Fine structures of zeolite-linde-L (LTL): Surface structures, growth unit and defects
Fine structures of zeolite-linde-L (LTL): Surface structures, growth unit and defects
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DOI：
10.1002/chem.200306064
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发表时间：
2004-10-11
影响因子：
4.3
通讯作者：
Catlow, CRA
中科院分区：
文献类型：
--
作者：
Ohsuna, T;Slater, B;Catlow, CRA
采用高分辨率电子显微镜（HREM）对纳米级和微米级沸石- linde - l （LTL）合成晶体的表面结构进行了成像。在晶体内观察到柱状孔洞和旋转的、纳米尺寸的、轮状缺陷，其中孔洞的最小尺寸等于旋转缺陷的最小尺寸。原子计算机模拟的表面结构预测与HREM的观察结果相一致，并提供了对完美和缺陷LTL晶体生长机制的深入了解。旋转缺陷结构形成的能量学分析表明，缺陷产生的驱动力是热力学的，并且在高浓度的情况下可以产生旋转缺陷。柱状孔洞的形成在能量上略有不利，因此我们推测旋转和纳米空位缺陷的发生率强烈依赖于动力学因素和反应条件。纳米和微晶LTL的形貌是截然不同的，我们利用模拟的见解提出了晶体形状差异的解释。
High-resolution electron microscopy (HREM) has been used to image the surface structure of nano- and micrometer-sized synthetic crystals of zeolite-Linde-L (LTL). Columnar holes and rotational, nano-sized, wheel-like defects were observed within the crystals, where the hole has a minimum size equal to that of the rotational defect. Predictions of surface structure from atomistic computer simulation concur with the observations from HREM and provide insight into the crystal growth mechanism of perfect and defective LTL. Analysis of the energetics of the formation of rotational defect structures reveals that the driving force for defect creation is thermodynamic and furthermore, the rotational defects could be created in high concentrations. Formation of a columnar hole is found to be slightly energetically unfavourable and therefore we speculate that the incidence of both rotational and nano-sized vacancy defects is strongly dependent on kinetic factors and reaction conditions. The morphology of nano- and microcrystalline LTL is contradistinct and we use insights from simulation to propose an explanation of the disparity in crystal shape.