人工合成翡翠及其宝石学特征的研究

发布时间：2018-09-01 10:16

【摘要】：在翡翠宝石学研究中,合成翡翠是较少被详细研究的领域。本文在运用固相烧结法将化学原料粉末通过烧结制备合翡翠样品的基础上,详细研究了溶胶-凝胶法制备合成翡翠粉体原料的工艺,通过正交实验得出了最佳工艺条件,同时进行了后续的高温烧结和再烧结实验制备合成翡翠样品的工艺研究。采用常规的宝石学研究方法、X射线粉末衍射、扫描电子显微镜、红外光谱、热重-差热、吸收光谱及色度学测试等现代测试技术,对合成翡翠样品的粉体制备工艺、烧结工艺以及其矿物宝石学特征进行了系统的研究和分析。实验结果表明,固相烧结法制得的合成翡翠样品内部具有大量形状不规则的孔洞,孔洞直径较大。固相烧结法制得样品的元素含量百分比与硬玉接近,样品中形成A1203与Si02的混合结构,致色元素进入晶格而使样品呈显出不均匀的绿色-紫粉色。溶胶-凝胶法制备合成翡翠粉体原料的最佳工艺条件为：金属醇盐浓度1.0mol/L,去离子水的添加量(H2O/[Si]摩尔比)为20：1,pH值为2,水浴温度为60℃C,致色剂含量为0.75wt%。各因素对合成翡翠粉体原料的制备结果影响程度的次序为：pH值金属醇盐浓度和水浴温度去离子水的增加量致色剂硝酸铬的含量。通过溶胶-凝胶法最佳工艺条件制得的合成翡翠粉料是良好的合成翡翠前驱体。溶胶-凝胶法制得的粉体原料经高温烧结后制得合成翡翠样品,其外观多呈深绿色,且含有大量孔洞。这是由于部分杂质元素氧化为气体未能挥发而残留在样品内形成的,实验结果指出添加助熔剂后孔洞会变少。同时结果也表明溶胶-凝胶法制得的粉体原料在其结晶温度1000℃C时再次保温,会得到霞石(NaAlSiO4)结构,而非硬玉结构,这是由于硬玉是典型的高压矿物,在常压下是一种亚稳态,易分解为NaAlSiO4和Si02,即NaAlSi2O6 →NaAlSiO4+SiO2。通过比较溶胶-凝胶法合成翡翠样品与固相烧结法合成翡翠样品的颜色外观、基本宝石学性质以及物相组成与结构等,表明溶胶-凝胶法较固相烧结法更适合制备合成翡翠。为了达到实验效果,在烧结实验的基础上进行了溶胶-凝胶法合成翡翠的再烧结实验。结果表明再烧结样品的致密度明显提高,内部具分布均匀的细小孔洞,样品呈现黄绿色,颜色饱和度较高,明度略低。再烧结样品内可析出NaAlSiO4晶体,其元素的含量百分比与硬玉基本相同,且红外光谱与硬玉类似,但合成者的吸收带宽化且分裂较差。
[Abstract]:In the research of jadeite gemstone, synthetic jadeite is seldom studied in detail. In this paper, based on the preparation of jadeite powder by solid phase sintering, the process of synthesizing jadeite powder by sol-gel method is studied in detail. The optimum technological conditions are obtained by orthogonal experiment. At the same time, the process of synthesizing jadeite samples by high temperature sintering and re-sintering was studied. The preparation technology of jadeite powder was studied by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM), infrared spectroscopy (IR), thermogravimetric differential thermogravimetry (TG-DTA), absorption spectrum and colorimetry. The sintering process and its mineral gemstone characteristics were systematically studied and analyzed. The experimental results show that there are a large number of irregular holes in the samples of synthetic jadeite by solid phase sintering, and the diameter of the pores is large. The percentage of elements in the samples obtained by solid-phase sintering method was close to that of jadeite. The mixed structure of A1203 and Si02 was formed in the samples. The chromizing elements entered the lattice and made the samples appear inhomogeneous green and purple pink. The optimum conditions for the preparation of jadeite powder by sol-gel method are as follows: the concentration of metal alcohol is 1.0 mol / L, the molar ratio of deionized water (H2O/ [Si]) is 20: 1 (pH = 2), the water bath temperature is 60 鈩，

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