在NiMnCo-Cu-C体系中生长宝石级金刚石单晶

Growth of Synthetic Gem Diamonds in NiMnCo-Cu-C System

利用温度梯度法在NiMnCo-Cu-C体系、于5.5GPa、1250℃条件下进行了宝石级金刚石单晶的生长研究,结果发现,Cu片在触媒中的放置位置和其在金属触媒中所占体积分数对宝石级金刚石单晶的生长具有明显影响。当Cu片放置在碳源和触媒之间时,将不会有充足的碳源扩散到籽晶上,晶体无法生长;但放在触媒中其他位置,体积分数适当时,不会对晶体生长有明显影响。随着Cu体积分数增加,优质晶体生长将变得困难,当体积分数在20%时,晶体有生长,但晶体内部跟表面明显存在由于包裹体存在造成的生长坑洞;当体积分数在40%左右时,晶体将不再生长。不过当Cu在触媒中的体积分数适当时,会降低碳源在触媒中的输运,从而对抑制自发核生长起到一定的作用。

By temperature gradient method under high temperature and high pressure,large size synthetic diamond crystals were grown at 5.5 GPa and 1250 ℃ in NiMnCo-Cu-C system.It is found that,the arrangement order of copper plates in NiMnCo alloy plates and its volume fraction in the whole solvent metals have great effects on the growth of diamond crystals.When copper plates are placed between carbon source and NiMnCo alloy plates,carbon source is not enough for the growth of gem diamonds,so no crystals grow.However,when appropriate fraction of copper plate is placed in other position of NiMnCo alloy plates,no obvious effects on the crystal growth were found.With volume fraction of copper plate increased,high-quality crystals cannot be obtained easily.For example,when copper plates of 20% volume fraction are added into the NiMnCo alloy,although large crystals could grow,growth flaws,such as hole,metal inclusion,often appear;when copper plates of 40% volume fration are added,no crystals grow.Furthermore,when volume fration of copper plates is controlled properly,the solubility of carbon source in metal solvent could be adjusted in a certain extent,and so the spontaneous growth of diamond crystals could be checked effectively.