AFM and HRSEM Invesitigation of Zeolite A Crystal Growth. Part 1: In the Absence of Organic Additives

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• 作者：Pablo Cubillas ; Sam M. Stevens ; Nicola Blake ; Ayako Umemura ; Chin B. Chong ; Osamu Terasaki ; Michael W. Anderson
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：June 30, 2011
• 年：2011
• 卷：115
• 期：25
• 页码：12567-12574
• 全文大小：1099K
• 年卷期：v.115,no.25(June 30, 2011)
• ISSN：1932-7455

文摘

The crystallization of zeolite A by the verified synthesis method was studied by means of high-resolution scanning electron microscopy (HRSEM) and atomic force microscopy (AFM). These methods show an evolution in the growth mode of zeolite A from an adhesive type at the beginning of the synthesis (high supersaturation) to birth-and-spread growth at the end of the synthesis (low supersaturation). Additionally, HRSEM provides direct proof on the formation of zeolite A crystals at the surface of the amorphous gel and the aggregation of crystals at early stages of synthesis, which leads to intergrowth formation. For the first time, high-resolution AFM images were taken on the {110} and {111} faces of zeolite A. Growth on {110} faces takes place by a birth-and-spread mechanism, and the shape of the terraces is rectangular, with growth along the 100 directions being twice as fast as in the 110 directions. Growth on the {111} faces also takes place by a birth-and-spread mechanism via triangular-shaped terraces with edges parallel to 110 directions. Possible surface terminations for both faces are discussed, and crystal habit and surface topography are modeled by Monte Carlo simulations.