Growth and characterization of large, high quality cubic diamond crystals

High quality cubic diamond crystals were grown using the temperature gradient method at high pressure and high temperature (HPHT), in a new FeNi alloy as solvent. The crystals were grown at relatively low temperatures suitable for the growth of {100} faces. An increase in the radial growth rate, and inhibition of the axial growth caused the growth of large, high quality cubic diamond single crystals at high growth rates. For example, over 33 h, the radial growth rate was 0.22 mm/h, while the axial growth rate was only 0.08 mm/h; the growth rate by weight was also increased to 7.3 mg/h. The yellow color of our crystal samples was more uniform than samples from Sumitomo Corporation of Japan and Element Six Corp. The Raman FWHW of the 1332 cm⁻¹ peak in our diamond sample was smaller than the Element Six Corp. sample, but larger than that of the Sumitomo Corp. sample. The nitrogen content of our diamond samples was 240 ppm, which was much higher than the Sumitomo and Element Six samples because of the higher growth rate of our diamond samples.