摘要
以焰熔法合成无色蓝宝石为基体、采用Fe和Ti化合物为渗色剂、在超高温条件下进行扩散处理的合成蓝宝石近期出现在国内外珠宝市场上。采用EPMA，FTIR，UV—VIS等分析测试方法，对扩散处理合成蓝宝石的宝石学特征及其扩散机制进行了测试与研究。结果表明，扩散处理合成蓝宝石渗层的主要化学成分ω（FeOT）为1．69％～1．02％，ω（TiO2）为0．57％～0．39％，其横断面上FeOT和TiO2化学配比极不均匀，化学成分自外向内呈现较明显的分带现象；Fe^2＋／Ti^4＋荷移是导致扩散处理合成蓝宝石中VIS吸收光谱b带（573-578nm）形成并呈色的主要原因，当ω（FeOT）：ω（TiO2）≤3：1时，有利于维持渗层中Fe^2＋／Ti^4＋荷移的基本配比关系，从而形成蓝色渗层；扩散处理合成蓝宝石的红外吸收光谱中，一组由v（OH）伸缩振动致红外吸收弱谱带分别出现在3371，3309，3231cm^-1处，并伴有v（NH）伸缩振动致3186cm^-1红外吸收弱谱带；此外，扩散处理合成蓝宝石的刻面上残留不规则的网状淬火裂纹及热蚀凹坑，内部存在气泡或气泡群，在SW下发出强度不等且不均匀的蓝白色荧光。研究认为，扩散处理合成蓝宝石中Fe^2＋和Ti^4＋离子的微观扩散迁移作用受控于表层空位迁移能、空位扩散系数及空位浓度梯度。
A new type of synthetic sapphire with diffusion treatment has recently appeared on gem markets, which is treated from the flame fusion synthetic colourless sapphires by the diffusion with the compound of iron and titanium at super-high temperatures. The gemmological characteristics and diffusion mechanism of diffusion-treated synthetic sapphire are investigated in depth by using EDMA, FTIR, UV-VIS and so on. The results show that the main chemical compositions of infiltrated layer of the diffusion-treated synthetic sapphire consist of w（FeOT）=1. 69%-1.02% and w（TiO2）=0. 57%-0. 39%, which are not well- distributed on transection and the chemical compositional zoning occurs from the surface to the interior of the samples. The colouration of the diffusion-treated synthetic sapphire is mainly attributed to b band（573 to 578 nm） among the VIS absorption spectra, which results from the charge transfer of Fe^2＋/Ti^4＋. When the ratio of w（FeOT） · w（TiO2 ） is less than 3 ： 1, it is suitable for keeping the charge transfer of Fe^2＋/Ti^4＋ to form the blue infiltrated layer. A group of weak FTIR absorption bands at 3 371, 3 309, 3 231 cm^-1 are attributed to the v（OH） stretching vibration, and the weak absorption band at 3 186 cm^-1 is attributed to the v（NH） stretching vibration. The irregular net-like quenched cracks and etching hollows by the high temperature exit in the surface of some samples and a few of gas bubbles exit in the interior. The samples are uneven bluish white fluorescence under SW ultraviolet. The research indicates that the micro-diffusion transference of Fe^2＋ and Ti^4＋ ions in the diffusiontreated synthetic sapphire is controlled by vacancy transference energy, vacancy diffusion coefficient and vacancy concentration gradient.
出处
《宝石和宝石学杂志》
CAS
2006年第3期4-9,I0001,共7页
Journal of Gems & Gemmology
