In contrast to well-studied nanoscale metal and metal chalcogenide solution syntheses, current low-temperature methodologies for the synthesis of metal nitrides still leave much room for improvement. Nitride synthetic methods commonly involve ammonia or amines, which often require high-temperature thermolysis to produce nitrides. The biggest challenge for solvothermal metal nitride synthesis involves finding a nitrogen source that is thermally unstable enough to yield crystalline metal nitrides at low temperatures (< 400 ºC). Metal azides have an established foothold in explosives and air-bag systems and, under the proper conditions, they are useful in metal nitride synthesis. Our group has previously reported on a solvothermal metathesis route to GaN from GaCl3 and NaN3 under moderate temperature non-aqueous solvothermal conditions. Metal azides and azide polymers are likely reaction intermediates. This presentation will describe extensions of this methodology to other metal nitrides, such as InN, Mn3N2, Cu3N, Ni3N, and W2N. Several of these products are metastable and decompose to the elements by 500 ºC and Ni3N is a room-temperature ferromagnet. The low temperatures (< 300 °C) used in these solvothermal syntheses lead to nanocrystalline nitrides with particle sizes ranging from nanoscale to submicron dimensions. Critical synthetic parameters and structural analysis on several metal nitride reactions will be presented.
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