Reversible Loss of Bernal Stacking during the Deformation of Few-Layer Graphene in Nanocomposites

Abstract

The deformation of nanocomposites containing graphene flakes with different numbers of layers has been investigated with the use of Raman spectroscopy. It has been found that there is a shift of the 2D band to lower wavenumber and that the rate of band shift per unit strain tends to decrease as the number of graphene layers increases. It has been demonstrated that band broadening takes place during tensile deformation for mono- and bilayer graphene but that band narrowing occurs when the number of graphene layers is more than two. It is also found that the characteristic asymmetric shape of the 2D Raman band for the graphene with three or more layers changes to a symmetrical shape above about 0.4% strain and that it reverts to an asymmetric shape on unloading. This change in Raman band shape and width has been interpreted as being due to a reversible loss of Bernal stacking in the few-layer graphene during deformation. It has been shown that the elastic strain energy released from the unloading of the inner graphene layers in the few-layer material (∼0.2 meV/atom) is similar to the accepted value of the stacking fault energies of graphite and few layer graphene. It is further shown that this loss of Bernal stacking can be accommodated by the formation of arrays of partial dislocations and stacking faults on the basal plane. The effect of the reversible loss of Bernal stacking upon the electronic structure of few-layer graphene and the possibility of using it to modify the electronic structure of few-layer graphene are discussed.

Interlayer interaction and related properties of bilayer hexagonal boron nitride: ab initio study

“…7,[18][19][20][21][22][23][24][25][26] It has been demonstrated that such dislocations have a strong effect on the electronic [22][23][24][25]27 and optical 26 properties of graphene. The analysis of structure of dislocations in few-layer graphene by transmission electron microscopy has already helped to get an experimental estimate of the barrier to relative displacement of the layers.…”

Polycrystalline graphene and other two-dimensional materials

“…Finally, a different type of topological defect is possible in multilayer systems such as bilayer graphene. Several groups have reported observations of boundaries between domains with structurally equivalent AB and AC stacking orders in bilayer graphene [53][54][55][56][57] . These stacking domain boundaries observed by means of DF-TEM appear as regions of continuous registry shift that are a few-nanometres wide, and often form dense networks in bilayer graphene.…”

The microstructure of a graphene-reinforced tennis racquet

“…Raman spectroscopy has been employed for a number of years to characterise both structure and mechanical properties of carbon fibres [10][11][12][13][14][15] and is now used extensively to characterise different forms of graphene-based materials [7,8,16,17].…”