高純度サブミクロンαアルミナ表面上の4配位アルミニウムイオン

概要

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The surface of six different grades of commercial sub-micron high purity α-Al_2O_3 powders produced by two different processes, in-situ chemical vapor deposition ("A" powders), and hydrolysis of aluminum alkoxide ("B" powders) methods, were evaluated by temperature programmed desorption mass spectrometry (TPDMS) and diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Desorption of CO_2 molecules was detected for all the powders, but the quantity was greater for the "B" powders than the "A" powders. The maximum of the CO_2 desorption peak was in the range of 230-270℃ for all powders. The desorbed CO_2 peak was considered to evolve from adsorbed CO_2 molecules forming hydrogen carbonyl groups through interaction with the Al^<IV>-OH groups on the α-Al_2O_3 surfaces. The DRIFT spectra of the powders heated at 700℃ under vacuum confirmed a larger population of Al^<IV>-OH groups on the surface of the "B" powders. The present study clearly demonstrates the presence and quality of the Al^<IV> on the surface of α-Al_2O_3 powders and the effect of the type of manufacturing process on their proportion.
2006-05-01