PRECIPITATION OF DIAMOND FROM MEXCYHZ SOLUTIONS AT 1 ATM

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.