【作者】 胡美华；

【导师】 贾晓鹏；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2012， 博士

【摘要】 金刚石是集最大硬度、最大热导率、最小压缩率、最宽透光波段、耐腐蚀等诸多优异性能于一体的极限功能材料，它广泛的应用于工业、科技、国防、钻石行业等领域。金刚石的合成研究有助于我国金刚石生产技术水平的整体提高。金刚石合成分为两大基本的方法，一个是高温高压合成法；另一个是低压气相合成法；其中，高温高压合成方法又分为直接转化法和溶剂法，直接转化法合成条件苛刻，不易控制；溶剂法分为膜生长法和温度梯度法，溶剂法可以大幅度的降低合成的压力和温度，在金刚石合成方面具有明显的优越性。本文分别使用膜生长法和温度梯度法在国产六面顶压机上进行柱状金刚石和多晶种法板状金刚石单晶的合成与研究，实现了柱状和板状金刚石晶体的可控生长，探讨了晶体生长的机理。更多还原

【Abstract】 Diamond is the miraculous materials that exhibit a range of excellent properties,such as the hardest, the highest room temperature thermal conductivity, a broadtransmission spectral range, and inert to all acid and base reagents. Diamond hasbeen used in many fields as industry, scientific research, national defence, medicaltreatment etc. For example, it has been used as an abrasive and cutting tools, heatspreaders for semiconductor laser, high power laser weapon, windows for infrared,anvils of DAC and etc. Among many methods of man made diamond synthesis,solvent method invented by G. E. is also one of effective methods. Catalyst, synthetictechnics, and crystal morphology are always researching topics of diamond industry.How to synthesize crystal with special morphology and expand applications ofdiamond is one of focus.Various transition metals and alloys have been used as catalysts for diamondsynthesis. In the diamond synthesis process under high temperature and highpressure, as the synthesized temperature increases at the constant pressure, themorphologies of the diamond changes from cubic with dominated {100} crystalfaces, cubo octahedral with dominated {100} and {111} crystal faces, to octahedralshapes with dominated {111} crystal faces. When diamond tools made by diamondcrystal with ordinary morphology were used, the phenomenon of “threshing”widespread existed, because the rounded degree of diamond crystals is about1.Chemical bonds are formed between diamond particles and binder, the ratio value ofthe contact area of diamond and binder to exposed area of diamond is small, whichresults that the holding force is small when diamond is walloped and the diamond crystals is easy shed from tools, so the life time of diamond tools become shorter.Changing the diamond crystal morphology by exploiting the novel diamondsynthesis catalyst and updating the synthesis process can increase the holding forceof diamond crystals in the tool matrix, and then the life time of diamond tools isextended. Doctor Liu has synthesized the strip shape diamond using our groupdesigned Fe based and Ni based catalysts, but, the quality and ratio of length toradio can not meet the practical requirements, and we have not a completeunderstanding of the growth mechanism of strip shape diamonds, which need afurther study.A range of excellent properties of diamond can be most vividly shown by thegem diamond crystal (the size is larger than1mm). Sheet shape diamond crystals canbe used as heat spreaders for semiconductor laser and high power laser weapon, thesubstrate of the chemical vapor deposition process for diamond synthesis also needsheet shape diamond; especially, in the high hardness and high precision processingtools, sheet shape diamond crystal is the first choice because of the specialmorphology and minimum amount of cutting. On gem quality diamond synthesistechnology, the cell for diamond growth by temperature gradient method under highpressure and high temperature is usually embedded one diamond seed, and small sizegrowth cell is fit for single seed method for gem diamond synthesis. With thecontinuous development of high pressure technology, the growth cell has beenexpanding, and the only one seed embedded is not meet the actual situation, so, wemust adjust assembly structure to meet the growth of more seeds at the same time.Multiseed method is an effective way to make more crystals grow at the same timeand improve the efficiency of growth cell. But, for the synthesis conditions, it isharsh for the multiseed method for high quality sheet cubic diamonds synthesis.Meanwhile, as the development of industry, people need more and more diamonds.Now, how to improve production efficiency and reduce production costs is one ofthe urgent problems of diamond industry. So, to solve the problems of diamond toolsand increase the synthetic efficiency, it is urgent to expand the types of diamond,synthesize the high quality strip and sheet cubic diamonds, and study the growth mechanism for the controlled growth of diamond crystals.Synthesis and studies on strip shape industrial diamond and multiseed methodgrowth of sheet cubic diamond crystals were performed by optimizing the catalystfor diamond synthesis; improving the synthetic technology and assembly structure ofgem diamond growth.更多还原