Combustion synthesis of rod-like AIN nanoparticles

Rod-like aluminum nitride (AlN) nanoparticles were prepared by the nitriding combustion synthesis method. A charge composed of Al and AlN diluent powders (40/60 mol%) with 5 mass% MgO as additive was combusted under 1 MPa nitrogen atmosphere. The combustion temperature of the reaction was 2030°C and the speed was 1.58 mm/s. The FE-SEM observation showed that the rod-like AlN nanoparticles have diameters in the range of 90-300 nm and maximum length about 2 μm. It also showed evidences of the core-shell model of nitridation where the nanorods grew near the flow-out of eggshell-type AlN hollows. The EDX analyses showed the formation of Mg-Al-O-N droplets on the tips of AlN nanorods which strongly suggested that the vapor-liquid-solid (VLS) mechanism was the predominant growth mode. However, when the liquid droplets necessary for VLS were exhausted with continuous covering on the surface of the growing nanorods, the growth mode changed probably to vapor-solid (VS) mechanism. Furthermore, a growth model of the formation of rod-like AlN nanoparticles was proposed and discussed in accordance with experimental results.