绿色合成碳硅石的宝石学特征研究

Gemmological Characteristic of Green Synthetic Moissanite

  • 摘要: 合成碳硅石作为第三代半导体材料, 由于其卓越的导热性和半导体性能,在新能源、新材料及航空航天等工业领域受到广泛关注与应用。此外,浅黄色及浅绿色者因其具有高硬度、高折射率及高色散值等优良属性,常常被应用于国内外珠宝市场,并一度被认为是钻石最好的替代品。然而,针对绿色合成碳硅石的研究存在较大空缺。因此,为丰富合成碳硅石的宝石学资料及科学意义,本研究采用宝石显微镜、衰减全反射红外光谱仪、紫外-可见分光光度计、显微激光共聚焦拉曼光谱仪等大型仪器对绿色合成碳硅石样品的常规宝石学特征、致色成因及谱学特征进行了系统研究。结果表明,绿色合成碳硅石呈现金刚光泽,折射率大于1.78,相对密度约为3.22。红外吸收光谱分析显示,绿色合成碳硅石样品主要为Si-C伸缩振动,成分比较纯净,但存在一定的晶格缺陷。紫外-可见吸收光谱表明,样品中N元素的浅施主能级是其呈色的主要原因。激光拉曼光谱结果揭示,绿色合成碳硅石样品主要为6H型,少数为15R型。由于杂质元素浓度、成分不均,结构稳定性降低,从而导致样品呈6H-15R多型混合结构。

     

    Abstract: Synthetic moissanite, as the third-generation semiconductor material with excellent thermal conductivity and semiconductor properties, has been widely recognized and applied in industrial fields such as new energy, new materials, and aerospace, etc. Additionally, the light yellow, and light green synthetic moissanites with high hardness, high refractive index, and high dispersion value widely used in domestic and foreign jewelry markets was once considered to be the best substitute for diamonds. However, there are less investigations on green synthetic moissanite. In this paper, the gemmological characteristics, colour genesis, and spectral characteristics of green synthetic moissanite samples were systematically studied using gem microscopes, infrared spectroscopy, UV-Visible spectroscopy, and laser Raman spectroscopy, in order to enrich the gemmological data of synthetic moissanite. The results show that the green synthetic moissanite samples are adamantine luster, refractive index above 1.78, and the specific gravity about 3.22. The infrared absorption spectroscopy analysis mainly shows Si-C stretching vibrations with relatively pure composition and partial lattice imperfections. The UV-visible absorption spectroscopy shows that the superficial donor energy level of N element is the main factor for moissanite's color. Moreover, the laser Raman spectroscopy reveals that the green synthetic moissanite samples are mainly 6H type accompanied by minor 15R type. Moissanite samples being 6H-15R polytype mixed structures are attributed to the concentrations of impurity elements and the uneven compositions which reduced the structural stability.

     

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