Analysis of structures and surface states of the nanodiamond particle synthesised by detonation

Various apparatus were used to analyse the structures and the surface states of the nanodiamond particles synthesised by detonation, including a high-resolution transmission electron microscope (HRTEM), an energy diffraction spectrometer (EDS), an X-ray diffractometer (XRD), a Raman spectrometer (Raman), a Fourier transform infrared spectrometer (FTIR) and a differential scanning calorimeter (DSC). The grain size of the nanodiamond particles was in the range of 2-12 nm. However, the average grain size was approximately 5 nm. Moreover, the shapes of the nanodiamond particles were spherical or elliptical. The nanodiamond as-synthesised was very pure, which almost contained carbon only. The contents of the impurity element including O, N and S were very small, which came from the synthesis and purification processes when fabricating the nanodiamond. The surfaces of the nanodiamond particles absorbed many functional groups, such as hydroxy, carbonyl, carboxyl and ether-based resin. The initial oxidation temperature of the nanodiamond powder in air was about 520°C, which was lower than that of the bulk diamond. However, the oxidation temperature of the nanographite existing in the nanodiamond powder was about 228°C. The graphitisation temperature of the nanodiamond in Ar gas was approximately 1305°C.