Amperometric oxygen sensors based on dense Tb–Y–Zr–O electrodes

Abstract

The fabrication and operation of a new type of amperometric linear response oxygen sensor is demonstrated that utilizes a 16 μm thick, dense Tb–YSZ film of composition Y 0.2Tb 0.24Zr 0.56O 2− y as a solid state chemical oxygen diffusion barrier. The device exhibits a near linear response between 750 and 850°C between 0.2 and 4.5% O 2 in nitrogen. The effective linear range of operation at 800°C is extended to above 8.0% O 2 with the application of albite (Na–Al–Si–O) glass to limit leakage at the edges (gas–substrate-diffusion barrier interface) of the device. Thin film high temperature cyclic voltammetry performed on Tb–YSZ films of similar stoichiometry indicate thermodynamic stability to below 10 −30 atm pO 2 at 750°C. The initial performance of this device taken together with the inherent chemical stability of the diffusion barrier suggests that devices of this type may be suitable for use as control sensors for lean-burn internal combustion engines.