Modification of the ultradispersed diamonds surface by vacuum heat treatment

Abstract

The effect of vacuum annealing temperature at 10^–2 Pa on the surface structure and functionality of ultradisperse diamond (UDD) produced by detonation synthesis was studied using Raman scattering, IR absorption, x-ray diffraction, and electron paramagnetic resonance techniques. Vacuum annealing at ≤ 750 °C did not affect the structure of diamond nanoparticles although amorphous sp2-hybridized carbon began to form on the particle surfaces at higher temperatures. The UDD surface was com-pletely graphitized and the diamond structure of the particle nucleus was preserved after annealing at 1050 °C. Very few functional groups were observed on the UDD surface after annealing at 660–750 °C so that the surface remained highly active.