Ia型褐色金刚石高温高压改色实验研究

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	Ia型褐色金刚石高温高压改色实验研究
	常娜
导师	刘永刚
	2013
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位名称	硕士
学位专业	矿物学、岩石学、矿床学
关键词	“ia型褐色金刚石高温高压实验改色处理六面顶压机红外光谱吸收光谱激光拉曼光谱紫外荧光三维荧光光谱”
摘要	Ia型金刚石是世界上最重要的金刚石种类，约占金刚石总量的98%。利用大腔体压机通过优化温度、压力和时间等因素改善工业用途的Ia型褐色金刚石的体色，是提高其经济价值并满足日益加剧的彩色金刚石市场需求的重要技术手段。但由于受金刚石原料的来源及实验技术条件的限制导致国内高温高压环境下对褐色金刚石的改色处理进展缓慢。本文对自上世纪60年代以来国内、外对Ia型金刚石高温高压（HTHP）改色处理的研究及所取得的成果进行了总结。已有的研究显示在伴有塑性变形的基础上，不同结构的杂质氮是主要的致色元素。根据高温高压环境下Ia型褐色金刚石内部杂质氮反应原理以及动力学机理，提出只要设计合理的样品组装方式以及恰当的改色处理所需的温压条件，我国普遍使用的六面顶压机同样具备对Ia型褐色金刚石进行商业化改色处理的潜力。本次研究主要利用中国科学院地球化学研究所高温高压实验室JL-3600t紧装式六面顶压机对11颗Ia型褐色金刚石进行了高温高压（HTHP）下的改色实验探索。通过金刚石稳定区和非稳定区的实验研究，我们发现在金刚石稳定区处理后的金刚石样品可以保持较好的完整性，新增裂隙、裂痕的几率较小，表面无石墨化痕迹，样品体色的褐色调可以减弱，透明度得到提高；在金刚石非稳定区处理后的样品，完整性较好，新增裂隙几率较小，表面容易发生石墨化现象，整体褐色调稍有减弱，个别样品有微弱的绿色调出现。并对实验前后的样品进行红外吸收光谱、激光拉曼光谱、紫外荧光、三维荧光光谱特征的分析对比，得出实验样品在高温高压环境下金刚石类型不发生变化，但C-H峰被破坏并且因内部杂质氮原子的变化致使样品荧光强度增强。由此表明高温高压实验对Ia型金刚石内部非C-C键结构具有明显的影响，并指出在六面顶压机的基础上进一步提高实验的压力，拓展实验温度有利于实现将Ia型褐色金刚石改色达到宝石级的最终目的。
其他摘要	Type Ia diamonds are the most important diamonds in the world, accounting for approximate 98% of the natural diamonds. The body color of type Ia brown diamonds can be enhanced through optimizing the operational factors of large-volume press such as temperature, pressure and time. Thus, high temperature and high pressure (HTHP) treatment is an important technical approach for obtaining colored diamonds to increase their economic value and meet the needs of the market. However, only slow progress has been made in the HTHP research of brown diamonds in China, because of the limited sources and experimental conditions. Few diamonds of type Ia can reach the gem grade after HTHP treatment. In this thesis, the domestic and international achievements of type Ia diamonds under HTHP treatment are reviewed since the 1960s. Previous researches showed that the plastic deformation and the different structure of nitrogen impurity in diamonds are the major factors affecting colour alteration process of the type Ia diamonds. According to the reaction principle and kinetic mechanism of internal nitrogen impurity in the type Ia diamonds under HTHP conditions, with reasonable design for assembly and proper temperature-pressure conditions, the widely used cubic-anvil apparatus in china should have the potential to improve the color of type Ia diamonds. In this thesis, eleven brown diamonds of type Ia are chosen as samples for HTHP treatment on JL-3600 ton cubic anvil apparatus at Geochemistry Institute. According to the experimental results, we found the samples treated in diamond stable region can keep better integrity and less new fractures. The samples’ surface do not have graphitization traces. Not only body color of these brown samples can be reduced, but also transparency of them can be improved. Diamond samples treated in the unstable region still have good integrity and risk of increased fracture is small. The surface graphitization of of these diamonds occurs easily. The brown tone of samples is slightly reduced and individual sample shows slightly green color. The spectroscopic characteristics of Infrared, Raman, Fluorescence and 3-D Fluorescence of these brown diamond samples are also checked before and after HTHP treatments respectively. Experiment results showed that the type of these diamonds are not changed after HTHP treatment, but the C-H bonds in them were damaged and the structure of impurity nitrogen atoms in samples are also changed on some extend. It suggests that high temperature and high pressure experiments have effects on internal structure of non-C - C bonds. Finally, we point out that expanding P-T ranges of HPHT experiments on cubic-anvil apparatus is a beneficial way to achieve gem grade diamonds if the type Ia brown diamonds are used as the initial samples.
学科领域	地球深部物质与流体作用地球化学
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/5822
专题	研究生_研究生_学位论文
推荐引用方式 GB/T 7714	常娜. Ia型褐色金刚石高温高压改色实验研究[D]. 北京. 中国科学院研究生院,2013.

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