结构弛豫对Al3+/Yb3+共掺石英玻璃结构和性能的影响

Effect of Structure Relaxation on Structure and Properties of Yb3+/Al3+-Codoped Silica Glasses

采用溶胶–凝胶法结合高温烧结工艺制备Al^3＋/Yb^3＋共掺石英玻璃,通过在玻璃转变温度（Tg）以下对玻璃进行等温退火,研究了退火时间对Al^3＋/Yb^3＋共掺杂石英玻璃密度、折射率和光谱性质的影响,并利用X射线衍射、Fourier转换红外（FTIR）、Raman光谱、核磁共振等结构分析手段探索其影响机理。结果表明：当退火温度为900℃时,随着退火时间增加,Al^3＋/Yb^3＋掺杂石英玻璃的折射率逐渐增大,紫外吸收边逐渐蓝移,Yb^3＋离子的吸收和发射截面逐渐下降,退火200 h后Yb^3＋离子出现2个荧光寿命;在Tg温度以下退火,玻璃的非晶态特征和Al的配位数不会发生明显变化;玻璃的假想温度及结构混乱度随退火时间增加逐渐下降。

Yb^3＋/Al^3＋-co-doped silica glasses were prepared by sol-gel process and subsequent high-temperature sintering. The effect of sub-Tg annealing duration on the density, refractive index and spectra of glass was investigated. The related mechanism was analyzed by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR）, Raman spectroscopy, and nuclear magnetic resonance （NMR）, respectively. The results show that the refractive index of Yb^3＋/Al^3＋-co-doped silica glasses increases and the absorption and emission cross sections decrease with increasing annealing time at annealing temperature of 900 ℃. When sub-Tg annealing time increases, the UV-Vis absorption edge becomes blue shift, and two fluorescence lifetime of Yb^3＋ ions appears after 200 h annealing. The amorphous state and coordinating numbers of Al^3＋ ions basically remain unchanged in sub-Tg annealing process. The fictive temperature, Tf, and the structural disorder of glass decrease with the increase of annealing time.