摘要：以实验方法证明奈米级微粒氧化铝粉末在θ→α相变过程中存在临界晶径dc 及基础晶径dp。实验对两种不同晶径之θ -Al₂O₃ 粉末于设定温度热处理条件下制得观察样品 ,再藉热差分析 (DTA)、X -光绕射、及穿透式电子显微技术 ,获得有关数据加以证实

Abstract ：The existence of the critical and primary crystallite size phenomena for θ－to α－phase transformation of the nano－sized boehmite－derived Al₂O₃ powder was confirmed．Experiments were conducted based on the conclusions drown by previ ous studies by which a series of thermal treated samples from θ powders of two different sizes were prepared．Crystallite size phenomena then examined using DTA，XRD，and T EM techniques through these samples． 

Key words：alumina；critical size；primary size