Oxygen Surface Exchange of Y[sub 0.2]Ce[sub 0.8]O[sub 2−x] under Reducing Atmosphere

Oxygen surface exchange was measured for Y 0.2 Ce 0.8 O 2 − x (YDC) and Y 0.15 Zr 0.85 O 2 − y (YSZ) over a wide range of oxygen partial pressures ( 7.3 × 10 − 21 to 0.17 bar ) by isotope oxygen exchange ( 18 O / 16 O ) using secondary‐ion mass spectrometry analysis at 973 K . Diffusion depth profiles of 18 O in YDC and YSZ were analyzed by an appropriate fitting equation to calculate diffusion coefficient (D) and surface exchange coefficient ( k ). The diffusion coefficients (D) for YDC and YSZ are consistent with the reference data. The k values for both materials were similar ( about k = 5 − 9 × 10 − 8 cm s − 1 ) at the same temperatures. The k value increases with decreasing oxygen partial pressure for both YDC and YSZ. A relationship between the k value and the concentrations of electron and oxygen vacancy is discussed.