铕离子对拟薄水铝石相变和微结构的影响机理研究

Effect of Europium Ion on Pseudoboehmite Phase Transition and Microstructure

摘要:

拟薄水铝石溶胶中加入Eu(NO3)3后，采用喷雾干燥拟薄水铝石干凝胶。通过TG-DSC、XRD和FETEM等方法，对比分析了Eu离子对拟薄水铝石相变和微结构的影响机理。结果表明，掺杂Eu离子使拟薄水铝石相变过程中γ-Al2O3→θ-Al2O3和θ-Al2O3→α-Al2O3的相变温度分别提高了172 K和13 K。Eu3 离子全部进入γ-Al2O3和θ-Al2O3晶格，并提高了γ-Al2O3结晶度，因此提高γ-Al2O3→θ-Al2O3相变温度。相变生成α-Al2O3时，Eu离子全部以EuA112O19存在于α-Al2O3晶界间阻止了Al3 体相扩散，因此导致θ-Al2O3→α-Al2O3相变温度升高。

Abstract:

After dropping Eu(NO3)3 into pseudoboehmite sol solution, europium-added pseudoboehmite xerogel was prepared by spray-drying process. Effect of Eu3 ion on pseudoboehmite phase transition and microstructure has investigated by differential thermal gravimetric analysis, powder X-ray diffraction and field emission transmission electron microscopy. The results show that phase transition temperatures of γ-Al2O3→θ-Al2O3 and θ-Al2O3→α-Al2O3 in the Eu3 -doped pseudoboehmite phase transition process are increased by 172 K and 13 K, respectively. Eu3 ions entered entirely into γ-Al2O3 or θ-Al2O3 crystal lattices, and crystallinity of γ-Al2O3 was improved, thus increasing the phase transition temperature of γ-Al2O3→θ-Al2O3. When α-Al2O3 formed in the phase transition process, Eu3 ion, which presented wholly in the form of compound EuA112O19, existed between α- Al2O3 grains. Bulk diffusion of Al3 was hindered, resulting in an increase of phase transformation temperature of θ-Al2O3→α-Al2O3 process.