【作者】 秦作路；

【导师】 马红艳；

【作者基本信息】 广西大学 ， 化学工艺， 2007， 硕士

【摘要】 本文从矿物学，宝石学的角度出发，采用多种现代测试手段，对我国淡水珍珠进行研究，揭示了珍珠结晶层生物矿化特征的内在本质，尤其是在珍珠矿物组成，空间分布，结构特征方面有了一定的认识。利用红外光谱证实了在淡水无光珠中存在球文石。球文石是碳酸钙的同质多象变体，最不稳定，很少在自然界出现。球文石是降低淡水珍珠品质的主要内在因素之一，其含量越高，淡水珍珠质量越差。对不同颜色的优质淡水养殖珍珠进行激光拉曼光谱的研究，并试图从中找出珍珠的颜色以及其中的有机物和拉曼光谱的关系。结果发现，和纯白色系列优质珠相比，粉红色系列优质珠多了1134及1526cm^-1两个峰；紫色系列优质珠中的1017，1295，2231，2609cm^-1在纯白色珍珠和粉红色系列中均未曾出现；在有色珍珠中探测到某有机物的拉曼峰：由C—C伸缩振动引起的1121，1134cm^-1及C=C伸缩振动引起的1503，1526cm^-1，推测此有机物为聚乙炔类物质，不同于以前的研究者所认为的类胡萝卜素。不同色系的珍珠，其拉曼光谱有着明显的区别；随着同色系颜色的加深，有机物拉曼谱峰的强度也越来越强，说明颜色和有机物密切相关。原子力显微镜和扫描电镜观察。利用原子力显微镜（AFM）结合传统的扫描电镜（SEM）观察不同质量的珍珠表面，在微米级至纳米级的范围内对珍珠表面进行了超显微结构特征分析，探讨SEM下无法涉及的珍珠纳米级表面结构与珍珠物理特性（光泽度、粗糙度、伴色）之间的相关性。研究显示，珍珠等级与文石层、文石微层、文石板块及其内部文石集合体有序度、致密度等均呈正相关关系。偏光显微镜观察发现优质珍珠和劣质珍珠镜下特征不同。优质珍珠镜下均匀洁净，无色或极淡的黄色。单偏光下为致密的同心纹层结构。劣质珠镜下较脏，黄褐色，大圈层结构明显，核心处可见到放射状或粒状碳酸钙晶体组成，为文石相。优质珍珠内核在单偏光显微镜下存在较薄的棱柱层，此棱柱层在正交偏光显微镜呈平行消光，由此可确定棱柱层矿物为文石。更多还原

【Abstract】 With the angle of mineralogy and geomology comprehensive and systematic studies and freshwater pearls from China have been made by means of various modern testing methods. The results show that the main inner factors affecting the quality of pearl（colors, transparency, luster） are the arrangement way of mineral ,the grain size of mineral, the space distribution of mineral and the characteristics of mineral.By optical microscope, vaterite , a very unstable polymorphism of calcium carbonate, which rarely appears in nature, has been discovered. This paper describes the microscope characteristics of vaterite in lusterless freshwater pearls. The content of vaterite is one of the main inner factors which affects the quality of freshwater pearls.Raman spectrum is applied to freshwater cultured pearl of good quality with different colors. It’s expected to find the relationship between colors, organic substance inside of pearl and Raman spectrum. The conclusions were as follows: the wavenumbers, 1134 and 1526cm^-1,only appeared in the Raman spectrum of red pearls, compared with the Raman spectrum of white pears; the Raman shifts which were found in Raman spectrum of violet pears, 1017, 1295, 2231 and 2609cm^-1, disappeared in the Raman spectrum of white and red pearls; the Raman shifts of certain organic compound, 1121, 1134cm^-1 of C—C wavenumbers and 1503, 1526cm^-1 of C = C wavenumbers , appeared in colored pearls and the organic substance was considered as polyacetylenic materials but not carotenoids which was proposed by previous researchers. Pearls with different colors obviously vary with Raman spectrum. More deeply the same color becomes, more stronger the Raman spectrum of organic substance is.Using AFM and traditional SEM , the authors studied the super-microscopic structure of pearls from micron- size to nanometer- size by observing the surfaces of pearls with different qualities , and discussed the correlation between the nanometer- size surface structure invisible with SEM and the physical properties （luster ,roughness and concomitant color） of pearl. The research shows that the grade of pearl has a positive correlation with ordering and compactness of layers , micro-layers , blocks and aggregates of aragonite.It is different between good pearls and poor pearls under Optical Microscope. Good quality pearls are mostly clean, no colors or very weak yellow. But poor quality pearls are dirty, snuff colors and have obvious circle texture. The prism layer in core of good pearl, appears under optical microscope and has parallel extinction under cross-section microscope. So it is considered to be aragonite.更多还原