Ceramic nanocomposites prepared via the in situ formation of a novel TiZrN2 nanophase in a polymer-derived Si3N4 matrix
Résumé
The first demonstration of a nanoscaled titanium zirconium nitride (TiZrN2) single-phase isolated during the preparation of polymer-derived silicon nitride (Si3N4) matrix nanocomposites is discussed. We employed a polysilazane, which was chemically modified with Zr[N(CH2CH3)2]4 and Ti[N(CH3)2]4 then ammonolyzed before a pyrolysis step under ammonia (1000 °C) and a heat-treatment in flowing nitrogen (1000–1700 °C). Based on a careful control of the precursor chemistry in the early stage of the process and nano-/microstructural investigations of the material performed during its preparation, we were able to identify TiZrN2 nanocrystals with a size as low as 9 nm distributed in α- and β-Si3N4 phases at a temperature as low as 1500 °C. We particularly proved that the TiZrN2 nanophase could be generated because of the use of the polysilazane evoluting towards a covalently-bonded Si3N4 matrix . This unique nanostructure is expected to provide particular functionality to Si3N4 as noble metal-free catalysts and components with high plasmonic quality.
Domaines
Matériaux
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