PZT/ZnO actuator responding to reducing gases

Abstract

The bending behaviour of a piezoelectric actuator consisting of a dense PZT (Pb 0.995Nb 0.01(Zr 0.53Ti 0.47) 0.99O 3) plate and a porous ZnO (ZnO + 10 mol% NiO + 0.2 mol% Li 2O) plate in response to reducing-gas (CO, H 2) atmospheres has been investigated. The actuator is prepared by bonding the dense PZT and press-formed ZnO disks using a hot-press technique with glass frits at the interface. The PZT and ZnO plates, cut off from the hot-pressed body, have high resistivities of the same level in air but only the ZnO showed a decrease in resistivity on introduction of reducing gas at 250 °C. An applied d.c. electric field is confirmed to concentrate on the PZT part of the PZT/ZnO actuator on introduction of reducing gases. The shrinkage caused by a d.c. bias at the PZT side of the actuator increases due to the concentration of electric field, and then the actuator shows a change of bending displacement from 3 μm in air to 7 μm in 0.40 vol.% air-balanced CO gas under 250 kV m −1. It is found that the applied voltage is distributed to both plates in air, but concentrates in the PZT part in reducing-gas atmosphere due to a decrease in resistance of the ZnO part.