Covalent-bonded graphyne polymers with high hardness

Hu, Meng; He, Julong; Wang, Q.; Huang, Quan; Tian, Yongjun; Xu, Bin

doi:10.3103/s1063457614040042

Cited by 14 publications

(26 citation statements)

References 48 publications

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“…Theoretical calculations of the structures of graphyne layer fragments and single graphyne layers and their properties were continued in . A number of theoretical works dealt with studying the structures of graphyne crystals consisting of gra phyne layer stacks [39,40], graphyne crystals having a three dimensional rigid cage structure [36,41], and the structure and properties of intercalated and doped graphyne [42][43][44][45][46][47][48][49][50][51][52][53]. Graphyne nanostructures, which are similar to fullerenes, were first theoreti cally studied in [54], and graphyne nanotubes were first described in [55].…”

Section: Introductionmentioning

confidence: 99%

Structural modifications of graphyne layers consisting of carbon atoms in the sp- and sp 2-hybridized states

Belenkov

Mavrinskii

Belenkova

et al. 2015

J. Exp. Theor. Phys.

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A model scheme is proposed for obtaining layered compounds consisting of carbon atoms in the sp and sp 2 hybridized states. This model is used to find the possibility of existing the following seven basic structural modifications of graphyne: α , β1 , β2 , β3 , γ1 , γ2 , and γ3 graphyne. Polymorphic modifica tions β3 graphyne and γ3 graphyne are described. The basic structural modifications of graphyne contain diatomic polyyne chains and consist only of carbon atoms in two different crystallographically equivalent states. Other nonbasic structural modifications of graphyne can be formed via the elongation of the carbyne chains that connect three coordinated carbon atoms and via the formation of graphyne layers with a mixed structure consisting of basic layer fragments, such as α-β graphyne, α-γ graphyne, and β-γ graphyne. The semiempirical quantum mechanical MNDO, AM1, and PM3 methods and ab initio STO6 31G basis calcu lations are used to find geometrically optimized structures of the basic graphyne layers, their structural parameters, and energies of their sublimation. The energy of sublimation is found to be maximal for γ2 gra phyne, which should be the most stable structural modification of graphyne.

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Section: Introductionmentioning

confidence: 99%

Structural modifications of graphyne layers consisting of carbon atoms in the sp- and sp 2-hybridized states

Belenkov

Mavrinskii

Belenkova

et al. 2015

J. Exp. Theor. Phys.

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“…The elastic constants as simulated by these force‐fields are tabulated in Table and the calculated off‐axis linear compressibility properties are graphically represented in Fig. , where they are also compared to those obtained from the analysis of the data via ab initio simulations by Hu et al . A comparison of this data suggests that although the actual magnitudes of the elastic constants may differ depending on the method used, the trends observed are rather similar.…”

Section: Resultsmentioning

confidence: 97%

“…Systems were optimized to the default Materials Studio 8.0 convergence criteria to less than 0.0001 kcal mol −1 A −1 using the SMART minimizer integrated in Materials Studio 8. The fractional atomic positions as well as the unit cell parameter of the systems obtained were then compared to those obtained via ab initio methods by Hu et al . Also the elastic constants c ij which relate stress

σ

to strain

ϵ

according to

σ = true[c_{i j} true] ϵ

were calculated from the second derivative of the energy expression since

c_{i j} = \frac{1}{V} \frac{\partial^{2} E}{\partial ϵ_{i} \partial ϵ_{j}}, i, j = 1,2,...,6,

where E is the energy expression, V is the volume of the unit cell,

ϵ_{2} = ϵ_{y}

, and

ϵ_{3} = ϵ_{z}

are the strains in the x , y, and z directions, respectively, while,

ϵ_{5} = γ_{x z}

and

ϵ_{6} = γ_{x y}

are the shear strains in the yz , xz, and xy planes, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Off‐axis mechanical properties including the Poisson's ratios and linear compressibility were then calculated from both sets of force‐field simulated elastic constants as well as from the ab initio results by Hu et al . These were analyzed so as to identify any negative Poisson's ratio and negative compressibility that may be present.…”

Section: Methodsmentioning

confidence: 99%

“…This work will look at two all‐carbon networks, recently proposed by Hu et al which have a characteristic honeycomb‐like motif in their nanostructure, a geometry which, as noted above, is well known for its potential to exhibit negative compressibility. These novel all‐carbon systems were predicted using the newly developed USPEX and CALYPSO methods based on ab initio simulations.…”

Section: Introductionmentioning

confidence: 99%

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Carbon allotropes exhibiting negative linear compressibility

Formosa

Cauchi

Grima

2015

Physica Status Solidi (b)

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Negative linear compressibility, i.e., the phenomenon of expansion rather than shrinkage in at least one direction upon the application of a hydrostatic compressive pressure is an unusual mechanical property which is attracting more interest in the recent years. Here, through analysis of published data by Hu et al. [J. Superhard Mater. 36, 257–269 (2014)] as well as through static force‐field based simulations, it is shown that it is possible to achieve this property in the novel carbon allotropes built from sp2 and sp3 hybridized carbon atoms which have a two‐dimensional projection that resembles a honeycomb motif in their (001) plane. This is in accordance with earlier predictions that honeycombs deforming through a hinging‐like mechanism could exhibit this property for certain geometries.

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