Oxide ion and proton conduction controlled in nano-grained yttria stabilized ZrO2 thin films prepared by pulse laser deposition

Abstract

Nano-grained yttria stabilized ZrO2 (YSZ) thin films were prepared by pulse laser deposition using a high energy ArF excimer laser in order to attain high-quality solid electrolyte thin films. The YSZ thin films exhibited smooth surfaces, which had not been previously achieved due to serious droplet generation. While the ionic conductivities of the two films prepared at different oxygen pressures are similar in the high temperature region, they differ significantly, over five orders of magnitude, at temperatures below 100 °C. The dense YSZ films had extremely low ion conductivity (∼10−11 S cm−1) at room temperature due to slow oxide ion transport in the YSZ inner-grains, while the porous YSZ films had excellent ionic conductivity (∼10−6 S cm−1) due to fast proton transport via the YSZ grains surface. Variation in the porosity of the films, controlled by oxygen pressure, was attributed to the origin of the transition from oxide ion to proton conduction.