Phase Transformation and Infrared Absorption Spectra of Amorphous and Crystalline Nano-Al_2O_3 Powder

Amorphous and crystalline nano-Al_2O_3 powders prepared by directly oxidic method and roomtemperature hydrolytic method , using aluminum amalgam as precursors, were characterized byXRD, TEM and DTA. It was found that the amorphous nano-Al_2O_3 powder only underwentγ→α transformation having no transition phase, and the transformation process of crystallinenano-Al_2O_3 powder is γ→θ→ α and incomplete. The IR measurements were performed and the characteristic IR spectria of amorphous nano-Al_2O_3 nanoγ-Al_2O_3 and nanoθ-Al_2O_3 were obtained.The above results were analyzed and discussed from viewpoints of low-temperature relaxation ofamorphous nano-Al_2O_3 powder and lattice distortion of α-Al_2O_3.