Enhanced structural and phase stability of titania inverse opals

The applications and processing of nanostructured materials at high temperatures require stability of their morphology. However, in such environments (>1000. °C), these structures are prone to significant undesired microstructural changes that result in a loss of functional properties. The thermal stability of titania inverse opal films, prepared from self-assembled templates of monodisperse polystyrene spheres by infiltration utilizing atomic layer deposition and subsequent calcination, was assessed. Resistance to grain growth and a shift in the anatase-to-rutile transformation to higher temperatures was observed, with dramatic stability under vacuum. Vacuum annealed samples retained the anatase phase and exhibited minimal grain growth even after 3. h at 1300. °C. Photonic properties were retained until the transformation onset. The remarkable resistance was attributed to inhibition of surface diffusion and structure-substrate constraints. In addition to being technologically enabling, the results provide further insight into the titania system and its phase transformation mechanism.

Subjects

Anatase-to-rutile

Inverse opal

Phase transformation

Photonic crystal

Titania

DDC Class

600: Technik

More Funding Information

Financial support from the Ger-man Research Foundation (DFG) via SFB 986 “M3”, projectsC2, C3, C4, and C5.

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Enhanced structural and phase stability of titania inverse opals