Impedance spectrum of a single grain boundary in yttrium stabilized zirconia

Impedance measurements are reported for a bicrystal and single crystals of yttrium-stabilized ZrO₂ (YSZ) over the range from 100 to 10⁷ Hz, and for temperatures from 200 to 500°C in air. In addition to the impedances introduced by the conduction process within the grains and by charge transfer process at the electrodes, the grain-boundary introduced an additional impedance which was observed as an additional arc when the impedance was plotted in the complex plane. These data and an examination by both optical and scanning electron microscopy reveal the grain boundary to be a gap between the adjacent crystals, with occasional bridges of YSZ. These results illustrate the potential of impedance spectroscopy for studying intercrystalline interfaces in solid conductors.