Combined study of the ground and excited states in the transformation of nanodiamonds into carbon onions by electron energy-loss spectroscopy.

ABSTRACT: The electron momentum density and sp²/sp³ ratio of carbon materials in the thermal transformation of detonation nanodiamonds (ND) into carbon nano-onions are systematically studied by electron energy-loss spectroscopy (EELS). Electron energy-loss near-edge structures of the carbon K-ionization in the electron energy-loss spectroscopy are measured to determine the sp² content of the ND-derived samples. We use the method developed by Titantah and Lamoen, which is based on the ability to isolate the ?^* spectrum and has been shown to give reliable and accurate results. Compton profiles (CPs) of the ND-derived carbon materials are obtained by performing EELS on the electron Compton scattering region. The amplitude of the CPs at zero momentum increases with increasing annealing temperature above 500?°C. The dramatic changes occur in the temperature range of 900-1300?°C, which indicates that the graphitization process mainly occurs in this annealing temperature region. Our results complement the previous work on the thermal transformation of ND-derived carbon onions and provide deeper insight into the evolution of the electronic properties in the graphitization process.

SUBMITTER: Feng Z 

PROVIDER: S-EPMC6405772 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature