Development of LaxMOy nanoparticles dispersed in a layered silicate matrix

Abstract

Stoichiometric La x M(fsa) 2 en,NO 3 · H 2 O heterobinuclear complexes (M = Ni, Cu, Co; (fsa) 2 en = N,N′-bis (3-carboxysalicydene)ethylene diamine) were synthesized by a careful control of pH during the two steps of the complexation. In the case of nickel and cobalt, the thermal treatment of these complexes led to well crystallized LaNiO 3 or LaCoO 3 perovskite type phases, whereas a La 2 CuO 4 type structure was obtained from the LaCu complex. Whatever M, the oxide phases are formed at much lower temperatures than needed by classical methods. The cell parameters of these structures are in good agreement with data given in the literature. A large interlayer distance expand was induced by exchanging the sodium cations of montmorillonite with the La x M(fsa) 2 en cations, c . from 12.5 Å to ≈23.5Å. Lamellar silicate/oxide nanocomposites were formed by heating the Mont/La x M(fsa) 2 en under air atmosphere at 400 °C. These new materials could have important applications for selective oxidizing catalysis.