Structural study for intermediate-phases of alumina observed through dehydration process of aluminum hydroxide

摘要

Intermediate phases in a dehydration process from gibbsite (Al(OH)_3) to corundum (alpha-Al_2O_3) were investigated by TG/DTA, and XRD using synchrotron radiation and a heat stage. TG/DTA analysis indicated distinct dehydration region from 265 to 320 deg C with large weight loss, a small endothermic peak at 250 deg C and a large peak at 320 deg C. Variation of intermediate phase in the dehydration process and their abundance were elucidated with in-situ XRD measurement for gibbsite single crystal using monochromatic SR. From these results, we have found a new phase appearing from 200 to 280 deg C with low crystallinity.