Electrical conductivity in the system ZrO 2–Y 2O 3–Sc 2O 3

Abstract

In order to clarify the reason why the electrical conductivity of zirconia solid solution decreases abruptly, when it was highly doped with aliovalent oxide, the system (Y 1− x Sc x ) 0.3Zr 0.7O 1.85 was studied by means of DC- and AC- conductivity measurements. Y 0.3Zr 0.7O 1.85 ( x=0.0) showed lower conductivity than that of Y 0.2Zr 0.8O 1.90. It was found that the decrease in the electrical conductivity was due to the presence of a grain boundary phase as a `microdomain' by the complex impedance measurements. On the other hand, the substitution of Sc 3+ for Y 3+ increased the electrical conductivity, and at the same time, the grain boundary phase disappeared. This fact suggested that the high level doping induced a second phase at the grain boundary, resulting in the decrease in the electrical conductivity.