FORMATION OF THE CRYSTAL STRUCTURE OF A L~MELLAR SILICATE

In the decomposition of Ni(CO)~ that is adsorbed on an activated lamellar silica surface, a crystalline matrix structure forms. Silica crystallization is accompaniedobY an increase in particle size (cluster formation) of metallic Ni particles up to 200-230 A, due to the reaction of the active metal particles bound to the silica surface microcrystallites. As the total concentration of reacting Ni increases, the intensity of the Bragg reflection bands in the x-ray diffraction patterns increases (Fig. I). When this happens, the degree of symmetry of the forming crystal lattice and the size of the metal particles are practically unchanged; this indicates an increase in the number of metal particles on the matrix surface. As Fig. 2 Shows, the ratio of the intensity of the Bragg reflection bands of crystalline silica to that of the Ni lines is practically constant. This demonstrates that the degree of crystallinity of the newly forming structure depends on the concentration of reacting Ni, and increases with it.