钡硼硅酸盐玻璃中Ti的结构及其作用

Structure of Ti and Its Effect on Property of BaO-SiO_2-B_2O_3-TiO_2 System Glass

采用顺磁共振和X射线光电子能谱,结合密度和折射率测定研究了BaO SiO2 B2O3 TiO2 系统玻璃中Ti的价态及Ti3+和Ti4+的结构状态,分析了TiO2 结构对玻璃性能的影响。研究结果表明:在正常空气气氛下熔制的玻璃中,Ti主要以Ti4+形式存在,所产生的顺磁信号归因于玻璃的本征缺陷和熔制时TiO2 中氧的逸出而形成的氧空位捕获电子,且随温度升高,氧空位浓度减少;在还原性气氛下,有部分Ti3+ 形成,出现g∥=1.995 4,g⊥=1.982 3两处顺磁峰,随温度升高,g∥峰增强,g⊥峰降低;Ti3+ 处于带四方畸变的[TiO6 ]八面体配位场中;玻璃中Ti4+的配位数以[TiO4]为主,且随TiO2 含量增加,[TiO4]有向[TiO6]转变的趋势,这种转变发生在TiO2 含量约为20%处;TiO2 的加入能提高玻璃结构网络的连接程度和堆积密度,从而使玻璃的密度和折射率线性增大。

The valency of Ti and the structure state of Ti3+ and Ti4+ in BaO-SiO2B2O3TiO2 system glass were studied using electron spin resonance (ESR) and X-ray photoelectron spectroscopy (XPS) combined with measurement of density and refractive index. The effects of TiO2 structure on property of these glass were discussed. The results show that Ti exists in the glass which is obtained by melting in the normal air condition in the form of Ti4+. The signal of paramagnetism produced is attributed to the disfigurement of glass, and the oxygen cavities which is formed by the oxygen escaping from TiO2 in the melting process when they are capturing the electrons. The concentration of oxygen cavities decreases with the increase of the temperature. Some Ti3+ are formed in the ambience with deoxidize, so there are two signals of paramagnetism, g parallel = 1.9954 and g perpendicular = 1.9823 which depend on temperature differently. It means that the peak value of g parallel boosts up with the increase of the temperature while the peak value of g perpendicular falls. Ti3+ can only exist in the coordination field of [TiO6] octahedron which contains aberrance from tetrahedron. Ti4+ in glass exist mainly in the [TiO4] tetrahedrons, and a small amount of [TiO4] tetrahedrons has the tendency to change to [TiO6] octahedrons when TiO2 content increases to about 20%. The density and refractive index of glass are increased evidently with the addition of TiO2, which plays the role of enhancing connection and compactness degree of glass structure net.