On the preferred orientation and microstructural manipulation of molecular sieve films prepared by secondary growth
On the preferred orientation and microstructural manipulation of molecular sieve films prepared by secondary growth
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DOI：
10.1021/cm9802402
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发表时间：
1998-08
影响因子：
8.6
通讯作者：
A. Gouzinis;M. Tsapatsis
中科院分区：
文献类型：
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作者：
A. Gouzinis;M. Tsapatsis
利用前驱体层的二次生长制备了mfi负载薄膜。制备的前驱体层不含添加剂，在二次生长前不采用煅烧步骤。结合微观结构控制薄膜厚度，取向，连续性和表面粗糙度。确定了热液条件，如薄膜的生长主要是由前驱体层颗粒的直接生长进行的。制备的多晶薄膜具有柱状微观结构。晶粒的面外取向可以通过二次生长条件来控制，因此，晶粒的c轴范围从垂直于衬底到与衬底垂直方向的角度为~ 34°，而面内取向则是随机的。膜的初始生长速率在较长时间内保持恒定，活化能为70 kJ/mol。面外取向的程度随着薄膜厚度的增加而增加，直到达到一定程度。
MFI-supported films were prepared using secondary growth of precursor layers. The precursor layers were prepared free of additives and no calcination step was used before secondary growth. Combined microstructural control over film thickness, orientation, continuity, and surface roughness was achieved. Hydrothermal conditions were identified, such as film growth proceeds predominantly by direct growth of the particles of the precursor layer. The prepared polycrystalline films have a columnar microstructure. The out-of-plane grain orientation can be manipulated by secondary growth conditions, and is such that the c-axes of the grains range from perpendicular to the substrate to an angle of ∼34° from the direction normal to the substrate, whereas the in-plane grain orientation is random. Initial film growth rates were sustained at a constant value for extended periods of time with an activation energy of 70 kJ/mol. The degree of out-of-plane orientation increases with film thickness up to a point where chan...