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O: Fachverband Oberflächenphysik

O 31: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth I

O 31.9: Vortrag

Dienstag, 21. März 2017, 12:30–12:45, WIL C107

DFT study of the stability of thin zirconia films and meta-stable bulk phases — •Jakub Planer, Wernfried Mayr-Schmölzer, Florian Mittendorfer, and Josef Redinger — Institute of Applied Physics and Center for Computational Materials Science, TU Vienna, Wiedner Hauptstrasse 8-10/134, 1040 Vienna, Austria

Zirconium dioxide (ZrO₂) has been intensively studied due to its huge potential in various applications. Bulk ZrO₂ and thin films can be used as an electrolyte in solid-oxide fuel cells, an oxygen gas sensor or as a catalyst for methanol synthesis. We used the Vienna Ab-Initio Simulation Package (VASP) to perform DFT calculations comparing the performance of GGA, vdW-DF, hybrid and RPA approaches to investigate the structural stability of the cubic, tetragonal and monoclinic zirconia bulk phases and derived slab configurations. All functionals reproduce the experimentally found order of stability (monoclinic, tetragonal, cubic) and we present two new meta-stable phases. The first one, called meta-monoclinic, is depending on the functional 10-60 meV/f.u. ZrO₂ more stable than the tetragonal phase, but still 50-70 meV less stable than the monoclinic ground state. The second one is structurally similar to anatase titania and is calculated to be 20 meV/f.u. above the monoclinic ground state for GGA and 200 meV/f.u. for vdW-DF functionals. We also present GGA calculations of the stability of thin zirconia films derived from the different bulk phases. We will discuss the dependence of the surface energy and the film stability upon layer thickness.