A new approach to the synthesis of molybdenum bimetallic nitrides and oxynitrides

A simple processing route to molybdenum bimetallic nitrides and oxynitrides has been developed, based on the use of precursors resulting from freeze-d rying of aqueous solutions of the appropriate common metal salts. Thermal d ecomposition of amorphous freeze-dried powders originates crystalline mixed oxides, which have been carefully characterized. Nitridation of the crysta lline intermediate having Ni:Mo = 2:3 metal ratio led to single-phased Ni2M o3N. For the V-Mo-O-N system, nitridation of both amorphous and crystalline precursors results in bimetallic oxynitrides. In this way, not only the al ready known V2Mo(OxNy) catalyst but also a new compound of different metal stoichiometry, V3Mo2(OxNy), has been prepared. The materials have been char acterized by X-ray powder diffraction, elemental analysis, scanning electro n microscopy, thermogravimetry under air flow, and temperature programmed o xidation. The existence of a solid solution of stoichiometry V1-zMoz(OxNy) (0 less than or equal to z less than or equal to 1) having rock-salt struct ure is discussed.