Characterization and electrochemical properties of chromium-substituted pyrochlore Y₂Ti_2−xCr _xO_7−δ

Abstract: Pyrochlore oxides Y₂Ti_2−xCr_xO_7−δ have been investigated as electrolyte for solid oxide fuel cell. The as-prepared powder was synthesized by sol–gel method and characterized by powder X-ray diffraction, scanning electron microscope/energy-dispersive spectroscopy, inductively coupled plasma atomic emission spectroscopy, temperature-programmed reduction and AC impedance. Y₂Ti_2−xCr_xO_7−δ existed in single phase in a range of 0 < x ≤ 0.8, and the cell parameters decreased as the amount of Cr dopant increased. XPS analyses indicate that the average oxidation state of Crⁿ⁺ ions decreased with the increased Cr content. Measurements of ionic conductivities induced that the optimized performance was observed at x = 0.2 with 0.01 S/cm at 700 °C due to an optimized condition of carrier concentration and carrier mobility. Graphical Abstract: Y₂Ti_2−xCr_xO_7−δ existed in single phase in a range of 0 < x ≤ 0.8 and the optimized performance of ionic conductivity was observed at x = 0.2 with 0.01 S/cm at 700 °C.[Figure not available: see fulltext.]