A ROUTE TO THE DISPERSION OF ULTRAFINE COBALT PARTICLES ON ZEOLITE NA-X THROUGH SALT OCCLUSION AND REDUCTION

Ultrafine magnetic cobalt particles, encapsulated within a zeolitic ho st, have been prepared via the seldom-used method of salt occlusion fo llowed by reduction to the metallic state. Powder X-ray diffraction an d electron microscopy clearly showed the formation of 150-250 Angstrom cobalt particles which were too large to be contained in the supercag e of the zeolite. An increase in cobalt content increases the number o f these cobalt particles, but not their size. We thus propose that the se particles are encapsulated within locally distorted areas of the ze olite structure. This work demonstrates the clear potential of zeolite s as templates or host matrices for the synthesis of ultrafine metal p articles.