Abstract
The changes caused by heat treatment of gibbsite powder at 300-1473 K were studied using the X-ray diffraction (XRD), X-ray photoemission (XPS) spectra and 27Al magic angle spinning nuclear magnetic resonance spectroscopy (27Al MAS NMR). XRD analysis indicates that the transformation sequence involves the formation of κ-Al2O3 as an intermediate phase between χ- and α-Al2O3. The crystallite size of χ-Al2O3 is as small as 10 nm. XPS analysis indicates that the ratio of aluminium atoms to oxygen atoms in χ-Al2O3 and κ-Al2O3 increases, whereas the expected ratio is observed in α-Al 2O3. The percentage of AlO4 units in the transition aluminas follows the same behaviour as the ratio of Al/O.
Original language | English |
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Pages (from-to) | 8-15 |
Number of pages | 8 |
Journal | Journal of Solid State Chemistry |
Volume | 215 |
DOIs | |
Publication status | Published - 1 Jan 2014 |
Keywords
- Gibbsite
- Transition alumina
- X-ray diffraction
- X-ray photoelectron microscopy