A limiting current oxygen sensor with La0.8Sr0.2(Ga0.8Mg0.2)1-x Fe x O3-δ dense diffusion barrier

Abstract

La0.8Sr0.2(Ga0.8Mg0.2)1-x Fe x O3-δ (LSGMF, x = 0.2–0.9) was prepared by a solid-state reaction method, and the characterization was investigated. Limiting current oxygen sensors were fabricated with La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) as solid electrolyte and La0.8Sr0.2(Ga0.8Mg0.2)0.1Fe0.9O3-δ (LSGMF9) as dense diffusion barrier. The influences of temperature, oxygen concentration, and the thickness of dense diffusion barrier (L) on sensing properties of oxygen sensors were investigated. The results show that the crystal structure of samples is perovskite. The electrical conductivity increases with increasing x. A transition from semiconductive to pseudometallic behavior which is associated with oxygen losses from the lattice is observed with an increase of temperature for x = 0.3, 0.5, and 0.7. The thermal expansion coefficient (TEC) in the temperature range 300–1000 °C increases to a maximum and then decreases with increasing x. TECs between LSGMF9 and LSGM are close. The limiting current oxygen sensor exhibits an excellent sensing performance, and the limiting current responses depend linearly on the oxygen concentration. As the L value increases, the limiting current decreases. The polarization resistance of the sensor decreases with increasing oxygen concentration.