Crystal growth behavior of zeolites elucidated by atomic force microscopy

Seeded growths of faujasite and zeolite A were investigated by atomic force microscopy (AFM). For seeded growth, clear aluminosilicate solutions (90Na(2)O:xAl(2)O(3):9SiO(2):5760H(2)O, where x = 0.1-1.0), which are useful for faujasite or zeolite A growth on seeded faujasite or zeolite A, respectively, were prepared at 353 K. Changes at the same position were observed along with growth period, and it was revealed that crystal growth behaviors of faujasite and zeolite A were different in the same aluminosilicate solution. Corresponding aluminosilicate solutions were characterized by Raman spectroscopy. By combining the results of both AFM and Raman spectroscopy, the behavior of aluminosilicate species incorporating into the solid phase from the liquid one was discussed. Key precursors of crystal growth for faujasite and zeolite A were proposed to be six-membered and four-membered rings, respectively.