Innocenzi Plinio, Malfatti Luca, Kidchob Tongjit, Falcaro Paolo, Costacurta Stefano, Guglielmi Massimo, Mattei Giovanni, Bello Valentina, Amenitsch Heinz
Laboratorio di Scienza dei Materiali e Nanotecnologie, Nanoworld Institute, Dipartimento di Architettura e Pianificazione, Università di Sassari, Palazzo Pou Salid, 07041 Alghero (Sassari), Italy.
J Synchrotron Radiat. 2005 Nov;12(Pt 6):734-8. doi: 10.1107/S0909049505014585. Epub 2005 Oct 18.
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.
报道了自组装介观结构混合薄膜中相变的两个例子。这些材料是使用四乙氧基硅烷作为硅源合成的，在有或没有添加甲基三乙氧基硅烷的情况下进行水解。引入了透射电子显微镜、小角X射线散射和计算机模拟的联合使用，以实现对有序相的清晰识别。对自组装中间相作为热处理函数的结构研究使得能够跟踪整体相变。沉积态薄膜中中间相的初始对称性与热处理后样品中观察到的对称性相关联。煅烧过程中二氧化硅薄膜的一维收缩导致了从面心正交相到体心立方相的相变。相反，在混合薄膜中，相变并未涉及晶胞的变化，而是垂直于基底的晶胞参数的收缩。
