合成变石的宝石学特征及紫外-可见光吸收光谱分析

运用紫外-可见光吸收光谱等测试方法对合成变石样品的颜色特征进行了分析,初步研究了合成变石的致色元素及其质量分数对变色效应的影响。分析结果表明:合成变石常见的紫色调现象与吸收光谱中紫区未被完全吸收有关,通过添加少量有利于紫区吸收的致色元素,有望减弱合成变石的紫色调;随着V元素的增加,橙黄区吸收带的分布趋于合理,使红光与绿光的透过更趋平衡,有利于产生较理想的变色效应;合成变石的紫外-可见光吸收光谱与其结晶学方向有密切关系,(001)方向的吸收光谱在橙黄区有强吸收带,具有明显的变色效应特征,(100)和(010)方向虽有强二色性,但对变色效应贡献不大。

Analysis on Gemmological Characteristics and Ultraviolet-Visible Spectrum of Synthetic Alexandrite

The colour characteristic of synthetic alexandrite samples are analysed by the ultraviolet-visible spectral analysis. The influence on colour change effect by the colouring elements and their contents are primarily studied. The results indicate that the common violet tone of synthetic alexandrite is related to the incomplete absorption of absorption spectrum in the violet region, which could be weaken by joining a few colouring elements that redound to absorption from the violet region.The absorption band in the orange-yellow region could distribute rationally by increasing the vanadium element which balances the permeation of light between the red region and green region for perfect colour change effect. The UV-VIS spectrum of synthetic alexandrite has the great relationship with the crystallography direction. The absorption spectrum of sample in the direction of (001) has a strong absorption band in the orange-yellow region where the sample has the obvious characteristics of colour change effect.In the directions of (100) and (010), the sample has strong dichroism, but the colour change effect is not obvious.