扬子克拉通西部金刚石的表面形貌特征及其振动光谱研究

Study on the Surface Morphology and Its Vibrational Spectra of Diamond From the Western Yangtze Craton

基于金刚石表面形貌的研究,有可能为反演金刚石的形成环境及为金刚石的合成工艺设计提供科学线索。采用光学显微镜、红外光谱、拉曼光谱对扬子克拉通西部的天然砂矿金刚石表面形貌与杂质氮、氢含量及有序度的关系研究结果表明,金刚石的表面形貌包括与晶体生长相关的微形貌、与晶体定向相关的熔蚀形貌、与晶体定向无关的熔蚀形貌及与应力形变相关的形貌等四大类;金刚石以IaAB型为主,氮含量介于22.90~752.40μg·g^(-1)之间,绝大部分样品的sp^(3)杂化C—H键浓度含量高于sp^(2)杂化C—H键,氢杂质的存在有利于A氮心向B氮心转变;sp^(3)杂质C—H键的存在对金刚石表面出现的形貌类型可能不会造成实质性的影响,但极利于形成熔蚀坑;各种表面形貌的存在都会降低金刚石的表面有序度,但发育晕线者的表面有序度相对最高,而发育三角形生长片层者表面有序度最低。

Based on the possibility to provide scientific clues for the inversion of diamond formation environment and the design of the diamond synthesis process,the paper studied the relationship between the surface morphology,the content of impurity nitrogen and hydrogen and the degree of order in structure of natural placer diamonds from the western Yangtze Craton by using the optical microscope,infrared spectroscopy and Raman spectroscopy.The results show that the surface morphology on diamond includes micro-morphology related to crystal growth,ablation morphology depend on crystal orientation,ablation morphology independ on crystal orientation,and morphology related to stress deformation.The diamonds mainly belong to type IaAB and the nitrogen content in them is 22.90~752.40μg·g^(-1).The concentration of sp^(3) hybridized C—H bond is higher than of sp^(2) hybridized C—H bond in most of the samples,that indicated the existence of hydrogen was conducive to transformation from the A nitrogen center to B nitrogen center in diamond and the sp^(3) hybridized C—H bond may result in the formation of corrosion pits and affect slightly the others morphology of the diamond surface.All of the surface morphologies would lower the degree of order of diamond.The degree of surface order was the highest in diamond with halo and the lowest in diamond with growth lamella.