First-principles characterization of a heteroceramic interface:ZrO2(001)deposited on anα−Al2O3(11¯02)substrate

Abstract

We have studied an alumina/zirconia interface using the all-electron projector augmented wave formalism within density functional theory. We present the electronic, structural, and energetic properties of the ${\mathrm{ZrO}}_{2}(001)/\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\ifmmode\bar\else\textasciimacron\fi{}02)$ interface as well as of the free $\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\ifmmode\bar\else\textasciimacron\fi{}02)$ and ${\mathrm{ZrO}}_{2}(001)$ surfaces. We find that the generalized gradient correction significantly lowers the oxide surface energies, compared to values obtained by the local density approximation. The monoclinic-tetragonal transition in ${\mathrm{ZrO}}_{2}(001)$ thin films is discussed as well as strain effects involved in the interface formation. The stoichiometric alumina/zirconia interface is found to be weakly bonded, regardless of the film thickness, and the ${\mathrm{ZrO}}_{2}(001)/\ensuremath{\alpha}\ensuremath{-}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(11\ifmmode\bar\else\textasciimacron\fi{}02)$ interface has a rather epitaxial character, due to a low lattice mismatch of $\ensuremath{\sim}4%.$ The impact of such weak interactions on ceramic coating stability is discussed.