摘要
为由温度坡度方法(TGM ) 的大合成钻石晶体的生长，晶种的砂砾尺寸在生长率和大成年晶体的质量上有大效果。因为种子表面的有限区域，碳来源的最大的散开流动，能被种子吸收，与种子尺寸有关。并且与增加，种子缩放，生长率也显著地增加。然而，种子尺寸应该比某个价值低，它直接决定水晶质量。例如，当种子尺寸从 0.5～1.8 公里增加时，与 NiMnCo 合金，作为金属溶剂，生长率从大约 1.1～3.2 mg/h 极大地增加；当尺寸在 2.0 公里以外时，越来越多的金属包括将被合并到成年晶体，并且水晶质量重重地被破坏。有限元素分析(FEA ) 证明由于生长房间的特殊集会，在金属溶剂的碳来源的散开是很不同类的，它能被大成年晶体的外观和碳来源的遗体直接证实。并且碳来源的这不同类的散开将对大钻石晶体的生长很有害，特别当大尺寸的晶种被使用时。
For the growth of large synthetic diamond crystals by temperature gradient method （TGM）, the grit sizes of seed crystals have great effects on the growth rate and quality of large grown crystals. Because of the limited area of seed surfaces, the maximum diffusion flux of carbon source, which could be absorbed by the seed, is related to the seed size. And with increasing the seed sizes, the growth rates also increase markedly. However, the seed sizes should be lower than a certain value, which determines the crystal quality directly. For example, with NiMnCo alloy as the metal solvent, when the seed size increases from 0.5 to 1.8 mm, the growth rate increases greatly from about 1.1 to 3.2 mg/h; when the size is beyond 2.0 mm, more and more metal inclusions would be incorporated into the grown crystals, and the crystal quality is destroyed heavily. Finite element analysis （FEA） shows that, due to the special assembly of growth cell, the diffusion of carbon source in the metal solvent is very inhomogeneous, which could be substantiated directly by the appearances and shapes of large grown crystals and the remains of carbon source. And this inhomogeneous diffusion of carbon source would be very harmful to the growth of large diamond crystals, especially when large-size seed crystals are used.
基金
supported by the National Natural Science Foundation of China under grant No.50172018.
关键词
温度梯度方法
金刚石
异成分扩散
有限元分析
Temperature gradient method
Diamond
Inhomogeneous diffusion
Finite element analysis
