用不同粒度的籽晶生长优质宝石级金刚石单晶

Growth of Large High-quality Single Crystal Diamond with Seeds of Different Grain Sizes

利用温度梯度法生长宝石级金刚石单晶过程中,由于籽晶接收碳源能力有限,单一晶种将很难完全吸收扩散下来的碳源,因而导致籽晶的粒度对晶体生长速度和品质都会产生很大影响。随着籽晶粒度的增大,晶体的生长速度增幅非常明显,但不是粒度越大越好,存在临界粒度,超过临界粒度,优质单晶就很难生长。以N iMnCo触媒为例,籽晶粒度由0.5mm增加到2.0mm后,晶体的生长速度可由1.0mg/h提高到3.0mg/h,但籽晶粒度超过2mm后,晶体内部包裹体大幅度增加。

The grain sizes of seed grits have great effects on the growth rate and quality of grown crystals during the growth of large high-quality single crystal diamond by temperature gradient method （ TGM ） under high pressure and high temperature （HPHT）. The growth rates also increased markedly with the increase of seed grain sizes. However, the grain sizes cannot be increased to beyond the critical grain size, which determined the crystal quality. For example, with NiMnCo alloy as the metal solvent, the growth rate also increased greatly from 1.0mg/h to 3.0mg/h when the seed size was increased from 0. 5mm to 2.0mm; But more and more metal inclusions would be incorporated into the grown crystals when the grain size was beyond 2.0mm.