| Sumario: | The effects of small additions of transition metal dopants (Fe,Mn and Cr) on the structure and conductivity of yttria stabilized zirconia (YSZ) have been investigated by XRD, SEM and electrical measurements. YSZ was doped with 1,3, and 5 % of dopant cations using a mixed oxide technique. Impedance spectroscopy techniques illustrate that Mn doped compositions showed the most dramatic changes, and Cr doped compositions most closely approximated pure YSZ. Constant frequency (10 kHz) conductivity measurements were performed as a function of oxygen partial pressure in the range 800-1100 °C. At high temperature, for zirconia based systems, the cell impedance at this frequency is usually representative of the bulk material behavior. However, the presence of the transition metal dopants resulted in a shift of this frequency response, inducing errors when calculating the conductivity from these constant frequency measurements. In fact, the ac conductivity was found constant for oxygen partial pressures from 10"^^-10^ Pa, as confirmed by impedance spectroscopy measurements taken during the oxidation-reduction cycle. This suggests that these small dopant concentrations do not significantly influence the electronic conductivity of YSZ.
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