Strain Tuning and Strong Enhancement of Ionic Conductivity in SrZrO₃-RE₂O₃ (RE = Sm, Eu, Gd, Dy, and Er) Nanocomposite Films

Fast ion transport channels at interfaces in thin films have attracted great attention due to a range of potential applications for energy materials and devices, for, solid oxide fuel cells, sensors, and memories. Here, it is shown that in vertical nanocomposite heteroepitaxial films of SrZrO₃-RE₂O₃ (RE = Sm, Eu, Gd, Dy, and Er) the ionic conductivity of the composite can be tuned and strongly enhanced using embedded, stiff, and vertical nanopillars of RE₂O₃. With increasing lattice constant of RE₂O₃ from Er₂O₃ to Sm₂O₃, it is found that the tensile strain in the SrZrO₃ increases proportionately, and the ionic conductivity of the composite increases accordingly, by an order of magnitude. The results here conclusively show, for the first time, that strain in films can be effectively used to tune the ionic conductivity of the materials.