Diamond Growth and Morphology under the Influence of Impurity Adsorption

Abstract

In this paper, we report on the diamond growth and morphology evolution of diamond crystals of cube-octahedron series under the effect of impurity adsorption. In the first series of experiments it is established that in the Ni0.7Fe0.3–C system without impurity additives diamonds of predominantly cubic, cuboctahedral and octahedral habit crystallize at 1300, 1335, and 1370 °C, respectively. In the second series of experiments, the effect of H2O additive, in amount 0.3 wt %, on diamond growth and morphology was studied at different temperatures. It is found that the impurity adsorption effect leads to growth inhibition followed by complete blocking of growth of the {100} faces. At these conditions, the {111} faces continue to grow but reduce in area due to the inhibition of the ends of the {111} growth layers. As a result, a rich morphological diversity of antiskeletal diamond crystals was produced, whose growth and design are determined by the impurity adsorption effect and crystallization temperature. The established regularities of the crystal morphology evolution are in good agreement with the existing concepts of crystal growth under the impurity adsorption effect and structural crystal-chemical features of the diamond faces. Metal–carbon complexes containing hydrogen related groups together with hydroxyl, carbonyl and carboxyl groups are supposed to act as the adsorbing impurities.