Fig. 4: Crystalline characterization of the prepared graphene fibres.

a Schematic depicting the ideal crystalline graphene fibre. Note, the solid fibres deviate from a concentric texture on the cross-section due to the severe shrinkage during solidification. b, c Transmission electron microscope (TEM) images of a graphene fibre along transverse (b) and longitudinal (c) direction, illustrating the three-dimensional crystalline structure in a single fibre. d Wide-angle X-ray scattering pattern of the concentric graphene fibre, showing the high crystallinity. e The azimuthal scanning curves of the random (grey line), concentric (red line), and spiral (blue) graphene fibres. f Density and orientation order of the prepared graphene fibres. g The crystalline size of the 3D graphitic crystallites. h The typical tensile stress-strain curves of the prepared graphene fibres. i Relationship between the Young’s modulus and density of graphene fibres. j Overall properties of the fabricated graphene fibres, including thermal and electrical conductivities, tensile strength, and Young’s modulus. Error bars in (f), (j) represent s.d. of the measured properties.