Effect of piezoelectric vibration on electrical properties of YSZ film prepared by MOCVD

To improve electric properties of ion-conductors at low temperatures, ion-conducting/piezoelectric multifunctional film was prepared. Yttria-stabilized zirconia (YSZ) film as an ion-conducting film was deposited on a MgO substrate by metal-organic chemical vapor deposition (MOCVD). The significant [100] preferred orientation of cubic-YSZ single-phase film c ontaining 8 mol%Y₂O₃ was obtained at a deposition temperature of 973 K. The film consisted of fine grains of about 400 nm in diameter and had a columnar structure. It was capable of ionic conduction, as shown by the fact that a semicircle and a spike appeared at high and low frequencies, respectively, in the complex impedance measurement. The obtained YSZ thin film was placed on a multilayer piezoelectric actuator composed of seven sheets of a PZT (lead zirconate titanate) system. The effect of piezoelectric vibration on the electric properties of the ion-conducting film was investigated. The impedance value of the YSZ thin film decreased with increasing amplitude of piezoelectric vibration. The electrical conductivity of the YSZ thin film at 353 K, with an applied vibration frequency of 115 kHz and a voltage of 40 V, was about 2×10^-4Sm^-1. The value of this conductivity was 10³ times greater than that without vibration. Vibration by the actuator was thus suggested to improve the ionic conduction of the YSZ thin film.