Formation Mechanism of Nano AlN Powder by Gas-Reduction-Nitridation

AlN powders were synthesized by gas-reduction- nitridation of γ-Al2O3 powders using NH3 and C3H8 as reactant gases. AlN was identified from the products that synthesized at 1100-1400 oC for 120 min in the NH3-C3H8 gas flow, and it was confirmed that AlN can be easily fabricated by the gas-reduction-nitridation of γ-Al2O3. The products synthesized at 1100oC for 120min contained unreacted γ-Al2O3. By the 27A1 MAS NMR spectra, Al-N bonding in the product increased with an increase in the nitridation ratio of the tetrahedral AlO4 shoulder which decreased prior to that of the octahedral AlO6 shoulder. It seems that γ-Al2O3 was preferentially nitrided from AlO4 rather than AlO6. AlN nano particles were easily converted directly from γ -Al2O3 at a low temperature because the AlO4 within γ-Al2O3was preferentially nitrided.