Observation of La-exchanged NaY zeolite using aberration-corrected scanning transmission electron microscopy
Observation of La-exchanged NaY zeolite using aberration-corrected scanning transmission electron microscopy
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DOI：
10.1016/j.micromeso.2020.110711
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发表时间：
2021-02-01
影响因子：
5.2
通讯作者：
Sato, Koichi
中科院分区：
文献类型：
--
作者：
Hiyoshi, Norihito;Ikeda, Takuji;Sato, Koichi
通过对La交换NaY沸石(LANAY)的观察，尝试用球差校正的扫描电子显微镜(Cs校正STEM)测定金属在沸石中的位置，并估算其在沸石中的占位情况。用NaY分子筛离子交换法制备了LaNaY分子筛，并用高角环状暗场(HAADF)-STEM对其进行了观察。沸石骨架和La原子柱的同时成像显示，La位置在I位和I‘位。根据每个La站点的平均HAADF强度，估计两个站点I和I‘的La占有率约为四分之一。测位I的La占有率远大于X射线衍射法测得的La占有量，表明STEM数据反映了Laay的高度脱水状态。此外，还描述了单个La原子的观测方法。
The determination of metal location in zeolite and an estimation of site occupancy by using spherical aberrationcorrected scanning transmission electron microscopy (Cs-corrected STEM) were attempted through the observation of La-exchanged NaY zeolite (LaNaY). LaNaY was prepared by the ion exchange of NaY zeolite and observed using high-angle annular dark-field (HAADF)-STEM. Simultaneous imaging of both the zeolite framework and La atomic columns revealed the La positions to be in sites I and I'. From the averaged HAADF intensity of each La site, the La occupancy was estimated to be about a fourth for both sites I and I'. The estimated La occupancy of site I was much larger than that measured by XRD, suggesting that the STEM data reflects the highly dehydrated state of LaNaY. In addition, methods for observation of individual La atoms are described.