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 sp 2 /sp 3 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 sp 2 content of the ND-derived samples. We use the method developed by Titantah and Lamoen, which is based on the ability to isolate the π * 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.

Compton profile of few-layer graphene investigated by electron energy-loss spectroscopy

“…The EELS is acquired by tilting the incident beam through a few degrees (~5°) for ECOSS measurement so that only large-angle-scattered electrons are collected 9,10 . The ECOSS technique has proven to be an important alternative for experimentally investigating the electron momentum density distribution of nanomaterials 11,12 .…”

Electrochemical synthesis of carbon nano onions

“…However, it seemed difficult to separate them from the original diamond source. [24][25][26][27] Detonation synthesis of CNOs via liquid carbon condensation has been also reported. 28 All in all, most of the methods mentioned above not only require high energy consumption, but also have a very low yield of CNOs with complex purification treatment.…”

Atmospheric-Pressure Flame Vapor Deposition of Nanocrystalline Diamonds: Implications for Scalable and Cost-Effective Coatings

“…The GIXRD scan detected a peak at 43.9° (Figure S4), which corresponds to diamond (111) planes, confirming the crystallinity of FVD-grown diamond thin films . The EELS spectrum of the carbon K edge in Figure h shows a major σ* peak centered around 291 eV, which is a characteristic diamond peak arising from the transition of 1s core level electrons to the unoccupied anti-bonding σ* states for sp 3 -bonded carbon (1s → σ* transition). − The shape of the carbon K-edge fine structure extended beyond 290 eV also resembles the distinct near-edge features of 1s → σ* transitions for diamond. Besides, no π* peak at 285 eV for sp 2 carbon (1s → π* transition) was detected, suggesting that the graphitic carbon phase was not present in the sample.…”