ELECTRONIC CONDUCTIVITY OF ZrO_2-CeO_2-ScO_(1.5) SOLID SOLUTIONS

摘要

The electronic conductivity of [(ZrO_2)_(1-x)(CeO_2)_x]_(0.8)(ScO_(1.5))_(0.2) (ZCS20, x = 0, 0.1, 0.2) solid solutions was measured by a DC polarization method with a modified Hebb-Wagner's type ion blocking cell. The measured conductivity of ZCS20(x = 0), which can be described as 11 mol% Sc_2O_3 - 89 mol% ZrO_2 (11ScSZ), showed a typical linear dependence on p(O_2)~(1/4) in the higher p(O_2) region and on p(O_2)~(-1/4) in the lower p(O_2) region, which can be attributed to the hole and electron conductivity, respectively. The electronic conductivity of 11ScSZ was slightly higher than that of 11 mol% Y_2O_3 - 89 mol% ZrO_2 (11YSZ). The absolute values of the electronic conductivity were extremely lower than the oxide ion conductivity in a wide p(O_2) range, which indicates that 11ScSZ has a high transference number of oxide ion. The electron conductivity increased with the amount of CeO_2 concentration from x = 0.1 to 0.2, and the p(O_2) range where the electron conductivity appears became wider. These features were similar to those observed for [(ZrO_2)_(1-x)(CeO_2)_x]_(0.8)(YO_(1.5))_(0.2) (ZCY20) solid solutions, however the electron conductivity of ZCS20s was about three times larger than that of ZCY20s. The total electrical conductivity of ZCS20s was also larger than that of ZCY20s, and the total electric conductivity of ZCS20(x = 0.1) was larger than that of 8 mol% Y_2O_3 - 89 mol% ZrO_2 (8YSZ) above T= 823 K.