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以Al（NO3）3和NH3水为原料制备Al（OH）3干凝胶，经煅烧合成了α-Al2O3纳米粉Al（OH）3干凝胶煅烧过程中的物相变化顺序为Al（OH）3→γ-AlOOH→γ-Al2O3→δ-Al2O3→θ-Al2O3→α-Al2O3.Al（OH）3凝胶中的NH4NO3显著降低γ、δ、θ及α-Al2O3的形成温度，其中α-Al2O3的形成温度降低50～100℃．2％α-Al2O3籽晶可使θ→α相变温度降低200℃．NH4NO3和籽晶共同作用可使θ→α相变在900℃完成，相变温度约降低300℃．获得的α-Al2O3，无明显团聚，粒度分布均匀，近似球形，平均粒径约为10nm．
Al (OH) 3 xerogel was prepared from Al (OH 3) xerogel and Al (OH 3) xerogel by calcination. The phase sequence of Al (OH) ) 3 → γ-AlOOH → γ-Al2O3 → δ-Al2O3 → θ-Al2O3 → α-Al2O3.Al (OH) 3 gel significantly reduces the formation temperatures of γ, δ, -Al2O3 formation temperature is reduced by 50 ~ 100 ℃. The 2% α-Al2O3 seed crystal can reduce the θ → α phase transformation temperature by 200 ℃. The combined effect of NH4NO3 and seed can make the phase transformation of θ → α at 900 ℃, and the phase transition temperature is reduced by about 300 ℃. Obtained α-Al2O3, no significant agglomeration, uniform particle size distribution, approximately spherical, the average particle size of about 10nm.