We describe herein a new process for the synthesis of diamond in the p
resence of various metals and atomic H in a microwave plasma. Along wi
th the traditional high pressure high temperature (HPHT) process and t
he chemical vapor deposition (CVD) process, for diamonds synthesis thi
s makes it a third route for this purpose. Starting materials used are
intimate mixtures of various forms of carbon with one of many metals.
These are exposed to a pure H-2 microwave-assisted plasma at temperat
ures in the range 600-1100 degrees C. Novel amorphous alloys are forme
d containing 40 to 70 atomic percent of carbon. From these liquid allo
ys diamonds are precipitated with temperature change and/or with possi
ble evaporation of complex, hydrogen-rich Me-C-H species. The carbon c
ontent of the metallic liquid drops sequentially down to 5-6%C as more
and more diamonds are precipitated therefrom. Au, Ag, Fe, Cu, Ni, and
many other metals are used in most runs, Others e.g. La, Mn, Sn, each
give distinctive habits or morphology to the diamonds grown. Single c
rystals have been grown from these MexCyHz metallic liquids on natural
diamond substrates, using the same low pressure solid state source (L
PSSS) technique. They show high perfection. A mechanism is proposed qu
ite analogous to the HPHT process, to explain this precipitation from
metallic solutions, with atomic hydrogen ''substituting'' for high pre
ssure.