The effect of seed size on the growth of silicalite-1 films on gold surfaces

Silicalite-1 films grown on gold surfaces seeded with colloidal crystals with a size of 60, 165 and 320 nm were investigated by reflection-absorption infrared spectroscopy, scanning electron microscopy and X-ray diffraction in order to follow up the formation of nano-scale defects and to determine the optimal synthesis conditions for preparation of silicalite-1 films with a low concentration of defects. Using 60-nm-sized colloidal crystals, the seeding method was capable of producing silicalite-1 films with low concentrations of defects and with thicknesses ranging from 100 to 300 nm, which are predominantly oriented with the a-axis perpendicular to the surface. Hydrothermal treatment times of the 60-nm-seeded surfaces longer than 36 h as well as the seeding with 165 or 320 nm colloidal crystals substantially enhanced the formation of defects in the films. (C) 2000 Elsevier Science B.V. All rights reserved.