Imaging of crystal growth-induced fine surface features in zeolite A by atomic force microscopy

Evolution of Surface Morphology with Introduction of Stacking Faults in Zeolites

“…In mixed TPA-TBA preparations, in which there is an extensive degree of faulting and intergrowths, these are accommodated as small aligned crystallites. In the FAU-EMT systems the [18]crown-6 template plays the dominant templating role often incorporated preferentially over [15]crown-5 and re- www.chemeurj.org sults in an overgrowth of small FAU crystals on EMT only when the concentration of [18]crown-6 is depleted in solution.…”

“…[10][11][12][13] AFM is particularly advantageous in that it can be used either to look at crystal surfaces following synthesis (ex-situ) or in solution during growth (in-situ). AFM investigations of natural zeolites [14][15][16] and synthetic zeolites such as zeolite A, [17,18] silicalite-1, [19,20] zeolite Y [21] and zeolite L [22] have indicated a layer-by-layer growth mechanism, in which the particles add to the terrace edges, forming kinks followed by expansion of the terrace and simultaneous surface nucleation. The surface structure of silicalite-1 prepared using two different templates, that is, the tetrapropylammonium ion (TPA) and trimeric TPA, have also been elucidated by employing HRTEM and AFM techniques.…”

“…FAU has a cubic unit cell, and EMT has a hexagonal unit cell with the sodalite cages connected in a wurtzite and zincblende arrangement, respectively. Specific SDAs such as [18]crown-6 (18C6) and [15]crown-5 (15C5) are used to synthesise the pure forms of EMT and FAU, respectively. By using a mixture of SDAs specific for each system in the synthesis gel (MFI-MEL [23,[28][29][30] and FAU-EMT [31][32][33] ), it is possible to vary the amount of intergrowths by varying the SDA compositional ratios.…”

Crystal Shape Engineering

“…Low accelerating voltage FE-SEM studies have provided clear images of growth terraces and spirals on faces of zeolite and zeo-type materials. [113][114][115] These studies have been important in determining growth mechanisms for these systems. [114][115][116] Atomic force microscopy has been used to characterize the surface microstructure of a variety of It is also well known that foreign molecules (additives or impurities) influence the growth shape of crystals.…”

Softening and Hardening of Macro‐ and Nano‐Sized Organic Cocrystals in a Single‐Crystal Transformation

“…The pyramids most likely form at the conclusion of the crystal growth process. [32] AFM height images obtained for the millimeter-sized crystals after photoreaction are shown in Figure 2 c,d. Both morphologies remained intact, although slight irregularities as rough edges and granular sub-nanometer features appeared on the outer terrace regions.…”