高純度αアルミナ粉の表面水和物相 Surface Hydration States of High Purity α-Al_2O_3 Powders

Surface conditions of three types of commercial high purity alpha alumina powders produced by three different processes, in-situ chemical vapor deposition (A powders), hydrolysis of aluminum alkoxide (B powders), and a pioneer chemical vapor deposition (no longer in the market) (C powder) methods are evaluated by FT-IR (Fourier transform infrared) transmission and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. The spectroscopy results suggest that the surface characteristics of as-received high purity alpha alumina powders are not unique. In some of the B powders with small size, a mixture of aluminum trihydroxides like bands is observed. A specific band at 3472 cm^<-1> observed on the B and C powders does not belong to band spectra of the aluminum hydroxide references. Relating to the predicted band on infrared spectra of hydrated alpha alumina surface obtained from reported molecular dynamics calculation, this band may be associated with hydrogen bonded hydroxyl groups of a fully hydroxylated alpha alumina surface.