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Temperature-Dependent 4‑, 5- and 6‑Fold Coordination of Aluminum in MOCVD-Grown Amorphous Alumina Films: A Very High Field 27Al-NMR study

Sarou-Kanian, Vincent and Gleizes, Alain and Florian, Pierre and Samélor, Diane and Massiot, Dominique and Vahlas, Constantin Temperature-Dependent 4‑, 5- and 6‑Fold Coordination of Aluminum in MOCVD-Grown Amorphous Alumina Films: A Very High Field 27Al-NMR study. (2013) Journal of Physical Chemistry C, 117 (42). 21965-21971. ISSN 1932-7447

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Official URL: http://dx.doi.org/10.1021/jp4077504

Abstract

The only easy way to prepare amorphous alumina is via thin film deposition. For this reason, the disorder in amorphous alumina has not yet been fully investigated. We have used very high-field (20 T) solid state 27Al NMR spectroscopy to analyze the structural modifications of amorphous alumina thin films with deposition temperature (Td). The films were deposited by metalorganic chemical vapor deposition in the Td range of 360−720 °C. Depending on Td, film composition is either AlO1+x(OH)1−2x (0 ≤ x ≤ 0.5) or Al2O3. From 27Al 1D magic angle spinning(MAS) and 2D multiple-quantum magic angle spinning (MQMAS) NMR analyses, the films grown between 360 and 600 °C contain between 38 and 43 atom % of 5-fold coordinated aluminum sites ([5]Al). The percentages of [6]Al and [4]Al sites vary spectacularly, reaching their respective minimum (5 atom %) and maximum (54 atom%) around 515 °C. The analysis of a very thin film (85 nm) of Al2O3 reveals the presence of metallic aluminum at the interface with the substrate and suggests that the respective percentages of [n]Al sites slightly differ from those in thicker films. The observed Td dependence of amorphous alumina structure can be correlated with that of film properties previously reported,namely, Young’s modulus, hardness, and corrosion protection.

Item Type:Article
Additional Information:Thanks to the American Chemical Society. The definitive version is available at http://pubs.acs.org The original PDF of the article can be found at Journal of Physical Chemistry C website : http://pubs.acs.org/doi/abs/10.1021/jp4077504
HAL Id:hal-01165521
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université d'Orléans (FRANCE)
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Deposited By: Diane SAMELOR
Deposited On:19 Jun 2015 10:07

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