人工合成金刚石研究进展

1796年英国科学家S.Tennant的精确燃烧实验，首次揭示金刚石是由纯碳构成的宝石，从此人类开始了漫长的人工合成金刚石的探索.金刚石通常只能在极端条件下形成，因此，合成技术的突破是人类合成水平提高的一个重要标志，文章对这一领域一些重要工作做了简单回顾，也讨论了作者在合成金刚石方面的工作.我们在440℃的低温条件下，用碱金属（Li，Na，K）还原超临界CO2,得到透明、大尺寸的金刚石晶体，首次实现了金刚石燃烧实验的逆过程，即把低能、直线型CO2分子变成了碳-碳四面体连接的金刚石,开辟了人工合成金刚石的新途径.也讨论了它与天然金刚石起源之间的可能联系.

Recent progress in diamond synthesis

Rrecent advances in diamond synthesis are reviewed. Artificial diamonds synthesized under high pressure and high temperature has led to wide usage of such diamonds in industry. Low temperature coating of diamonds has been studied for some time and chemical vapor deposition has been developed. In our group dense carbon dioxide is reduced by alkali metals (Li, Na, K) to produce colourless large diamond crystals at 800 atm and 400 ℃. Diamonds readily burn in air, forming carbon dioxide. This is the first time that the reverse conversion of carbon dioxide to diamond has been realized. Carbonates are important candidates as potential hosts for carbon in the Earth's mantle and crust, It is known that the mantle in the past has been strongly reducing, based on the thermodynamic analyses of diamond inclusions. It is suggested that diamond within the Earth could be produced from carbon dioxide wherever carbon dioxide exists and conditions (eg. temperature, pressure, and reducing environment) are satisfied.