Kinetics of SiC formation during high P-T reaction between diamond and silicon

Time-resolved in situ X-ray diffraction at simultaneous high pressures (P) and high temperatures (T) was used to monitor kinetics of the reaction between diamond and silicon. Analysis of the data indicated that the reaction was diffusion controlled, and the diffusion was taking place through grain boundaries. For the nm size diamond the activation energy (170 kJ/mol) was smaller than that for μm size diamond (260 kJ/mol), and the reaction started at a temperature below the melting point of silicon. These effects are attributed to nanocrystalline structure and strained bonds within grain boundaries.