【摘要】 以新疆阿尔泰矿区的粉红色、绿色和褐绿色电气石晶体为研究对象,通过X射线荧光光谱仪、分光光度计分析了电气石的晶体结构,并对电气石晶体退火处理前后200～3300nm吸收光谱进行测定。结果表明:粉红色电气石的呈色与Mn3+的d电子跃迁有关,产生的吸收带有390,450nm和517nm;电气石的绿色调主要与交换耦合Fe3+-Fe3+离子对间的电荷转移形成的420nm吸收带和Fe2+-Fe3+离子对间的电荷转移形成的718nm吸收带有关;电气石晶体中,羟基伸缩振动(O-Hstr)引起的强吸收带在3800～3400cm-1,羟基与金属离子配位构成M-OH的伸缩和弯曲联合振动,在4800～4000cm-1产生5～6个吸收带,而羟基伸缩振动的第1倍频引起的吸收带则出现在7300～6700cm-1;在高温下,-(OH)(3)基团上的H+发生脱离,并与W晶格位置上的O2-发生键合形成-OH(1)基团。电气石晶体的结构式可简化表示为XY3Z6(Si6O18)(BO3)3(OH)3·(O2-,OH,F)。更多还原

【Abstract】 Pink,green and brownish green tourmalines from the Altay deposit in Xinjiang,China were selected for this research. The crystal structure of the tourmaline and optical absorption spectra(200–3 300 nm) before and after annealing were analyzed by using ultraviolet–visible near infrared spectrometry. The results show that the pink color of tourmaline originates from the d-electron transition of Mn3+,which produces 390,450 and 517 nm absorption bands;the green color is mainly attributed to charge transfers between exchange coupling Fe3+–Fe3+ ion pairs and Fe2+–Fe3+ ion pairs,which produce 420 and 718 nm strong absorption bands respectively. As for the absorption bands in the near infrared region,the bands in the range of 3 800–3 400 cm–1 are attributed to hydroxyl stretching modes,the bands in the range of 7 300–6 800 cm–1 are attributed to the first fundamental overtone of hydroxyl stretching modes. The bands in the range of 4 800–4 000 cm–1 are attributed to the combination of stretching and bending modes of cationic hydroxyl units. H+ is divorced from the —OH(3) groups at high temperatures and then bonds with O2– at the W-site,which generates new —OH groups. In addition,tourmaline crystal can be represented by the structural formula XY3Z6(Si6O18)(BO3) 3(OH) 3·(O2–,OH,F) .更多还原