| 摘要 |
Single-crystal diamond is composed of carbon in which a concentration of a carbon isotope 12 C is not lower than 99.9 mass % and a plurality of inevitable impurities other than carbon. The inevitable impurities include nitrogen, boron, hydrogen, and nickel, and a total content of nitrogen, boron, and hydrogen of the plurality of inevitable impurities is not higher than 0.01 mass %. In order to manufacture single-crystal diamond, initially, a hydrocarbon gas in which a concentration of the carbon isotope 12 C is not lower than 99.9 mass % is subjected to denitrification (S1). A carbon source material obtained by thermal decomposition of the hydrocarbon gas subjected to denitrification on a base material in a vacuum chamber, for example, at a temperature not lower than 1200°C and not higher than 2300°C is prepared (S2), diamond is synthesized from the carbon source material, and a seed crystal is cut from the diamond (S3). While this seed crystal is accommodated in a cell together with a solvent and a carbon source, single-crystal diamond is grown from the seed crystal with a high-temperature and high-pressure synthesis method (S4). |
