27Al MAS-NMR spectra of alumina aerogels
- 1 September 1993
- journal article
- Published by Springer Nature in Journal of Materials Research
- Vol. 8 (9) , 2109-2111
- https://doi.org/10.1557/jmr.1993.2109
Abstract
The 27Al MAS-NMR spectra of alumina aerogels were determined. The spectra showed different profiles according to the supercritical methods used during drying. The alumina aerogel supercritically dried in a CO2 extractor (80 °C, 15.7 MPa) displayed a pentahedral-coordinated aluminum structure. On the other hand, the alumina aerogel supercritically dried in an autoclave (270 °C, 26.5 MPa) revealed no pentahedral-coordinated aluminum structure. The absence of pentahedral-coordinated aluminum was one factor for the lower temperature of transformation from the γ to the θ phase.Keywords
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