Synthesis of AlN Nanopowder from γ-Al2O3 by Reduction–Nitridation in a Mixture of NH3–C3H8 |
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Authors: | Tomohiro Yamakawa Junichi Tatami Toru Wakihara Katsutoshi Komeya Takeshi Meguro Kenneth J D MacKenzie Shinichi Takagi Masahiro Yokouchi |
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Affiliation: | Graduated School of Environment and Information Sciences, Yokohama National University, Yokohama 240-8501, Japan; School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand; Kanagawa Industrial Technology Research Institute, Evina 243-0435, Japan |
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Abstract: | Aluminum nitride (AlN) powders were synthesized by gas reduction–nitridation of γ-Al2O3 using NH3 and C3H8 as the reactant gases. AlN was identified in the products synthesized at 1100°–1400°C for 120 min in the NH3–C3H8 gas flow confirming that AlN can be formed by the gas reduction–nitridation of γ-Al2O3. The products synthesized at 1100°C for 120 min contained unreacted γ-Al2O3. The 27A1 MAS NMR spectra show that Al–N bonding in the product increases with increasing reaction temperature, the tetrahedral AlO4 resonance decreasing prior to the disappearance of the octahedral AlO6 resonance. This suggests that the tetrahedral AlO4 sites of the γ-Al2O3 are preferentially nitrided than the AlO6 sites. AlN nanoparticles were directly formed from γ-Al2O3 at low temperature because of this preferred nitridation of AlO4 sites in the reactant. AlN nanoparticles are formed by gas reduction–nitridation of γ-Al2O3 not only because the reaction temperature is sufficiently low to restrict grain growth, but also because γ-Al2O3 contains both AlO4 and AlO6 sites, by contrast with α-Al2O3 which contains only AlO6. |
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