Yttria-stabilized Zirconia - Effect of Stabilization of Ionic Conductivity

Effect of Stabilization of Ionic Conductivity

The addition of yttria to pure zirconia replaces some of the Zr4+ ions in the zirconia lattice with Y3+ ions. This produces oxygen vacancies, as three O2- ions replace four O2- ions. It also permits yttrium stabilized zirconia to conduct O2- ions (and thus conduct an electrical current), provided there is sufficient vacancy site mobility, a property that increases with temperature. This ability to conduct O2- ions makes yttria-stabilized zirconia well suited to use in solid oxide fuel cells, although it requires that they operate at high enough temperatures.

The ionic conductivity of the stabilized zirconias increases with increasing dopant concentration (linearly for low dopant concentrations), then saturates, and then starts to decrease. The maximum ionic conductivity is obtained at Y₂O₃ concentration of about 8% (1000 °C).