【作者】 李尚升；

【导师】 贾晓鹏；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2009， 博士

【摘要】 本文是利用温度梯度法在国产六面顶压机上进行优质Ⅱa型宝石级金刚石单晶的合成研究。在稳定性实验组装确立后,提出了调整温度梯度的新方法。在此基础上,对除氮剂Al或Ti(Cu)分别在NiMnCo触媒和FeNiCo触媒中合成Ⅱa型宝石级金刚石的生长特性与机理进行了详细研究,取得结果如下:1.针对Φ14mm和Φ10mm两种腔体组装,通过二者高温高压下长时间稳定性及叶蜡石内部高温处温度的比较,实验确定Φ10组装来生长Ⅱa型宝石级金刚石。2.实验在已有传统调节温度梯度方法的基础上,首次提出了新方法——特型石墨管的使用。3.选用Al作除氮剂、NiMnCo或FeNiCo作触媒,分别研究了在这两种添加Al的触媒中Ⅱa型宝石级金刚石的生长特性。通过在FeNiCo触媒中添加AlN,首次验证了高温高压下合金触媒中AlN的分解,进而全面分析了Al在合成宝石级金刚石中的除氮机理。4.选用Ti(Cu)作除氮剂、NiMnCo或FeNiCo作触媒,分别研究了在这两种添加Ti(Cu)的触媒中Ⅱa型宝石级金刚石单晶的生长特性。优化生长工艺沿{111}面合成出尺寸达4.3mm的无色优质Ⅱa型宝石级金刚石大单晶。5.本文详细研究了在生长Ⅱa型宝石级金刚石过程中所产生的黑色微晶石墨粉末对金刚石晶体生长的影响及其产生机理。改进生长工艺消除微晶石墨对金刚石生长的影响,实验沿{100}面合成出尺寸达3.4mm的无色优质Ⅱa型宝石级金刚石大单晶。6.将除氮剂Ti(Cu)添加到FeNiCo触媒中采用多晶种法合成出尺寸在2mm左右的优质Ⅱa型宝石级金刚石单晶。更多还原

【Abstract】 High-quality large diamond crystals have been synthesized by temperature gradient method (TGM) under high pressure and high temperature (HPHT) in China-made cubic anvil high-pressure apparatus in this paper. After ascertaining the stability assembly of the experiments, the new method of the adjusting temperature gradient was put forward. The growth traits of typeⅡa large diamonds, which have been synthesized in the NiMnCo or FeNiCo with the additive of Al or Ti (Cu) as a nitrogen getter on the basis of above works, were researched. The conclusions of the research are as follows:1. As to both assembly whose diameter of the bath areΦ14mm andΦ10mm, the assembly ofΦ10mm has been ascertained to grow typeⅡa large diamonds by the stability of long time under HPHT and the compare of the temperature in the high temperature of the pyrophyllite.2. The new method of the adjusting temperature gradient, which was the use of special shape graphite tube, was put forward firstly on the traditional methods of the adjusting temperature gradient.3. While Al as a nitrogen getter was added into the NiMnCo or FeNiCo. the growth traits of typeⅡa large diamonds in the both alloy solvent were investigated respectively. The decomposition of A1N in the alloy solvent under HPHT was firstly validated then the mechanism of Al for eliminating nitrogen in synthesizing large diamonds was analysed entirely by A1N added into FeNiCo solvent.4. While Ti (Cu) as a nitrogen getter was added into the NiMnCo or FeNiCo. the growth traits of typeⅡa large diamonds in the both alloy solvent were investigated respectively. The colorless high quality typeⅡa large diamond crystal whose size is 4.3mm was synthesized by optimizing the growth process.5. The effect of black micro-crystal graphite on the crystal growth and the producing mechanism of micro-crystal graphite, which was producing in the course of growing typeⅡa large diamonds, have been researched.6. While Ti (Cu) as a nitrogen getter was added into FeNiCo, the high quality typeⅡa large diamond crystals whose size is about 2mm were synthesized by multiple seeds method.更多还原