Synthesis of aluminium nitride nanopowder

Aluminium nitride (AlN) nanopowder was successfully synthesized from aluminium oxide via a single-step reaction with ammonia as a source of nitrogen. The process was carried out in a horizontal mullite tube reactor located in an electric furnace in the ranges of temperature, time and gas ? ow rate of 1050-1350 oC, 1-5 h and 100-150 l/h, respectively. Nanopowders of �� -Al2O3 and �. -Al2O3 were used as starting materials. In? uence of temperature, time, gas ? ow rate and type of aluminium oxide on reaction productivity, powder morphology and product phase composition was investigated. Dynamic light scattering (DLS), Ramman spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and specio c surface area measurements by the BET isotherm technique were used to characterized the obtained materials. Aluminium nitride prepared under optimal reaction conditions, comprising the reaction time of 5 h, the temperature of 1250 oC, and the gas? ow rate of 150 l/h, was found to be nanocrystalline powder with a mean crystallite size of about 60 nm in the synthesis from gamma aluminium oxide and 65 nm in case of alfa aluminium oxide as a starting material. The productivity of nitridation reaction in such conditions was close to 99%, basing on gravimetric measurements. In case of the synthesis from gamma oxide, PXRD analysis indicated the pure hexagonal aluminium nitride structure which was cono rmed by TEM analysis. In case of alfa aluminium oxide nitridation, the obtained aluminium nitride contained the unreacted oxide. Additionally, the investigation of average agglomerate sizes in the water suspension conducted by DLS showed that aluminium nitride obtained from �� -Al2O3 had an average particle size of 282 nm, and in the case of �. -Al2O3 used as a starting material it was 2219 nm..