Superhard and high-strength yne-diamond semimetals

Hu, Meng; Huang, Quan; Zhao, Zhisheng; Xu, Bin; He, Julong

doi:10.1016/j.diamond.2014.04.005

Cited by 22 publications

(28 citation statements)

References 44 publications

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“…Furthermore, as reported in ref ( 15 ), the search discovered many new crystal structures that were not registered in SACADA in 2017. One exception was 4H-diamond, 41 , 44 and both present and previous searches did not find this structure. This is because our algorithm restricts the search to areas in which the shape of the cell is not very far from cubic.…”

Section: Resultscontrasting

confidence: 73%

“…At 100 GPa, two diamond structures described by different unit cells ( MIN0 100GPa and MIN1 100GPa , #1 in SACADA 4 ) were the most stable, where these two are structurally almost identical but differ slightly in energy (∼0.059 eV/unit-cell) probably because of computational errors arisen from differences in representations of cells. 4H-diamond 41 , 44 ( MIN2 100GPa , #111 in SACADA 4 ), 12R-diamond 22 ( MIN3 100GPa , #209 in SACADA 4 ), and lonsdaleite ( MIN4 100GPa , #37 in SACADA 4 ) were also obtained. Cco-C 8 (or Z -carbon) 5 , 6 ( MIN5 100GPa , #141 in SACADA 4 ), M -carbon 7 ( MIN6 100GPa , #224 in SACADA 4 ), F-carbon 24 − 30 ( MIN7 100GPa , #225 in SACADA 4 ), oC16 23 ( MIN8 100GPa , #210 in SACADA 4 ), and C 2/ m -16 40 ( MIN9 100GPa , #186 in SACADA 4 ) were also found in the lower energy region.…”

Section: Resultsmentioning

confidence: 87%

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Global Search for Crystal Structures of Carbon under High Pressure

Takagi

Maeda

2020

ACS Omega

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In this study, a systematic search for structures of carbon crystals under high pressure was performed by using the artificial force induced reaction method including periodic boundary conditions. To perform a search under an arbitrary pressure, an algorithm to take account of the pressure was implemented in the GRRM program. At 100 GPa, the search generated 710 unique structures automatically. These structures were compared with 982 structures obtained by the search under zero pressure. The structures at 100 GPa were much denser than those under zero pressure. Besides, new structures that were denser than diamond were obtained at 100 GPa.

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Section: Resultscontrasting

confidence: 73%

Section: Resultsmentioning

confidence: 87%

Global Search for Crystal Structures of Carbon under High Pressure

Takagi

Maeda

2020

ACS Omega

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“…[1][2][3][4][5][6][7][8][9][10] Graphdiyne, which consists of a sp-sp 2 hybrid network and is formed by replacing one-third of the C-C bonds in a graphene sheet with diacetylenic (-CRC-CRC-) linkages, has been synthesized experimentally 11 despite its ground-state energy being higher (about 0.9 eV per atom) than that of graphite. In carbyne, graphdiyne, graphyne, [12][13][14][15][16][17][18][19] yne-diamond, [20][21][22] Rh12, and Rh18, 23 sp atoms form a linear skeleton structure with alternate single and triple bonds (-CRC-) n , which is also the basic structural unit of polyynes. Another sp hybridized category consists of compounds with cumulative double bonds (QCQCQ) n and is termed as cumulenes.…”

Section: Introductionmentioning

confidence: 99%

Novel carbon polymorphs with cumulative double bonds in three-dimensional sp–sp² hybrid framework

Liu

et al. 2018

Phys. Chem. Chem. Phys.

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A conspicuous amount of theoretical study has been published on the properties of carbon allotropes with alternate single and triple bonds, (-C[triple bond, length as m-dash]C-)n. However, theoretical characterizations of carbon allotropes with cumulative double bonds ([double bond, length as m-dash]C[double bond, length as m-dash]C[double bond, length as m-dash])n is almost non-existent in literature. Based upon first-principles calculations, two new three-dimensional (3D) microporous carbon allotropes consisting of whorl chains connected by cumulative double bonds in a sp-sp2 hybrid framework have been proposed in this study. One of these structures, namely, Trig-C9 was obtained by an evolutionary particle swarm structural search, while the other structure, denoted as Trig-C15, was obtained by inserting double bonds into Trig-C9. Both the 3D sp-sp2 hybridized carbons have a trigonal structure with 9 and 15 atoms in the hexagonal primitive cells. The calculated results demonstrate that these polymorphs are thermodynamically, mechanically, and dynamically feasible. Trig-C9 and Trig-C15 are indirect semiconductors with band gaps of 2.70 eV and 1.25 eV, respectively. Their unique frameworks render them mechanical ductility and significant elastic anisotropy. These results open up new horizons for the exploration of new carbon phases with unique structural, mechanical, and electronic properties.

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“…The most probable signals can be connected with optical properties of the materials, such as Raman spectra, optical coefficients in the regions of infrared (IR), visible and ultraviolet (UV) spectra, as well as the energy dependence of the absorption and refractive indices. Here we calculate different optical properties of the six lowest-energy sp 3 carbon allotropes: cubic diamond, lonsdaleite [4], 4H-diamond [10], SiC12 [11], C28 [12] and mtn [13]. The main goal of our study is to find the quantitative level of difference between optical properties of cubic diamond and relevant carbon allotropes, which can be measured experi-mentally.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2017

Kompʹût. opt.

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We study optical properties of lowest-energy carbon allotropes in the infrared, visible and ultraviolet spectral ranges in the general gradient approximation of the density functional theory. In our calculations we use an all-electron approach as well as a pseudo-potential approximation. In the infrared range, complex dielectric functions, infrared and Raman spectra have been calculated using a CRYSTAL14 program. Electronic properties and energy-dependent dielectric functions in the visible and ultraviolet spectral ranges are calculated using a VASP program. We describe with good accuracy the experimentally known optical properties of a cubic diamond crystal. Using the obtained set of relevant calculation parameters, we predict the optical constants, dielectric functions and Raman spectra of the lowest-energy hypothetical carbon allotropes and lonsdaleite.

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Superhard and high-strength yne-diamond semimetals

Cited by 22 publications

References 44 publications

Global Search for Crystal Structures of Carbon under High Pressure

Global Search for Crystal Structures of Carbon under High Pressure

Novel carbon polymorphs with cumulative double bonds in three-dimensional sp–sp² hybrid framework

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Superhard and high-strength yne-diamond semimetals

Cited by 22 publications

References 44 publications

Global Search for Crystal Structures of Carbon under High Pressure

Global Search for Crystal Structures of Carbon under High Pressure

Novel carbon polymorphs with cumulative double bonds in three-dimensional sp–sp2 hybrid framework

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Novel carbon polymorphs with cumulative double bonds in three-dimensional sp–sp² hybrid framework