Size Tailored Nanoparticles of ZrN Prepared by Single-Step Exothermic Chemical Route

Abstract ZrN nanoparticles were prepared by an exothermic reduction of ZrCl 4 with NaN 3 in the presence of NaCl flux ina nitrogen atmosphere. Using a solid-state combustion approach, we have demonstrated that the zirconium nitride nanoparticlessynthesis process can be completed in only several minutes compared with a few hours for previous synthesis approaches. Thechemistry of the combustion process is not complex and is based on a metathesis reaction between ZrCl 4 and NaN 3 . Becauseof the low melting and boiling points of the raw materials it was possible to synthesize the ZrN phase at low combustiontemperatures. It was shown that the combustion temperature and the size of the particles can be readily controlled by tuningthe concentration of the NaCl flux. The results show that an increase in the NaCl concentration (from 2 to 13 M) results ina temperature decrease from 1280 to 750 o C. ZrN nanoparticles have a high surface area (50-70 m 2 /g), narrow pore sizedistribution, and nano-particle size between 10 and 30 nm. The activation energy, which can be extracted from the experimentalcombustion temperature data, is: E = 20 kcal/mol. The method reported here is self-sustaining, rapid, and can be scaled up fora large scale production of a transition metal nitride nanoparticle system (TiN, TaN, HfN, etc.) with suitable halide salts andalkali metal azide.Key wordszirconium nitride, nanoparticles, combustion synthesis, particle size, sodium chloride.