Process parameters for diamond synthesis assisted by DC plasma using a water-ethylene glycol solution

Influence of the liquid composition, concentration of the potassium acetate, substrate-liquid distance and liquid layer thickness on the diamond formation were surveyed under a constant current for deposition during 1 h. Optimum deposition conditions were found to be 0.1 mol % potassium acetate, 8 mm substrate-liquid distance and 10-20 mm liquid layer thickness. Diamond forming liquid composition was then examined under a constant substrate temperature. It ranged from 60 to 99.9 mol % ethylene glycol; end compositions showed a poor yield. A constant substrate temperature was maintained under a constant current for temperatures lower than 900 degrees C. However, an important current reduction was required during the deposition to keep the substrate temperature higher than 1000 degrees C. (C) 1999 Kluwer Academic Publishers.