Improved ionic conductivity in strained yttria-stabilized zirconia thin films

Abstract

Yttria-stabilized zirconia (YSZ) thin films with thickness ranging from 6 nm to 100 nm were prepared by RF sputtering on (0001) Al2O3 substrates and exhibited epitaxial growth along (111)[110] YSZ//(0001)[101¯0] Al2O3. While the thicker films exhibited oxygen ion conductivities similar to bulk samples, the thinnest films exhibited increased ionic conductivity and a reduced activation energy of 0.79 eV between 300 °C–650 °C. Concomitant with the improved conductivity of the thinner films is an increase in the out-of-plane lattice parameter, matching theoretical expectations regarding tensile strain, and the introduction of edge dislocations, which may additionally assist in-plane ionic conduction.