Determination of oxygen content in perovskite-type cathode coatings

La_0.75Sr_0.25MnO_3-δ (LSM) and La _0.6Sr_0.4CoO_3-δ (LSCO) coatings were prepared by the atmospheric plasma spraying method and flame spraying method. Both coatings were annealed at 800°, 900°, 1000°C for 5, 10, 15 and 20h. Oxygen content of LSM and LSCO coatings were determined by redox titration. It is interesting to note that, oxygen content of LSM and LSCO coatings strongly varied with the annealing temperature and annealing time. The experimental results show that, at same annealing temperature, oxygen vacancy decreases with the increase of annealing time. For LSM coatings, at 800°C, the oxygen vacancy, δ, were decreased from 0.419 to 0.258 with the annealing time increased from 5h to 20h. Under the same annealing time, oxygen vacancy decreased with increase of annealing temperature. For LSCO coatings, the oxygen vacancies, δ, were decreased from 0.698 to 0.573 and to 0.535 after annealed at 800°C, 900°C and 1000°C for 5 h.