SEMINAIRE COMMUN LMGP - 05.10.2022 - PhD student Helle-Mai Piirsoo et Kristel Möls

PhD student Helle-Mai Piirsoo
University of Tartu, Institute of Physics, Laboratory of Thin Film Technology

PhD student Kristel Möls
University of Tartu, Institute of Physics, Laboratory of Thin Film Technology
 

Nanoindentation is used to investigate the mechanical properties of thin films and small surface features. With this method, a small diamond probe is used to generate local elastic and plastic deformation in material, while load-displacement curve is registered. Young’s modulus and hardness of the material can be found. Some nanoindenters including the Hysitron TriboIndenter TI980 (Bruker) enable wear tests and scanning probe microscopy to gain additional information about the mechanical behavior of materials [1]. Possibilities and difficulties of the method are introduced with examples of materials and results. Among the examples (Al₂O₃-Ta₂O₅ double-and triple-layered nanolaminates [1], SnO₂-ZrO₂ double-layers, graphene with Al₂O₃, Al₂O₃ doped ZrO₂ thin films) the titanium oxide (TiO₂) thin films deserve more attention in the second part of the presentation.

The scrutinyite (α-PbO₂) type of titanium dioxide (TiO₂), labeled as “TiO₂-II” belongs to the list of metastable and high pressure phases of titania. TiO₂-II has attracted interest because of its relative stability at room temperature and ambient pressures compared to the other high pressure phases of titania, its higher density compared to rutile and the interesting optical properties that have shown advantages in photocatalytic applications [2]. In this talk an overview of mechanical, optical and structural properties of ALD films on sapphire substrate containing TiO2-II phase will be presented.

References

1. H.-M. Piirsoo, T. Jõgiaas, P. Ritslaid, K. Kukli, A. Tamm, Coatings, 2022, 12, 404
2. K. Möls, L. Aarik, H. Mändar, A. Kasikov, T. Jõgiaas, A. Tarre, J. Aarik, Coatings, 2021, 11, 1280