摘要:
本文在5.1-5.6 GPa,1230-1600?C的压力、温度条件下,以FeNiMnCo作为触媒,进行单质硼添加宝石级金刚石单晶的生长研究.借助于有限元法,对触媒内的温度场进行模拟.研究得到了FeNiMnCo-C-B体系下,金刚石单晶生长的P-T相图.该体系下合成金刚石单晶的最低压力、温度条件分别为5.1 GPa,1230?C左右.研究发现,在单晶同一{111}扇区内部,硼元素呈内多外少的分布规律.有限元模拟结果给出,该分布规律是由在晶体生长过程中,{111}扇区的增长速度逐渐减小所致.{111}晶向的晶体生长实验结果表明,硼元素优先从{111}次扇区进入晶体.研究发现,这是该扇区增长速度相对较快,硼元素扩散逃离可用时间短导致的.另外,同磨料级掺硼金刚石单晶生长相比,对于温度梯度法生长掺硼宝石级金刚石单晶,由于晶体的增厚速度较慢,即使硼添加量相对较高,也可以实现表面无凹坑缺陷的优质金刚石单晶的生长.
关键词:
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高温高压
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温度梯度
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金刚石
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触媒
Abstract:
In this paper, by choosing catalyst of FeNiMnCo alloy, boron-doped diamond single crystals are synthesized under 5.1-5.6 GPa and 1230-1600 ?C; the temperature field is studied by finite element method (FEM). First, the P-T phase diagram for diamond single crystal growth, in the synthesis system of FeNiMnCo-C-B, is obtained, and the lowest synthesis conditions of 5.1 GPa and 1230 ?C is found in the studies. By simulation with FEM, it is found that the content of boron element should be less and less in the growth of diamond single crystal in the {111} sector, and the reason is that the growth speed is reduced in the sectors. By growing diamond crystals with{111}faces, it is also found that the content of boron element in {111} secondary sector is greater than that in {111} primary sector, which is duo to the rapid growth of {111} secondary sector. Compared with the synthesis of diamond single crystal by film growth method, the diamond crystals thus obtained has no pits, the doping content of boron can be greater, and the diamond can be synthesized by temperature gradient method.
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