INFLUENCE OF SILICATES UPON THE GROWTH OF SYNTHETIC DIAMOND CRYSTALS

摘要

The synthesis and growth of diamond crystals at the pressure of 5.5 GPa and 1500 deg C was performed in the Fe-Ni-C system with an add of silicate components (samples of natural olivine and basalt) up to 20 wt. percent. In case of insignificant content of the impurities (1-5 wt percent), the morphology of diamond crystals doesn't differ from crystals growing in the pure metal-carbon system. Indroduction of more than 5 percent of silicates leads to the changes of diamond crystals morphology, manifested in the loss of morphological stability by the {111} faces, due to which triangular vicinal hillocks with the step-like lateral surfaces become transformed into subindividuals. In so doing, the single initial crystal finally transforms into a parallel aggregate. In process of growth, diamond crystals incept the inclusions of silicate phases. The local concentration of silicate phases screens off diamond growth. In case of seed location above the schists, at 20 percent of silicate content in the system, the total blocking of diamond growth takes place.