Liquid-phase Synthesis of Crystalline Metal Nitride Nanoparticles with Semiconductor-type Properties (NanoNitrid)

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The synthesis of metal nitride nanoparticles with uniform particle size, high crystallinity and purity remains a challenge. This is due to the difficulty of complete deprotonation of ammonia in ammonolysis reactions and the inertness of nitrogen in nitridation reactions. Therefore, high temperatures (>500 °C) and in many cases oxygen-containing starting materials (metal oxides, metal hydroxides) are usually used, which is naturally counterproductive with respect to uniform, agglomerate-free and oxygen-free metal nitride nanoparticles. On the other hand, metal nitride nanoparticles are highly interesting with respect to their material properties, including quantum-confinement effects, catalysis, gas sorption and electronic or optical properties of semiconductors.The aim of this project is to move away from the initially targeted microemulsions with liquid ammonia (1st funding period) to a new, far more advantageous synthesis strategies. Accordingly, metal amide nanoparticles are first nucleated in liquid ammonia and subsequently converted into crystalline metal nitride nanoparticles in a one-pot approach in pyridine (or similar) or in ionic liquids. Target compounds are binary and ternary metal nitride nanoparticles with semiconducting properties (i.e., Sc2N3, Y2N3, Mn3N2, Zn3N2; ZnMN2 with M: Si, Ge, Sn, Ti, Zr, or MWN3 with M: Sc, Y, La). Furthermore, we will develop concepts for size and shape control of selected compounds, which are yet largely unknown for nanoscale metal nitrides. For the characterization of size, structure and phase purity of the as-prepared metal nitrides (especially absence of metal oxides/carbides), modern electron microscopy and spectroscopy are naturally the central analytical methods.