采用原位X-射线吸收光谱的方法,结合密度泛函的理论研究,考察了杂原子磷酸铝分子筛水热晶化过程中Mn^2+,Fe^3+,Co^2+,Ni^2+等杂原子由骨架外向骨架内迁移的变化规律。实验中采用了自主设计、用于原位表征的分子筛晶化池,该晶化池可同时满足XAFS表征和分子筛水热晶化过程的要求。研究结果表明,在水热晶化的升温过程中,杂原子经历了由骨架外六配位向骨架四配位的转变,其转变规律与杂原子的离子半径、价态有关;合成体系中Si、F-^的存在显著地影响了杂原子的转变途径。
The in situ X-ray absorption spectroscopy characterization and DFT computation were carried out to get insight into the crystallization process of metal ions substituted AlPO4-5 (metal ions Me= Mn^2+ , Fe^3+ , Co^2+ , Ni^2+ ). A special synthesis cell was designed to meet the demands of both the in situ XAFS characterization and the hydrothermal process. The transformation process of the metal ions from 6-fold to 4-fold coordination structure was influenced by the metal ion size and covalence, and the existence of Si and F in the precursor gel changed the synthesis process considerably.