Direct nitridation process has been performed to synthesize morphology controllable aluminum nitrides (AlN). Three different morphologies of γ-AlOOH were treated under NH3 flow at 1400°C for 4 h. Hydrazine (N2H4) was employed in this study as a nitriding agent to promote nitridation reaction. In the presence of hydrazine, a high purity of aluminum nitride (AlN) could be achieved with less than 5 wt.% of oxygen impurities. Interestingly, after being exposed to elevated temperatures, the initial morphology was still retained. Whereas the TEM measurement indicated surface roughening due to the release of H2O. The investigation of sintering behavior of the prepared AlN powders revealed that plate-like morphology had the lowest shrinkage completing temperature (1574°C).
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