Mechanical properties of carbyne: experiment and simulations

Abstract

The results of the high-field technique for obtaining and testing the carbyne strength in situ are presented. By using molecular dynamics simulation and ab initio calculations, a comprehensive analysis of the results is executed. High-field technique for experimental measurement of the carbyne strength in situ is briefly described. It is shown that the technique used gives a lower estimation for strength of carbyne, which equals 251 GPa at T = 77 K. This value is close to the strength 7.85 nN (250 GPa) of contact atomic bond between carbyne and graphene sheet, from which the monatomic chain is pulled. The strength of carbyne itself is determined by strength of an edge atomic bond and it is ≈ 12.35 nN (393 GPa) at T = 0 K. For carbynes containing more than 10 to 12 atoms, the coefficient of elasticity (k Y = 145.40 nN) and the elastic modulus (Y = 4631 GPa) are ascertain.

Routines for the synthesis of carbyne with more than 6000 atoms

“…While the chain length is fixed, the optimization process focuses only on the radial direction of the CNT. An isolated long LCC is always unstable in a room-temperature environment due to strong atomic fluctuations [10][11][12][13][14][15]. The kink angle is a measure of the atomic fluctuations in the LCC.…”

“…If all covalent bonds in the LCC are stable, the LCC with a length of 15000 atoms should have weaker atomic fluctuations than the LCC with a length of 6000 atoms. However, extensive studies of LCC show that the elongation of LCC always leads to chain termination or self-dissociation [10][11][12][13][14][15]25,27]. So far, the formation of all stable covalent bonds in an extremely long LCC has not been observed experimentally.…”

“…Carbon exists in many different forms, including 3D structures with sp 3 hybridization, such as diamond, or 2D structures with sp 2 bonds like graphite and graphene. While the latter already exhibits edge modes, a third type of one-dimensional sp hybridization yields the allotrope carbyne [9][10][11][12][13][14][15]. As a truly one-dimensional monoatomic semiconductor, it exhibits exceptionally mechanical strength with a band gap that can be widely tuned by strain [16], and basically consists of an edge everywhere.…”

“…Unfortunately, there is no systematic routine that provides the theoretical input for optimising the chain length of carbyne regardless of whether the chain is doped or not, which hinders experimental bottom-up studies of edge magnetism. The preparation of carbon chains with a length in the order of 20 atoms has been a difficult problem in the last decade [13,26]. To extend the chain length, Shi et al encapsulated the carbyne with carbon nanotubes (CNTs) as a nanoreactor, resulting in carbon chains with up to 6000 atoms [25].…”

Toward the Synthesis of Highly Processable Long-Chain Carbyne Using Multilevel Pulse Injection

“…In 2015, Kotrechko et al demonstrated that an acetylenic carbon chain of 44 units could be synthesized in a stable form both via simulations and initial experimental syntheses. Furthermore, they found that carbyne's tensile strength (393 GPa) and Young's modulus (4.6 TPa) were indeed the highest of any known material in the world [3]. Shortly after this work, Shi et al (2016) devised a method for synthesizing carbyne in high purity, chain length, and yield; by growing carbyne inside of double-walled carbon nanotubes (DWCNTs), the acetylenic chains become highly stable and protected from the external environment by their nanoscaffolds [4].…”