Variation of the Vibration Profile of Piezoelectric Resonant Sensors with Different Electrode Conductivity at High Temperatures

摘要

Langasite based piezoelectric resonators coated with metal oxide films are used as gas sensors for high-temperature applications. The influence of changes in electrical and mechanical properties of those films on the vibration behavior of the resonator is investigated with a laser Doppler interferometer. For this purpose, two different electrode geometries are used, leading to a microbalance mode and a conductivity mode. Thereby, the shift of the resonance frequency caused by a change of the film mass as well as the modification of the vibration profile can be distinguished. Resonators used in the conductivity mode provide information about the oxygen partial pressure. By using both effects simultaneously, a higher gas selectivity of those sensors is achieved.