中文摘要：

利用温度梯度法,在5.3—5.7 GPa压力、1200—1600℃的温度条件下,将B2O3粉添加到FeNiMnCo＋C合成体系内,进行B2O3添加宝石级金刚石单晶的合成.研究得到了FeNiMnCo触媒生长B2O3添加宝石级金刚石单晶的相图分布规律.结果表明B2O3添加会使晶体生长的＂V＂形区上移和低温六面体单晶生长区间变宽.通过晶体生长实验,研究合成了不同形貌的B2O3添加宝石级金刚石单晶.研究同时证实,B2O3的过量添加会对宝石级金刚石单晶生长带来不利影响.当B2O3的添加量高于约3 wt‰、生长时间超过20 h时,很难实现优质B2O3添加宝石级金刚石单晶的生长.但B2O3的适量添加（不超过1 wt‰）,有助于提高低温板状六面体宝石级金刚石单晶的成品率.通过对晶体生长速度的研究发现,B2O3的添加使得优质晶体的生长速度明显降低,随着晶体生长时间的延长,B2O3添加剂对晶体生长的抑制作用会越发明显.扫描电镜测试结果表明,合成体系内B2O3添加剂的引入,导致晶体表面的平整度明显下降.

英文摘要：

In the present paper, by the temperature gradient method, the gem-diamond single crystals with B2O3-added in the synthetic system of the FeNiMnCo-C are synthesized under 5.3–5.7 GPa and 1200–1600℃. The P-T phase diagram of diamond single crystal growing in the synthesis system of the FeNiMnCo-C-B2O3, is obtained. By B2O3-added in synthesis system, the V-shape section for the diamond growth, which is the region between the solvent/carbon eutectic melting line and diamond/graphite equilibrium line under pressure and temperature, is moved upwards. We find that the minimum pressure of diamond growing increases from 5.3 GPa to 5.4 GPa and the synthesis range of the low temperature hexahedron diamond growth becomes wider, which can be due to the chemical energy increase of the carbon depositing in the diamond surface by the additive of the B2O3. The synthetic diamond single crystal exhibits a perfect hexahedral shape or cubo-octahedral shape or octahedral shape. In the system of the Fe Ni Mn Co-C-B2O3, we think that the catalyst activity decreases with the generation of CO2, so high-quality diamond single crystal can hardly be synthesized when the content of the B2O3 is more than 3 wt‰ and synthesis time is more than 20 h. However, when the content of the B2O3 is no more than 1 wt‰, the rate of finished products of the low temperature hexahedron diamond will increase significantly. Because the amount of the B2O3 additive is so small, in the syntheses of B2O3-added diamond single crystals, the black areas which appear when B element enters into diamond crystal lattice are not observed. The growth rate of diamond single crystal will be reduced obviously by B2O3-added in synthetic system. Under our system synthesis,when the growth time is 10 h, the growth rate of the diamond will reduce 0.22 mg/h by 2 wt‰ B2O3 added in synthetic system. When the growth time extends to 20 h, the growth rate increases to 0.47 mg/h. Moreover, with the extension of growth time, the catalyst activity decreases continuously with the