FeNi、NiMnCo及其复合触媒中Ⅰb型金刚石的生长特性

本文以Ni₇₀Mn₂₅Co₅和Fe₆₄Ni₃₆合金及其复合合金作为触媒,采用高温高压温度梯度法在5.6 GPa压力下,对不同温度下沿(100)晶面生长的Ⅰb型金刚石的生长特性进行了研究,研究表明:以Fe₆₄Ni₃₆触媒合成出的金刚石在以(111)晶面为主的晶形高温生长范围内出现了一段约50 K范围的裂晶生长区,而以Ni₇₀Mn₂₅Co₅触媒合成的金刚石在生长温度范围内,特别是在以(111)晶面为主的晶体生长高温区域内容易出现连晶缺陷;高温下Fe₆₄Ni₃₆触媒过度熔融可能是晶体容易产生裂晶的原因,Ni₇₀Mn₂₅Co₅触媒熔体黏性较低可能是容易形成连晶的原因;采用两种触媒复合的方式有效避免了裂晶和连晶的产生;拉曼光谱表征发现连晶的晶体内部质量与单晶的晶体质量相近,裂晶中晶格畸变和杂质较多,晶体内应力较大,复合触媒体系合成的金刚石晶体内应力小,质量好。

Growth Characteristics of Type Ⅰb Diamonds in FeNi,NiMnCo and Their Composite Catalysts

In this paper, Ni₇₀Mn₂₅Co₅ and Fe₆₄Ni₃₆ alloys and their composite alloys were used as catalysts to study the growth characteristics of typeⅠb diamonds grown along (100) crystal plane at different temperatures under 5.6 GPa pressure by high temperature and high pressure temperature gradient method. The results show that the diamond synthesized with Fe₆₄Ni₃₆ catalyst has a cracking growth zone of about 50 K in the high temperature growth range of (111) crystal plane. The diamond synthesized with Ni₇₀Mn₂₅C_o5 catalyst is prone to crystal stock defects in the growth range, especially in the high temperature crystal growth range of (111) crystal plane. The excessive melting of Fe₆₄Ni₃₆ catalyst at high temperature may be the cause of crystal cracking, and the low viscosity of Ni₇₀Mn₂₅Co₅catalyst melt may be the reason for easy formation of crystal stock. The combination of two kinds of catalysts can effectively avoid the formation of cracking and crystal stock. Raman spectroscopic characterization shows that the internal quality of crystal stock is similar to that of single crystals. There are more lattice distortion and impurities in the cracky crystals and the stress in the crystal is larger.The diamond crystal synthesized by compound catalyst system has low internal stress and good quality.