Low-Frequency Vibrations of Aluminas

Abstract

The γ-, δ-, λ-, κ-, η-, θ- and α-aluminas were prepared by heating the crystalline aluminium hydroxides at selected temperatures. The vibrational spectra of those aluminas were determined in the far-infrared (FIR) region. In order to assign the low-frequency vibrations of aluminas, the characteristic frequencies of octahedral AlO6 and tetrahedral AlO4 groups were determined by using both the crystal structures of θ- and α- aluminas.