The impact of YSZ surface steps on structure and morphology of La2Zr2O7 islands growing on YSZ(1 0 0) surfaces by vapour–solid reaction

La2Zr2O7 (LZO) islands of well-defined crystallographic orientation are growing on YSZ(1 0 0) single crystal surfaces, when the latter are exposed to La2O3 vapours at elevated temperature. The initial stage of this topotaxial vapour–solid reaction is investigated by HRTEM, AFM, and XRD, specifically considering the influence of steps on the YSZ(1 0 0) surface onto the LZO nucleation process. It is shown how this influence results in a particular structure and morphology of the LZO islands. Compared with the previously studied cases of LZO island formation on flat surface regions and at the rims of surface pits, new features are observed. These are discussed in terms of the preferred nucleation of the islands at step kinks, their specific growth kinetics under the influence of the step edges, and the partial relaxation of stresses arising in the growing islands by the deformation of the step edges.