Synthetic Route to Metal Nitrides: High-Pressure Solid-State Metathesis Reaction

Abstract

We report a general synthetic route to well-crystallized metal nitrides through a high-pressure solid-state metathesis reaction (HPSSM) between boron nitride (BN) and ternary metal oxide A(x)M(y)O(z) (A = alkaline or alkaline-earth metal and M = main group or transition metal). On the basis of the synthetic metal nitrides (Fe3N, Re3N, VN, GaN, CrN, and W(x)N) and elemental products (graphite, rhenium, indium, and cobalt metals), the HPSSM reaction has been systematically investigated with regard to its general chemical equation, reaction scheme, and characteristics, and its thermodynamic considerations have been explored by density functional theory (DFT) calculations. Our results indicate that pressure plays an important role in the synthesis, which involves an ion-exchange process between boron and the metal ion, opening a new pathway for material synthesis.

High-pressure Raman spectroscopy of Re 3 N crystals

“…The nitrogen-rich rhenium nitrides are inclined to be formed at higher pressures. For example, metal Re is unable to react with nitrogen at 5 GPa [13], Re 3 N can be prepared at $14 GPa, and Re 2 N is able to be synthesized above 20 GPa [4]. Fig.…”

“…The Re 3 N samples were synthesized through the HPSSM reaction between sodium perrhenate (NaReO 4 ) and BN at 14 GPa and 1973 K [13], the chemical reaction equation can be depicted as follows:…”

“…The reaction precursors were mixed in the optimized molar ratio and then were placed in a platinum capsule which was used to seal and heat the samples in the synthesis experiments [13][14][15][16] synthesis conditions, including pressure, temperature, heatingtime, molar ratio and sample-shape, were optimized in this work.…”

“…On the other hand, in order to obtain bulk material of rhenium nitrides for further studies and potential applications, the synthesis of rhenium nitrides using large volume press (LVP) technology has been tried by some research groups [12,13]. Kawamura et al [12] synthesized MoS 2 -type ReN 2 through a metathesis reaction between ReCl 5 and Li 3 N at 7.7 GPa and 1873 K. Lei et al [13] reported a novel synthetic route to metal nitrides, including Re 3 N, through a high-pressure solid-state metathesis (HPSSM) reaction between boron nitride (BN) and alkaline or alkaline-earth ternary metal oxides.…”

“…Kawamura et al [12] synthesized MoS 2 -type ReN 2 through a metathesis reaction between ReCl 5 and Li 3 N at 7.7 GPa and 1873 K. Lei et al [13] reported a novel synthetic route to metal nitrides, including Re 3 N, through a high-pressure solid-state metathesis (HPSSM) reaction between boron nitride (BN) and alkaline or alkaline-earth ternary metal oxides. By now the synthesis of well-crystallized Re 3 N bulk is still a challenge due to the demanding synthetic conditions as well as the significant elemental difference between Re and N. Raman spectroscopy under high pressure, which could provide important information on vibrational properties of Re 3 N, has not been performed yet due to the lack of high-quality crystalline samples.…”