Formation mechanism of diamond nanocrystal from catalysed carbon black

Abstract

Recently, our group has synthesized nanocrystal n-diamond and diamond-likecarbon (DLC) from catalysed carbon black. Based on the results of XRD, TGAand DTA, a formation mechanism has been proposed to explain the phasetransformation from carbon black to diamond nanocrystal. With the increase oftemperature and hence the carbon diffusion in iron, the phase sequence is fromFe(OH)3 intoFe2O3,α-Fe,γ-Fe, then liquid iron. When the carbon in the liquid iron is saturated, DLC or graphiteseparates out of the liquid iron. With decrease of temperature, the carbon inγ-Fe is separated out, and n-diamond nuclei form and grow.