Evaluation of isotope diffusion coefficient and surface exchange coefficient of ScSZ series oxide by oxygen isotope exchange method

In this work, the Isotope diffusion coefficient (D*) and surface exchange coefficient (k*) of Sc2O3 stabilized ZrO2 (ScSZ) series oxide, 6 mol% Sc2O3-ZrO2 (6ScSZ), 10 mol% Sc2O3-ZrO2 (10ScSZ) and 10 mol% Sc2O3- 1 mol% CeO2-ZrO2 (10Sc1CeSZ) were evaluated by using oxygen isotope exchange method. It was found that these ScSZ oxides showed a relatively higher D* value; 10Sc1CeSZ showed 1.1 × 10− 7 cm2 s− 1, 10ScSZ showed 9.3 × 10− 8 cm2 s− 1 and 6ScSZ showed 6.1 × 10− 8 cm2 s− 1 at 711 °C, respectively. In addition, its activation energy was 1.0 eV for 10Sc1CeSZ, 1.1 eV for 10ScSZ and 1.0 eV for 6ScSZ, respectively. The rapid change of D* due to the phase transition was also confirmed at around 600 °C in the case of 10ScSZ. The surface exchange coefficient (k*) of these ScSZ oxides showed a relatively high value at lower temperature. 10Sc1CeSZ showed 1.3 × 10− 8 cm s− 1 at 498 °C under lower vapor pressure of less than 20 Pa.