新型TiO2镀膜坦桑石特征分析

Characteristic Analysis of A New Type of Coated Tanzanite

近几年,随着坦桑石在国内市场不断升温,其价格也-路攀升,对坦桑石的优化处理技术也因此逐 步出现在市场中.针对日常检测中发现的镀膜坦桑石,采用常规宝石学测试、放大观察、化学成分分析以及谱 学特征分析等进行系统研究.结果表明,该类样品为亭部经TiO2 镀膜的坦桑石,膜层厚度约为48nm. 放大 观察可见其亭部光泽明显强于冠部,膜层的脱落区域大小不等、多为不规则状,尤其在棱线交汇处脱落明显; 经 XRF半定量测试分析,亭部 Ti含量较高,可达3.5%,经 XPS测试分析, Ti的原子态价为＋4 ,可以判断膜 层的成分为TiO2;紫外-可见光光谱显示,与天然坦桑石不同,由于膜层的存在,样品冠部出现350 nm宽峰, 亭部不仅出现350 nm宽峰,还出现255 nm谱峰.故采用多方法综合分析,可对此类镀膜坦桑石进行准确鉴定.

Gemmological tests , microscopic examination, chemical and spectroscopic analysis were used to study a new type of coated tanzanite. The results confirmed th at the tanzanites were Ti02 coated which the coat was on the pavilion and the thickness was about 48 nm. The samples showed some areas had abrasions on the pavilion facets and especially on the junc-tions by microscopic examination. Chemical analysis showed that the composition of the coat is Ti02 and the content of Ti can reach to 3. 5%. Different from natural tan zani tes , a band of 350 nm on the crown and a band of 350 nm as well as 255 nm band on the pavilion can be ob-served by using ultraviolet visible spectroscopy （UV-Vis） because of the coats. The results showed that this kind of coated tanzanites can be identified by using multiple methods.