Strain Effects on Oxygen Ionic Conductivity of Yttria-Stabilized Zirconia Thin Films Subjected to Elastic Waves

The effects of dynamic strain on the electrical conductivity of yttria-stabilized zirconia (YSZ) thin films were studied. In particular, the influence of the time-varying density fluctuations produced by elastic waves was examined. YSZ thin films deposited on SiO2 bar-type waveguides were heated in a furnace, and a piezoactuator placed outside the furnace was used to generate the elastic waves incident on the films. The effects of the elastic waves on the current intensity in the films were observed for a constant voltage. The current intensity exhibited a distinct increase with the application of the elastic waves, which produced a dynamic strain of up to 100 × 10−6 in the films. Further, the current increment ratio increased with the dynamic strain. In a low-oriented YSZ film, the increment ratio showed a clear linear dependence on the dynamic strain, with the rate of change being 0.68% MPa−1. This is close to the value calculated based on a mathematical model for standing waves and the effects of the static strain induced during mechanical testing. The results confirmed that the strain effects were caused by the dynamic strain resulting from the waves and that their origin is the same as that for static strain.