Thin Film Praseodymium-Cerium Oxide Langasite-Based Microbalance Gas Sensor

Langasite (La3Ga5SiO14) has proven to be a viable piezoelectric material for use in high temperature bulk acoustic wave gas sensors. To detect changes in pO2 under oxidizing conditions, we utilized a PLD deposited Pr0.15Ce0.85O2 − δ film as the gas sensitive layer given its ready reduction under these conditions. The sensor was operated at 600∘C and showed strong sensitivity to changes in oxygen partial pressure, saturating at a frequency shift of −360 Hz below 1%O2/Ar (pO2 = 103 Pa). The frequency shift was calculated to be too large to be solely accounted for by the corresponding change of mass in the PCO film. Stress induced by dilation of the PCO lattice upon reduction is viewed as being a likely source of sensor sensitivity.