AVS 51st International Symposium
    Advanced Surface Engineering Monday Sessions
       Session SE-MoM

Paper SE-MoM3
Structure and Optical Behavior of As-Grown and Annealed Titania/Alumina Nanolaminate Films

Monday, November 15, 2004, 9:00 am, Room 303D

Session: Nanolayered and Gradient Coatings for Surface Engineering
Presenter: M.A. Omari, University of Wisconsin-Milwaukee
Authors: M.A. Omari, University of Wisconsin-Milwaukee
R.S. Sorbello, University of Wisconsin-Milwaukee
C.R. Aita, University of Wisconsin-Milwaukee
Correspondent: Click to Email
Titania-alumina nanocomposites are of current interest for optical, catalytic, and sensor applications. A wide range of desirable properties can be obtained by varying the amount of each constituent. A convenient way of incorporating tailored nanocomposites in thin film structures is by using a nanolaminate structure. We report here the fabrication, structure, and optical behavior of titania-alumina nanolaminates. 150 nm-thick multilayer films were grown at room temperature on silica substrates by sequential reactive sputtering of metal targets in argon/20% oxygen rf discharges. The nominal titania layer thickness was varied from 1.25 to 45 nm, and the alumina layer thickness was kept constant at 5 nm. X-ray diffraction and spectrophotometry were used for film analysis. The films were cyclically annealed at 700 and 1000 deg. C from 15 min to 10 h. Alumina was amorphous in as-grown and annealed films. Titania in as-grown films consisted of rutile nanocrystals embedded in an amorphous matrix. No anatase was present, nor was anatase formed by annealing. High temperature annealing produced a series of crystalline (Ti,Al)-oxide interface phases. Optical band gap and refractive index measurements indicate that significant interfacial mixing occurred in as-grown films, as well.