X-Ray diffraction study of multiwalled carbon nanotubes

What is it about?

Structural features of multiwalled carbon nanotubes (MWCNTs) have been analyzed quantitatively by high-energy X-ray diffraction (HE-XRD) with atomic pair distribution function (PDF) technique. It has been found that the nanotubes are mainly of scroll type and own an atomic arrangement defined on the nanometer length scale in terms of a unit cell and symmetry. They exhibit multipart local (sub-nano- meter) and intermediate range (on nano-length-scale) structures. The structural information at different length-scales was used to probe the interlayer spacing distribution within the nanotubes. The radial dependence of interlayer spacing observed in pristine nanotubes presents tendency for alteration to uniform spacing of layer in the course of heating-cooling cycle in the range of 298-450 K. These spatial changes illustrate modification of Fermat type stroll with uneven interlayer distances in pristine nano- tubes to more stable equidistant interlayer Archimedean spiral type in the heating-cooling treated ones.

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Why is it important?

The CNT-based devices may experience thermal manipulations during fabrication and operation processes that lead to different thermal expansion and residual stress affecting to the device reliability. It is well known that heat treatments of CNT induce its structural changes. Therefore, the thermal properties of CNTs are of fundamental interest and a critical in controlling the performance and stability of nanotube devices.

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