钛酸锶钡微晶玻璃的铈掺杂效应研究

Cerium Doping Effect in Barium Strontium Titanate Glass-Ceramics

通过X射线光电子能谱、紫外-可见漫反射光谱、傅里叶变换红外光谱和拉曼光谱研究了(Ba,Sr)TiO3微晶玻璃的铈掺杂效应。玻璃体系为BaO-SrO-TiO2-Al2O3-SiO2(Ce摩尔分数为0%、1%、2%、3%)。随着Ce摩尔含量增加,Ce在(Ba,Sr)TiO3晶格中的占位从Ce 4+取代Ti 4+位的形式逐渐变成了以Ce 3+进入Ba 2+/Sr2+位的形式,伴随Ce3+和Ce4+离子相对含量的变化。玻璃中添加CeO2增加了网络结构的连通性。在微晶玻璃中,随着Ce摩尔分数的增加(0%到2%),禁带宽度减小,电子跃迁所需能量降低,价带电子易从价带跃迁至导带,电导率增加;相反地,Ce摩尔分数从2%增加到3%时,禁带宽度增加,电导率下降。拉曼光谱结果证实了铈离子(Ce3+和Ce4+)在(Ba,Sr)TiO3晶格中的取代,并发现铈掺杂改变了该晶相的四方性。

Cerium doping effect in(Ba,Sr)TiO3 glass-ceramics has been investigated by X-ray photoelectron spectroscopy,ultraviolet-visible diffuse-reflectance spectroscopy,Fourier transform infrared spectroscopy and Raman spectroscopy.Studies were performed on specimens for BaO-SrO-TiO2-Al 2O3-SiO2 glass system(with 0%,1%,2%and 3%mole fraction of cerium).With the change of relative content of Ce 3+and Ce 4+,cerium mainly acts as Ce 4+in the Ti 4+-site of(Ba,Sr)TiO3 lattice at low content and then cerium substitution gradually occurs in the Ba 2+/Sr 2+-site as Ce 3+with increasing cerium mole content.The CeO2 addition in the glass could effectively improve the connectivity of network structure.In(Ba,Sr)TiO3 glass-ceramics,with the increase of cerium content(0%to 2%),the value of band gap energy decreases,electronic transition energy decreases,then electrons transit from the valence band to the conduction band easily,and the conductivity increases.In contrast,when the mole fraction of cerium increased from 2%to 3%,the value of band gap energy increases,so the conductivity decreases.The results of Raman spectra confirm that cerium ions diffuse into the(Ba,Sr)TiO3 lattice structure and modify the tetragonality of the barium strontium titanate phase.