METHOD OF PRODUCING DIAMONDS

1311575 Synthesizing diamond UKRAINSKY ORDENA TRUDOVOGO KRASNOGO ZNAMENI NAUCHNO - ISSLEDOVATELSKY KONSTRUKTORSKO - TEKHNOLOGICHESKY INSTITUT SINTETICHESKIKH SVERKHTVERDYKH MATERIALOV I INSTRUMENTA GOSPLANA UKRAINSKOI SSR and ORDENA TRUDOVOGO KRASNOGO ZNAMENI INSTITUT FIZICHESKOI KHIMII AKADEMII NAUK SSSR 23 April 1971 [24 April 1970] 11140/71 Heading C1A Diamond is produced by depositing carbon from an atmosphere containing at least one carbon containing compound on to a diamond seed at a temperature of from 600‹ to 1600‹ C. and under a pressure of from 0À1 to 75 mm. Hg in which the carbon compound is mixed with oxygen in an amount not greater than that required to oxidize the non-diamond carbon formed simultaneously with the deposition of the diamond. Oxygen is preferably used in an amount such that its partial pressure is from 0À1 to 5% of the total pressure used. The carbon compound may be a hydrocarbon, preferably an alkane, e.g. methane, ethane, propane, heptane, octane, or a mixture of two or more thereof. An oxygen containing compound, e.g. water vapour, which decomposes under the conditions used may be utilized as a source of oxygen. 2 to 5% by volume of oxygen may be used.