SiO2-Al2O3-ZnO-Na2O(F,Br)体系光热折变玻璃的析晶机理研究

使用"五步法"热定影工艺制备体布拉格光栅,阐述了光热折变玻璃内部的析晶机理,借助拉曼光谱与扫描电镜直观探测到了离子迁移过程与NaF析晶过程,通过掺杂与未掺杂KBr两种组分玻璃的衍射效果以及透过率光谱对比,发现了位于350~600 nm处的吸收带,确定成核过程内部形成的胶体为溴化银与纳米银复合物.该胶体聚合生长为胶团,诱导NaF晶体在其表面析出生长,实现折射率调制.并且从胶体成核阶段、NaF析晶阶段、曝光剂量三个方面探究影响光热折变玻璃内部析晶颗粒的关键因素,研究结果表明:成核过程中Ag0n·(AgBr)m]胶团大小是决定NaF析晶大小的关键;NaF析晶阶段主要影响析晶颗粒数量而对改变NaF析晶大小作用不大;NaF析晶大小随着曝光剂量出现先减小后增大的现象,在1.8 J/cm^2附近出现拐点、析晶颗粒最小.

Crystallization Mechanism of Photo-thermal-refractive Glass in SiO2-Al2O3-ZnO-Na2O(F,Br) System

The volume Bragg grating was prepared by using the "five-step" thermal fixing process,crystallization mechanism of the photo-thermo-rraphictive glass is described,and the ion migration process and NaF crystallization process are intuitively detected by Raman spectroscopy and scanning electron microscopy. The absorption band at 350~600 nm is found by transmission spectrum,and the colloid formed in the internal nucleation process is determined to be a silver bromide and silver nanocomposite.The key factors influencing the crystallized particles in photo-thermal-refractive glass were investigated from three aspects:nucleation process,NaF crystallization process and UV exposure dosage. It is found that the size ofAgn^0·(AgBr)m]micelles is the key to determine the crystal size of NaF during nucleation. The crystallization process mainly affects the number of crystal particles and has little effect on changing the crystal size. As the exposure dosage increases,the crystallization size of NaF decreases first and then increases,the inflection point is around 1.8 J/cm^2,and the crystalline particles are the smallest.