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Thermal-induced phase transitions in self-assembled mesostructured films studied by small-angle X-ray scattering

Innocenzi, Plinio and Malfatti, Luca and Kidchob, Tongjit and Falcaro, Paolo and Costacurta, Stefano and Guglielmi, Massimo and Mattei, Giovanni and Bello, Valentina and Amenitsch, Heinz (2005) Thermal-induced phase transitions in self-assembled mesostructured films studied by small-angle X-ray scattering. Journal of Synchrotron Radiation, Vol. 12 , p. 734-738. ISSN 0909-0495. Article.

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DOI: 10.1107/S0909049505014585

Abstract

Two examples of phase transition in self-assembled mesostructured hybrid thin films are reported. The materials have been synthesized using tetraethoxysilane as the silica source hydrolyzed with or without the addition of methyltriethoxysilane. The combined use of transmission electron microscopy, small-angle X-ray scattering and computer simulation has been introduced to achieve a clear identification of the organized phases. A structural study of the self-assembled mesophases as a function of thermal treatment has allowed the overall phase transition to be followed. The initial symmetries of mesophases in as-deposited films have been linked to those observed in samples after thermal treatment. The monodimensional shrinkage of silica films during calcination has induced a phase transition from face-centered orthorhombic to body-centered cubic. In hybrid films, instead, the phase transition has not involved a change in the unit cell but a contraction of the cell parameter normal to the substrate.

Item Type:Article
ID Code:967
Status:Published
Refereed:Yes
Uncontrolled Keywords:SAXS, self-assembly, mesoporous films, phase transition
Subjects:Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 Scienza e tecnologia dei materiali
Divisions:001 Università di Sassari > 01 Dipartimenti > Architettura e pianificazione
Publisher:International Union of Crystallography
ISSN:0909-0495
Copyright Holders:© 2005 International Union of Crystallography
Publisher Policy:Depositato in conformità con la politica di copyright dell'International Union of Crystallography
Deposited On:18 Aug 2009 10:03

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