HPHT diamond crystallization in the Ni-Mn-C system: Effect of Mg additions

Abstract

This study investigated the feasibility of diamond crystal synthesis under high-pressure high temperature (HPHT) using the Ni-Mn-C system with 1–5 wt% of Mg at 4.5 GPa, 1250 ± 50 °C, for 180 s. The objective of using magnesium as a dopant was to evaluate its impact on crystal growing mechanisms and on the defects so as to employ the diamonds in cutting tools, once the synthetic parameter values are smaller than those found in the literature. The crystal morphology depicted a transformation from octahedral to cube-octahedral shape as Mg was weight increased. According with the results from Raman spectroscopy, full width at half maximum (FWHM), residual stress, X-ray diffraction (XRD), the high Mg crystals presented a solubility limit during the diamonds synthesis, with druses at 4 and 5 wt% of Mg and a noticeable displacement peak in XRD and Raman spectra.