Superelasticity of Carbon Nanocoils from Atomistic Quantum Simulations

Abstract

A structural model of carbon nanocoils (CNCs) on the basis of carbon nanotubes (CNTs) was proposed. The Young’s moduli and spring constants of CNCs were computed and compared with those of CNTs. Upon elongation and compression, CNCs exhibit superelastic properties that are manifested by the nearly invariant average bond lengths and the large maximum elastic strain limit. Analysis of bond angle distributions shows that the three-dimensional spiral structures of CNCs mainly account for their unique superelasticity.

Elastic behavior of carbon nanocoils: A molecular dynamics study

“…Several modeling techniques have been proposed in literature such as geometrical 17,18 and topological 25 methods. Here, modeling is carried out based on the procedure proposed recently by Biyikli et al for generation of graphitic nanostructures.…”

“…16 Among theoretical studies, atomistic quantum simulations have been carried out to investigate the superelasticity of CNCs. 17 Based on the performed tight binding (TB) and density functional theory (DFT) calculations, spring constants of 15.37-44.36 N/m were obtained. Ghaderi and Hajiesmaili have applied molecular structural mechanics (MSM) approach to CNCs.…”

“…Although many reasons are behind the discrepancy between the results such as model size and structure, applied assumptions, methods and parameters etc., the main reason seems to be length scale and type of the study whether it is experimental or theoretical. 17,[21][22][23][24] Often, in experimental works, like, 14,16 the results for spring constant and modulus are low and the CNCs studied are large (on the order of hundreds of nanometers) whereas in theoretical works, such as, 17,18 the results are high and the CNCs are small (on the order of nanometers).…”

Electronic and optical properties of deformed graphitic and helical nanobutes

“…To je način na koji je postignuta stabilnost sistema sa defektima. U slučaju kontinualnih sistema sa defektima, poput tečnih kristala, krivina (ekraniranje) je uvek rasporedeno glatko po mnogostrukosti, dok, kod 2D kristalnih sistema, postoje modeli [63] koji pretpostavljeju da je krivina diskretno rasporedena, tj. koncentrisana u pojedinim tačkama.…”

“…U istom ogledu je izmereno da elastična konstanta ("spring constant") u linearnom režimu istezanja iznosi 0.12 N/m. Pored merenja elastičnih osobina, vršeni su i molekularno dinamički proračuni [74,63] elastičnih funkcija odziva kao i procenta kidanja meduatomskih veza prilikom deformacija. Rezultat je znatno veća elastičnost HUNT u poredenju sa JUNT ("superelastičnost").…”