Synthesis of Transition Metal Nitride Powders from Metal-urea NitrateComplex Precursors

A novel and general route to synthesize transition metal nitrides (CrN and ζ-Fe2N) from metal-urea nitrate complexes was presented. Metal-urea nitrate complex is proved to be a useful precursor to prepare transition metal nitrides. FTIR and TG-DSC were adopted for the characterization of the complexes. Urea molecules bond with metal·ion through oxygen-to-metal coordinate bonds. The transformation from metal-urea nitrate to metal nitride is thought through the reaction between oxide powder and ammonia gas after its pyrolysis. The influences of the reaction temperature and the holding time on the nitridation of different metal-urea nitrate were investigated by using XRD. The holding time for the complete nitridation of iron-urea nitrate is shorter, compared with that for chromium-urea nitrate, and the temperature needed by the former is lower. The morphology of nitride powders was observed by using SEM.