First-principles characterization of a heteroceramic interface:ZrO2(001)deposited on anα−

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 ZrO2(001)/a-Al2O3(11̄02) interface as well as of the free a-Al2O3(11̄02) and ZrO2(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 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 ZrO 2(001)/a-Al2O3(11̄02) interface has a rather epitaxial character, due to a low lattice mismatch of ;4%. The impact of such weak interactions on ceramic coating stability is discussed.