Study on the oxygen exchange capacities of Ce2Sn2O7 pyrochlore

Ce₂Sn₂O₇ pyrochlore was synthesized by a hydrothermal method. X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the composition and valence state of the sample. The oxygen exchange property of the Ce₂Sn₂O₇ phase was measured by an oxidation reaction in sealed air atmosphere and a followed reduction reaction in 5% H₂-95% N₂ atmosphere. Gas chromatography (GC) was used to analyze the oxygen change in the reaction. The results show that Ce₂Sn₂O₇ sample has excellent oxygen absorption capacity at 250°C as Ce³⁺ ions are oxidized to Ce⁴⁺ ions. The oxidized sample can be reduced by 5% H₂-95% N₂. The refreshed sample remains the capacity of oxygen absorption, while the oxygen exchange capacity degrades with the reduction times.