掺杂Mn^(2+)软玉尾矿玻璃的制备及谱学特征

Preparation and Spectral Characteristics of Mn^(2+)Doped Nephrite Tailings Glass

软玉又称和田玉,是我国使用最早的一种天然玉石材料,深受国人喜爱。2008年北京奥运会的“金镶玉”奖牌,让全世界重新认识了中国元素,认识了和田玉,人们再一次兴起了对和田玉的追捧,市场需求量增加的同时导致尾矿堆积如山,在一定程度上,不仅浪费土地资源而且污染环境。开展软玉尾矿的高价值利用研究具有重要的理论与实际意义。软玉的主要矿物成分为透闪石,其化学式为[Ca_(2)Mg_(5)Si_(8)O_(22)(OH)_(2)],是一种典型的双链硅酸盐,可作为硅酸盐体系玻璃的重要天然矿物原料。采用熔融法将原料加热到1500℃保温2 h,取出熔融体倒入铁制模具中,然后在600℃中退火2 h,最后得到软玉尾矿玻璃。随着MnO含量的增加,软玉尾矿玻璃颜色逐渐加深,主要色调为棕黄色,透明,玻璃光泽,内部干净,无裂纹,折射率和介电常数逐渐减小,相对密度逐渐增大。采用傅里叶变换红外光谱、拉曼光谱和紫外-可见光谱等测试技术获取了掺杂Mn^(2+)软玉尾矿玻璃的光谱学特征,并探讨了Mn^(2+)含量对软玉尾矿玻璃品质和颜色的影响。结果表明:掺杂Mn^(2+)软玉尾矿玻璃的红外光谱和拉曼光谱都出现了与气体分子有关1370和1500 cm^(-1)附近的谱峰;MnO含量为1%,样品Tb-3的红外光谱在450~500 cm^(-1)范围振动谱峰明显强于其他三个样品,拉曼特征峰最强,红外光谱和拉曼光谱出现差异,说明随着Mn^(2+)含量的增加,软玉尾矿玻璃的颜色加深,透明度降低,其内部结构中Si-O键能先增强然后减弱,当MnO含量为1%时,内部结构最致密。结合软玉尾矿化学成分和紫外-可见光谱分析,软玉尾矿玻璃的棕黄色,主要与Fe和Mn元素有关。由Fe^(2+)-Fe^(3+)对产生的电荷转移使得可见光在蓝紫区(400~460 nm)产生吸收峰,Mn^(2+)的最外层d-d电子跃迁使得可见光蓝绿区(480~550 nm)产生一宽吸收带,致使可见光中黄橙区透过率比较好,从而形成了棕黄色。研究基本确定了掺杂Mn^(2+)软玉尾矿玻璃的制备工艺和谱学特征,探讨了其应用前景,为软玉尾矿高价值利用提出了科学方向,具有重要的理论研究意义和应用价值。

Nephrite,also known as He tian Yu,is one of China's earliest and most popular natural jade material.Thanks to China's element connoted in the“Jin Xiang Yu”gold medal used in the 2008 Beijing Olympic Games,the jade has been re-understanding by people and shows increasing demand in the market.As a result,more nephrite has been exploited with more tailing produced,leaving the situation of resource wasting and environmental pollution.Therefore,it is of great theoretical and practical significance to the high-value utilization of nephrite tailings.The main mineral composition of nephrite is tremolite,with ideal crystal formula of[Ca_(2)Mg_(5)Si_(8)O_(22)(OH)_(2)].It is a typical double-chain silicate,which can be used as an important natural raw material for silicate glass.The nephrite glass was obtained by firstly melting the raw material at 1500℃for 2 h,then pouring the melt into an iron mould immediately and finally annealing at 600℃for 2 h.Results showed that with the increase of MnO content,there was a deepening tendency in color of the tailings glass to brownish yellow,transparent,glass luster,clean inside,no crack,refractive index,and increasing tendencies in dielectric content and relative density.Four nephrite tailings glass samples with spectral characteristics were investigated by XRF,FTIR,Raman spectrometer and UV-Vis-NIR spectrometer,and the effects of Mn^(2+)content on the quality and color of nephrite tailings glass were discussed.The results show that the spectral peaks near to 1370 and 1500 cm^(-1)in both infrared and Raman spectra were attributed to the gas molecules dissolved in nephrite tailings glass melt;When the content of MnO is 1%,the infrared spectra of sample Tb-3 is in the range of 450~500 cm^(-1),and the peak intensity of vibration spectrum is significantly stronger than that of the other three samples.The difference between infrared and Raman spectra indicates that the energy of the Si-O bond in the internal structure of Mn^(2+)nephrite tailings becomes stronger firstly and then weaker,leading to the densest internal structure at MnO of 1%.Compared the chemical composition and UV-vis-NIR spectra with the results of chemical analysis,it is suggested that the color of nephrite tailings glass is due to the combination of Fe and Mn elements.The charge transfer generated by Fe^(2+)-Fe^(3+)pair makes the blue-violet region(400~460 nm)produce a wide absorption band,and the outermost d-d electron jump of Mn^(2+)makes the blue-green region(480~550 nm)produce a wide absorption band generating the transmittance in the yellow,orange region,and further producing brownish-yellow.This research confirmed the preparation process and spectral characteristics of Mn^(2+)doped nephrite tailings glass,discussed its application prospect,and provided a scientific direction for the high-value utilization of nephrite tailings,suggesting important theoretical research and application values.