缅甸抹谷紫方钠石光致变色效应脱色效率研究

Study of decoloration efficiency of photochromism in hackmanite from Mogok,Myanmar(Burma)

光致变色效应是紫方钠石最显著且极具价值的光学特征。本文通过EDXRF、FTIR、UV-VIS-NIR、D65标准光源、照度计以及色度学方法,对缅甸抹谷紫方钠石光致变色效应脱色效率进行了定量研究。紫方钠石的主量元素为Na、Al、Si和O,此外含有少量Cl和S,微量元素可含Ca、K和Fe, UV-VIS-NIR光谱存在472、540和667 nm的3个吸收峰,其中以540 nm吸收强度最大,脱色过程中,其光谱吸收峰峰位不变,但强度随时间逐渐减小,540 nm吸收峰面积在0~80 s与时间呈线性负相关(R^(2)=0.99);脱色过程中,当照度从5 000 lx升高至30 000 lx时,紫方钠石脱色效率明显升高,明度L^(*)升高,彩度C^(*)降低,色品a^(*)降低且色品b^(*)升高,色调由紫色向粉色调轻微变化,是电荷转移导致F中心被破坏的直接结果。

Photochromism is the most significant and valuable optical characteristic in hackmanite.EDXRF,FTIR,UV-VIS-NIR,D65 standard light source,illuminator and colorimetry method were applied in this paper to study the decolortation efficiency of photochromism in hackmanite from Mogok,Myanmar(Burma).The results indicated that the major elements of hackmanite are Na,Al,Si,O,Cl and S,its trace elements should include Ca,K and Fe.There are three absorption peaks of 472,540 and 667 nm in UV-VIS-NIR spectrum,with 540 nm having the stron-gest absorption peak.The peaks stay stable but their intensity decrease with time during decoloration.The absorp-tion peak area of 540 nm is significantly negative corelated with time during 0~80 s(R^(2)=0.99).The decoloration efficiency grows significantly when the luminance increases from 5000 lx to 30000lx.During decoloration,the lightness of hackmanite color increases,while its chroma decreases.The color parameter a^(*)decreases and b^(*)increase.Its hue turns from purple to pink slightly.All the color effect of photochromism in hackmanite is a direct result of charge transfer leading to the destruction of the F center in hackmanite.