Detailsmentioning

confidence: 99%

Superhard sp2–sp3 hybrid carbon allotropes with tunable electronic properties

Zhao

et al. 2016

AIP Advances

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Four sp2–sp3 hybrid carbon allotropes are proposed on the basis of first principles calculations. These four carbon allotropes are energetically more favorable than graphite under suitable pressure conditions. They can be assembled from graphite through intralayer wrinkling and interlayer buckling, which is similar to the formation of diamond from graphite. For one of the sp2–sp3 hybrid carbon allotropes, mC24, the electron diffraction patterns match these of i-carbon, which is synthesized from shock-compressed graphite (H. Hirai and K. Kondo, Science, 1991, 253, 772). The allotropes exhibit tunable electronic characteristics from metallic to semiconductive with band gaps comparable to those of silicon allotropes. They are all superhard materials with Vickers hardness values comparable to that of cubic BN. The sp2–sp3 hybrid carbon allotroes are promising materials for photovoltaic electronic devices, and abrasive and grinding tools.

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Exotic Cubic Carbon Allotropes

Cited by 57 publications

References 66 publications

High-Energy Density and Superhard Nitrogen-Rich B-N Compounds

High-Energy Density and Superhard Nitrogen-Rich B-N Compounds

Nanodiamond-Rich Layer across Three Continents Consistent with Major Cosmic Impact at 12,800 Cal BP

Superhard sp2–sp3 hybrid carbon allotropes with tunable electronic properties

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