Rapid In Situ\nInvestigation of Nitride Synthesis:\nAmbient Atmospheric Nitridation of 3d Metal Oxides Using Dicyandiamide

The synthesis of metal nitrides, which are a class of\nfunctional\nmaterials, generally requires an air-free atmosphere, hindering their\nefficient exploration and production. In this study, we demonstrate\nthe rapid screening of the nitridation conditions of 3d transition\nmetal oxides under an ambient atmosphere via in situ synchrotron X-ray\ndiffraction (XRD). Among V<sub>2</sub>O<sub>5</sub>, NaVO<sub>3</sub>, and a mixture of NH<sub>4</sub>VO<sub>3</sub> and NaHCO<sub>3</sub> as the precursors and Dicyandiamide as the nitrogen source, in situ\nXRD analysis shows that NaVO<sub>3</sub> is a suitable precursor to\nform a single-phase rock salt structure, which is an anion-rich oxynitride,\nV<sub>0.69</sub>N<sub>0.53</sub>O<sub>0.47</sub>. The nitridation\nof NaFeO<sub>2</sub> with Dicyandiamide results in the formation of\nFe<sub>3</sub>N through FeNCN, which is converted to Fe<sub>3</sub>C after further heating. The reaction of NaMnO<sub>2</sub> affords\nMnNCN, while NaCrO<sub>2</sub> does not produce chromium nitride/carbodiimide.\nGuided by the in situ XRD results, these metal oxides and Dicyandiamide\nare placed in an alumina crucible and heated in a box furnace under\nan ambient atmosphere to synthesize nitride/carbodiimide/carbide on\na gram scale without a gas cylinder. This study presents a novel and\nefficient method for synthesizing various nitrides, oxynitrides, carbodiimides,\nand carbides under ambient conditions using in situ synchrotron XRD\nand box furnace, thereby significantly simplifying the nitride synthesis\nprocess.