Nano-ionics: Trivial and non-trivial size effects on ion conduction in solids

The significance of nano-size effects for ion transport in solids is highlighted both experimentally - by presenting various results of recent investigations - and theoretically - by considering expected size effects using a top-down approach. It is helpful to distinguish between trivial size effects (effects that equally occur at single interfaces but are augmented by the high interfacial density) and true size effects (involving local modifications due to the finite boundary conditions). The latter ones essentially include space charge overlap and structural interference leading to two characteristic sizes with respect to defect chemistry. The contribution also briefly touches upon effects of dimensionality and shape as well as of discreteness of carrier distribution.