Abstract
Total conductivities of yttria stabilized zirconia ceramics in series samples of (YO1.5)0.250-(Zr0.750-xTix)O2 and (YO1.5)0.550-(Zr0.450-xTix)O2 prepared through sol-gel route and transparent zirconia (Zr0.772Y0.134Ti0.094O1.933) have been measured by an ac impedance method as a function of oxygen partial pressure, PO2, between 1073 and 1273K. The total conductivity showed an increase with decreasing the oxygen partial pressure at low PO2 region by the enhanced contribution of the partial electronic conductivity. The partial conductivity of oxide ions, which is independent of PO2, slightly decreased with increasing the TiO2 content both of (YO1.5)0.250-(Zr0.750-xTix)O2 and (YO1.5)0.550-(Zr0.450-xTix)O2. The partial conductivity of electrons, proportional to -1/4 power of PO2, showed a marked increase with increasing TiO2 concentration at the same temperature and PO2 conditions. Substitution of Ti4+ for Zr4+ decreases the formation enthalpy of oxygen vacancy, resulting in an increase of the concentration of electrons.
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