EVIDENCE FOR HYDROTHERMAL GROWTH OF DIAMOND IN THE C-H-O AND C-H-O HALOGEN SYSTEM

Powder x-ray diffraction (XRD) and Raman evidence are presented for th e formation of crystalline diamond in the ''hydrothermal'' pressure-te mperature regime 1-5 kbars, < 1000 degrees C. Two different methods ap pear to enable diamond to nucleate and grow. One-a Low Pressure Solid- State Source (LPSSS) route-utilizes special solid precursors, especial ly low temperature glassy carbon (GC-500), with very fine diamond seed s in sealed gold capsules with H2O at, say, 800 degrees C and 1 kbar. The other includes pyrolysis of highly selected organic solid/liquid p recursors (halogenated aliphatics such as iodoform) onto similar diamo nd seeds. Tn all the cases, powder x-ray diffraction evidence shows a marked increase of the diamond XRD peaks, likewise the Raman spectrum shows a strong increase of the 1331 cm(-1) line. However, the crystals apparently are too small to be seen in the SEM. TEM diffraction data, on the other hand, seem to lend support to the possibility of all the grown diamonds being very small.