ELECTRICAL-PROPERTIES OF TRANSITION-METAL-DOPED YSZ

The electrical properties of Mn-doped YSZ (yttria stabilized zirconia) were investigated. The polarization cell was employed to determine the electronic conductivity of Mn 4 mol% doped YSZ (8 mol% Y2O3). The observed conductivities were 2.6 x 10(-4) S cm-1 in air (p-tye) and 1 x 10(-4) S cm-1 at the oxygen pressuer of 10(-14) Pa (n-type). The hole conductivity was higher than that of Mn-free YSZ by about one order of magnitude. The transference number of oxide ion was higher than 0.99 in the oxygen potential range from 10(-15) to 10(5) Pa. The ionic conductivity showed oxygen-pressure dependence, which was explained by oxygen-vacancy formation due to the valence change of Mn ion in the YSZ lattice. The electrochemical impedance was studied with Pt electrode on Mn-doped surface of YSZ. It was suggested that the mixed valence state of the Mn ion affected the response of the electrode.