Keyword: «thermal treatment»

The effect of thermal treatment on the Raman spectra of detonation nanodiamonds was investigated in comparison with those of natural nanodiamonds. It was found that annealing in air at 430–550 °C leads to the appearance of a distinct diamond peak at 1328 cm⁻¹ and a decrease in the intensity of disordered carbon bands. Thermal treatment reduces the fraction of sp²-hybridized carbon atoms and improves the stability of nanodiamond particles in aqueous suspensions.

The effect of thermal treatment on the composition of functional groups in detonation and natural nanodiamonds was studied using X-ray photoelectron spectroscopy. It was shown that annealing in air at 400–550 °C leads to a decrease in the fraction of sp²-hybridized carbon atoms and an increase in the sp³ component. Changes in oxygen- and nitrogen-containing functional groups were revealed, indicating oxidation processes and restructuring of surface chemical bonds in nanodiamond particles.

The detonation and natural nanodiamonds were investigated using nuclear magnetic resonance (NMR) spectroscopy before and after thermal treatment. The NMR spectra of the initial samples revealed signals from sp³- and sp²-hybridized carbon atoms corresponding to the diamond core and disordered carbon shell. Thermal annealing at 550 °C leads to a decrease in non-diamond sp² carbon and changes in the surface functional groups. The results confirm the effectiveness of thermal purification of nanodiamonds.

The effect of thermal treatment on the composition of oxygen-containing functional groups in natural (NND) and detonation (DND) nanodiamonds was studied using FTIR spectroscopy and Boehm titration. It was found that annealing in air at 550 °C alters the ratio of hydroxyl and carbonyl groups, removes non-diamond carbon forms, and improves the ordering of the surface structure. The results are consistent with XPS data and confirm the effectiveness of thermal treatment for nanodiamond purification.