The effect of an iron powder catalyst clad with a Fe2O3 layer on the nucleation of diamonds

In this paper, we have researched the effect of a Fe2O3 clad layer covering iron catalyst particles on the nucleation of a diamond under high pressure and high temperature (HPHT). The Fe2O3 layer is deoxidized by graphite to form Fe3O4 and FeO at 5.7 GPa and 1600 degrees C. At the same time the iron melts and is exuded through the Fe2O3 layer, and then contacts with graphite, to cause the nucleation and growth of a diamond. Compared with a pure iron catalyst, the Fe2O3 Clad layer distinctly restrains the nucleation of the diamond. Furthermore, the thicker the clad layer becomes, the more obvious this effect is. The Mossbauer spectrum, X-ray diffraction (XRD) and a scanning electronic microscope (SEM) were used to characterize and analyze the experimental samples. (c) 2005 Elsevier B.V. All rights reserved.