Interface energies of(100)YSZand(111)YSZepitaxial islands on(0001)α-Al2O3substrates from first principles

Abstract

We present an ab initio study of the interface energies of cubic yttria-stabilized zirconia (YSZ) epitaxial layers on a ${(0001)}_{\ensuremath{\alpha}{\text{-Al}}_{2}{\text{O}}_{3}}$ substrate. The interfaces are modeled using a supercell geometry and the calculations are carried out in the framework of density-functional theory (DFT) and the local-density approximation (LDA) using the projector augmented wave (PAW) pseudopotential approach. Our calculations clearly establish the existence of competing growth mechanisms between ${(111)}_{\text{YSZ}}\ensuremath{\parallel}{(0001)}_{\ensuremath{\alpha}{\text{-Al}}_{2}{\text{O}}_{3}}$ and ${(100)}_{\text{YSZ}}\ensuremath{\parallel}{(0001)}_{\ensuremath{\alpha}{\text{-Al}}_{2}{\text{O}}_{3}}$ interfaces. This result is central to understanding the behavior of YSZ thin solid film islanding on ${(0001)}_{\ensuremath{\alpha}{\text{-Al}}_{2}{\text{O}}_{3}}$ substrates, either flat or in presence of defects.