Molecular dynamics simulations of interfaces between NiO and cubic ZrO₂

Abstract

The structures of eight heterophase interfaces between cubic ZrO₂ and NiO simulated by molecular dynamics (MD) are compared with those of the corresponding isolated surfaces to better understand the factors influencing interface formation and coherency in ceramic oxides. The near coincident site lattice (NCSL) theory used to construct initial configurations with small lattice mismatch between low index crystal planes is extended to describe interface planes with rectangular symmetry. Interface energies, works of adhesion, expansion volumes, lattice strains and planar structure factors are reported for several bicrystals. Most interfaces are found to consist of disordered, open structures with correspondingly high energies as a consequence of the strong repulsive forces between like-charged ions brought into close proximity. The exception is the (111) NiO//(100) c-ZrO₂ interface, which exhibits good coherency across the interphase boundary and consists of a shared oxygen plane. The relatively high crystallinity of the interface explains its low energies and small excess volume. The results are discussed in the context of developing a simulation-based method for identifying interface configurations with high lattice coherency and strong cohesiveness for optimizing the properties of composites of technologically important materials.

Acknowledgments

This work was carried out as part of the Nanocoating Technology Project, funded by the New Energy and Industrial Technology Development Organization (NEDO) of Japan.