Topotactical Nitridation of α-MoO₃ Fibers to γ-Mo₂N Fibers and Its Field Emission Properties

Abstract

We demonstrate the synthesis of large-scale high-quality single-crystalline γ-Mo2N fibers using α-MoO3 fibers as precursors by temperature-programmed reactions with NH3. The formation mechanism is discussed, and the morphology, structure, composition, and chemical states of the prepared fibers were characterized by X-ray diffraction pattern, field emission scanning electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction pattern, and X-ray photoelectron spectroscopy studies. The normal field emission properties of the product were investigated, and the turn-on field of 0.6 V/μm is reported for the first time. The Fowler−Nordheim (F-N) plot obtained from the current density-applied field (J-E) characteristic is almost found to be linear, and the I-t plot shows that the emission current remains nearly constant over 2 h. The γ-Mo2N fibers exhibit an enhanced performance as compared to other nitrides. Therefore, our field emission results show that the γ-Mo2N fibers might be potential field emitters in the future devices.