Spectroscopic characterisation and discussion of nanocarbon ensembles in electrical applications

Nanocarbon ensembles (NCE) composed of ultrananocrystalline diamond (UNCD) powders by reacting with methane at 1200 K are complementarily characterised by optical microscope (OM), Raman, fourier transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The porous bulk material of NCE are further confirmed to be composed of nanodiamond crystallites surrounded and networked by nanographite-like phases. The Raman scattering overtone of nanographite phases in NCE is newly observed. H inclusion in NCE is also shown by FT-IR. The XPS results first reveal the disorderliness of the sp²- and sp³-C bonding environment in NCE. The AFM morphology of NCE is shown for the first time in this work. The porosity and H inclusion may contribute to the low thermoelectric power factor of NCE. However, NCE may be another good nanocarbon material for field emission applications. An alternative one-step synthesis of NCE by spark plasma sintering (SPS) is suggested to prepare the inhomogeneous B-doped NCE nanocarbon materials for thermoelectric applications.