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MM: Fachverband Metall- und Materialphysik

MM 26: Poster Session

MM 26.18: Poster

Dienstag, 23. März 2010, 14:45–16:30, Poster C

Ab-initio investigation of the interface structure of TiO₂ grown on Al₂O₃ — •Maxim Popov^1,2, Jürgen Spitaler^1,2, Claudia Walter², and Claudia Ambrosch-Draxl² — ¹Materials Center Leoben Forschung G.m.b.H, Rosegger-str. 12, 8700 Leoben, Austria — ²Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben, Austria

Oxide based layered structures are increasingly exploited for hard coatings. As a model system we study the interface between a TiO₂ thin film grown on an Al₂O₃ (0 0 0 1) substrate by sputter deposition. X-ray diffraction analysis of the sample reveals that TiO₂ grows in the rutile structure with the (1 0 0) plane parallel to the substrate. We use ab-initio calculations based on density-functional theory (DFT) combined with elasticity considerations to determine the local atomic arrangement at the interface region. Since the two materials forming the interface exhibit a rather large lattice mismatch, we first calculate the full elastic constant tensors for bulk Al₂O₃ and TiO₂. Then the interface between Al₂O₃ and TiO₂ is constructed by connecting the two surfaces in such a way that the stresses on both sides are balanced. In a next step the geometry of the complete interface is further relaxed within DFT. We present the optimized interface structure for three interfaces differing in the termination of the substrate or overlayer,respectively.