Pressure influenced combustion synthesis of - and -Al2O3nanocrystalline powders

Aluminium oxide nanocrystals have been prepared via a straightforward reaction, initiated at low temperatures (<300 °C), between aluminium nitrate and hydrazine. The initial pressure parameter is found to be responsible for the variations of the particle size (ranging from nanocrystalline to sub-microcrystalline) and for the resulting crystalline phase (γ- or α - Al 2 O 3 ) of these powders. The fibre-like morphology obtained for the as-synthesized γ - Al 2 O 3 permits the synthesis of nanocrystalline α - Al 2 O 3 ( nm) even after a high temperature treatment at 1200 °C. The findings suggest a promising approach for controlling the size and crystal phase of the particles.