Solid state synthesis of a new ternary nitride MgMoN2nanosheets and micromeshes

Abstract

In this study, a new ternary nitride MgMoN₂ was synthesized by a solid-state reaction of Mo, Mg and NaN₃ in a stainless steel autoclave at 700 °C. The crystal structure of MgMoN₂ (a = 2.91081 Å, c = 10.55029 Å, Z = 2) was determined by Rietveld refinement based on the X-ray diffraction data (XRD), which comprises of alternating layers of MgN₆ octahedral and MoN₆ trigonal prisms. The field-emission scanning electron microscopy (FE-SEM) and the transmission electron microscopy (TEM) show that the obtained MgMoN₂ was composed of nanosheets with a diameter of several micrometers and with a thickness of about 30 nm. As Mo was substituted by other molybdenum sources (such as MoO₃, (NH₄)₆Mo₇O₂₄·4H₂O or Na₂MoO₄·4H₂O), the FE-SEM images, TEM images and the selected-area electron diffraction (SEAD) patterns show that the obtained MgMoN₂ was composed of single-crystalline micromeshes with different pore sizes. An oriented aggregation mechanism was considered for the formation of MgMoN₂ nanosheets and micromeshes. The as-obtained MgMoN₂ micromesh is promising as a catalyst support in chemical filtration and in separations under severe operating conditions.