Characterisation of microcrystalline diamonds deposited by HFCVD

The performances of CVD microcrystalline diamond powders by the seeding and self-nucleation method, including the particle size composition, crystal morphology, and diamond purity, are evaluated by the China industry standard of conventional diamond powders (JB/T 7990-2012). The detection results show over 80% particles grown on the seeds exhibit a cubo-octahedral with smooth surfaces and no obvious growth defects, while they can hardly meet the corresponding commercial requirements of particle size composition due to the existence of 10%-23% spontaneous particles (0.5~1.2 μm). For the powders deposited by self-nucleation method, the particle size composition agrees well with the model defined by the industry standard, and 70.5% crystals exhibit the cubo-octahedral or icosahedron morphology, as well as their surface quality are little worse than those grown on the seeds due to unwanted secondary nucleation. Besides, the two types of CVD powders have a high purity detected by micro-Raman spectroscopy.