The electrical conductivity of highly textured yttria-stabilized zirconia thin films, deposited onto a MgO substrate, could be enhanced significantly at thicknesses below 60nm. The structure of the films was characterized by a negligible dislocation network, coupled with only one film/substrate interface. This resulted in the absence of blocking effects. The in-plane conductivity, as a function of temperature and film thickness, exhibited a nanoscale effect; with exceptionally high ionic conductivity for film thicknesses below 60nm. This behavior was attributed to a significant contribution arising from interface conductivity, with decreasing film thickness. Analysis of the results was performed by using a rule-of-mixtures model, and the grain- and interface-related conductivities were separated. It was estimated that the thickness of the interface layer was about 1.6nm, and the interfacial conductivity was over 3 orders of magnitude higher than the lattice-related conductivity.

Nanoscale Effects on the Ionic Conductivity in Highly Textured YSZ Thin Films. I.Kosacki, C.M.Rouleau, P.F.Becher, J.Bentley, D.H.Lowndes: Solid State Ionics, 2005, 176[13-14], 1319-26