Abstract
The relationship between the crystal size of zeolite LTA nanocrystals and the molar composition of reactant mixture has been investigated in order to prepare the regularly oriented and highly dense zeolite LTA films. The building-block zeolite LTA nanocrystals which have various crystal sizes have been synthesized by controlling the molar composition of starting materials, Al, tetramethylammonium hydroxide (TMAOH), NaCl, and H2O. Using the nanocrystals with controlling TMAOH content and H2O content, the zeolite LTA thin film have been obtained. These thin films have been fabricated from the suspension of the zeolite LTA nanocrystals. The morphology and the density are different on the variation of the TMAOH content and H2O content. There are many craps between the building-block crystals on the film and the surface is rough with decreasing the H2O content. Their crystal shape remains cubic when the crystal size decreases. On the other hand, with the change of TMAOH content, more regularly oriented assembly is obtained. The edge of cubic crystal becomes less sharp. The shape of zeolite crystals becomes spheres with decreasing the TMAOH content. These surfaces of the films are regularlly oriented and highly dense. It is considered that the reason is the building-block crystals of zeolite LTA have such sphere shapes.
