Synthesis of transition metal nitride by nitridation of metastable oxide precursor

Metastable transition metal oxides were used as precursors to synthesize transition metal nitrides at low temperature. Amorphous MoO2 was prepared by reduction of (NH4)6Mo7O24 solution with hydrazine. As-synthesized amorphous MoO2 was transformed into fcc γ-Mo2N at 400 °C and then into hexagonal δ-MoN by further increasing the temperature to 600 °C under a NH3 flow. The nitridation temperature employed here is much lower than that employed in nitridation of crystalline materials, and the amorphous materials underwent a unique nitridation process. Besides this, the bimetallic nitride Ni2Mo3N was also synthesized by nitridating amorphous bimetallic precursor. These results suggested that the nitridation of amorphous precursor possessed potential to be a general method for synthesizing many interstitial metallic compounds, such as nitrides and carbides at low temperature.

graphical abstractAmorphous oxide was used as new precursor to prepare nitride at low temperature. Pure γ-Mo2N and δ-MoN were obtained at 400 °C and at 600 °C, respectively.Figure optionsDownload as PowerPoint slideHighlights
► We bring out a new method to synthesize transition metal nitrides at low temperature.
► Both mono- and bimetallic molybdenum nitrides were synthesized at a mild condition.
► The formation of two different molybdenum nitrides γ-Mo2N and δ-MoN can be controlled from the same metastable precursor.
► The nitridation temperature was much lower than that reported from crystalline precursors.
► The metastable precursor had different reaction process in comparison with crystalline precursor.